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oxford semiconductor ltd. 69 milton park, abingdon, oxon, ox14 4rx, uk tel: +44 (0)1235 824900 fax: +44(0)1235 821141 oxford semiconductor 1999 ox16pci954 data sheet revision 1.3 ? feb. 1999 part no. ox16pci954 - tqc60 - a f eatures four 16c950 high performance uart channels 8/32 - bit pass - through local bus ieee1284 epp parallel port multi - function target pci controller, fully pci 2.2 and pci power management 1.0 compliant uarts fully software compatible with 16c550 - type d evices. baud rates up to 15mbps in asynchronous mode and 60mbps in external 1x clock mode 128 - byte deep fifo per transmitter and receiver flexible clock prescaler from 1 to 31.875 automated in - band flow control using programmable xon/xoff in both direction s automated out - of - band flow control using cts#/rts# and/or dsr#/dtr# arbitrary trigger levels for receiver and transmitter fifo interrupts and automatic in - band and out - of - band flow control infra - red (irda) receiver and transmitter operation 9 - bit data f raming as well as 5,6,7 and 8 12 multi - purpose io pins which can be configured as interrupt input pins can be reconfigured using optional non - volatile configuration memory (eeprom) global interrupt status and readable fifo levels to facilitate implemen tation of efficient device drivers operation via io or memory mapping. detection of bad data in the receiver fifo 5.0v operation 160 tqfp package d escription the ox16pci954 is a single chip solution for pci - based serial and parallel expansion add - in ca rds. it is a dual function pci device, where function 0 offers four ultra - high performance ox16c950 uarts, and function 1 is configurable to offer either an 8 bit local bus or a bi - directional parallel port. serial port cards with up to 8 ports (or with 4 serial ports and a parallel port) can be designed without redefining any device or timing parameters. each channel in the ox16pci954, the fastest available pc - compatible uart, offers data rates up to 15mbps and 128 - deep transmitter and receiver fifos. dee p fifos reduce cpu overhead and allow utilisation of higher data rates. each channel is software compatible with the widely used industry - standard 16c550 devices and compatibles as well as the ox16c95x family of high performance uarts. in addition to incre ased performance and fifo size, the uarts also provide the full set of ox16c95x enhanced features including automated in - band flow control, readable fifo levels etc. the efficient 32 - bit, 33mhz target - only pci interface is compliant with version 2.2 of th e pci bus specification and version 1.0 of pci power management specification. for applications that do not require the internal parallel port or the local bus, card designers can assign a subsystem vendor id and a subsystem id using 32 input pins. if the uarts are not required, the local bus can be extended from 8 - bit operation to a full 32 - bit pass - through interface. for full flexibility, all the default register values can be overwritten using an optional microwire tm serial eeprom. to enhance device dri ver efficiency and reduce interrupt latency, internal uarts have multi - port features such as shadowed fifo fill levels, a global interrupt source register and good - data status, readable in four adjacent dword registers visible to logical functions in io sp ace and memory space. expansion of serial cards beyond four channels is possible using the 8 - bit pass - through local bus function. the addressable space can be increased up to 256 bytes, and divided into four chip - select regions. in 32 - bit mode the bus ca n map up to 16kb of memory address space. this flexible expansion scheme caters for cards with up to 20 serial ports using external 16c950, 16c952, 16c954 or compatible devices, for composite applications such as combined serial and parallel port expansion cards. the ox16pci954 also provides an ieee1284 epp parallel port which fully supports the existing centronics interface. the parallel port can be enabled in place of the local bus. ox16pci954 integrated quad uart and pci interface
data sheet revision 1.3 page 2 ox16pci954 oxford semiconductor ltd. c ontents features ................................ ................................ ................................ ................................ .......................... 1 description ................................ ................................ ................................ ................................ ..................... 1 contents ................................ ................................ ................................ ................................ .......................... 2 1 performance comparis on ................................ ................................ ................................ ............... 5 2 block diagram ................................ ................................ ................................ ................................ ...... 6 3 pin information ................................ ................................ ................................ ................................ ..... 7 4 pin descriptions ................................ ................................ ................................ ................................ ... 8 5 configuration & oper ation ................................ ................................ ................................ .......... 13 6 pci target controlle r ................................ ................................ ................................ ................... 14 6.1 operation ................................ ................................ ................................ ................................ ............................. 14 6.2 configuration spac e ................................ ................................ ................................ ................................ ........ 14 6.2.1 pci configuration sp ace register map ................................ ................................ ................................ ... 15 6.3 accessing logical fu nctions ................................ ................................ ................................ ........................ 16 6.3.1 pci access to intern al uarts ................................ ................................ ................................ ..................... 16 6.3.2 pci access to 8 - bit local bus ................................ ................................ ................................ ...................... 16 6.3.3 pci access to parall el port ................................ ................................ ................................ ...................... 17 6.3.4 pci acces s to 32 - bit local bu s ................................ ................................ ................................ .................... 17 6.4 accessing local conf iguration registers ................................ ................................ .............................. 18 6.4.1 local configuration and control register ?lcc? (offset 0x00) ................................ ..................... 18 6.4.2 multi - purpose i/o co nfiguration register ?mic? (offset 0x04) ................................ ......................... 19 6.4.3 local bus timing par ameter register 1 ?l t1? (offset 0x08): ................................ ............................... 20 6.4.4 local bus timing par ameter register 2 ?l t2? (offset 0x0c): ................................ .............................. 22 6.4.5 uart receiver fifo l evels ?url? (offset 0x10) ................................ ................................ ........................ 23 6.4.6 uart transmitter fif o l evels ?utl? (offset 0x14) ................................ ................................ .................. 23 6.4.7 uart interrupt sourc e register ?uis? (o ffset 0x18) ................................ ................................ ........... 24 6.4.8 global interrupt sta tus and control regi ster ?gis? (offset 0x1c) ................................ ............. 25 6.5 pci interrupts ................................ ................................ ................................ ................................ ..................... 26 6.6 power management ................................ ................................ ................................ ................................ ........... 27 6.6.1 power management of function 0 ................................ ................................ ................................ ............ 27 6.6.2 power management of function 1 ................................ ................................ ................................ ............ 28 7 internal ox16c950 ua rts ................................ ................................ ................................ ................ 29 7.1 operation ? mode sel ection ................................ ................................ ................................ ........................... 29 7.1.1 450 mode ................................ ................................ ................................ ................................ ............................ 29 7.1.2 550 mode ................................ ................................ ................................ ................................ ............................ 29 7.1.3 extended 550 mode ................................ ................................ ................................ ................................ ......... 29 7.1.4 750 mode ................................ ................................ ................................ ................................ ............................ 29 7.1.5 650 mode ................................ ................................ ................................ ................................ ............................ 29 7.1.6 950 mode ................................ ................................ ................................ ................................ ............................ 30 7.2 register description tables ................................ ................................ ................................ ......................... 31 7.3 reset configuration ................................ ................................ ................................ ................................ ........ 34 7.3.1 hardware reset ................................ ................................ ................................ ................................ ............. 34 7.3.2 software reset ................................ ................................ ................................ ................................ .............. 34 7.4 transmitter and rece iver fifos ................................ ................................ ................................ ................... 35 7.4.1 fifo control registe r ?fcr? ................................ ................................ ................................ ........................ 35 7.5 line control & statu s ................................ ................................ ................................ ................................ ...... 36 7.5.1 false start bit dete ction ................................ ................................ ................................ ........................... 36
data sheet revision 1.3 page 3 ox16pci954 oxford semiconductor ltd. 7.5.2 line control registe r ?lcr? ................................ ................................ ................................ ........................ 36 7.5.3 line status register ?lsr? ................................ ................................ ................................ ............................ 37 7.6 interr upts & sleep mode ................................ ................................ ................................ ................................ . 38 7.6.1 interrupt enable reg ister ?ier? ................................ ................................ ................................ ................. 38 7.6.2 interrupt status reg ister ?isr? ................................ ................................ ................................ ................. 39 7.6.3 interrupt descriptio n ................................ ................................ ................................ ................................ .. 39 7.6.4 sleep mode ................................ ................................ ................................ ................................ ....................... 40 7.7 modem interface ................................ ................................ ................................ ................................ ................ 40 7.7.1 modem control regist er ?mcr? ................................ ................................ ................................ .................. 40 7.7.2 modem status registe r ?msr? ................................ ................................ ................................ ..................... 41 7.8 other standard regis ters ................................ ................................ ................................ ............................. 41 7.8.1 divisor latch regist ers ?dll & dlm? ................................ ................................ ................................ .......... 41 7.8.2 scratch pad register ?spr? ................................ ................................ ................................ ......................... 41 7.9 automatic flow contr ol ................................ ................................ ................................ ................................ 42 7.9.1 enhanced features re gister ?efr? ................................ ................................ ................................ ........... 42 7.9.2 special character de tection ................................ ................................ ................................ .................... 43 7.9.3 automatic in - band flow contro l ................................ ................................ ................................ .............. 43 7.9.4 automatic out - of - ban d flow control ................................ ................................ ................................ .... 43 7.10 baud rate generation ................................ ................................ ................................ ................................ ...... 44 7.10.1 general operation ................................ ................................ ................................ ................................ ........ 44 7.10.2 clock prescaler regi ster ?cpr? ................................ ................................ ................................ ................ 44 7.10.3 times clock register ?tcr? ................................ ................................ ................................ .......................... 44 7.10.4 external 1x clock mo de ................................ ................................ ................................ .............................. 46 7.10.5 crystal oscillator c ircuit ................................ ................................ ................................ ........................ 46 7.11 additional features ................................ ................................ ................................ ................................ ......... 46 7.11.1 addition al status register ? asr? ................................ ................................ ................................ ............... 46 7.11.2 fi fo fill levels ?tfl & rfl? ................................ ................................ ................................ ............................. 47 7.11.3 additional control r egister ?acr? ................................ ................................ ................................ ........... 47 7.11.4 transmitter trigger level ?ttl? ................................ ................................ ................................ ................ 48 7.11.5 receiver interrupt. trigger level ?rtl? ................................ ................................ ................................ . 48 7.11.6 flow control levels ?fcl? & ?fch? ................................ ................................ ................................ .............. 48 7.11.7 device identific ation registers ................................ ................................ ................................ ................ 48 7.11.8 clock sel ect register ?cks? ................................ ................................ ................................ ....................... 49 7.11.9 nine - bit mode regist er ?nmr? ................................ ................................ ................................ ....................... 49 7.11.10 modem disable mask ? mdm? ................................ ................................ ................................ ............................ 50 7.11.11 readable fcr ?rfc? ................................ ................................ ................................ ................................ .......... 50 7.11.12 good - data status reg ister ?gds? ................................ ................................ ................................ .............. 50 8 local bus ................................ ................................ ................................ ................................ ............... 51 8.1 overview ................................ ................................ ................................ ................................ ............................... 51 8.2 operation ................................ ................................ ................................ ................................ ............................. 51 8.3 configuration & prog ramming ................................ ................................ ................................ ...................... 52 9 bidirectional parall el port ................................ ................................ ................................ ....... 53 9.1 operation and mode s election ................................ ................................ ................................ ..................... 53 9.1.1 spp mode ................................ ................................ ................................ ................................ ........................... 53 9.1.2 ps2 mode ................................ ................................ ................................ ................................ ............................ 53 9.1.3 epp mode ................................ ................................ ................................ ................................ ........................... 53 9.1.4 ecp mode (not suppor ted) ................................ ................................ ................................ .......................... 53 9.2 parallel port interr upt ................................ ................................ ................................ ................................ 53 9.3 register description ................................ ................................ ................................ ................................ ........ 54 9.3.1 parallel port data r egister ?pdr? ................................ ................................ ................................ ........... 54 9.3.2 device status regist er ?dsr? ................................ ................................ ................................ ...................... 54 9.3.3 device control regis ter ?dcr? ................................ ................................ ................................ ................... 5 5 9.3.4 epp address register ?eppa? ................................ ................................ ................................ ....................... 55 9.3.5 epp data registers ? eppd1 - 4? ................................ ................................ ................................ ....................... 55 9.3.6 extended control reg ister ?ecr? ................................ ................................ ................................ ............. 55
data sheet revision 1.3 page 4 ox16pci954 oxford semiconductor ltd. 10 serial eeprom ................................ ................................ ................................ ................................ .. 56 10.1 specification ................................ ................................ ................................ ................................ ....................... 56 10.2 eep rom data organisatio n ................................ ................................ ................................ ............................. 56 10.2.1 zone0: header ................................ ................................ ................................ ................................ .................. 56 10.2.2 zone1: local configu ration registers ................................ ................................ ................................ ... 57 10.2.3 zone2: identificatio n registers ................................ ................................ ................................ ................ 58 10.2.4 zone3: pci configura tion registers ................................ ................................ ................................ ........ 58 11 operating conditions ................................ ................................ ................................ .................. 59 12 dc electrical charac teristics ................................ ................................ .............................. 59 12.1 non - pci i/o buffers ................................ ................................ ................................ ................................ ............. 59 12.2 pci i/o buffers ................................ ................................ ................................ ................................ ..................... 60 13 ac electrical charac teristics ................................ ................................ .............................. 61 13.1 pci bus ................................ ................................ ................................ ................................ ................................ .... 61 13.2 local bus ................................ ................................ ................................ ................................ .............................. 61 13.3 serial ports ................................ ................................ ................................ ................................ ........................ 62 14 timing waveforms ................................ ................................ ................................ .......................... 63 15 package information ................................ ................................ ................................ ................... 70 16 ordering information ................................ ................................ ................................ ................. 70 notes ................................ ................................ ................................ ................................ ............................... 71 contact details ................................ ................................ ................................ ................................ ......... 72 disclaimer ................................ ................................ ................................ ................................ ..................... 72
data sheet revision 1.3 page 5 ox16pci954 oxford semiconductor ltd. 1 p erformance c omparison feature ox16pci954 16c554 + plx9050 16c654 + plx9050 internal serial channels 4 0 0 integral 1284 epp parallel port yes no no multi - function pci device yes no no support for pci power management yes no no zero wait - state read/write operation yes 1 no no no. of available local bus interrupt pins 12 2 2 dword access to uart interrupt source registers & fifo levels yes no no good - data status yes no no full plug and play with external eeprom yes yes yes subsyste m vendor id & subsystem id with no external eeprom yes no no external 1x baud rate clock yes no no max baud rate in normal mode 15 mbps 115 kbps 1.5 mbps max baud rate in 1x clock mode 60 mbps n/a n/a fifo depth 128 16 64 sleep mode yes no yes auto x on/xoff flow yes no yes auto cts#/rts# flow yes no yes auto dsr#/dtr# flow yes no no no. of rx interrupt thresholds 128 4 4 no. of tx interrupt thresholds 128 1 4 no. of flow control thresholds 128 n/a 4 transmitter empty interrupt yes no no readab le status of flow control yes no no readable fifo levels yes no no clock prescaler options 248 n/a 2 rx/tx disable yes no no software reset yes no no device id yes no no 9 - bit data frames yes no no rs485 buffer enable yes no no infra - red (irda) yes no yes table 1 : ox16pci950 performance compared with plx + generic uart combinations note 1: zero wait - state applies only to internal uarts improvements of the ox16pci954 over discrete solutions: higher degree of integration: ox16pci954 offers four internal 16c950 high - performance uarts and one bi - directional parallel port. improved access timing: access to internal uarts require zero or one pci wait states. a pci read transaction from an internal uart can complete within fi ve pci clock cycles and a write transaction to an internal uart can complete within four pci clock cycles. reduces interrupt latency: ox16pci954 offers shadowed fifo levels and interrupt status registers of internal uarts, and interrupt status of intern al uarts and mio pins to reduce the device driver interrupt latency.
data sheet revision 1.3 page 6 ox16pci954 oxford semiconductor ltd. power management: ox16pci954 complies with pci power management specification 1.0 and pc98/99 power management specifications. both functions offer the extended capabilities for power m anagement. this achieves significant power saving by enabling device drivers to power down the pci function and the channel clock (in power state d3). wake - up is requested via pme# from ri in power - state d3 or any modem line and sin in power - state d2. op tional eeprom: ox16pci954 can be reconfigured from an external eeprom. however, this is not required in many applications as default values are provided for typical applications up to 8 serial ports, and in some cases the subsystem id and subsystem vendor id can be set via input pins. multi - function device: ox16pci954 is a multi - function device to enable users to load individual device drivers for internal serial ports, the internal parallel port and peripheral devices connected to the local bus. quad internal ox16c950 uarts ox16pci954 contains four ultra - high performance uarts, which can increase driver efficiency using features such as 128 - byte deep transmitter & receiver fifos, data rates up to 60mbps, flexible clock options, automatic flow control, programmable interrupt and flow control trigger levels and readable fifo levels. 2 b lock d iagram internal data / control bus function 1 lbd[7:0] lba[7:0] lbcs[3:0] lbwr# lbrd# lbrst function 0 interrupt logic pci interface ad[31:0] c/be[3:0]# frame# devsel# irdy# trdy# stop# clk par serr# perr# idsel rst# inta# intb# pme# fifosel config. interface mode[1:0] xtalo xtali clock & baud rate generator uart_ck_out lbclk ee_do ee_di eeprom interface ee_ck ee_cs quad uarts sout[3:0] sin[3:0] rts[3:0]# dtr[3:0]# cts[3:0]# dsr[3:0]# dcd[3:0]# ri[3:0]# mio pins mio[11:0] parallel port pd[7:0] ack# pe busy slct err# slin# init# afd# stb# local bus figure 1 : ox16pci954 block diagram
data sheet revision 1.3 page 7 ox16pci954 oxford semiconductor ltd. 3 p in i nformation mode ?00?: quad uarts + 8 - bit local bus lba0 lbrst lbrst# mio7 mio6 mio5 mio4 mio3 mio2 mio1 mio0 inta# intb# rst# gnd clk vdd ad20 vdd gnd ad19 ad18 ad31 ad30 ad29 gnd ad28 ad27 ad26 gnd vdd ad25 ad24 c/be3# idsel ad23 gnd ad22 ad21 pme# 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 85 84 83 82 81 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 103 lba1 lba2 lba3 lbcs0# lbcs1# lbcs2# lbcs3# lbrd# lbwr# vdd gnd lbclk lba4 lba5 lba6 lba7 vdd ri3# dcd3# cts3# dtr3# rts3# lbdout lbd0 dsr3# lbd1 lbd2 lbd3 vdd gnd lbd4 lbd5 lbd6 lbd7 mio8 mio9 mio10 mio11 sin3 gnd ad17 ad16 c/be2# frame# irdy# trdy# devsel# gnd stop# perr# serr# par c/be1# ad15 ad14 ad13 gnd ad2 ad1 ad0 ee_cs ee_do ad12 ad11 gnd vdd ad10 ad9 gnd ad8 c/be0# ad7 ad6 gnd vdd ad5 ad4 ad3 gnd vdd 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 36 37 38 39 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 18 OX16PCI954-TQC60-A 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 156 157 158 159 160 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 138 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 45 44 43 42 41 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 63 sout3 sout2 rts2# dtr2# cts2# dsr2# dcd2# ri2# vdd uart_ck_out gnd sin2 sin1 ri1# dcd1# vdd xtlo mode0 mode1 test ee_di ee_ck gnd dsr1# cts1# dtr1# rts1# vdd gnd sout1 sout0 rts0# dtr0# cts0# dsr0# dcd0# ri0# sin0 fifosel xtli mode ?01?: quad uarts + parallel p ort pe ack# nc mio7 mio6 mio5 mio4 mio3 mio2 mio1 nc inta# intb# rst# gnd clk vdd ad20 vdd gnd ad19 ad18 ad31 ad30 ad29 gnd ad28 ad27 ad26 gnd vdd ad25 ad24 c/be3# idsel ad23 gnd ad22 ad21 pme# 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 85 84 83 82 81 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 103 busy slct err# nc nc nc nc nc nc vdd gnd nc slin# init# afd# stb# vdd ri3# dcd3# cts3# dtr3# rts3# nc pd0 dsr3# pd1 pd2 pd3 vdd gnd pd4 pd5 pd6 pd7 mio8 mio9 mio10 mio11 sin3 gnd ad17 ad16 c/be2# frame# irdy# trdy# devsel# gnd stop# perr# serr# par c/be1# ad15 ad14 ad13 gnd ad2 ad1 ad0 ee_cs ee_do ad12 ad11 gnd vdd ad10 ad9 gnd ad8 c/be0# ad7 ad6 gnd vdd ad5 ad4 ad3 gnd vdd 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 36 37 38 39 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 18 OX16PCI954-TQC60-A 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 156 157 158 159 160 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 138 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 45 44 43 42 41 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 63 sout3 sout2 rts2# dtr2# cts2# dsr2# dcd2# ri2# vdd nc gnd sin2 sin1 ri1# dcd1# vdd xtlo mode0 mode1 test ee_di ee_ck gnd dsr1# cts1# dtr1# rts1# vdd gnd sout1 sout0 rts0# dtr0# cts0# dsr0# dcd0# ri0# sin0 fifosel xtli mode ?10?: quad uarts + pin - assignable subsystem id & subsystem vendor id sub_v_id0 nc nc sub_id7 sub_id6 sub_id5 sub_id4 sub_id3 sub_id2 sub_id1 sub_id0 inta# intb# rst# gnd clk vdd ad20 vdd gnd ad19 ad18 ad31 ad30 ad29 gnd ad28 ad27 ad26 gnd vdd ad25 ad24 c/be3# idsel ad23 gnd ad22 ad21 pme# 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 85 84 83 82 81 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 103 sub_id12 sub_id13 sub_id14 sub_id15 nc nc vdd gnd nc vdd ri3# dcd3# cts3# dtr3# rts3# nc dsr3# vdd gnd sub_v_id15 sub_id8 sub_id9 sub_id10 sub_id11 sin3 gnd ad17 ad16 c/be2# frame# irdy# trdy# devsel# gnd stop# perr# serr# par c/be1# ad15 ad14 ad13 gnd ad2 ad1 ad0 ee_cs ee_do ad12 ad11 gnd vdd ad10 ad9 gnd ad8 c/be0# ad7 ad6 gnd vdd ad5 ad4 ad3 gnd vdd 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 36 37 38 39 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 18 OX16PCI954-TQC60-A 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 156 157 158 159 160 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 138 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 45 44 43 42 41 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 63 sout3 sout2 rts2# dtr2# cts2# dsr2# dcd2# ri2# vdd nc gnd sin2 sin1 ri1# dcd1# vdd xtlo mode0 mode1 test ee_di ee_ck gnd dsr1# cts1# dtr1# rts1# vdd gnd sout1 sout0 rts0# dtr0# cts0# dsr0# dcd0# ri0# sin0 fifosel xtli sub_v_id8 sub_v_id9 sub_v_id10 sub_v_id11 sub_v_id12 sub_v_id13 sub_v_id154 sub_v_id4 sub_v_id6 sub_v_id5 sub_v_id7 sub_v_id1 sub_v_id2 sub_v_id3 mode ?11?: 32 - bit bridge lba0 lbrst lbrst# mio7 mio6 mio5 mio4 mio3 mio2 mio1 mio0 inta# intb# rst# gnd clk vdd ad20 vdd gnd ad19 ad18 ad31 ad30 ad29 gnd ad28 ad27 ad26 gnd vdd ad25 ad24 c/be3# idsel ad23 gnd ad22 ad21 pme# 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 85 84 83 82 81 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 103 lba1 lba2 lba3 lbcs0# lbcs1# lbcs2# lbcs3# lbrd# lbwr# vdd gnd lbclk lba4 lba5 lba6 lba7 vdd lbd9 lbd10 lbd12 lbd13 lbd14 lbdout lbd0 lbd11 lbd1 lbd2 lbd3 vdd gnd lbd4 lbd5 lbd6 lbd7 mio8 mio9 mio10 mio11 lbd8 gnd ad17 ad16 c/be2# frame# irdy# trdy# devsel# gnd stop# perr# serr# par c/be1# ad15 ad14 ad13 gnd ad2 ad1 ad0 ee_cs ee_do ad12 ad11 gnd vdd ad10 ad9 gnd ad8 c/be0# ad7 ad6 gnd vdd ad5 ad4 ad3 gnd vdd 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 36 37 38 39 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 18 OX16PCI954-TQC60-A 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 156 157 158 159 160 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 138 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 45 44 43 42 41 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 63 lbd15 lba8 lba9 lba10 lba11 nc nc nc vdd nc gnd nc lbd16 lbd17 lbd18 vdd nc mode0 mode1 test ee_di ee_ck gnd lbd19 lbd20 lbd21 lbd22 vdd gnd lbd23 lbd24 lbd25 lbd26 lbd27 lbd28 lbd29 lbd30 lbd31 fifosel gnd figure 2 : pinout in all configurable modes (package = 160 tqfp)
data sheet revision 1.3 page 8 ox16pci954 oxford semiconductor ltd. 4 p in d escriptions mode 00 01 10 11 dir 1 name description pci interface 139, 140, 141, 143, 144, 145, 148, 149, 152, 154, 155, 156, 159, 160, 1, 2, 14, 15, 16, 19, 20, 23, 24, 26, 28, 29, 32, 33, 34, 36, 37, 38 p_i/o ad[31:0] multiplexed pci address/data bus 150, 3, 13, 27 p_i c/be[3:0]# pci comman d/byte enable 136 p_i clk pci system clock 4 p_i frame# cycle frame 7 p_o devsel# device select 5 p_i irdy# initiator ready 6 p_o trdy# target ready 9 p_o stop# target stop request 12 p_i/o par parity 11 p_o serr# system error 10 p_i/o perr# parit y error 151 p_i idsel initialization device select 134 p_i rst# pci system reset 132,133 p_od inta#, intb# pci interrupts 138 p_od pme# power management event serial port pins 46 n/a i fifosel fifo select. for backward compatibility with 16c550, 16c6 50 and 16c750 devices the uarts? fifo depth is 16 when fifosel is low. the fifo size is increased to 128 when fifosel is high. the unlatched state of this pin is readable by software. the fifo size may also be set to 128 by setting fcr[5] when lcr[7] is se t, or by putting the device into enhanced mode. 80, 79, 55, 54 n/a o sout[3:0] irda_out[3:0] uart serial data outputs uart irda data output when mcr[6] of the corresponding channel is set in enhanced mode 87, 69, 68, 47 n/a i i sin[3:0] irda_in[3:0] uart serial data inputs uart irda data input when irda mode is enabled (see above) 85, 74, 66, 49 n/a i dcd[3:0]# active - low modem data - carrier - detect input 82, 77, 59, 52 n/a o o o dtr[3:0]# 485_en[3:0] tx_clk_out[3:0] active - low modem data - terminal - ready output. if automated dtr# flow control is enabled, the dtr# pin is asserted and deasserted if the receiver fifo reaches or falls below the programmed thresholds, respectively. in rs485 half - duplex mode, the dtr# pin may be programmed to reflect the state of the the transmitter empty bit to automatically control the direction of the rs485 transceiver buffer (see register acr[4:3]) transmitter 1x clock (baud rate generator output). for isochronous applications, the 1x (or nx) transmitte r clock may be asserted on the dtr# pins (see register cks[5:4])
data sheet revision 1.3 page 9 ox16pci954 oxford semiconductor ltd. mode 00 01 10 11 dir 1 name description serial port pins 81, 78, 58, 53 n/a o rts[3:0]# active - low modem request - to - send output. if automated rts# flow control is enabled, the rts# p in is deasserted and reasserted whenever the receiver fifo reaches or falls below the programmed thresholds, respectively. 83, 76, 60, 51 n/a i cts[3:0]# active - low modem clear - to - send input. if automated cts# flow control is enabled, upon deassertion of the cts# pin, the transmitter will complete the current character and enter the idle mode until the cts# pin is reasserted. note: flow control characters are transmitted regardless of the state of the cts# pin. 84, 75, 61, 50 n/a i i dsr[3:0]# rx_clk_in[3:0] active - low modem data - set - ready input. if automated dsr# flow control is enabled, upon deassertion of the dsr# pin, the transmitter will complete the current character and enter the idle mode until the dsr# pin is reasserted. note: flow con trol characters are transmitted regardless of the state of the dsr# pin external receiver clock for isochronous applications. the rx_clk_in is selected when cks[1:0] = ?01?. 86, 73, 67, 48 n/a i i ri[3:0]# tx_clk_in[3:0] active - low modem ring - indicator input external transmitter clock. this clock can be used by the transmitter (and indirectly by the receiver) when cks[6]=?1?. 64 n/a o xtlo crystal oscillator output 63 n/a i xtli crystal oscillator input or external clock pin. maximum frequency 60mhz 8 - bit local bus 71 n/a o uart_clk_out buffered crystal output. this clock can drive external uarts connected to the local bus. can be enabled / disabled by software. 122 n/a o lbrst local bus active - high reset 123 n/a o l brst# local bus active - low reset 102 n/a o lbdout local bus data out enable. this pin can be used by external transceivers; it is high when lbd[7:0] are in output mode and low when they are in input mode. 109 n/a o lbclk buffered pci clock. can be enab led / disabled by software 114 - 7 n/a o o lbcs[3:0]# lbds[3:0]# local bus active - low chip - select (intel mode) local bus active - low data - strobe (motorola mode) 112 n/a o o lbwr# lbrdwr# local bus active - low write - strobe (intel mode) local bus read - not - write control (motorola mode) 113 n/a o z lbrd# hi - z local bus active - low read - strobe (intel mode) permanent high impedance (motorola mode) 105 - 8 118 - 21 n/a o lba[7:0] local bus address signals 92 - 5 98 - 101 n/a see 32 - bit local bus i/o lbd[7:0] local bus data sign als
data sheet revision 1.3 page 10 ox16pci954 oxford semiconductor ltd. mode 00 01 10 11 dir 1 name description parallel port n/a 122 n/a i i ack# intr# acknowledge (spp mode). ack# is asserted (low) by the peripheral to indicate that a successful data transfer has taken place. identical function to ack# (ep p mode). n/a 121 n/a i pe paper empty. activated by printer when it runs out of paper. n/a 120 n/a i i busy wait# busy (spp mode). busy is asserted (high) by the peripheral when it is not ready to accept data wait (epp mode). handshake signal for i nterlocked ieee 1284 compliant epp cycles. n/a 108 n/a od o slin# addrstb# select (spp mode). asserted by host to select the peripheral address strobe (epp mode) provides address read and write strobe n/a 119 n/a i slct peripheral selected. asserted b y peripheral when selected. n/a 118 n/a i err# error. held low by the peripheral during an error condition. n/a 107 n/a od o init# init# initialize (spp mode). commands the peripheral to initialize. initialize (epp mode). identical function to spp mo de. n/a 106 n/a od o afd# datastb# auto feed (spp mode, open - drain) data strobe (epp mode) provides data read and write strobe n/a 105 n/a od o stb# write# strobe (spp mode). used by peripheral to latch data currently available on pd[7:0] write ( epp mode). indicates a write cycle when low and a read cycle when high n/a bus n/a i/o pd[7:0] parallel data bus 32 - bit local bus n/a 122 o lbrst local bus active - high reset n/a 123 o lbrst# local bus active - low reset n/a 102 o lbdout local bus data out enable. this pin can be used by external transceivers; it is high when lbd[7:0] are in output mode and low when they are in input mode. n/a 109 o lbclk buffered pci clock. can be enabled / disabled by software n/a 114 - 7 o o lbcs[3:0]# lbds[3:0]# local bus active - low chip - select (intel mode) local bus active - low data - strobe (motorola mode) n/a 112 o o lbwr# lbrdwr# local bus active - low write - strobe (intel mode) local bus read - not - write control (motorola mode) n/a 113 o z lbrd# hi - z local bus active - low read - strobe (intel mode) permanent high impedance (motorola mode) n/a 76 - 9, 105 - 8, 118 - 121 o lba[12:0] local bus address signals see 8 - bit local bus n/a 47 - 55, 58 - 61, 66 - 68, 80 - 87, 92 - 95,98 - 101 i/o lbd[31:0] local bus data signa ls
data sheet revision 1.3 page 11 ox16pci954 oxford semiconductor ltd. mode 00 01 10 11 dir 1 name description subsystem id & subsystem vendor id pins n/a n/a i sub_id[15:0] subsystem id. after reset the subsystem id of function 0 will default to the value assigned to these pins n/a n/a i sub_v_id[15:0] subsyste m vendor id. after reset the subsystem vendor id of function 0 will default to the value assigned to these pins. multi - purpose & external interrupt pins 131 n/a n/a 131 n/a n/a 131 n/a i/o z mio0 hi - z multi - purpose i/o 0. can drive high or lo w, or assert a pci interrupt permanent high impedance 130 130 n/a 130 i/o z mio1 hi - z multi - purpose i/o 1. can drive high or low, or assert a pci interrupt permanent high - impedance when lcc[6:5] 1 ?00? 129 129 n/a 129 i/o i mio2 pme_in multi - pu rpose i/o 2. when lcc[7] = 0, this pin can drive high or low, or assert a pci interrupt. input power management event. when lcc[7] is set this input pin can assert a function 1 pme# 124 - 128 88 - 91 n/a 124 - 8, 88 - 91 i/o mio[3:11] multi - purpose i/o pins. can drive high or low, or assert a pci interrupt eeprom pins 41 o ee_ck eeprom clock 39 o ee_cs eeprom active - high chip select 42 iu ee_di eeprom data in. when the serial eeprom is connected, this pin should be pulled up using 1 - 10k resistor. when the eep rom is not used the internal pullup is sufficient. 40 o ee_do eeprom data out. miscellaneous pins 43 iu test must be connected to gnd 44,45 i mode[1:0] mode selector: 00: function 0 is quad uart, function 1 is 8 - bit local bus 01: function 0 is quad ua rt, function 1 is parallel port 10: function 0 is quad uart, function 1 is unusable as the local bus pins are used to assign subsystem id and subsystem vendor id to function 0 11: function 0 is unusable, function 1 is 32 - bit local bus power and ground 2 18, 31, 57, 72, 97, 111, 147, 157 v ac vdd supplies power to output buffers in switching (ac) state 22, 65, 104, 137 v dc vdd power supply. supplies power to core logic, input buffers and output buffers in steady state 8, 17, 25, 30, 35, 56, 70, 96, 110 , 142, 146, 153, 158 g ac gnd supplies gnd to output buffers in switching (ac) state 21, 62, 103, 135 g dc gnd ground (0 volts). supplies gnd to core logic, input buffers and output buffers in steady state table 2 : pin description s
data sheet revision 1.3 page 12 ox16pci954 oxford semiconductor ltd. note 1: direction key: i input iu input with internal pull - up o output i/o bi - directional od open drain nc no connect z high impedance p_i pci input p_o pci output p_i/o pci bi - directional p_od pci open drain g ground v 5.0v power note 2: power & ground there are two gnd and two vdd rails internally. one set of rails supply power and ground to output buffers while in switching state (called ac power) and another rail supply the core logic, input buffers and output buffers in steady - state (called d c rail). the rails are not connected internally. this precaution reduces the effects of simultaneous switching outputs and undesirable rf radiation from the chip. further precaution is taken by segmenting the gnd and vdd ac rails to isolate the pci, local bus and uart pins.
data sheet revision 1.3 page 13 ox16pci954 oxford semiconductor ltd. 5 c onfiguration & o peration the ox16pci954 is a multi - function, target - only pci device, compliant with the pci local bus specification, revision 2.2 and pci power management specification, revision 1.0. the ox16pci954 affords maximum c onfiguration flexibility by treating the internal uarts, local bus and the parallel port as separate logical functions. each function has its own configuration space and is therefore recognised and configured by the pci bios seperately. the functions used are configured by the mode[1:0] pins as shown in table 3 . the ox16pci954 is configured by system start - up software during the bootstrap process that follows bus reset. the system scans the bus and reads the vendor and device id entification codes from any devices it finds. it then loads device - driver software according to this information and configures the i/o, memory and interrupt resources. device drivers can then access the functions at the assigned addresses in the usual fas hion, with the improved data throughput provided by pci. each function operates as though it was a separate device; however there are a set of local configuration registers that can be used to enable signals and interrupts, configure timings, and improve the efficiency of multi - port drivers. this architecture enables separate drivers to be installed for each function. generic port drivers can be hooked to use the functions individually, or more efficient multi - port drivers can hook both functions, accessin g the local configuration registers from either. all registers default after reset to suitable values for typical applications such a 4/8 port serial, or combo 4 - port serial/1 - port parallel add - in cards. however, all identification, control and timing reg isters can be redefined using an optional serial eeprom. mode [1:0] configuration 00 function 0 is quad uart, function 1 is 8 - bit local bus 01 function 0 is quad uart, function 1 is parallel port 10 function 0 is quad uart, function 1 is unusable as the local bus pins are used to assign subsystem id and subsystem vendor id to function 0 11 function 0 is unusable, function 1 is 32 - bit local bus table 3 : mode configuration
data sheet revision 1.3 page 14 ox16pci954 oxford semiconductor ltd. 6 pci t arget c ontroller 6.1 operation the ox16pci954 respo nds to the following pci transactions: - configuration access: the ox16pci954 responds to type 0 configuration reads and writes if the idsel signal is asserted and the bus address is selecting the configuration registers for function 0 or 1. the device wil l respond to the configuration transaction by asserting devsel#. data transfer then follows. any other configuration transaction will be ignored by the ox16pci954. io reads/writes: the address is compared with the addresses reserved in the i/o base addre ss registers (bars). if the address falls within one of the assigned ranges, the device will respond to the io transaction by asserting devsel#. data transfer follows this address phase. for the uarts and 8 - bit local bus controller, only byte accesses are possible. for io accesses to these regions, the controller compares ad[1:0] with the byte - enable signals as defined in the pci specification. the access is always completed; however if the correct be signal is not present the transaction will have no effec t memory reads/writes: these are treated in the same way as i/o transactions, except that the memory ranges are used. memory access to single - byte regions is always expanded to dwords in the ox16pci954. in other words, ox16pci954 reserves a dword per byte in single - byte regions. the device allows the user to define the active byte lane using lcc[4:3] so that in big - endian systems the hardware can swap the byte lane automatically. for memory mapped access in single - byte regions, the ox16pci954 compares the asserted byte - enable with the selected byte - lane in lcc[4:3] and completes the operation if a match occurs, otherwise the access will complete normally on the pci bus, but it will have no effect on either the internal uarts or the local bus controller. al l other cycles (64 - bit, special cycles, reserved encoding etc.) are ignored. the ox16pci954 will complete all transactions as disconnect - with - data, ie the device will assert the stop# signal alongside trdy#, to ensure that the bus master does not continue with a burst access. the exception to this is retry, which will be signalled in response to any access while the ox16pci954 is reading from the serial eeprom. the ox16pci954 performs medium - speed address decoding as defined by the pci specification. it asserts the devsel# bus signal two clocks after frame# is first sampled low on all bus transaction frames which address the chip. the internal uarts are accessed with zero wait states inserted. fast back - to - back transactions are supported by the ox16pci95 4 as a target, so a bus master can perform faster sequences of write transactions to the uarts or local bus when an inter - frame turn - around cycle is not required. the device supports any combination of byte - enables to the pci configuration registers, the local configuration registers (see base address 2 and 3) and the local bus controller in 32 - bit mode. if a byte - enable is not asserted, that byte is unaffected by a write operation and undefined data is returned upon a read. the ox16pci954 performs parit y generation and checking on all pci bus transactions as defined by the standard. note this is entirely unrelated to serial data parity which is handled within the uart functional modules themselves. if a parity error occurs during the pci bus address phas e, the device will report the error in the standard way by asserting the serr# bus signal. however if that address/command combination is decoded as a valid access, it will still complete the transaction as though the parity check was correct. the ox16pci 954 does not support any kind of caching or data buffering in addition to that already provided within the uarts by the transmit and receive data fifos. in general, registers in the uarts and on the local bus can not be pre - fetched because there may be sid e - effects on read. 6.2 configuration space the ox16pci954 is a dual - function device, where each logical function has its own configuration space. all required fields in the standard header are implemented, plus the power management extended capability regist er set. the format of the configuration space is shown in table 4 overleaf. in general, writes to any registers that are not implemented are ignored, and all reads from unimplemented registers return 0.
data sheet revision 1.3 page 15 ox16pci954 oxford semiconductor ltd. 6.2.1 pci configuration space register map configuration register description offset 31 16 15 0 address device id vendor id 00h status command 04h class code revision id 08h bist 1 header type reserved reserved 0ch base address register 0 (bar0) 10h base address register 1 (bar 1) 14h base address register 2 (bar 2) ? local configuration registers in io space 18h base address register 3 (bar3) ? local configuration registers in memory space 1ch reserved 20h reserved 24h reserved 28h subsystem id subsystem vendor id 2ch re served 30h reserved cap_ptr 34h reserved 38h reserved reserved interrupt pin interrupt line 3ch power management capabilities (pmc) next ptr cap_id 40h reserved reserved pmc control/status register (pmcsr) 44h table 4 : pci con figuration space reset value program read/write function 0 function 1 register name uarts disabled 8 - bit bus 32 - bit bus parallel port disabled eeprom pci vendor id 0x1415 0x1415 w r device id 0x9501 0x9500 0x9511 0x9512 0x9513 0x9510 w r command 0x0000 0x0000 - r/w status 0x0290 0x0290 w (bit 4) r/w revision id 0x00 0x00 - r class code 0x070006 0x068000 0x068000 0x070101 0x068000 w r header type 0x80 0x80 - r bar 0 0x00000001 0x00000001 - r/w bar 1 0x00000000 0x00000000 0000 0001 0000 0000 - r/w bar 2 0x000000 01 0x00000001 - r/w bar 3 0x00000000 0x00000000 - r/w subsystem vid 0x1415 0x1415 w r subsystem id 0x0000 0x0000 w r cap ptr. 0x40 0x40 - r interrupt line 0x00 0x00 - r/w interrupt pin 0x01 0x02 w r cap id 0x01 0x01 - r next ptr. 0x00 0x00 - r pm capabilities 0x6c01 0x6c01 w r pmc control/ status register 0x0000 0x0000 - r/w table 5 : pci configuration space default values
data sheet revision 1.3 page 16 ox16pci954 oxford semiconductor ltd. 6.3 accessing logical functions access to the uarts, local bus and parallel port is achieved via standard i/o and memory mapping, at addresses defined by the base address registers (bars) in configuration space. the bars are configured by the system to allocate blocks of i/o and memory space to the logical functions, according to the size required by the func tion. the addresses allocated can then be used to access the functions. the mapping of these bars is shown in table 6 . function 1 bar function 0 local bus parallel port 0 internal uarts (i/o mapped) local bus (i/o mapped) para llel port base registers 1 internal uarts (memory mapped) local bus (memory mapped) parallel port extended registers 2 local configuration registers (i/o mapped) 3 local configuration registers (memory mapped) 4 unused 5 unused table 6 : base address register definition 6.3.1 pci access to internal uarts io and memory space bar 0 and bar 1 of function 0 are used to access the internal uarts. the function reserves a 32 - byte block of i/o space and a 4k byte block of memory space. once the i/o access enable and memory access enable bits in the command register (configuration space) are set, the uarts can be accessed following the mapping shown in table 7 . uart address pci offset from base address 0 for functio n0 in io space (hex) (hex) uart0 uart1 uart2 uart3 000 00 08 10 18 001 01 09 11 19 002 02 0a 12 1a 003 03 0b 13 1b 004 04 0c 14 1c 005 05 0d 15 1d 006 06 0e 16 1e 007 07 0f 17 1f uart address pci offset from base address 1 for function0 in memory space (hex) 000 00 20 40 60 001 04 24 44 64 002 08 28 48 68 003 0c 2c 4c 6c 004 10 30 50 70 005 14 34 54 74 006 18 38 58 78 007 1c 3c 5c 7c table 7 : pci address map for internal uarts (i/o and memory) note 1: since 4k of memory space is reserved and the full bus address is not used for decoding, there are a number of aliases of the uarts in the allocated memory region 6.3.2 pci access to 8 - bit local bus when the local bus is enabled (mode 00), access to the bus works in simil ar fashion to the internal uarts. the function reserves a block of i/o space and a block of memory space. the i/o block size is user definable in the range of 4 to 256 bytes; the memory range is fixed at 4k bytes. i/o space in order to minimise the usage of io space, the block size for bar0 of function1 is user definable in the range of 4 to 256 bytes. having assigned the address range, the user can define two adjacent address bits to decode up to four chip selects internally. this facility allows glueles s implementation of the local bus connecting to four external peripheral chips. the address range and the lower address bit for chip - select decoding (lower - address - cs - decode) are defined in the local bus configuration register (see lt2[26:20] in section 6.4 ). the 8 - bit local bus has eight address lines (lba[7:0]) which correspond to the maximum io address space. if the maximum allowable block size is allocated to the io space (i.e. 256 bytes), then as access in io space is byte aligned, lba[7:0] equal pci ad[7:0] respectively. when the user selects an address range which is less than 256 bytes, the corresponding upper address lines will be set to logic zero. the region can be divided into four chip - select regions when the user selects the second uppermost non - zero address bit for chip - select decoding. for example if 32 - bytes of io space are reserved, the local bus address lines a[4:0] are active and the remaining address lines are set to zero. to generate four chip - selects the user should select a3 as the lower - address - cs - decode. in this case a[4:3] will be used internally to decode chip - selects, asserting lbcs0# when the address offset is 00 - 07h, lbcs1# when
data sheet revision 1.3 page 17 ox16pci954 oxford semiconductor ltd. offset is 08 - 0fh, lbcs2# when offset is 10 - 17h, and lbcs3# when offset is 18 - 1fh. the region can be divided into two chip - select regions by selecting the uppermost address bit to decode chip selects. in the above example, the user can select a4 as the lower - address - cs - decode, thus using a[5:4] internally to decode chip sel ects. as in this example lba5 is always zero, only chip - select lines lbcs0# and lbcs1# will be decoded into, asserting lbcs0# when address offset is 00 - 0fh and lbcs1# when offset is 10 - 1fh. the region can be allocated to a single chip - select region by ass igning an address bit beyond the selected range to lower - address - cs - decode (but not above a8). in the above example, if the user selects a5 as the lower - address - cs - decode, a[6:5] will be used to internally decode chip - selects. as in this example lba[7:5] a re always zero, only the chip select line lbcs0# may be selected. in this case address offset 00 - 1fh asserts lbcs0# and the other chip - select lines remain inactive permanently. with default values, the address map for local bus io address accesses is the same as for internal uarts. memory space: the memory base address registers have an allocated fixed size of 4k bytes in the address space. since the local bus has 8 address lines and the ox16pci954 only implements dword aligned accesses in memory space, t he 256 bytes of addressable space per chip select is expanded to 1k. unlike an i/o access, for a memory access the upper address lines are always active and the internal chip - select decoding logic ignores the user setting for lower - address - cs - decode (lt2[2 6:23]) and uses pci ad[11:10] to decode into 4 chip - select regions. when the local bus is accessed in memory space, a[9:2] are asserted on lba[7:0]. the chip - select regions are defined below. pci offset from bar 1 in function1 (memory space) local bus chip - select (data - strobe) lower address upper limit lbcs0# (lbds0#) 000h 3fch lbcs1# (lbds1#) 400h 7fch lbcs2# (lbds2#) 800h bfch lbcs3# (lbds3#) c00h ffch table 8 : pci address map for local bus (memory) note: the descriptio n given for i/o and memory accesses is for an intel - type configuration for the local bus. for motorola - type configuration, the chip select pins are redefined to data strobe pins. in this mode the local bus offers up to 8 address lines and four data - strobe pins. 6.3.3 pci access to parallel port when the parallel port is enabled (mode 01), access to the port works via bar definitions as usual, except that there are two i/o bars corresponding to the two sets of registers defined to operate an ieee1284 epp and bi - directional parallel port. the user can change the i/o space block size of bar0 by over - writing the default values in lt2[25:20] using the serial eeprom (see section 6.4 ). for example the user can reduce the allocated space fo r bar0 to 4 - bytes by setting lt2[22:20] to ?001?. the i/o block size allocated to bar1 is fixed at 8 - bytes. legacy parallel ports expect the upper register set to be mapped 0x400 above the base block, therefore if the bars are fixed with this relationshi p, generic parallel port drivers can be used to operate the device in all modes. example: bar0 = 0x00000379 (8 bytes at address 0x378) bar1 = 0x00000779 (8 bytes at address 0x778) if this relationship is not used, custom drivers will be needed. 6.3.4 pci acces s to 32 - bit local bus access to the local bus in 32 - bit mode is similar to 8 - bit mode (see section 6.3.2 ) with the following exceptions: the local bus offers a 32 - bit bi - directional data bus and 12 bit address bus the pci addre ss signals ?ad[13:2]? are asserted on lba[11:0] block size in memory space is programmable by lt2[28:27] (see section 6.4 ) the lower - address - cs - decode (lt2[26:23]) parameter is used to decode up to 4 chip selects the block size allocation for chip - select regions is defined in table 9 . number of chip selects memory block size (kbytes) lt2[28:27] lt2[26:23] 1 16 ?01? ?1010? 2 16 ?01? ?1001? 4 16 ?01? ?1000? 1 4 ?00? ?1000? 2 4 ?00? ?0111? 4 4 ?00? ?0110? table 9 : pci access to 32 - bit local bus (memory)
data sheet revision 1.3 page 18 ox16pci954 oxford semiconductor ltd. 6.4 accessing local configuration registers the local configuration registers are a set of device specific registers which can be accessed from either function. they are mapped to the i/o and memory addresses set up in bar2 and bar3 of each function, with the offsets defined for each register. access is limited to byte only for i/o accesses; memory accesses can also be word or dword accessed, however on little - endian systems such as intel 80x86 the byte order will be reversed. 6.4.1 local configuration and control register ?lcc? (offset 0x00) this register defines control of ancillary functions such as power management, external clock reference signals and the serial eeprom. the indivi dual bits are described below. bits description read/write reset eeprom pci 1:0 mode. these bits return the state of the mode[1:0] pins. - r xx 2 enable uart clock output. when this bit is set, the buffered uart clock output pin (uart_clk_out) is ac tive. when low uart_clk_out is permanently low. w rw 0 4:3 endian byte - lane select for memory access to 8 - bit peripherals. 00 = select data[7:0] 10 = select data[23:16] 01 = select data[15:8] 11 = select data[31:24] memory access to ox16pci954 is always dword aligned. when accessing 8 - bit regions like the internal uarts, the 8 - bit local bus and the parallel port, this option selects the active byte lane. as both pci and pc architectures are little endian, the default value will be used by systems, however, some non - pc architectures may need to select the byte lane. these bits are ignored in 32 - bit local bus. w rw 00 6:5 power - down filter time. these bits define a value of an internal filter time f or power - down interrupt request in power management circuitry in function0. once function0 is ready to go into power down mode, ox16pci954 will wait for the specified filter time and if function0 is still in power - down request mode, it can assert a pci int errupt (see section 6.6 ). w rw 00 00 = power - down request disabled 01 = 4 seconds 10 = 129 seconds 11 = 518 seconds 7 function1 mio2_pme enable. a value of ?1? enables mio2 pin to set the pme_status in pmcsr register, and hence assert the pme# pin if enabled. a value of ?0? disables mio2 from setting the pme_status bit (see section 6.6 ). w rw 0 23:8 reserved. these bits are used for test purposes. the device driver must write zeros to these bi ts. - r 0000h 24 eeprom clock. for pci read or write to the eeprom , toggle this bit to generate an eeprom clock (ee_ck pin). - w 0 25 eeprom chip select. when 1 the eeprom chip - select pin ee_cs is activated (high). when 0 ee_cs is de - active (low). - w 0 26 eeprom data out. for writes to the eeprom, this output bit is the input - data of the eeprom. this bit is output on ee_do and clocked into the eeprom by ee_ck. - w 0 27 eeprom data in. for reads from the eeprom, this input bit is the output - data of the eeprom connected to ee_di pin. - r x 28 eeprom valid. a 1 indicates that a valid eeprom program is present - r x 29 reload configuration from eeprom. writing a 1 to this bit re - loads the configuration from eeprom. this bit is self - clearing after eeprom read - w 0 30 reserved - - 0 31 reserved - r 0
data sheet revision 1.3 page 19 ox16pci954 oxford semiconductor ltd. 6.4.2 multi - purpose i/o configuration register ?mic? (offset 0x04) this register configures the operation of the multi - purpose i/o pins ?mio[11:0] as follows. bits description read/write reset eeprom pci 1:0 mio0 configuration register (mode[1:0] 1 ?01?). 00 - > mio0 is a non - inverting input pin 01 - > mio0 is an inverting input pin 10 - > mio0 is an output pin driving ?0? 11 - > mio0 is an output pin driving ?1? unused (mode[1:0]=?01?). when parallel port is enabled, mio[0] pin is unused and will remain in forcing output mode. w rw 00 3:2 mio1 configuration register (lcc[6:5]=?00?). 00 - > mio1 is a non - inverting input pin 01 - > mio1 is an inverting input pin 10 - > mio1 is an output pin driving ?0? 11 - > mio1 is an output pin driving ?1? unused (lcc[6:5] 1 ?00?). when power - down mode in function0 is enabled, mio1 pin is unused and will remain in forcing output mode. w rw 00 5:4 mio2 configuration register (lcc[7]=?0?). 00 - > mio2 is a non - inverting input pin 01 - > mio2 is an inverting input pin 10 - > mio2 is output pin driving ?0? 11 - > mio2 is output pin driving ?1? pme_input (lcc[7]=?1?). when lcc[7] is set, mio2 pin is re - defined to pme_input. it?s polarity will be controlled by mic[4]. it sets the st icky pme_status bit in function1. w rw 00 7:6 mio3 configuration register. 00 - > mio3 is a non - inverting input pin 01 - > mio3 is an inverting input pin 10 - > mio3 is an output pin driving ?0? 11 - > mio3 is an output pin driving ?1? w rw 00 9:8 mio4 conf iguration register. 00 - > mio4 is a non - inverting input pin 01 - > mio4 is an inverting input pin 10 - > mio4 is an output pin driving ?0? 11 - > mio4 is an output pin driving ?1? w rw 00 11:10 mio5 configuration register. 00 - > mio5 is a non - inverting inp ut pin 01 - > mio5 is an inverting input pin 10 - > mio5 is an output pin driving ?0? 11 - > mio5 is an output pin driving ?1? w rw 00 13:12 mio6 configuration register. 00 - > mio6 is a non - inverting input pin 01 - > mio6 is an inverting input pin 10 - > mio6 is an output pin driving ?0? 11 - > mio6 is an output pin driving ?1? w rw 00 15:14 mio7 configuration register. 00 - > mio7 is a non - inverting input pin 01 - > mio7 is an inverting input pin 10 - > mio7 is an output pin driving ?0? 11 - > mio7 is an output pin driving ?1? w rw 00
data sheet revision 1.3 page 20 ox16pci954 oxford semiconductor ltd. bits description read/write reset eeprom pci 17:16 mio8 configuration register. 00 - > mio8 is a non - inverting input pin 01 - > mio8 is an inverting input pin 10 - > mio8 is an output pin driving ?0? 11 - > mio8 is an output pin driving ?1? w rw 00 19:18 mio9 configuration regi ster. 00 - > mio9 is a non - inverting input pin 01 - > mio9 is an inverting input pin 10 - > mio9 is an output pin driving ?0? 11 - > mio9 is an output pin driving ?1? w rw 00 21:20 mio10 configuration register. 00 - > mio10 is a non - inverting input pin 01 - > mio10 is an inverting input pin 10 - > mio10 is an output pin driving ?0? 11 - > mio10 is an output pin driving ?1? w rw 00 23:22 mio11 configuration register. 00 - > mio11 is a non - inverting input pin 01 - > mio11 is an inverting input pin 10 - > mio11 is a n output pin driving ?0? 11 - > mio11 is an output pin driving ?1? w rw 00 31:24 reserved - r 00h 6.4.3 local bus timing parameter register 1 ?lt1? (offset 0x08): the local bus timing parameter registers (lt1 and lt2) define the operation and timing para meters used by the local bus. the timing parameters are programmed in 4 - bit registers to define the assertion/de - assertion of the local bus control signals. the value programmed in these registers defines the number of pci clock cycles after a reference cy cle when the events occur, where the reference cycle is defined as two clock cycles after the master asserts the irdy# signal. the following arrangement provides a flexible approach for users to define the desired bus timing of their peripheral devices. th e timings refer to i/o or memory mapped access to bar0 and bar1 of function1. bits description read/write reset eeprom pci 3:0 read chip - select assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lb cs[3:0]# pins are asserted (low) during a read operation from the local bus. 1 these bits are unused in motorola - type interface. w rw 0h 7:4 read chip - select de - assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lbcs[3:0]# pins are de - asserted (high) during a read from the local bus. 1 these bits are unused in motorola - type interface. w rw 3h (2h for parallel port) 11:8 write chip - select assertion (intel - type interface). defines the number of clock cyc les after the reference cycle when the lbcs[3:0]# pins are asserted (low) during a write operation to the local bus. 1 these bits are unused in motorola - type interface. w rw 0h
data sheet revision 1.3 page 21 ox16pci954 oxford semiconductor ltd. bits description read/write reset eeprom pci 15:12 write chip - select de - assertion (intel - type interface). defines the numb er of clock cycles after the reference cycle when the lbcs[3:0]# pins are de - asserted (high) during a write operation to the local bus. 1 read - not - write de - assertion during write cycles (motorola - type interface). defines the number of clock cycles after t he reference cycle when the lbrdwr# pin is de - asserted (high) during a write to the local bus. 1 w rw 2h 19:16 read control assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lbrd# pin is asserted (lo w) during a read from the local bus. 1 read data - strobe assertion (motorola - type interface). defines the number of clock cycles after the reference cycle when the lbds[3:0]# pins are asserted (low) during a read from the local bus. 1 w rw 0h (1h for paral lel port) 23:20 read control de - assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lbrd# pin is de - asserted (high) during a read from the local bus. 1 read data - strobe de - assertion (motorola - type inter face). defines the number of clock cycles after the reference cycle when the lbds[3:0]# pins are de - asserted (high) during a read from the local bus. 1 w rw 3h (2h for parallel port) 27:24 write control assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lbwr# pin is asserted (low) during a write to the local bus. 1 write data - strobe assertion (motorola - type interface). defines the number of clock cycles after the reference cycle when the lbds[3:0]# pins are asserted (low) during a write to the local bus. 1 w rw 0h (1h for parallel port) 31:28 write control de - assertion (intel - type interface). defines the number of clock cycles after the reference cycle when the lbwr# pin is de - asserted (high) during a w rite to the local bus. 1 write data - strobe de - assertion (motorola - type interface). defines the number of clock cycles after the reference cycle when the lbds[3:0]# pins are de - asserted (high) during a write cycle to the local bus. 1 w rw 2h note 1: onl y values in the range of 0h to ah (0 - 10 decimal) are valid. other values are reserved. these parameters apply to both 8 - bit and 32 - bit local bus configurations. see notes in the following page.
data sheet revision 1.3 page 22 ox16pci954 oxford semiconductor ltd. 6.4.4 local bus timing parameter register 2 ?lt2? (offset 0x0c): bits description read/write reset eeprom pci 3:0 write data bus assertion. this register defines the number of clock cycles after the reference cycle when the lbd pins actively drive the data bus during a write operation to the local bus. 1 w rw 0h 7:4 write data bus de - assertion. this register defines the number of clock cycles after the reference cycle when the lbd pins go high - impedance during a write operation to the local bus. 1,2 w rw fh 11:8 read data bus assertion. this register defines the number of clock cycles after the reference cycle when the lbd pins actively drive the data bus at the end of a read operation from the local bus. 1 w rw 4h (2h for parallel port) 15:12 read data bus de - assertion. this register defines the number of clock cycles after the reference cycle when the lbd pins go high - impedance during at the beginning of a read cycle from the local bus. 1 w rw 0h 19:16 reserved. - r 0h 22:20 io space block size of bar0 in function1. w r 000 = reserved 001 = 4 bytes 010 = 8 bytes 011 = 16 bytes 100 = 32 bytes 101 = 64 bytes 110 = 128 bytes 111 = 256 bytes ?100? (=?010? for parallel port) 26:23 local bus chip ? select parameter ?lower - address - cs - decode?. 2 w rw io space in 8 - bit local bus memory space and io space in 32 - bit local bus 0000 = a2 0001 = a3 0010 = a4 0011 = a5 0100 = a6 0101 = a7 0110 = a8 0111 = a9 1000 = res 1001 = res 1010 = res 1011 = res 1100 = res 1101 = res 1110 = res 1111 = res 0000 = a4 0001 = a5 0010 = a6 0011 = a7 0100 = a8 0101 = a9 0110 = a10 0111 = a11 1000 = a12 1001 = a13 1010 = a14 1011 = res 1100 = res 1101 = res 1110 = res 1111 = res ?0001? (=?0010? for parallel port) 28:27 memory space block size of bar1 in function1 (mode[1:0]=?11?, i.e. 32 - bit local bus). w r 00 00 = 4 kbytes 01 = 16 kbytes 10 = reserved 11 = reserved when 8 - bit local bus or parallel port is selected (mode[1:0]=?00? or ?01?), the memory block size is fixed at 4k and these bits are ignored. 29 local bus software reset. when this bit is a 1 the local bus r eset pin is activated. when this bit is a 0 the local bus reset pin is de - activated. 3 - rw 0 30 local bus clock enable. when this bit is a 1 the local bus clock (lbck) pin is enabled. when this bit is a 0 lbck pin is permanently low. the local bus clock is a buffered pci clock. w rw 0 31 bus interface type. when low (=0) the local bus is configured to intel - type operation, otherwise it is configured to motorola - type operation. note that when mode[1:0] is ?01?, this bit is hard wired to 0. w rw 0 note 1 : only values in the range of 0 to ah (0 - 10 decimal) are valid. other values are reserved as writing higher values causes the pci interface to retry all accesses to the local bus as it is unable to complete the transaction in 16 pci clock cycles. note 2: the lower - address - cs - decode parameter is described in sections 6.3.2 & 6.3.4 . these bits are unused for memory access to the 8 - bit local bus which uses a fixed deco ding to allocate 1k regions to 4 chip selects. for further information on the local bus, see section 8 . note 3: local bus, uarts and the parallel port are all reset with pci reset. in addition, the user can issue the software reset command.
data sheet revision 1.3 page 23 ox16pci954 oxford semiconductor ltd. lt2[15:0] enable the card designer to control the data bus during the idle periods. the default values will configure the local bus data pins to remain forcing (lt2[7:4] = fh). lt[15:8] is programmed to place the bus in high - impedance at t he beginning of a read cycle and set it back to forcing at the end of the read cycle. for systems that require the data bus to stay in high - impedance, the card designer should write an appropriate value in the range of 0h to ah to lt2[7:4]. this will place the data bus in high impedance at the end of the write cycle. whenever the value programmed in lt2[7:4] does not equal fh, the local bus controller will ignore the setting of lt2[15:8] as the data bus will be high - impedance outside write cycles. in this c ase the card designer should place external pull - ups on the data bus pins lbd[7:0] (or lbd[32:0] in 32 - bit mode). while the configuration data is read from the external eeprom, the lbd pins remain in the high - impedance state. the timing registers define the local bus timing parameters based on signal changes relative to a reference cycle which is defined as two pci clock cycles after irdy# is asserted for the first time in a frame. the following parameters are fixed relative to the reference cycle. the l ocal bus address pins (lba[7:0] in 8 - bit local bus, lba[15:0] in 32 - bit local bus) are asserted during the reference cycle. in a write operation, the local bus data is available during the reference cycle, however i/o buffers change direction as programmed in lt2[3:0]. in a motorola type bus write operation, the read - not - write pin (lbrdwr#) is asserted (low) during the reference cycle. in a read cycle this pin remains high throughout the duration of the operation. the default settings in lt1 & lt2 registe rs provide one pci clock cycle for address and chip - select to control signal set - up time, one clock cycle for address and chip - select from control signal hold time, two clock cycles of pulse duration for read and write control signals and one clock cycle f or data bus hold time. these parameters are acceptable for using external ox16c950, ox16c952 and ox16c954 devices connected to the local bus, in intel mode. some redefinition will be required if the bus is to be operated in motorola mode. the user should take great care when programming the local bus timing parameters. for example defining a value for chip - select assertion which is larger that the value defined for chip - select de - assertion or defining a chip - select assertion value which is greater than con trol signal assertion will result in obvious invalid local bus cycles. 6.4.5 uart receiver fifo levels ?url? (offset 0x10) the receiver fifo level of all internal uarts are shadowed in local configuration registers as follows: bits description read/write res et eeprom pci 7:0 uart0 receiver fifo level (rfl[7:0]) - r 0x00h 15:8 uart1 receiver fifo level (rfl[7:0]) - r 0x00h 23:16 uart2 receiver fifo level (rfl[7:0]) - r 0x00h 31:24 uart3 receiver fifo level (rfl[7:0]) - r 0x00h 6.4.6 uart transmitter fifo l evels ?utl? (offset 0x14) the transmitter fifo level of all internal uarts are shadowed in local configuration registers as follows: bits description read/write reset eeprom pci 7:0 uart0 transmitter fifo level (tfl[7:0]) - r 0x00h 15:8 uart1 trans mitter fifo level (tfl[7:0]) - r 0x00h 23:16 uart2 transmitter fifo level (tfl[7:0]) - r 0x00h 31:24 uart3 transmitter fifo level (tfl[7:0]) - r 0x00h
data sheet revision 1.3 page 24 ox16pci954 oxford semiconductor ltd. 6.4.7 uart interrupt source register ?uis? (offset 0x18) the uart interrupt source register is described below: bits description read/write reset eeprom pci 5:0 uart0 interrupt source register (isr[5:0]) - r 01h 11:6 uart1 interrupt source register (isr[5:0]) - r 01h 17:12 uart2 interrupt source register (isr[5:0]) - r 01h 23:18 uart3 interrupt sour ce register (isr[5:0]) - r 01h 26:24 reserved - r 00h 27 uart0 good - data status - r 1 28 uart1 good - data status - r 1 29 uart2 good - data status - r 1 30 uart3 good - data status - r 1 31 global good - data status. this bit is the logical and of bits 27 t o 30, i.e. it is set if good - data status of all internal uarts is set. - r 1 good - data status for a given internal uart is set when all of the following conditions are met: isr reads a level0 (no - interrupt pending), a level 2a (receiver data avai labl e , a level 2b (receiver time - out) or a level 3 (transmitter thr empty) interrupt lsr[7] is clear so there is no parity error, framing error or break in the fifo lsr[1] is clear so no over - run error has occurred if the device driver software reads the re ceiver fifo levels (url) followed by this register, then if good - data status for a given channel is set, the driver can remove the number of bytes indicated by the fifo level without the need to read the line status register for that channel. this feature enhances the driver efficiency. for a given channel, if the good - data status bit is not set, then the software driver should examine the corresponding isr bits. for example if bit 29 is low, then the driver should examine bits 17 down to 12 to obtain the isr[5:0] for uart2. if the isr indicates a level 4 or higher interrupt, the interrupt is due to a change in the state of modem lines or detection of flow control characters. the device driver - software should then take appropriate measures as would in any other 550/950 driver. when isr indicates a level 1 (receiver status) interrupt then the driver can examine the line status register (lsr) of the relevant channel. since reading the lsr clears lsr[7], the device driver - software should either flush or empty the contents of the receiver fifo, otherwise the good - data status will no longer be valid. the uart receiver fifo level (url), uart transmitter fifo level (utl), uart interrupt source register (uis) and global interrupt status register (gis) are allocated adjacent address offsets (10h to 1ch) in the base address register. the device driver - software can read all of the above registers in single burst read operation. the location offset of the registers are such that the fifo levels are usually read before t he status registers so that the status of the n characters indicated in the receiver fifo levels are valid.
data sheet revision 1.3 page 25 ox16pci954 oxford semiconductor ltd. 6.4.8 global interrupt status and control register ?gis? (offset 0x1c) bits description read/write reset eeprom pci 3:0 these bits reflect the state of uart3 to uart0 internal interrupt lines, respectively. 1 - r 0x0h 4 mio0 (mode[1:0] 1 ?01?). this bit reflects the state of the internal mio[0]. the internal mio[0] reflects the non - inverted or inverted state of mio0 pin. 2 parallel port interrupt (mode[1:0]=?01?). this bit reflects the state of the parallel port internal interrupt line. - - r r x 0 5 mio1 (lcc[6:5]=?00?). this bit reflects the state of the internal mio[1]. the internal mio[1] reflects the non - inverted or inverted state of mio1 pin. 2 function0 power - down interrupt (lcc[6:5] 1 ?00?). in this mode this is a sticky bit. when set, it indicates a power - down request issued by function0 and would normally have asserted a pci interrupt if bit 21 was set (see section 7.9). reading this bit clears it. r x 0 15:6 these bits reflect the state of the internal mio[11:2]. the internal mio[11:2] reflect the non - inverted or inverted state of mio[11:2] pins respectively. 2 - r xxxh 19:16 uart interrupt mask. when set (=1) these bit ena ble each internal uart to assert a pci interrupt respectively. when cleared (=0) they prevent the respective channel from asserting a pci interrupt. 3 w rw fh 20 mio[0] interrupt mask (mode[1:0] 1 ?01?). when set (=1) this bit enables mio0 pin to assert a pc i interrupt. when cleared (=0) it prevents mio0 pin from asserting a pci interrupt. 2 parallel port interrupt mask (mode[1:0]=?01?). when set (=1) this bit enables the parallel port to assert a pci interrupt. when cleared (=0) it prevents the parallel port from asserting a pci interrupt. w w rw rw 1 1 21 mio[1] interrupt mask (lcc[6:5]=?00?). when set (=1) this bit enables mio1 pin to assert a pci interrupt. when cleared (=0) it prevents mio1 pin from asserting a pci interrupt. 2 function0 power - d own interrupt mask (lcc[6:5] 1 ?00?). when set (=1) this bit enables the power - down logic in function0 to assert a pci interrupt. when cleared (=0) it prevents the power - down logic in function0 from asserting a pci interrupt. w w rw rw 1 0 31:22 m io interrupt mask. when set (=1) these bits enable each mio[11:2] pin to assert a pci interrupt respectively. when cleared (=0) they prevent the respective pins from asserting a pci interrupt. 2 w rw 3ffh note 1: gis[3:0] are the inverse of uis[24], uis [18], uis[6] and uis[0] respectively. systems that do not require the local bus or parallel port need not read this register to identify the source of the interrupt as long as they read the uis (offset 18h) register. note 2: the returned value is either the direct state of the corresponding mio pin or its inverse as configured by the multi - purpose i/o configuration register ?mic? (offset 0x04). as the internal mio can assert a pci interrupt, the inversion feature can define each external interrupt to be defined as active - low or active - high, as controlled by the mic register. note 3: the uart interrupt mask register bits are all set after a hardware reset to enable the interrupt from all internal uarts. this will cater for generic device - driver software that does not access the local configuration registers. the default setting for uart interrupt mask bits can be changed using the serial eeprom. note that even though by default the uart interrupts are enabled in this register, since after a reset the ier registers of individual uarts disables all interrupts, a pci interrupt will not be asserted after a hardware reset. note 4: when mode[1:0]=?10?, the mio pins are used to define a subsystem id value, therefore all interrupts due to mio pins are disabled regardless of the state of the gis register. the mio interrupts mask register bits are all set after a hardware reset to enable the interrupt from all mio pins from boot up. the default setting for mio interrupt mask bits can be changed using the serial ee prom.
data sheet revision 1.3 page 26 ox16pci954 oxford semiconductor ltd. 6.5 pci interrupts interrupts in pci systems are level - sensitive and can be shared. there are sixteen sources of interrupt in the ox16pci954, one in each uart channel and twelve from multi - purpose io pins (mio11 to mio0). the parallel port and mio0 sh are the same interrupt status bit (gis[4]). the pci power management power - down interrupt for internal uarts (function0) and mio1 share the status bit gis[5]. the local bus uses the mio pins to pass interrupts to the pci controller. all interrupts are ro uted to the pci interrupt pins, inta# or intb#. the default routing asserts function0 interrupts on inta# and function1 interrupts on intb#. these default routings may be modified by writing to the interrupt pin field in the configuration registers using t he serial eeprom facility. the interrupt pin field is normally considered a hard - wired read - only value in pci. it indicates to system software which pci interrupt pin (if any) is used by a function. the interrupt pin may only be modified using the serial e eprom facility, and card developers must not invoke any combination which violates the pci specification. note that ox16pci954 only has two pci interrupt pins, inta# and intb#. if in doubt, the default routings should be used. table 10 relates the interrupt pin field to the device pin used. interrupt pin device pin used 0 none 1 inta# 2 intb# 3 to 255 reserved table 10 : ?interrupt pin? definition during the system initialisation process and pci dev ice configuration, system - specific software reads the interrupt pin field to determine which (if any) interrupt pin is used by each function. it programmes the system interrupt router to logically connect this pci interrupt pin to a system - specific interru pt vector (irq). it then writes this routing information to the interrupt line field in the function?s pci configuration space. device driver software must then hook the interrupt using the information in the interrupt line field. interrupt status for al l sixteen sources of interrupt is available using the gis register in the local configuration register set, which can be accessed using i/o or memory accessed from both logical functions. this facility enables each function to snoop on interrupts asserted from the other function regardless of the interrupt routing. the interrupt from each uart channel is enabled using the ier register and the mcr register for that uart. if the interrupt is enabled and active, then the device will drive the pci interrupt pi n low. generic device driver software will use the ier register to enable interrupts. the ox16pci954 offers additional interrupt masking ability using gis[19:16] (see section 6.4.8 ). an internal uart channel may assert a pci in terrupt if the interrupt is enabled by ier and gis[19:16]. all interrupts can be enabled / disabled individually using the gis register set in the local configuration registers. when an mio pin is enabled, an external device can assert a pci interrupt by driving that pin. the sense of the mio external interrupt pins (active - high or active - low) is defined in the mic register. the parallel port can also assert an interrupt (note: this effectively disables the mio[0] interrupt).
data sheet revision 1.3 page 27 ox16pci954 oxford semiconductor ltd. 6.6 power management the ox16p ci954 is compliant with pci power management specification revision 1.0. each logical function implements its own set of power management registers and supports the power states d0, d2 and d3. power management is accomplished by power - down and power - up req uests, asserted via interrupts and the pme# pin respectively. each function can assert the pme# pin independently. the pme# pin is de - asserted when the sticky pme_status bit is cleared in both functions. power - down request is not defined by power managem ent 1.0. it is a device - specific feature and requires a bespoke device driver implementation. the device driver can either implement the power - down itself or in the case of function 0, use a special interrupt and power - down features offered by the device t o determine when the uarts are ready for power - down. the pme# pin can, in certain cases, activate the pme# signal when power is removed from the device, which will cause the pc to wake up from low - power state d3(cold). to ensure full cross - compatibility with systemboard implementations, use of an isolator fet is recommended. if power management capabilities are not required, the pme# pin can be treated as no - connect. 6.6.1 power management of function 0 function 0 can be configured to monitor the activity of t he serial channels, and issue a power - down interrupt when all four ports are inactive (no interrupts pending and both transmitter and receiver are idle). it can also issue a wake - up request on the pme# line from power states d2 and d3. the conditions for i nactive mode are the same as the ones for sleep - mode (see section 7.6.4 ); however power management operation and 16c950 sleep mode are separate and independent operations, affording maximum flexibility in power usage. whenever the device driver places function0 in power - state d3, the clock to all internal uarts is shut off immediately and will only be turned on when the device driver places function0 in power - state d0. in this case, only activity on the ri line (the trailing ed ge of a pulse) will assert a wake - up request. wake - up from power sate d2 is configurable, and can be triggered by activity on any combination of modem lines or the serial data input (sin) line. see section 7.11.10 to mask wakeu p events. in case of a wake up request from sin when function0 is in power - state d2, the clock for that channel is turned on so serial data framing can be maintained. when all channels are ready for power - down (i.e. inactive), the power management circuit ry waits for a period of time programmed in power - down filter time (lcc[6:5], see section 6.4.1 ) and if all channels are still inactive, the ox16pci954 can issue a pci interrupt if it is enabled. the filter stops the uarts from issuing too many interrupts whenever the uart activity is intermittent. upon a power down interrupt, the device driver can change the power - state of function0 as required. note that the power - state of the device is only changed by the device driver and at no point will the ox16pci954 change its own power state. the interrupt merely informs the device driver that this pci logical function can is ready for power down. when enabled, the power - down interrupt status is reflected in gis[5] which is normally use d to return the value of mio1. it also uses the corresponding interrupt mask bit, gis[21]. the interrupt masking operation is shown in table 11 . the device driver can enable the power - down request by first writing a power - down f ilter time to lcc[6:5] which is not ?00?. then it can either operate in polling mode by reading gis[5] or use a pci interrupt. when lcc[6:5] is not ?00?, gis[5] will be a ?sticky - bit? which is set whenever there is power - down request from function 0. this bit is cleared when the device driver reads the gis[5] register. gis[5] will assert a pci interrupt if gis[21] is set. function0 implements the pci power management power - states d0, d2 and d3. whenever the device driver changes the power - state to state d2 or d3, function0 takes the following actions: the internal clock to internal uarts is shut down. pci interrupt for function0 is disabled regardless of the value of gis[19:16]. access to i/o or memory bars of function0 is disabled. however, access to the c onfiguration space is still enabled. function0 can issue a wake up request by asserting pme# if it is enabled by pmcsr[8] of function0. the pme# assertion is immediate and does not use the power - down filter timer. it operates even if lcc[6:5] is set to ?0 0?. the wake up condition for function0 is as follows: - when function0 is in power - state d3, a trailing edge on the modem line ?ri? asserts pme# as long pmcsr[8] is set. when function0 is in power - state d3, a change in the state of any modem line which is enabled by a 16c950 - specific mask bit, or a change in the state of the serial input line if enabled by a 16c950 - specific mask bit can issue a wake up request by asserting the pme# signal (see section 8.4.11). after a hardware reset all of these mask bits are cleared to enable wake up pme# assertion from all modem lines and the sin line. as the wake up operation requires at least one mask bit to be enabled, the device driver can for example disable the masks from three uart channels so that only one channel can issue a wake up request, or
data sheet revision 1.3 page 28 ox16pci954 oxford semiconductor ltd. disable all masks with the exception of the ring indicator, so only a modem ring can wake up the computer. when function0 issues a wake up request, the pme_status (pmcsr[15]) will be set. this is a sticky bit which will be cleared by writing a ?1? to it. while pme_en (pmcsr[8]) in function0 is set, pme_status will assert the pme# pin to inform the device driver that a power management wake up event has occurred. after a wake up event is signalled, the device driver is expec ted to return the function to the d0 power - state. 6.6.2 power management of function 1 the power - down request for the local bus (function1) is application - dependent. the device driver can use any of the multi - purpose i/o lines, mio[12:3] to issue a power - down request. function1 implements the pci power management power - states d0, d2 and d3. whenever the device driver changes the power - state to state d2 or d3, function1 takes the following actions: - the external uart_clk_out pin is disabled regardless of the programmed value in lcc[2]. the local bus clock pin, lbck, is disabled regardless of the programmed value in lt2[30]. the pci interrupt for function1 is disabled. access to i/o or memory bars of function1 is disabled. however, access to the configuration s pace is still enabled. the device driver can optionally assert/de - assert any of its selected (design dependant) mio pins to switch off vcc, disable other external clocks, or activate shut - down modes to any external devices on the local bus. function1 can issue a wake up request by using the mio2 pin. when lcc[7] is set, rising or falling edge of mio2 will cause function1 to issue a wake up request by setting pme_status = (pmcsr[15]), if it is enabled by pmcsr[8] of function1. when lcc[7] is set, the mio2 p in will remain in input mode regardless of the value programmed in mic[5], however mic[4] still controls the input sense. pme_status is a sticky bit which will be cleared by writing a ?1? to it. while pme_en (pmcsr[8]) bit in function1 is set, pme_status w ill assert the pme# pin to inform the device driver that a power management wake up event has occurred. after a wake up event is signalled, the device driver is expected to return the function to the d0 power - state. settings for wake up events are shown in table 12 . lcc[6:5] gis[21] power - down filter time operation 00 x n/a function0 power - down interrupt is disabled. mio1 can assert as interrupt is gis[21] is set. 01 0 4 s function0 power - down interrupt is disabled. gis[5] 1 0 0 129 s reflects the state of the internal power - down mode for 11 0 518 s polling operation. mio1 interrupt is disabled. 01 1 4 s function0 power - down is enabled. gis[5] reflects the state 10 1 129 s of the internal power - down mode. mio1 interrupt is 11 1 515 s disabled. table 11 : function 0 (uarts) power down interrupt settings lcc[7] mic[4] mio2 rising mio2 falling function1 pme_status 0 x x x remains unchanged 1 0 yes x gets set 1 0 no x remains unchanged 1 1 x yes gets set 1 1 x no remains unchanged table 12 : function 1 (local bus) wake - up configuration
data sheet revision 1.3 page 29 ox16pci954 oxford semiconductor ltd. 7 i nternal ox16c950 uart s each of the four uart channels in the ox16pci954 operates individually as an ox16c950 high - peformance serial por t. each channel has its own full set of registers, but all share a common clock and fifosel pin. after a device reset, a common configuration state is loaded into all four channels, but after this time each can be operated individually through its own 8 - by te block of addressable space. 7.1 operation ? mode selection each channel is backward compatible with the 16c450, 16c550, 16c654 and 16c750 uarts. the operation of the ports depends on a number of mode settings, which are referred to throughout this section. the modes, conditions and corresponding fifo depth are tabulated below: uart mode fifo size fcr[0] enhanced mode (efr[4]=1) fcr[5] (guarded with lcr[7] = 1) fifosel pin 450 1 0 x x x 550 16 1 0 0 0 extended 550 128 1 0 x 1 650 128 1 1 x x 750 128 1 0 1 0 950 1 128 1 1 x x table 13 : uart mode configuration note 1: 950 mode configuration is identical to 650 configuration 7.1.1 450 mode after a hardware reset, bit 0 of the fifo control register (?fcr?) is cleared, hence the uarts a re compatible with the 16c450. the transmitter and receiver fifos (referred to as the ?transmit holding register? and ?receiver holding register? respectively) have a depth of one. this is referred to as ?byte mode?. when fcr[0] is cleared, all other mode selection parameters are ignored. 7.1.2 550 mode connect fifosel to gnd. after a hardware reset, writing a 1 to fcr[0] will increase the fifo size to 16, providing compatibility with 16c550 devices. 7.1.3 extended 550 mode connect fifosel to vdd. writing a 1 to fcr [0] will now increase the fifo size to 128, thus providing a 550 device with 128 deep fifos. 7.1.4 750 mode for compatibility with 16c750, connect fifosel to gnd. writing a 1 to fcr[0] will increase the fifo size to 16. in a similar fashion to 16c750, the fifo size can be further increased to 128 by writing a 1 to fcr[5]. note that access to fcr[5] is protected by lcr[7]. i.e., to set fcr[5], software should first set lcr[7] to temporarily remove the guard. once fcr[5] is set, the software should clear lcr[7] for normal operation. the 16c750 additional features are available as long as the uart is not put into enhanced mode; i.e. ensure efr[4] = ?0?. these features are: deeper fifos automatic rts/cts out - of - band flow control sleep mode 7.1.5 650 mode the ox16c95 0 is compatible with the 16c650 when efr[4] is set, i.e. the device is in enhanced mode. as 650 software drivers usually put the device in enhanced mode, running 650 drivers on the one of the uart channels will result in 650 compatibility with 128 deep fif os, as long as fcr[0] is set. this is regardless of the state of the fifosel pin. note that the 650 emulation mode of the ox16pci954 provides 128 - deep fifos rather than the 32 provided by a legacy 16c654.
data sheet revision 1.3 page 30 ox16pci954 oxford semiconductor ltd. in enhanced (650) mode the device has the follo wing features available over those provided by a generic 550. (note: some of these are similar to those provided in 750 mode, but enabled using different registers). deeper fifos sleep mode automatic in - band flow control special character detection infra - red ?irda - format? transmit and receive mode transmit trigger levels optional clock prescaler 7.1.6 950 mode the additional features offered in 950 mode generally only apply when the uart is in enhanced mode (efr[4]=?1?). provided fcr[0] is set, in enhanced mod e the fifo size is 128 regardless of the state of fifosel. note that 950 mode configuration is identical to that of 650 mode, however additional 950 specific features are enabled using the additional control register ?acr? (see section 7.11.3 ). in addition to larger fifos and higher baud rates, the enhancements of the 950 mode over 650 emulation mode are: selectable arbitrary trigger levels for the receiver and transmitter fifo interrupts improved automatic flo w control using selectable arbitrary thresholds dsr#/dtr# automatic flow control transmitter and receiver can be optionally disabled software reset of device readable fifo fill levels optional generation of an rs - 485 buffer enable signal four - byte device i dentification (0x16c95001) readable status for automatic in - band and out - of - band flow control external 1x clock modes (see section 7.10.4 ) flexible ?m+n/8? clock prescaler (see section 7.10.2 ) programmable sample clock to allow data rates up to 15 mbps (see section 7.10.3 ). 9 - bit data mode readable fcr register the 950 trigger levels are enabled when acr[5] is set where bits 4 to 7 of fcr are ignored. the n arbitrary trigger levels can be defined in rtl, ttl, fcl and fch registers (see section 7.11 ). the additional status register (?asr?) offers flow control status for the local and remote transmitters. fifo levels are readable using rfl and tfl registers. the uart has a flexible prescaler capable of dividing the system clock by any value between 1 and 31.875 in steps of 0.125. it divides the system clock by an arbitrary value in ?m+n/8? format, where m and n are 5 - and 3 - bit b inary numbers programmed in cpr[7:3] and cpr[2:0] respectively. this arrangement offers a great deal of flexibility when choosing an input clock frequency to synthesise arbitrary baud rates. the default division value is 4 to provide backward compatibilit y with 16c650 devices. the user may apply an external 1x (or nx) clock for the transmitter and receiver to the ri# and dsr# pin respectively. the transmitter clock may instead be asserted on the dtr# pin. the external clock options are selected through t he cks register (offset 0x02 of icr). it is also possible to define the over - sampling rate used by the transmitter and receiver clocks. the 16c450/16c550 and compatible devices employ 16 times over - sampling, where there are 16 clock cycles per bit. howeve r the 95x uart channels can employ any over - sampling rate from 4 to 16 by programming the tcr register. this allows the data rates to be increased to 460.8 kbps using a 1.8432mhz clock, or 15 mbps using a 60 mhz clock. the default value after a reset for t his register is 0x00, which corresponds to a 16 cycle sampling clock. writing 0x01, 0x02 or 0x03 will also result in a 16 cycle sampling clock. to program the value to any value from 4 to 15 it is necessary to write this value into the tcr i.e. to set the device to a 13 cycle sampling clock it would be necessary to write 0x0d to tcr. for further information see section 7.10.3 the uarts also offer 9 - bit data frames for multi - drop industrial applications.
data sheet revision 1.3 page 31 ox16pci954 oxford semiconductor ltd. 7.2 register description tables each uart is accessed through an 8 - byte block of i/o space (or through memory space). since there are more than 8 registers, the mapping is also dependent on the state of the line control register ?lcr? and additional control register ?acr?: 1. lcr[7 ]=1 enables the divider latch registers dll and dlm. 2. lcr specifies the data format used for both transmitter and receiver. writing 0xbf (an unused format) to lcr enables access to the 650 compatible register set. writing this value will set lcr[7] but leav es lcr[6:0] unchanged. therefore, the data format of the transmitter and receiver data is not affected. write the desired lcr value to exit from this selection. 3. acr[7]=1 enables access to the 950 specific registers. 4. acr[6]=1 enables access to the indexed c ontrol register set (icr) registers as described on page 33 . register name address r/w bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 thr 1 000 w data to be transmitted rhr 1 000 r data received ier 1,2 650/950 mode cts interrupt mask rts interrupt mask special char. detect 550/750 mode 001 r /w unused alternate sleep mode sleep mode modem interrupt mask rx stat interrupt mask thre interrupt mask rxrdy interrupt mask fcr 3 650 mode rhr trigger level thr trigg er level 750 mode rhr trigger level fifo size unused 950 mode 010 w unused tx trigger enable flush thr flush rhr enable fifo isr 3 010 r fifos enabled interrupt priority (enhanced mode) interrupt priority (all modes) interrupt pending lcr 4 011 r/w divisor latch access tx break force parity odd / even parity parity enable number of stop bits data length mcr 3,4 550/750 mode unused cts & rts flow control 650/950 mode 100 r/w baud prescale irda mode xon - any enable internal loop back unused rts dtr lsr 3,5 normal data error tx empty thr empty rx break framing error parity error overrun error rxrdy 9 - bit data mode 101 r 9 th rx data bit msr 3 110 r dcd ri dsr cts delta dcd trailing ri edge delta dsr delta cts spr 3 normal temporary data storage register and indexed control register offset value bits 9 - bit data mode 111 r/w unused 9 th tx data bit additional standard registers ? these registers require divisor latch access bit (lcr[7]) to be set to 1. dll 000 r/w divisor latch b its [7:0] (least significant byte) dlm 001 r/w divisor latch bits [15:8] (most significant byte) table 14 : standard 550 compatible registers
data sheet revision 1.3 page 32 ox16pci954 oxford semiconductor ltd. register name address r/w bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 to ac cess these registers lcr must be set to 0xbf efr 010 r/w cts flow control rts flow control special char detect enhance mode in - band flow control mode xon1 100 r/w xon character 1 9 - bit mode special character 1 xon2 101 r/w xon character 2 9 - bit mo de special character 2 xoff1 110 r/w xoff character 1 9 - bit mode special character 3 xoff2 111 r/w xoff character 2 9 - bit mode special character 4 table 15 : 650 compatible registers register name address r/w bit 7 b it 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 asr 1,6,7 001 r/w 7 tx idle fifo size fifo - sel special char detect dtr rts remote tx disabled tx disabled rfl 6 011 r number of characters in the receiver fifo tfl 3,6 100 r number of characters in the transmit ter fifo icr 3,8,9 101 r/w data read/written depends on the value written to the spr prior to the access of this register (see table 17 ) table 16 : 950 specific registers register access notes: note 1: requires lcr[7] = 0 note 2: requires acr[7] = 0 note 3: requires that last value written to lcr was not 0xbf note 4: to read this register acr[7] must be = 0 note 5: to read this register acr[6] must be = 0 note 6: requires acr[7] = 1 note 7: only bits 0 a nd 1 of this register can be written note 8: to read this register acr[6] must be = 1 note 9: this register acts as a window through which to read and write registers in the indexed control register set
data sheet revision 1.3 page 33 ox16pci954 oxford semiconductor ltd. register name spr offset 10 r/w bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 indexed control register set acr 0x00 r/w addit - ional status enable icr read enable 950 trigger level enable dtr definition and control auto dsr flow control enable tx disable rx disable cpr 0x01 r/w 5 bit ?integer? part o f clock prescaler 3 bit ?fractional? part of clock prescaler tcr 0x02 r/w unused 4 bit n - times clock selection bits [3:0] cks 0x03 r/w tx 1x mode tx clk select bdout on dtr dtr 1x tx clk rx 1x mode 0 receiver clock sel[1:0] ttl 0x04 r/w unused transmitt er interrupt trigger level (0 - 127) rtl 0x05 r/w unused receiver interrupt trigger level (1 - 127) fcl 0x06 r/w unused automatic flow control lower trigger level (0 - 127) fch 0x07 r/w unused automatic flow control higher trigger level (1 - 127) id1 0x08 r ha rdwired id byte 1 (0x16) id2 0x09 r hardwired id byte 1 (0xc9) id3 0x0a r hardwired id byte 1 (0x50) rev 0x0b r hardwired revision byte (0x01) csr 0x0c w writing 0x00 to this register will reset the uart (except the cks register) nmr 0x0d r/w unused 9 th bit schar 4 9 th bit schar 3 9 th bit schar 2 9 th bit schar 1 9 th - bit int. en. 9 bit enable mdm 0x0e r/w 0 0 sin wakeup disable modem wakeup disable d dcd wakeup disable trailing ri edge disable d dsr wakeup disable d cts wakeup disable rfc 0x0f r fcr[7 ] fcr[6] fcr[5] fcr[4] fcr[3] fcr[2] fcr[1] fcr[0] gds 0x10 r 0 0 0 0 0 0 0 good data status table 17 : indexed control register set note 10: the spr offset column indicates the value that must be written into spr prior to reading / writing any of the indexed control registers via icr. offset values not listed in the table are reserved for future use and must not be used. to read or write to any of the indexed controlled registers use the following procedure: writing to icr registers: ensure that the last value written to lcr was not 0xbf (reserved for 650 compatible register access value). write the desired offset to spr (address 111b). write the desired value to icr (address 101b). reading from icr registers: ensure that the last value writ ten to lcr was not 0xbf (see above). write 0x00 offset to spr to select acr. set bit 6 of acr (icr read enable) by writing x1xxxxxxb to address 101b. ensure that other bits in acr are not changed. (software drivers should keep a copy of the contents of the acr elsewhere since reading icr involves overwriting acr!) write the desired offset to spr (address 111b). read the desired value from icr (address 101b). write 0x00 offset to spr to select acr. clear bit 6 of acr bye writing x0xxxxxxb to icr, thus enabli ng access to standard registers again.
data sheet revision 1.3 page 34 ox16pci954 oxford semiconductor ltd. 7.3 reset configuration 7.3.1 hardware reset after a hardware reset, all writable registers are reset to 0x00, with the following exceptions: dll, which is reset to 0x01. cpr, which is reset to 0x20. the state of read - only registers following a hardware reset is as follows: rhr[7:0]: indeterminate rfl[6:0]: 0000000 2 tfl[6:0]: 0000000 2 lsr[7:0]: 0x60 signifying that both the transmitter and the transmitter fifo are empty msr[3:0]: 0000 2 msr[7:4]: dependent on modem input l ines dcd, ri, dsr and cts respectively isr[7:0]: 0x01, i.e. no interrupts are pending asr[7:0]: 1xx00000 2 the reset state of output signals are tabulated below: signal reset state sout inactive high rts# inactive high dtr# inactive high table 18 : output signal reset state 7.3.2 software reset an additional feature available in the ox16c950 uart is software resetting of the serial channel. this command has the same effect on a single channel as a hardware reset except it does not re set the clock source selections (i.e. cks register). to reset the uart write 0x00 to the channel software reset register ?csr?.
data sheet revision 1.3 page 35 ox16pci954 oxford semiconductor ltd. 7.4 transmitter and receiver fifos both the transmitter and receiver have associated holding registers (fifos), referred to a s the transmitter holding register (thr) and receiver holding register (rhr) respectively. in normal operation, when the transmitter finishes transmitting a byte it will remove the next data from the top of the thr and proceed to transmit it. if the thr i s empty, it will wait until data is written into it. if thr is empty and the last character being transmitted has been completed (i.e. the transmitter shift register is empty) the transmitter is said to be idle. similarly, when the receiver finishes receiv ing a byte, it will transfer it to the bottom of the rhr. if the rhr is full, an overrun condition will occur (see section 7.5.3 ). data is written into the bottom of the thr queue and read from the top of the rhr queue complet ely asynchronously to the operation of the transmitter and receiver. the size of the fifos is dependent on the setting of the fcr register. when in byte mode, these fifos only accept one byte at a time before indicating that they are full; this is compati ble with the 16c450. when in a fifo mode, the size of the fifos is either 16 (compatible with the 16c550) or 128. data written to the thr when it is full is lost. data read from the rhr when it is empty is invalid. the empty or full status of the fifos a re indicated in the line status register ?lsr? (see section 7.5.3 ). interrupts are generated when the uart is ready for data transfer to/from the fifos. the number of items in each fifo may also be read back from the transmitte r fifo level (tfl) and receiver fifo level (rfl) registers (see section 7.11.2 ). 7.4.1 fifo control register ?fcr? fifo setup: fcr[0]: enable fifo mode logic 0 t byte mode. logic 1 t fifo mode. this bit should be enabled before setting the fifo trigger levels. fcr[1]: flush rhr logic 0 t no change. logic 1 t flushes the contents of the rhr this is only operative when already in a fifo mode. the rhr is automatically flushed whenever changing between byte mode and a fifo mode. th is bit will return to zero after clearing the fifos. fcr[2]: flush thr logic 0 t no change. logic 1 t flushes the contents of the thr, in the same manner as fcr[1] does for the rhr. thr trigger levels: fcr[3]: tx trigger level enable logic 0 t transmit trigger levels enabled logic 1 t transmit trigger levels disabled when fcr[3]=0, the transmitter trigger level is always set to 1, thus ignoring fcr[5:4]. alternatively, 950 - mode trigger levels can be set using acr[5]. fcr[5:4]: compatible trigger level s 450, 550 and extended 550 modes: the transmitter interrupt trigger levels are set to 1 and fcr[5:4] are ignored. 650 mode: in 650 mode the transmitter interrupt trigger levels can be set to the following values: fcr[5:4] transmit interrupt trigger le vel 00 16 01 32 10 64 11 112 table 19 : transmit interrupt trigger levels these levels only apply when in enhanced mode and when fcr[3] is set, otherwise the trigger level is set to 1. a transmitter empty interrupt will be gene rated (if enabled) if the tfl falls below the trigger level. 750 mode: in 750 compatible mode, transmitter trigger level is set to 1, fcr[4] is unused and fcr[5] defines the fifo depth as follows: fcr[5]=0: fifo size is 16 bytes. fcr[5]=1: fifo size is 1 28 bytes. in non - enhanced mode and when fifosel pin is low, fcr[5] is writable only when lcr[7] is set. note that in enhanced mode, the fifo size is increased to 128 bytes when fcr[0] is set.
data sheet revision 1.3 page 36 ox16pci954 oxford semiconductor ltd. 950 mode: setting acr[5]=1 enables 950 - mode trigger levels set using the ttl register (see section 7.11.4 ), fcr[5:4] are ignored. rhr trigger levels fcr[7:6]: compatible trigger levels 450, 550, extended 550, 650 and 750 modes: the receiver fifo trigger levels are defined using fcr[7:6] . the interrupt trigger level and upper flow control trigger level where appropriate are defined by l1 in the table below. l2 defines the lower flow control trigger level. separate upper and lower flow control trigger levels introduce a hysteresis element in in - band and out - of - band flow control (see section 7.9 ). in byte mode (450 mode) the trigger levels are all set to 1. 950 mode: in similar fashion to for transmitter trigger levels, setting acr[5]=1 enables 950 - mode receiv er trigger levels. fcr[7:6] are ignored. mode 550 fifo size 16 ext. 550 / 750 fifo size 128 650 fifo size 128 fcr [7:6] l1 l2 l1 l2 l1 l2 00 1 n/a 1 1 16 1 01 4 n/a 32 1 32 16 10 8 n/a 64 1 112 32 11 14 n/a 112 1 120 112 table 20 : compatible receiver trigger levels a receiver data interrupt will be generated (if enabled) if the receiver fifo level (?rfl?) reaches the upper trigger level. 7.5 line control & status 7.5.1 false start bit detection on the falling edge of a start bit, the receiver will wait for 1/2 bit and re - synchronise the receiver?s sampling clock onto the centre of the start bit. the start bit is valid if the sin line is still low at this mid - bit sample and the receiver will proceed to read in a data character. ver ifying the start bit prevents noise generating spurious character generation. once the first stop bit has been sampled, the received data is transferred to the rhr and the receiver will then wait for a low transition on sin (signifying the next start bit). the receiver will continue receiving data even if the rhr is full or the receiver has been disabled (see section 7.11.3 ) in order to maintain framing synchronisation. the only difference is that the received data does not get transferred to the rhr. 7.5.2 line control register ?lcr? the lcr specifies the data format that is common to both transmitter and receiver. writing 0xbf to lcr enables access to the efr, xon1, xoff1, xon2 and xoff2, dll and dlm registers. this value (0xbf) co rresponds to an unused data format. writing the value 0xbf to lcr will set lcr[7] but leaves lcr[6:0] unchanged. therefore, the data format of the transmitter and receiver data is not affected. write the desired lcr value to exit from this selection. lcr[ 1:0]: data length lcr[1:0] determines the data length of serial characters. note however, that these values are ignored in 9 - bit data framing mode, i.e. when nmr[0] is set. lcr[1:0] data length 00 5 bits 01 6 bits 10 7 bits 11 8 bits table 21 : lcr data length configuration lcr[2]: number of stop bits lcr[2] defines the number of stop bits per serial character. lcr[2] data length no. stop bits 0 5,6,7,8 1 1 5 1.5 1 6,7,8 2 table 22 : lcr stop bit num ber configuration
data sheet revision 1.3 page 37 ox16pci954 oxford semiconductor ltd. lcr[5:3]: parity type the selected parity type will be generated during transmission and checked by the receiver, which may produce a parity error as a result. in 9 - bit mode parity is disabled and lcr[5:3] is ignored. lcr[5:3] parity t ype xx0 no parity bit 001 odd parity bit 011 even parity bit 101 parity bit forced to 1 111 parity bit forced to 0 table 23 : lcr parity configuration lcr[6]: transmission break logic 0 t break transmission disabled. logic 1 t forces the transmitter data output sout low to alert the communication terminal, or send zeros in irda mode. it is the responsibility of the software driver to ensure that the break duration is longer than the character period for it to be recognised rem otely as a break rather than data. lcr[7]: divisor latch enable logic 0 t access to dll and dlm registers disabled. logic 1 t access to dll and dlm registers enabled. 7.5.3 line status register ?lsr? this register provides the status of data transfer to cpu. lsr[0]: rhr data available logic 0 t rhr is empty: no data available logic 1 t rhr is not empty: data is available to be read. lsr[1]: rhr overrun error logic 0 t no overrun error. logic 1 t data was received when the rhr was full. an overrun error has oc curred. the error is flagged when the data would normally have been transferred to the rhr. lsr[2]: received data parity error logic 0 t no parity error in normal mode or 9 th bit of received data is ?0? in 9 - bit mode. logic 1 t data has been received that did not have correct parity in normal mode or 9 th bit of received data is ?1? in 9 - bit mode. the parity error flag will be set when the data item in error is at the top of the rhr and cleared following a read of the lsr. in 9 - bit mode lsr[2] is no longer a flag and corresponds to the 9 th bit of the received data in rhr. lsr[3]: received data framing error logic 0 t no framing error. logic 1 t data has been received with an invalid stop bit. this status bit is set and cleared in the same manner as lsr[2] . when a framing error occurs, the uart will try to re - synchronise by assuming that the error was due to sampling the start bit of the next data item. lsr[4]: received break error logic 0 t no receiver break error. logic 1 t the receiver received a break. a break condition occurs when the sin line goes low (normally signifying a start bit) and stays low throughout the start, data, parity and first stop bit. (note that the sin line is sampled at the bit rate). one zero character with associated break flag set will be transferred to the rhr and the receiver will then wait until the sin line returns high. the lsr[4] break flag will be set when this data item gets to the top of the rhr and it is cleared following a read of the lsr. lsr[5]: thr empty logic 0 t transmitter fifo (thr) is not empty. logic 1 t transmitter fifo (thr) is empty. lsr[6]: transmitter and thr empty logic 0 t the transmitter is not idle logic 1 t thr is empty and the transmitter has completed the character in shift register and is in idl e mode. (i.e. set whenever the transmitter shift register and the thr are both empty.) lsr[7]: receiver data error logic 0 t either there are no receiver data errors in the fifo or it was cleared by a read of lsr. logic 1 t at least one parity error, fram ing error or break indication in the fifo. in 450 mode lsr[7] is permanently cleared, otherwise this bit will be set when an erroneous character is transferred from the receiver to the rhr. it is cleared when the lsr is read. note that in 16c550 this bit is only cleared when all of the erroneous data are removed from the fifo . in 9 - bit data framing mode parity is permanently disabled, so this bit is not affected by lsr[2].
data sheet revision 1.3 page 38 ox16pci954 oxford semiconductor ltd. 7.6 interrupts & sleep mode the serial channel interrupts are asserted on the pci in ta# pin. the interrupts can be enabled or disabled using the gis register interrupt mask (see section 6.4.8 ) and the ier register. unlike generic 16c550 devices, the interrupt can not be disabled using the implementation - specif ic mcr[3]. 7.6.1 interrupt enable register ?ier? serial channel interrupts are enabled using the interrupt enable register (?ier?). ier[0]: receiver data available interrupt mask logic 0 t disable the receiver ready interrupt. logic 1 t enable the receiver re ady interrupt. ier[1]: transmitter empty interrupt mask logic 0 t disable the transmitter empty interrupt. logic 1 t enable the transmitter empty interrupt. ier[2]: receiver status interrupt normal mode: logic 0 t disable the receiver status interrupt. l ogic 1 t enable the receiver status interrupt. 9 - bit data mode: logic 0 t disable receiver status and address bit interrupt. logic 1 t enable receiver status and address bit interrupt. in 9 - bit mode (i.e. when nmr[0] is set), reception of a character with the address - bit (i.e. 9 th bit) set can generate a level 1 interrupt if ier[2] is set. ier[3]: modem status interrupt mask logic 0 t disable the modem status interrupt. logic 1 t enable the modem status interrupt. ier[4]: sleep mode logic 0 t disable sle ep mode. logic 1 t enable sleep mode whereby the internal clock of the channel is switched off. sleep mode is described in section 7.6. 4 . ier[5]: special character interrupt mask or alternate sleep mode 9 - bit data framing m ode: logic 0 t disable the received special character interrupt. logic 1 t enable the received special character interrupt. in 9 - bit data mode, the receiver can detect up to four special characters programmed in the special character registers (see map on page 32 ). when ier[5] is set, a level 5 interrupt is asserted when the receiver character matches one of the values programmed. 650/950 modes (non - 9 - bit data framing): logic 0 t disable the special character receive interr upt. logic 1 t enable the special character receive interrupt. in 16c650 compatible mode when the device is in enhanced mode (efr[4]=1), this bit enables the detection of special characters. it enables both the detection of xoff characters (when in - band flow control is enabled via efr[3:0]) and the detection of the xoff2 special character (when enabled via efr[5]). 750 mode (non - 9 - bit data framing): logic 0 t disable alternate sleep mode. logic 1 t enable alternate sleep mode whereby the internal clock of the channel is switched off. in 16c750 compatible mode (i.e. non - enhanced mode), this bit is used an alternate sleep mode and has the same effect as ier[4]. ier[6]: rts interrupt mask logic 0 t disable the rts interrupt. logic 1 t enable the rts in terrupt. this enable is only operative in enhanced mode (efr[4]=1). in non - enhanced mode, rts interrupt is permanently enabled ier[7]: cts interrupt mask logic 0 t disable the cts interrupt. logic 1 t enable the cts interrupt. this enable is only op erative in enhanced mode (efr[4]=1). in non - enhanced mode, cts interrupt is permanently enabled.
data sheet revision 1.3 page 39 ox16pci954 oxford semiconductor ltd. 7.6.2 interrupt status register ?isr? the source of the highest priority interrupt pending is indicated by the contents of the interrupt status register ?isr?. the re are nine sources of interrupt at six levels of priority (1 is the highest) as shown in table 24 . level interrupt source isr[5:0] see note 3 - no interrupt pending 1 000001 1 receiver status error or address - bit detected in 9 - bit mode 000110 2a receiver data available 000100 2b receiver time - out 001100 3 transmitter thr empty 000010 4 modem status change 000000 5 2 in - band flow control xoff or special character (xoff2) or special character 1, 2, 3 or 4 or bit 9 set in 9 - b it mode 010000 6 2 cts or rts change of state 100000 table 24 : interrupt status identification codes note1: isr[0] indicates whether any interrupts are pending. note2: interrupts of priority levels 5 and 6 cannot occur unless the uart is in enhanced mode. note3: isr[5] is only used in 650 & 950 modes. in 750 mode, it is ?0? when fifo size is 16 and ?1? when fifo size is 128. in all other modes it is permanently set to 0 7.6.3 interrupt description level 1: receiver status error inte rrupt (isr[5:0]=?000110?): normal (non - 9 - bit) mode: this interrupt is active whenever any of lsr[1], lsr[2], lsr[3] or lsr[4] are set. these flags are cleared following a read of the lsr. this interrupt is masked with ier[2]. 9 - bit mode: this interrupt is active whenever any of lsr[1], lsr[2], lsr[3] or lsr[4] are set. the receiver error interrupt due to lsr[1], lsr[3] and lsr[4] is masked with ier[3]. the ?address - bit? received interrupt is masked with nmr[1]. the software driver can differentiate between receiver status error and received address - bit (9 th data bit) interrupt by examining lsr[1] and lsr[7]. in 9 - bit mode lsr[7] is only set when lsr[3] or lsr[4] is set and it is not affected by lsr[2] (i.e. 9 th data bit). level 2a: receiver data availab le interrupt (isr[5:0]=?000100?): this interrupt is active whenever the receiver fifo level is above the interrupt trigger level. level 2b: receiver time - out interrupt (isr[5:0]=?001100?): a receiver time - out event, which may cause an interrupt, will oc cur when all of the following conditions are true: the uart is in a fifo mode there is data in the rhr. there has been no read of the rhr for a period of time greater than the time - out period. there has been no new data written into the rhr for a period of time greater than the time - out period. the time - out period is four times the character period (including start and stop bits) measured from the centre of the first stop bit of the last data item received. reading the first data item in rhr clears this in terrupt. level 3: transmitter empty interrupt (isr[5:0]=?000010?): this interrupt is set when the transmit fifo level falls below the trigger level. it is cleared on an isr read of a level 3 interrupt or by writing more data to the thr so that the trigg er level is exceeded. note that when 16c950 mode trigger levels are enabled (acr[5]=1) and the transmitter trigger level of zero is selected (ttl=0x00), a transmitter empty interrupt will only be asserted when both the transmitter fifo and transmitter shif t register are empty and the sout line has returned to idle marking state. level 4: modem change interrupt (isr[5:0]=?000000?): this interrupt is set by a modem change flag (msr[0], msr[1], msr[2] or msr[3]) becoming active due to changes in the input m odem lines. this interrupt is cleared following a read of the msr. level 5: receiver in - band flow control (xoff) detect interrupt, receiver special character (xoff2) detect interrupt, receiver special character 1, 2, 3 or 4 interrupt or 9 th bit set inter rupt in 9 - bit mode (isr[5:0]=?010000?): a level 5 interrupt can only occur in enhanced - mode when any of the following conditions are met: a valid xoff character is received while in - band flow control is enabled. a received character matches xoff2 while sp ecial character detection is enabled, i.e. efr[5]=1. a received character matches special character 1, 2, 3 or 4 in 9 - bit mode (see section 7.11.9 ). it is cleared on an isr read of a level 5 interrupt.
data sheet revision 1.3 page 40 ox16pci954 oxford semiconductor ltd. level 6 : cts or rts changed interrupt (isr[5:0]=?100000?): this interrupt is set whenever any of the cts# or rts# pins changes state from low to high. it is cleared on an isr read of a level 6 interrupt. 7.6.4 sleep mode for a channel to go into sleep mode, all of t he following conditions must be met: sleep mode enabled (ier[4]=1 in 650/950 modes, or ier[5]=1 in 750 mode): the transmitter is idle, i.e. the transmitter shift register and fifo are both empty. sin is high. the receiver is idle. the receiver fifo is em pty (lsr[0]=0). the uart is not in loopback mode (mcr[4]=0). changes on modem input lines have been acknowledged (i.e. msr[3:0]=0000). no interrupts are pending. a read of ier[4] (or ier[5] if a 1 was written to that bit instead) shows whether the power - d own request was successful. the uart will retain its programmed state whilst in power - down mode. the channel will automatically exit power - down mode when any of the conditions 1 to 7 becomes false. it may be woken manually by clearing ier[4] (or ier[5] if the alternate sleep mode is enabled). sleep mode operation is not available in irda mode. 7.7 modem interface 7.7.1 modem control register ?mcr? mcr[0]: dtr logic 0 t force dtr# output to inactive (high). logic 1 t force dtr# output to active (low). note tha t dtr# can be used for automatic out - of - band flow control when enabled using acr[4:3] (see section 7.11.3 ). mcr[1]: rts logic 0 t force rts# output to inactive (high). logic 1 t force rts# output to active (low). note that rt s# can be used for automatic out - of - band flow control when enabled using efr[6] (see section 7.9.4 ). mcr[2]: out1 logic 0 t force out1# output low when loopback mode is disabled. logic 1 t force out1# output high. mcr[3]: out 2/external interrupt enable logic 0 t force out2# output low when loopback mode is disabled. if int_sel# is low the external interrupt is in high - impedance state when mcr[3] is cleared. if int_sel# is high mcr[3] does not affect the interrupt. logic 1 t force out2# output high. if int_sel# is low the external interrupt is enabled and operating in normal active (forcing) mode when mcr[3] is high. if int_sel# is high mcr[3] does not affect the interrupt. mcr[4]: loopback mode logic 0 t normal operating m ode. logic 1 t enable local loop - back mode (diagnostics). in local loop - back mode, the transmitter output (sout) and the four modem outputs (dtr#, rts#, out1# and out2#) are set in - active (high), and the receiver inputs sin, cts#, dsr#, dcd#, and ri# are all disabled. internally the transmitter output is connected to the receiver input and dtr#, rts#, out1# and out2# are connected to modem status inputs dsr#, cts#, ri# and dcd# respectively. in this mode, the receiver and transmitter interrupts are fully operational. the modem control interrupts are also operational, but the interrupt sources are now the lower four bits of the modem control register instead of the four modem status inputs. the interrupts are still controlled by the ier. mcr[5]: enable xo n - any in enhanced mode or enable out - of - band flow control in non - enhanced mode 650/950 (enhanced) modes: logic 0 t xon - any is disabled. logic 1 t xon - any is enabled. in enhanced mode (efr[4]=1), this bit enables the xon - any operation. when xon - any is ena bled, any received data will be accepted as a valid xon (see in - band flow control, section 7.9.3 ).
data sheet revision 1.3 page 41 ox16pci954 oxford semiconductor ltd. 750 (normal) mode: logic 0 t cts/rts flow control disabled. logic 1 t cts/rts flow control enabled. in non - enhanced mode, t his bit enables the cts/rts out - of - band flow control. mcr[6]: irda mode logic 0 t standard serial receiver and transmitter data format. logic 1 t data will be transmitted and received in irda format. this function is only available in enhanced mode. it r equires a 16x clock to function correctly. mcr[7]: baud rate prescaler select logic 0 t normal (divide by 1) baud rate generator prescaler selected. logic 1 t divide - by - ?m+n/8? baud rate generator prescaler selected. where m & n are programmed in cpr (i cr offset 0x01). after a hardware reset, cpr defaults to 0x20 (divide - by - 4) and mcr[7] is reset. user writes to this flag will only take effect in enhanced mode. see section 7.9.1 . 7.7.2 modem status register ?msr? msr[0]: delta ct s# indicates that the cts# input has changed since the last time the msr was read. msr[1]: delta dsr# indicates that the dsr# input has changed since the last time the msr was read. msr[2]: trailing edge ri# indicates that the ri# input has changed from low to high since the last time the msr was read. msr[3]: delta dcd# indicates that the dcd# input has changed since the last time the msr was read. msr[4]: cts this bit is the complement of the cts# input. it is equivalent to rts (mcr[1]) in internal lo op - back mode. msr[5]: dsr this bit is the complement of the dsr# input. it is equivalent to dtr (mcr[0]) in internal loop - back mode. msr[6]: ri this bit is the complement of the ri# input. in internal loop - back mode it is equivalent to the internal out1. msr[7]: dcd this bit is the complement of the dcd# input. in internal loop - back mode it is equivalent to the internal out2. 7.8 other standard registers 7.8.1 divisor latch registers ?dll & dlm? the divisor latch registers are used to program the baud rate div isor. this is a value between 1 and 65535 by which the input clock is divided by in order to generate serial baud rates. after a hardware reset, the baud rate used by the transmitter and receiver is given by: divisor inputclock baudrate * 16 = where divisor is give n by dll + ( 256 x dlm ). more flexible baud rate generation options are also available. see section 7.10 for full details. 7.8.2 scratch pad register ?spr? the scratch pad register does not affect operation of the rest of the uart in any way and can be used for temporary data storage. the register may also be used to define an offset value to access the registers in the indexed control register set. for more information on indexed control registers see sections 7.2 and 7.11 .
data sheet revision 1.3 page 42 ox16pci954 oxford semiconductor ltd. 7.9 automatic flow control automatic in - band flow control, automatic out - of - band flow control and special character detection features can be used when in enhanced mode (flow control is software compatibl e with the 16c654). alternatively, 750 - compatible automatic out - of - band flow control can be enabled when in non - enhanced mode. in 950 mode, in - band and out - of - band flow controls are compatible with 16c654 with the addition of fully programmable flow contro l thresholds. 7.9.1 enhanced features register ?efr? writing 0xbf to lcr enables access to the efr and other enhanced mode registers. this value corresponds to an unused data format. writing 0xbf to lcr will set lcr[7] but leaves lcr[6:0] unchanged. therefore, the data format of the transmitter and receiver data is not affected. write the desired lcr value to exit from this selection. note: in - band transmit and receive flow control is disabled in 9 - bit mode. efr[1:0]: in - band receive flow control mode when in - band receive flow control is enabled, the uart compares the received data with the programmed xoff character(s). when this occurs, the uart will disable transmission as soon as any current character transmission is complete. the uart then compares the rece ived data with the programmed xon character(s). when a match occurs, the uart will re - enable transmission (see section 7.11.6 ). for automatic in - band flow control, bit 4 of efr must be set. the combinations of software receiv e flow control can be selected by programming efr[1:0] as follows: logic [00] t in - band receive flow control is disabled. logic [01] t single character in - band receive flow control enabled, recognising xon2 as the xon character and xoff2 as the xoff chara cter. logic [10] t single character in - band receive flow control enabled, recognising xon1 as the xon character and xoff1 and the xoff character. logic [11] t the behaviour of the receive flow control is dependent on the configuration of efr[3:2]. single c haracter in - band receive flow control is enabled, accepting xon1 or xon2 as valid xon characters and xoff1 or xoff2 as valid xoff characters when efr[3:2] = ?01? or ?10?. efr[1:0] should not be set to ?11? when efr[3:2] is ?00?. efr[3:2]: in - band transmit flow control mode when in - band transmit flow control is enabled, xon/xoff character(s) are inserted into the data stream whenever the rfl passes the upper trigger level and falls below the lower trigger level respectively. for automatic in - band flow cont rol, bit 4 of efr must be set. the combinations of software transmit flow control can then be selected by programming efr[3:2] as follows: logic [00] t in - band transmit flow control is disabled. logic [01] t single character in - band transmit flow control enabled, using xon2 as the xon character and xoff2 as the xoff character. logic [10] t single character in - band transmit flow control enabled, using xon1 as the xon character and xoff1 as the xoff character. logic[11] t the value efr[3:2] = ?11? is reserve d for future use and should not be used efr[4]: enhanced mode logic 0 t non - enhanced mode. disables ier bits 4 - 7, isr bits 4 - 5, fcr bits 4 - 5, mcr bits 5 - 7 and in - band flow control. whenever this bit is cleared, the setting of other bits of efr are ignored . logic 1 t enhanced mode. enables the enhanced mode functions. these functions include enabling ier bits 4 - 7, fcr bits 4 - 5, mcr bits 5 - 7. for in - band flow control the software driver must set this bit first. if this bit is set, out - of - band flow control i s configured with efr bits 6 - 7, otherwise out - of - band flow control is compatible with 16c750. efr[5]: enable special character detection logic 0 t special character detection is disabled. logic 1 t while in enhanced mode (efr[4]=1), the uart compares the incoming receiver data with the xoff2 value. upon a correct match, the received data will be transferred to the rhr and a level 5 interrupt (xoff or special character) will be asserted if level 5 interrupts are enabled (ier[5] set to 1). efr[6]: enable a utomatic rts flow control. logic 0 t rts flow control is disabled (default). logic 1 t rts flow control is enabled in enhanced mode (i.e. efr[4] = 1), where the rts# pin will be forced inactive high if the rfl reaches the upper flow control threshold. this will be released when the rfl drops below the lower threshold. 650 and 950 - mode drivers should use this bit to enable rts flow control.
data sheet revision 1.3 page 43 ox16pci954 oxford semiconductor ltd. efr[7]: enable automatic cts flow control. logic 0 t cts flow control is disabled (default). logic 1 t cts flow contro l is enabled in enhanced mode (i.e. efr[4] = 1), where the data transmission is prevented whenever the cts# pin is held inactive high. 650 and 950 - mode drivers should use this bit to enable cts flow control. a 750 - mode driver should set mcr[5] to enable rts/cts flow control. 7.9.2 special character detection in enhanced mode (efr[4]=1), when special character detection is enabled (efr[5]=1) and the receiver matches received data with xoff2, the 'received special character' flag asr[4] will be set and a level 5 interrupt is asserted, if enabled by ier[5]. this flag will be cleared following a read of asr. the received status (i.e. parity and framing) of special characters does not have to be valid for these characters to be accepted as valid matches. 7.9.3 automatic in - band flow control when in - band receive flow control is enabled, the uart will compare the received data with xoff1 or xoff2 characters to detect an xoff condition. when this occurs, the uart will disable transmission as soon as any current character t ransmission is complete. status bits isr[4] and asr[0] will be set. a level 5 interrupt will occur (if enabled by ier[5]). the uart will then compare all received data with xon1 or xon2 characters to detect an xon condition. when this occurs, the uart will re - enable transmission and status bits isr[4] and asr[0] will be cleared. any valid xon/xoff characters will not be written into the rhr. an exception to this rule occurs if special character detection is enabled and an xoff2 character is received that i s a valid xoff. in this instance, the character will be written into the rhr. the received status (i.e. parity and framing) of xon/xoff characters does not have to be valid for these characters to be accepted as valid matches. when the 'xon any' flag (mc r[5]) is set, any received character is accepted as a valid xon condition and the transmitter will be re - enabled. the received data will be transferred to the rhr. when in - band transmit flow control is enabled, the rfl will be sampled whenever the transmi tter is idle (briefly, between characters, or when the thr is empty) and an xon/xoff character will be inserted into the data stream if needed. initially, remote transmissions are enabled and hence asr[1] is clear. if asr[1] is clear and the rfl has passed the upper trigger level (i.e. is above the trigger level), xoff will be sent and asr[1] will be set. if asr[1] is set and the rfl falls below the lower trigger level, xon will be sent and asr[1] will be cleared. if transmit flow control is disabled after an xoff has been sent, an xon will be sent automatically. 7.9.4 automatic out - of - band flow control automatic rts/cts flow control is selected by different means, depending on whether the uart is in enhanced or non - enhanced mode. when in non - enhanced mode, mcr [5] enables both rts and cts flow control. when in enhanced mode, efr[6] enables automatic rts flow control and efr[7] enables automatic cts flow control. this allows software compatibility with both 16c650 and 16c750 drivers. when automatic cts flow cont rol is enabled and the cts# input becomes active, the uart will disable transmission as soon as any current character transmission is complete. transmission is resumed whenever the cts# input becomes inactive. when automatic rts flow control is enabled, the rts# pin will be forced inactive when the rfl reaches the upper trigger level and will return to active when the rfl falls below the lower trigger level. the automatic rts# flow control is anded with mcr[1] and hence is only operational when mcr[1]=1. this allows the software driver to override the automatic flow control and disable the remote transmitter regardless by setting mcr[1]=0 at any time. automatic dtr/dsr flow control behaves in the same manner as rts/cts flow control but is enabled by acr[3 :2], regardless of whether or not the uart is in enhanced mode.
data sheet revision 1.3 page 44 ox16pci954 oxford semiconductor ltd. 7.10 baud rate generation 7.10.1 general operation the uart contains a programmable baud rate generator that is capable of taking any clock input from 1.8432mhz to 60mhz and dividing it by any 16 - bit divisor number from 1 to 65535 written into the dlm (msb) and dll (lsb) registers. in addition to this, a clock prescaler register is provided which can further divide the clock by values in the range 1.0 to 31.875 in steps of 0.125. also, a further featur e is the times clock register ?tcr? which allows the sampling clock to be set to any value between 4 and 16. these clock options allow for highly flexible baud rate generation capabilities from almost any input clock frequency (up to 60mhz). the actual tr ansmitter and receiver baud rate is calculated as follows: prescaler divisor sc inputclock baudrate * * = where : sc = sample clock values defined in tcr[3:0] divisor = dll + ( 256 x dlm ) prescaler = 1 when mcr[7] = ?0? else: = m + ( n / 8 ) where: m = cpr[7:3] (integer par t ? 1 to 31) n = cpr[2:0] (fractional part ? 0.000 to 0.875 ) after a hardware reset, the precaler is bypassed (set to 1) and tcr is set to 0x00 (i.e. sc = 16). assuming this default configuration, the following table gives the divisors required to be pr ogrammed into the dll and dlm registers in order to obtain various standard baud rates: dlm:dll divisor word baud rate (bits per second) 0x0900 50 0x0300 110 0x0180 300 0x00c0 600 0x0060 1,200 0x0030 2,400 0x0018 4,800 0x000c 9,600 0x0006 19,200 0x0004 28,800 0x0003 38,400 0x0002 57,600 0x0001 115,200 table 25 : standard pc com port baud rate divisors (assuming a 1.8432mhz crystal) 7.10.2 clock prescaler register ?cpr? the cpr register is located at offset 0x01 of the icr the prescaler divides the system clock by any value in the range of 1 to ?31 7/8? in steps of 1/8. the divisor takes the form ?m+n/8?, where m is the 5 bit value defined in cpr[7:3] and n is the 3 bit value defined in cpr[2:0]. the prescaler is by - passed an d a prescaler value of ?1? is selected by default when mcr[7] = 0. note that since access to mcr[7] is restricted to enhanced mode only, efr[4] should first be set and then mcr[7] set or cleared as required. for higher baud rates use a higher frequency c lock, e.g. 14.7456mhz, 18.432mhz, 32mhz, 40mhz or 60.0mhz. the flexible prescaler allows system designers to use clocks that are not integer multiples of popular baud rates; when using a non - standard clock frequency, compatibility with existing 16c550 soft ware drivers may be maintained with a minor software patch to program the on - board prescaler to divide the high frequency clock down to 1.8432mhz. table 27 on the following page gives the prescaler values required to operate the uarts at compatible baud rates with various different crystal frequencies. also given is the maximum available baud rates in tcr = 16 and tcr = 4 modes with cpr = 1. 7.10.3 times clock register ?tcr? the tcr register is located at offset 0x02 of the icr the 16c 550 and other compatible devices such as 16c650 and 16c750 use a 16 times (16x) over - sampling channel clock. the 16x over - sampling clock means that the channel clock runs at 16 times the selected serial bit rate. it limits the highest baud rate to 1/16 of the system clock when using a divisor latch value of unity. however, the 16c950 uart is designed in a manner to enable it to accept other multiplications of the bit rate clock. it can use values from 4x to 16x clock as programmed in the tcr as long as the clock (oscillator) frequency error, stability and jitter are within reasonable parameters. upon hardware reset the tcr is reset to 0x00 which means that a 16x clock will be used, for compatibility with the 16c550 and compatibles. the maximum baud - rates av ailable for various system clock frequencies at all of the allowable values of tcr are indicated in table 28 on the following page. these are the
data sheet revision 1.3 page 45 ox16pci954 oxford semiconductor ltd. values in bits - per - second (bps) that are obtained if the divisor lat ch = 0x01 and the prescaler is set to 1. the ox16 p c i 95 4 has the facility to operate at baud - rates up to 15 mbps in normal mode. table 26 indicates how the value in the register corresponds to the number of clock cycles per bit. tcr[3:0] is used to program the clock. tcr[7:4] are unused and will return ?0000? if read. tcr[3:0] clock cycles per bit 0000 to 0011 16 0100 to 1111 4 - 15 table 26 : tcr sample clock configuration use of the tcr does not require the device to be in 650 o r 950 mode although only drivers that have been written to take advantage of the 950 mode features will be able to access this register. writing 0x01 to the tcr will not switch the device into 1x isochronous mode, this is explained in the following section . (tcr has no effect in isochronous mode). if 0x01, 0x10 or 0x11 is written to tcr the device will operate in 16x mode. reading tcr will always return the last value that was written to it irrespective of mode of operation. clock frequency (mhz) cpr val ue effective crystal frequency error from 1.8432mhz (%) max. baud rate with cpr = 1, tcr = 16 max. baud rate with cpr = 1, tcr = 4 1.8432 0x08 (1) 1.8432 0.00 115,200 460,800 7.3728 0x20 (4) 1.8432 0.00 460,800 1,843,200 14.7456 0x40 (8) 1.8432 0.00 9 21,600 3,686,400 18.432 0x50 (10) 1.8432 0.00 1,152,000 4,608,000 32.000 0x8b (17.375) 1.8417 0.08 2,000,000 8,000,000 33.000 0x8f (17.875) 1.8462 0.16 2,062,500 8,250,000 40.000 0xae (21.75) 1.8391 0.22 2,500,000 10,000,000 50.000 0xd9 (27.125) 1.8 433 0.01 3,125,000 12,500,000 60.000 0xff (31.875) 1.8824 2.13 3,750,000 15,000,000 table 27 : example clock options and their associated maximum baud rates system clock (mhz) sampling clock tcr value 1.8432 7.372 14.7456 18.43 2 32 40 50 60 16 0x00 115,200 460,750 921,600 1.152m 2.00m 2.50m 3.125m 3.75m 15 0x0f 122,880 491,467 983,040 1,228,800 2,133,333 2,666,667 3,333,333 4.00m 14 0x0e 131,657 526,571 1,053,257 1,316,571 2,285,714 2,857,143 3,571,429 4,285,714 13 0x0d 141, 785 567,077 1,134,277 1,417,846 2,461,538 3,076,923 3,846,154 4,615,384 12 0x0c 153,600 614,333 1,228,800 1,536,000 2,666,667 3,333,333 4,166,667 5.00m 11 0x0b 167,564 670,182 1,340,509 1,675,636 2,909,091 3,636,364 4,545,455 5,454545 10 0x0a 184,320 73 7,200 1,474,560 1,843,200 3.20m 4.00m 5.00m 6.00m 9 0x09 204,800 819,111 1,638,400 2,048,000 3,555,556 4,444,444 5,555,556 6,666,667 8 0x08 230,400 921,500 1,843,200 2,304,000 4.00m 5.00m 6.25m 7.50m 7 0x07 263,314 1,053,143 2,106,514 2,633,143 4,571,42 9 5,714,286 7,142,857 8,571428 6 0x06 307,200 1,228,667 2,457,600 3,072,000 5,333,333 6,666,667 8,333,333 10.00m 5 0x05 368,640 1,474,400 2,949,120 3,686,400 6.40m 8.00m 10.00m 12.00m 4 0x04 460,800 1,843,000 3,686,400 4,608,000 8.00m 10.00m 12.50m 15.0 0m table 28 : maximum baud rates available at all ?tcr? sampling clock values
data sheet revision 1.3 page 46 ox16pci954 oxford semiconductor ltd. 7.10.4 external 1x clock mode the transmitter and receiver can accept an external clock applied to the ri# and dsr# pins respectively. the clock options are s elected using the cks register (see section 7.11.8 ). the transmitter and receiver may be configured to operate in 1x (i.e. isochronous mode) by setting cks[7] and cks[3], respectively. in isochronous mode, trans mitter or receiver will use the 1x clock (usually, but not necessarily, an external source) where asynchronous framing is maintained using start - , parity - and stop - bits. however serial transmission and reception is synchronised to the 1x clock. in this mod e asynchronous data may be transmitted at baud rates up to 60mbps. the local 1x clock source can be asserted on the dtr# pin. note that line drivers need to be capable of transmission at data rates twice the system clock used (as one cycle of the system c lock corresponds to 1 bit of serial data). also note that enabling modem interrupts is illegal in isochronous mode, as the clock signal will cause a continuous change to the modem status (unless masked in mdm register, see section 7.11.10 ). 7.10.5 crystal oscillator circuit the uarts reference reference clock may be provided by its own crystal oscillator or directly from a clock source connected to the xtli pin. the circuit required to use the internal oscillator is shown in figure 3 . r 1 r 2 c 1 c 2 xtli xtlo figure 3 : crystal oscillator circuit frequency range (mhz) c 1 (pf) c 2 (pf) r 1 ( w w ) r 2 ( w w ) 1.8432 - 8 68 22 220k 470r 8 - 60 33 - 68 33 ? 68 220k - 2m2 470r table 29 : component values note: for better stability use a smaller value of r 1 . increase r 1 to reduce power consumption. the total capacitive load (c1 in series with c2) should be that specified by the crystal manufacturer (nominally 16pf). 7.11 additional features 7.11.1 addition al status register ?asr? asr[0]: transmitter disabled logic 0 t the transmitter is not disabled by in - band flow control. logic 1 t the receiver has detected an xoff, and has disabled the transmitter. this bit is cleared after a hardware reset or channel software reset. the software driver may write a 0 to this bit to re - enable the transmitter if it was disabled by in - band flow control. writing a 1 to this bit has no effect. asr[1]: remote transmitter disabled logic 0 t the remote transmitter is not disa bled by in - band flow control. logic 1 t the transmitter has sent an xoff character, to disable the remote transmitter (cleared when subsequent xon is sent). this bit is cleared after a hardware reset or channel software reset. the software driver may writ e a 0 to this bit to re - enable the remote transmitter (an xon is transmitted). note: writing a 1 to this bit has no effect. asr[2]: rts this is the complement of the actual state of the rts# pin when the device is not in loopback mode. the driver software can determine if the remote transmitter is disabled by rts# out - of - band flow control by reading this bit. in loopback mode this bit reflects the flow control status rather than the pin?s actual state. asr[3]: dtr this is the complement of the actual stat e of the dtr# pin when the device is not in loopback mode. the driver software can determine if the remote transmitter is disabled by dtr# out - of - band flow control by reading this bit. in loopback mode this bit reflects the flow control status rather than the pin?s actual state. asr[4]: special character detected logic 0 t no special character has been detected. logic 1 t a special character has been received and is stored in the rhr. this can be used to determine whether a level 5 interrupt was caused by receiving a special character rather than an xoff. the flag is cleared following the read of the asr.
data sheet revision 1.3 page 47 ox16pci954 oxford semiconductor ltd. asr[5]: fifosel this bit reflects the unlatched state of the fifosel pin. asr[6]: fifo size logic 0 t fifos are 16 deep if fcr[0] = 1. logic 1 t fifos a re 128 deep if fcr[0] = 1. asr[7]: transmitter idle logic 0 t transmitter is transmitting. logic 1 t transmitter is idle. this bit reflects the state of the internal transmitter. it is set when both the transmitter fifo and shift register are empty. 7.11.2 fi fo fill levels ?tfl & rfl? the number of characters stored in the thr and rhr can be determined by reading the tfl and rfl registers respectively. when data transfer is in constant operation, the values should be interpreted as follows: 1. the number of chara cters in the thr is no greater than the value read back from tfl. 2. the number of characters in the rhr is no less than the value read back from rfl. 7.11.3 additional control register ?acr? the acr register is located at offset 0x00 of the icr acr[0]: receiver d isable logic 0 t the receiver is enabled, receiving data and storing it in the rhr. logic 1 t the receiver is disabled. the receiver continues to operate as normal to maintain the framing synchronisation with the receive data stream but received data is n ot stored into the rhr. in - band flow control characters continue to be detected and acted upon. special characters will not be detected. changes to this bit will only be recognised following the completion of any data reception pending. acr[1]: transmitte r disable logic 0 t the transmitter is enabled, transmitting any data in the thr. logic 1 t the transmitter is disabled. any data in the thr is not transmitted but is held. however, in - band flow control characters may still be transmitted. changes to this bit will only be recognised following the completion of any data transmission pending. acr[2]: enable automatic dsr flow control logic 0 t normal. the state of the dsr# line does not affect the flow control. logic 1 t data transmission is prevented whenev er the dsr# pin is held inactive high. this bit provides another automatic out - of - band flow control facility using the dsr# line. acr[4:3]: dtr# line configuration when bits 4 or 5 of cks (offset 0x03 of icr) are set, the transmitter 1x clock or the outp ut of the baud rate generator (nx clock) are asserted on the dtr# pin, otherwise the dtr# pin is defined as follows: logic [00] t dtr# is compatible with 16c450, 16c550, 16c650 and 16c750 (i.e. normal). logic [01] t dtr# pin is used for out - of - band flow c ontrol. it will be forced inactive high if the receiver fifo level (?rfl?) reaches the upper flow control threshold. dtr# line will be re - activated (=0) when the rfl drops below the lower threshold (see fcl & fch). logic [10] t dtr# pin is configured to d rive the active - low enable pin of an external rs485 buffer. in this configuration the dtr# pin will be forced low whenever the transmitter is not empty (lsr[6]=0), otherwise dtr# pin is high. logic [11] t dtr# pin is configured to drive the active - high en able pin of an external rs485 buffer. in this configuration, the dtr# pin will be forced high whenever the transmitter is not empty (lsr[6]=0), otherwise dtr# pin is low. if the user sets acr[4], then the dtr# line is controlled by the status of the trans mitter empty bit of lcr. when acr[4] is set, acr[3] is used to select active high or active low enable signals. in half - duplex systems using rs485 protocol, this facility enables the dtr# line to directly control the enable signal of external 3 - state line driver buffers. when the transmitter is empty the dtr# would go inactive once the sout line returns to it?s idle marking state. acr[5]: 950 mode trigger levels enable logic 0 t interrupts and flow control trigger levels are as described in fcr register a nd are compatible with 16c650/16c750 modes. logic 1 t 16c950 specific enhanced interrupt and flow control trigger levels defined by rtl, ttl, fcl and fch are enabled. acr[6]: icr read enable logic 0 t the line status register is readable. logic 1 t the in dexed control registers are readable. setting this bit will map the icr set to the lsr location for reads. during normal operation this bit should be cleared.
data sheet revision 1.3 page 48 ox16pci954 oxford semiconductor ltd. acr[7]: additional status enable logic 0 t acces s to the asr, tfl and rfl registers is disable d. logic 1 t access to the asr, tfl and rfl registers is enabled. when acr[7] is set, the mcr, lcr and ier registers are no longer readable but remain writable, and the registers asr, tfl and rfl replace them in the register map for read operations. the s oftware driver may leave this bit set during normal operation, since mcr, lcr and ier do not generally need to be read. 7.11.4 transmitter trigger level ?ttl? the ttl register is located at offset 0x04 of the icr whenever 950 trigger levels are enabled (acr[5]= 1), bits 4 and 5 of fcr are ignored and an alternative arbitrary transmitter interrupt trigger level can be defined in the ttl register. this 7 - bit value provides a fully programmable transmitter interrupt trigger facility. in 950 mode, a priority level 3 interrupt occurs indicating that the transmitter buffer requires more characters when the interrupt is not masked (ier[1]=1) and the transmitter fifo level falls below the value stored in the ttl register. the value 0 (0x00) has a special meaning. in 950 m ode when the user writes 0x00 to the ttl register, a level 3 interrupt only occurs when the fifo and the transmitter shift register are both empty and the sout line is in the idle marking state. this feature is particularly useful to report back the empty state of the transmitter after its fifo has been flushed away. 7.11.5 receiver interrupt. trigger level ?rtl? the rtl register is located at offset 0x05 of the icr whenever 950 trigger levels are enabled (acr[5]=1), bits 6 and 7 of fcr are ignored and an altern ative arbitrary receiver interrupt trigger level can be defined in the rtl register. this 7 - bit value provides a fully programmable receiver interrupt trigger facility as opposed to the limited trigger levels available in 16c650 and 16c750 devices. it enab les the system designer to optimise the interrupt performance hence minimising the interrupt overhead. in 950 mode, a priority level 2 interrupt occurs indicating that the receiver data is available when the interrupt is not masked (ier[0]=1) and the rec eiver fifo level reaches the value stored in this register. 7.11.6 flow control levels ?fcl? & ?fch? the fcl and fch registers are located at offsets 0x06 and 0x07 of the icr respectively enhanced software flow control using xon/xoff and hardware flow control using rts#/cts# and dtr#/dsr# are available when 950 mode trigger levels are enabled (acr[5]=1). improved flow control threshold levels are offered using flow control lower trigger level (?fcl?) and flow control higher trigger level (?fch?) registers to pr ovide a greater degree of flexibility when optimising the flow control performance. generally, these facilities are only available in enhanced mode. in 650 mode, in - band flow control is enabled using the efr register. an xoff character may be transmitted when the receiver fifo exceeds the upper trigger level defined by fcr[7:6] as described in section 7.4.1 . an xon is then sent when the fifo is read down the lower fill level. the flow control is enabled and the appropriate mode is selected using efr[3:0]. in 950 mode, the flow control thresholds defined by fcr[7:6] are ignored. in this mode, threshold levels are programmed using fcl and fch. when flow control is enabled by efr[3:0] and the receiver fifo level (? rfl?) reaches the value programmed in the fch register, an xoff will be transmitted to stop the flow of serial data as defined by efr[3:0]. when the receiver fifo level falls below the value programmed in fcl the flow is resumed by sending an xon character (as defined in efr[3:0]). the fcl value of 0x00 is illegal. cts/rts and dsr/dtr out - of - band flow control use the same trigger levels as in - band flow control. when out - of - band flow control is enabled, rts# (or dtr#) line is de - asserted w hen the receiver fifo level reaches the upper limit defined in the fch and is re - asserted when the receiver fifo is drained below a lower limit defined in fcl. when 950 trigger levels are enabled (acr[5]=1), the cts# flow control functions as in 650 mode a nd is configured by efr[7]. however, rts# is automatically de - asserted and re - asserted when efr[6] is set and rfl reaches fch and drops below fcl. dsr# flow control is configured with acr[2]. dtr# flow control is configured with acr[4:3]. 7.11.7 device identific ation registers the identification registers is located at offsets 0x08 to 0x0b of the icr the uarts offer four bytes of device identification. the device id registers may be read using offset values 0x08 to 0x0b of the indexed control register. registers id1, id2 and id3 identify the device as an ox16c950 and return 0x16, 0xc9 and 0x50 respectively. the rev register resides at offset 0x0b of icr and identifies the revision of ox16c950. this register returns 0x01 for revision a of the ox16 p c i 954 .
data sheet revision 1.3 page 49 ox16pci954 oxford semiconductor ltd. 7.11.8 clock sel ect register ?cks? the cks register is located at offset 0x03 of the icr this register is cleared to 0x00 after a hardware reset to maintain compatibility with 16c550, but is unaffected by software reset. this allows the user to select a clock source and then reset the channel to work - around any timing glitches. cks[1:0]: receiver clock source selector logic [ x 0] t the output of baud rate generator (internal bdout#) is selected for the receiver clock. logic [01] t the dsr# pin is selected for the receiver clock. logic [11] t the transmitter clock is selected for the receiver. this allows ri# to be used for both transmitter and receiver. cks[2]: reserved cks[3]: receiver 1x clock mode selector logic 0 t the receiver is in nx clock mode as defined in the tcr register. after a hardware reset the receiver operates in 16x clock mode, i.e. 16c550 compatibility. logic 1 t the receiver is in isochronous 1x clock mode. cks[5:4] : transmitter 1x clock or baud rate generator output (bdout) on dtr# pin logic [00] t the function of the dtr# pin is defined by the setting of acr[4:3]. logic [01] t the transmitter 1x clock (bit rate clock) is asserted on the dtr# pin and the setting of acr[4:3] is ignored. logic [10] t the output of baud rate generator (nx clock) is asserted on the dtr# pin and the setting of acr[4:3] is ignored. logic [11] t reserved. cks[6]: transmitter clock source selector logic 0 t the transmitter clock source is the output of the baud rate generator (550 compatibility). logic 1 t the transmitter uses an external clock applied to the ri# pin. cks[7]: transmitter 1x clock mode selector logic 0 t the transmitter is in nx clock mode as defined in the tcr register. after a hardware reset the transmitter operates in 16x clock mode, i.e. 16c550 compatibility. logic 1 t the transmitter is in isochronous 1x clock mode. 7.11.9 nine - bit mode register ?nmr? the nmr register is located at offset 0x0d of the icr the uart offers 9 - bit data framing for industrial multi - drop applications. the 9 - bit mode is enabled by setting bit 0 of the nine - bit mode register (nmr). in 9 - bit mode the data length setting in lcr[1:0] is ignored. furthermore as parity is permanently disabled, the settin g of lcr[5:3] is also ignored. the receiver stores the 9th bit of the received data in lsr[2] (where parity error is stored in normal mode). note that the uart provides a 128 - deep fifo for lsr[3:0]. the transmitter fifo is 9 bits wide and 128 deep. the user should write the 9th (msb) data bit in spr[0] first and then write the other 8 bits to thr. as parity mode is disabled, lsr[7] is set whenever there is an overrun, framing error or received break condition. it is unaffected by the contents of lsr[2] (now the received 9th data bit). in 9 - bit mode, in - band flow control is disabled regardless of the setting of efr[3:0] and the xon1/xon2/xoff1 and xoff2 registers are used for special character detection. interrupts in 9 - bit mode: while ier[2] is set, u pon receiving a character with status error, a level 1 interrupt is asserted when the character and the associated status are transferred to the fifo. the uart can assert an optional interrupt if a received character has its 9 th bit set. as multi - drop sys tems often use the 9 th bit as an address bit, the receiver is able to generate an interrupt upon receiving an address character. this feature is enabled by setting nmr[2]. this will result in a level 1 interrupt being asserted when the address character i s transferred to the receiver fifo. in this case, as long as there are no errors pending, i.e. lsr[1], lsr[3], and lsr[4] are clear, '0' can be read back from lsr[7] and lsr[1], thus differentiating between an ?address? interrupt and receiver error or ov errun interrupt in 9 - bit mode. note however that should an overrun or error interrupt actually occur, an address character may also reside in the fifo. in this case, the software driver should examine the contents of the receiver fifo as well as process th e error.
data sheet revision 1.3 page 50 ox16pci954 oxford semiconductor ltd. the above facility produces an interrupt for recognizing any ?address? characters. alternatively, the user can configure the uart to compare the receiver data stream with up to four programmable 9 - bit characters and assert a level 5 interrupt afte r detecting a match. the interrupt occurs when the character is transferred to the fifo (see below). nmr[0]: 9 - bit mode enable logic 0 t 9 - bit mode is disabled. logic 1 t 9 - bit mode is enabled. nmr[1]: enable interrupt when 9 th bit is set logic 0 t rece iver interrupt for detection of an ?address? character (i.e. 9 th bit set) is disabled. logic 1 t receiver interrupt for detection of an ?address? character (i.e. 9 th bit set) is enabled and a level 1 interrupt is asserted. special character detection whi le the uart is in both 9 - bit mode and enhanced mode, setting ier[5] will enable detection of up to four ?address? characters. the least significant eight bits of these four programmable characters are stored in special characters 1 to 4 (xon1, xon2, xoff1 and xoff2 in 650 mode) registers and the 9 th bit of these characters are programmed in nmr[5] to nmr[2] respectively. nmr[2]: bit 9 of special character 1 nmr[3]: bit 9 of special character 2 nmr[4]: bit 9 of special character 3 nmr[5]: bit 9 of special character 4 nmr[7:6]: reserved bits 6 and 7 of nmr are always cleared and reserved for future use. 7.11.10 modem disable mask ?mdm? the mdm register is located at offset 0x0e of the icr this register is cleared after a hardware reset to maintain compatibility wi th 16c550. it allows the user to mask interrupts, sleep operation and power management events due to individual modem lines or the serial input line. mdm[0]: disable delta cts logic 0 t delta cts is enabled. it can generate a level 4 interrupt when enable d by ier[3]. in power - state d2, delta cts can assert the pme# line. delta cts can wake up the uart when it is asleep under auto - sleep operation. logic 1 t delta cts is disabled. in can not generate an interrupt, assert a pme# or wake up the uart. mdm[1]: disable delta dsr logic 0 t delta dsr is enabled. it can generate a level 4 interrupt when enabled by ier[3]. in power - state d2, delta dsr can assert the pme# line. delta dsr can wake up the uart when it is asleep under auto - sleep operation. logic 1 t de lta dsr is disabled. in can not generate an interrupt, assert a pme# or wake up the uart. mdm[2]: disable trailing edge ri logic 0 t trailing edge ri is enabled. it can generate a level 4 interrupt when enabled by ier[3]. in power - state d2, trailing edge ri can assert the pme# line. trailing edge ri can wake up the uart when it is asleep under auto - sleep operation. logic 1 t trailing edge ri is disabled. in can not generate an interrupt, assert a pme# or wake up the uart. mdm[3]: disable delta dcd logic 0 t delta dcd is enabled. it can generate a level 4 interrupt when enabled by ier[3]. in power - state d2, delta dcd can assert the pme# line. delta dcd can wake up the uart when it is asleep under auto - sleep operation. logic 1 t delta dcd is disabled. in c an not generate an interrupt, assert a pme# or wake up the uart. mdm[4]: reserved this bit must be set to ?0? mdm[5]: disable sin wake up logic 0 t when the device is in power - down state d2, a change in the state of the serial input line (i.e. start bit) can assert the pme# line logic 1 t when the device is in power - down state d2, a change in the state of the serial input line cannot assert the pme# line. mdm[7:6]: reserved 7.11.11 readable fcr ?rfc? the rfc register is located at offset 0x0f of the icr this r ead - only register returns the current state of the fcr register (note that fcr is write - only). this register is included for diagnostic purposes. 7.11.12 good - data status register ?gds? the gds register is located at offset 0x10 of the icr for the definition of good - data status refer to section 6.4.7 . gds[0]: good data status gds[7:1]: reserved
data sheet revision 1.3 page 51 ox16pci954 oxford semiconductor ltd. 8 l ocal bus 8.1 overview the ox16pci954 incorporates a bridge from pci to the local bus. it allows card developers to expand the capabilities of their products by adding peripherals to this bus. when mode[1:0] is ?00?, the local bus is comprised of a bi - directional 8 - bit data bus, an 8 - bit address bus, up to four chip selects, and a number of control signals that allow for easy interfacing to s tandard peripherals. it also provides twelve active - high or active - low interrupt inputs. when mode[1:0] is ?11?, the local bus is comprised of a bi - directional 32 - bit data bus, a 12 - bit address bus, up to four chip selects, and the same control signals a nd interrupts as in 8 - bit mode. in this mode the internal uarts are unused and the uart pins are used to extend the 8 - bit local bus to 32 - bit mode. the local bus is configured by lt1 and lt2 (see sections 6.4.3 & 6.4.4 ) in the local configuration register space. by programming these registers the card developer can alter the characteristics of the local bus to suit the characteristics of the peripheral devices being used. 8.2 operation the local bus ca n be accessed via i/o and memory space, in similar fashion to the internal uarts. the mapping to the devices will vary with the application, but the bus is fully configurable to facilitate simple development. the operation of the local bus is synchronised to the pci bus clock. the clock signal is output on pin lbclk if it has been enabled by setting lt2[30]. the eight bit bi - directional pins lbd[7:0] (lbd[31:0] in 32 - bit mode) drive the output data onto the bus during local bus write cycles. for reads, t he device latches the data read from these pins at the end of the cycle. the local bus address is placed on pins lba[7:0] (lba[11:0] in 32 - bit mode) at the start of each local bus cycle and will remain latched until the start of the subsequent cycle. if the maximum allowable block size (256 bytes) is allocated to the local bus in i/o space, then as access in i/o space is byte aligned, ad[7:0] are asserted on lba[7:0]. if a smaller address range is selected, the corresponding upper address lines will be s et to logic zero. the control bus is comprised of up to four chip - select signals lbcs[3:0]#, a read strobe lbrd# and a write strobe lbwr#, in intel - type interfaces. for motorola - type interfaces, lbwr# is re - defined to perform read/write control signal (lb rdwr#) and the chip - select signals (lbcs[3:0]#) are re - defined to data - strobe (lbds[3:0]#). a reference cycle is defined, as two pci clock cycles after the master asserts the irdy# signal for the first time within a frame. in general, all the local bus co ntrol signals change state in the first cycle after the reference cycle, with offsets to provide suitable setup and hold times for common peripheral devices. however, all the timings can be increased / decreased independently in multiples of pci clock cycl es. this feature enables the card designer to override the length of read or write operations, the address and chip - select set - up and hold timing, and the data bus hold timing so that add - in cards can be configured to suit different speed peripheral device s connected to the local bus. the designer can also program the data bus to remain in the high impedance state or actively drive the bus during idle periods. the local bus will always return to an idle state, where no chip - select (data - strobe in motorola mode) signal is active, between adjacent accesses. during read cycles the local bus interface latches data from the bus on the rising edge of the clock where lbrd# (lbds[3:0]# in motorola mode) goes high. card designers should ensure that their peripheral s provide the ox16pci954 with the specified data set - up and hold times with respect to this clock edge. the local bus cannot accept burst transfers from the pci bus. if a burst transfer is attempted the pci interface will signal 'disconnect with data' on the first data phase. the local bus does accept 'fast back - to - back' transactions from pci. a pci target must complete the transaction within 16 pci clock cycles from assertion of the frame# signal, otherwise it should signal a retry. during a read operati on from the local bus, ox16pci954 waits for master - ready signal (irdy#) and computes the number of remaining cycles to the de - assertion of the read control signal. if the total number of pci clock cycles for that frame is greater than 16 clock cycles, ox16 pci954 will post a retry. the master would normally return immediately and complete the operation in the following frame.
data sheet revision 1.3 page 52 ox16pci954 oxford semiconductor ltd. 8.3 configuration & programming the configuration registers for the local bus controller are described in sections 6.4.3 & 6.4.4 . the values of these registers after reset allow the host system to identify the function and configure its base address registers. alternatively many of the default values can be re - programmed during devi ce initialisation through use of the optional serial eeprom (see section 10 ). the i/o space block can be varied in size from 4 bytes to 256 bytes (32 bytes is the default) by setting lt2[22:20] accordingly. varying the block size means that i/o space can be allocated efficiently by the system, whatever the application. the i/o block can then be divided into one, two or four chip - select regions, depending on the setting in lt2[26:23]. to divide the area into four chip - select region, the user should select the second uppermost non - zero address bit as the lower - address - cs - decode. to divide into two regions, the user should select the uppermost address bit. if an address bit beyond the selected range is selected, the entire i/o s pace is allocated to cs0#. for example, if 32 bytes of i/o space are reserved, the active address lines are a[4:0]. to divide this into four regions, the lower address cs parameter should be set to a3, by programming the value ?0001? into lt2[26:23]. to se lect two regions, choose a4, and to maintain one region, select any value greater than a4. in 8 - bit mode, the memory space block is always 4k bytes, and always divided into four chip - select regions of 1k byte each. in 32 - bit mode, again the i/o space can be varied in size from 4 bytes to 256 bytes. it is also possible to increase the memory space block size from 4k bytes to 16k bytes. also in 32 - bit mode, the lower - address - cs - decode parameter afftects division of the i/o space and memory space into chip - s elect regions. a soft reset facility is provided so software can independently reset the peripherals on the local bus. the local bus reset signals, lbrst and lbrst#, are always active during a pci bus reset and also when the configuration register bit lt2 [29] is set to 1. the clock enable bit, when set, enables a copy of the pci bus clock output on the local bus pin lbclk. a buffered uart clock can also be asserted on the uart_clk_out pin; this means that a single oscillator can be used to drive serial po rts on the local bus as well as the internal uarts.
data sheet revision 1.3 page 53 ox16pci954 oxford semiconductor ltd. 9 b idirectional p arallel p ort 9.1 operation and mode selection the ox16pci954 offers a compact, low power, ieee - 1284 (epp - only) compliant host - interface parallel port, designed to interface to many periph erals such as printers, scanners and external drives. it supports compatibility modes, spp, nibble and ps2, as well as epp mode. the register set is compatible with the microsoft register definition. to enable the parallel port function, the mode[1:0] pin s should be set to ?01?. the system can access the parallel port via two 8 - byte blocks of i/o space; bar0 contains the address of the basic parallel port registers, bar1 contains the address of the upper registers. these are referred to as the ?lower block ? and ?upper block? in this section. if the upper block is located at an address 0x400 above the lower block, generic pc device drivers can be used to configure the port, as the addressable registers of legacy parallel ports always have this relationship. if not, a custom driver will be needed. 9.1.1 spp mode spp (output - only) is the standard implementation of a simple parallel port. in this mode, the pd lines always drive the value in the pdr register. all transfers are done under software control. input must b e performed in nibble mode. generic device driver - software may use the address in i/o space encoded in bar0 of function 1 to access the parallel port. the default configuration allocates 8 bytes to bar0 in i/o space. 9.1.2 ps2 mode this mode is also referred to as bi - directional or compatible parallel port. in this mode, directional control of the pd lines is possible by setting & clearing dcr[5]. otherwise operation is similar to spp mode. 9.1.3 epp mode to use the enhanced parallel port ?epp? the mode bits (ecr[7 :5]) must be set to ?100?. the epp address and data port registers are compatible with the ieee 1284 definition. a write or read to one of the epp port registers is passed through the parallel port to access the external peripheral. in epp mode, the stb#, init#, afd# and slin# pins change from open - drain outputs to active push - pull (totem pole) drivers (as required by ieee 1284) and the pins ack#, afd#, busy, slin# and stb# are redefined as intr#, datastb#, wait#, addrstb# and write# respectively. an epp p ort access begins with the host reading or writing to one of the epp port rgisters. the device automatically buffers the data between the i/o registers and the parallel port depending on whether it is a read or a write cycle. when the peripheral is ready t o complete the transfer it takes the wait# status line high. this allows the host to complete the epp cycle. if a faulty or disconnected peripheral failed to respond to an epp cycle the host would never see a rising edge on wait#, and subsequently lock up . a built - in time - out facility is provided in order to prevent this from happening. it uses an internal timer which aborts the epp cycle and sets a flag in the psr register to indicate the condition. when the parallel port is not in epp mode the timer is s witched off to reduce current consumption. the host time - out period is 10 m s as specified with the ieee - 1284 specification. the register set is compatible with the microsoft register definition. assuming that the upper block is located 400h above the lowe r block, the registers are found at offset 000 - 007h and 400 - 402h. 9.1.4 ecp mode (not supported) the extended capabilities port ?ecp? mode is not supported. 9.2 parallel port interrupt the parallel port interrupt is asserted on intb# (or inta# if specified with the serial eeprom). it is enabled by setting dcr[4]. when dcr[4] is set, an interrupt is asserted on the rising edge of the ack# (intr#) pin and held until the status register is read, which resets the int# status bit (dsr[2]).
data sheet revision 1.3 page 54 ox16pci954 oxford semiconductor ltd. 9.3 register description the parallel port registers are described below. (nb it is assumed that the upper block is placed 400h above the lower block). register name address offset r/w bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 spp (compatibility mode) registers pdr 000h r /w parallel port data register dsr (epp mode) 001h r nbusy ack# pe slct err# int# 1 timeout (other modes) 001h r nbusy ack# pe slct err# int# 1 1 dcr 002h r/w 0 0 dir int_en nslin# init# nafd# nstb# eppa 1 003h r/w epp address register eppd1 1 004h r/w epp data 1 register eppd2 1 005h r/w epp data 2 register eppd3 1 006h r/w epp data 3 register eppd4 1 007h r/w epp data 4 register - 400h - reserved - 401h - reserved ecr 402h r/w mode[2:0] reserved ? must write ?00001? - 403h - reserved table 30 : parallel port register set note 1 : these registers are only available in epp mode. note 2 : prefix ?n? denotes that a signal is inverted at the connector. suffix ?#? denotes active - low signalling the reset state of pdr, eppa and eppd1 - 4 is not determinable (i.e. 0xxx). the reset value of dsr is ?xxxxx111?. dcr and ecr are reset to ?0000xxxx? and ?00000001? respectively. 9.3.1 parallel port data register ?pdr? pdr is located at offset 000h in the lower block. it is the standard parallel port data register. writing to this register in mode 000 will drive data onto the parallel port data lines. in all other modes the drivers may be tri - stated by setting the direction bit in the dcr. reads from this register return the value on the data lines. 9.3.2 device status register ?dsr? dsr is located at offset 001h in the lower block. it is a read only register showing the current state of control signals from the peripheral. additionally in epp mode, bit 0 is set to ?1? when an operation tim es out (see section 9.1.3 ) dsr[0]: epp mode: timeout logic 0 t timeout has not occurred. logic 1 t timeout has occurred (reading this bit clears it). other modes: unused this bit is permanently set to 1. dsr[1]: unused th is bit is permanently set to 1.
data sheet revision 1.3 page 55 ox16pci954 oxford semiconductor ltd. dsr[2]: int# logic 0 t a parallel port interrupt is pending. logic 1 t no parallel port interrupt is pending. this bit is activated (set low) on a rising edge of the ack# pin. it is de - activated (set high) after reading the dsr. dsr[3]: err# logic 0 t the err# input is low. logic 1 t the err# input is high. dsr[4]: slct logic 0 t the slct input is low. logic 1 t the slct input is high. dsr[5]: pe logic 0 t the pe input is low. logic 1 t the pe input is high. dsr [6]: ack# logic 0 t the ack# input is low. logic 1 t the ack# input is high. dsr[7]: nbusy logic 0 t the busy input is high. logic 1 t the busy input is low. 9.3.3 device control register ?dcr? dcr is located at offset 002h in the lower block. it is a rea d - write register which controls the state of the peripheral inputs and enables the peripheral interrupt. when reading this register, bits 0 to 3 reflect the actual state of stb#, afd#, init# and slin# pins respectively. when in epp mode, the write#, datast b# and addrstb# pins are driven by the epp controller, although writes to this register will override the state of the respective lines. dcr[0]: nstb# logic 0 t set stb# output to high (inactive). logic 1 t set stb# output to low (active). during an e pp address or data cycle the write# pin is driven by the epp controller, otherwise it is inactive. dcr[1]: nafd# logic 0 t set afd# output to high (inactive). logic 1 t set afd# output to low (active). during an epp address or data cycle the datastb# pin is driven by the epp controller, otherwise it is inactive. dcr[2]: init# logic 0 t set init# output to low (active). logic 1 t set init# output to high (inactive). dcr[3]: nslin# logic 0 t set slin# output to high (inactive). logic 1 t set slin # output to low (active). during an epp address or data cycle the addrstb# pin is driven by the epp controller, otherwise it is inactive. dcr[4]: ack interrupt enable logic 0 t ack interrupt is disabled. logic 1 t ack interrupt is enabled. dcr[5]: dir logic 0 t pd port is output. logic 1 t pd port is input. this bit is overridden during an epp address or data cycle, when the direction of the port is controlled by the bus access (read/write) dcr[7:6]: reserved these bits are reserved and always set to ?00?. 9.3.4 epp address register ?eppa? eppa is located at offset 003h in lower block, and is only used in epp mode. a byte written to this register will be transferred to the peripheral as an epp address by the hardware. a read from this register will tran sfer an address from the peripheral under hardware control. 9.3.5 epp data registers ?eppd1 - 4? the eppd registers are located at offset 004h - 007h of the lower block, and are only used in epp mode. data written or read from these registers is transferred to/fro m the peripheral under hardware control. 9.3.6 extended control register ?ecr? the extended control register is located at offset 002h in upper block. it is used to configure the operation of the parallel port. ecr[4:0]: reserved these bits are reserved and must always be set to ?00001?. ecr[7:5]: mode these bits define the operational mode of the parallel port. logic ?000? spp logic ?001? ps2 logic ?010? reserved logic ?011? reserved logic ?100? epp logic ?101? reserved logic ?110? reserved logic ?111? reserved
data sheet revision 1.3 page 56 ox16pci954 oxford semiconductor ltd. 10 s erial eeprom 10.1 specification the ox16pci954 can be configured using an optional serial electrically - erasable programmable read only memory (eeprom). if the eeprom is not present, the device will remain in its default configuration after reset. a lthough this may be adequate for some applications, many will benefit from the degree of programmability afforded by this feature. the eeprom interface is based on the 93c46/56 serial eeprom devices which have a proprietary serial interface known as micro wire tm . the interface has four pins which supply the memory device with a clock, a chip - select, and serial data input and output lines. in order to read from such a device, a controller has to output serially a read command and address, then input serially the data. the 93c46/56 and compatible devices have a 16 - bit data word format but differ in memory size (and number of address bits). the ox16pci954 incorporates a controller module which reads data from the serial eeprom and writes data into the configu ration register space. it performs this operation in a sequence which starts immediately after a pci bus reset and ends either when the controller finds no eeprom is present or when it reaches the end of its data. the operation of this controller is descri bed below. following device configuration, driver software can access the serial eeprom through four bits in the device - specific local configuration register lcc[27:24]. software can use this register to manipulate the device pins in order to read and modi fy the eeprom contents. the ox16pci954 requires a total of 82 bytes of eeprom data to program all the eeprom writable registers. note that 93c46 and 93c56 eeprom devices offer 128 and 256 bytes of programmable data respectively. a windows based utility to program the eeprom is available. for further details please contact oxford semiconductor (see back cover). microwire tm is a trade mark of national semiconductor. for a description of microwire, please refer to national semiconductor data manuals. 10.2 eep rom data organisation the serial eeprom data is divided in four zones. the size of each zone is an exact multiple of 16 - bit words. zone0 is allocated to the header. a valid eeprom program must contain a header. the eeprom can be programmed from the pci bus . once the programming is complete, the device driver should either reset the pci bus or set lcc[29] to reload the ox16pci954 registers from the serial eeprom. the general eeprom data structure is shown in table 31 . data zone si ze (words) description 0 one header 1 one or more local configuration registers 2 one to four identification registers 3 two or more pci configuration registers table 31 : eeprom data format 10.2.1 zone0: header the header identifies the eeprom program as valid. bits description 15:4 these bits should return 0x950 to identify a valid program. once the ox16pci954 reads 0x950 from these bits, it sets lcc[28] to indicate that a valid eeprom program is present. 3 reserved. write ?0? to this bit. 2 1 = zone1 (local configuration) exists 0 = zone1 does not exist 1 1 = zone2 (identification) exists 0 = zone2 does not exist 0 1 = zone3 (pci configuration) exists 0 = zone3 does not exist the programming data for each zone follows the pr oceeding zone if it exists. for example a header value of 0x9507 indicates that all zones exist and they follow one another in sequence, while 0x9505 indicates that only zones 1 and 3 exist where the header data is followed by zone1 words, and since zone2 is missing zone1 words are followed by zone3 words.
data sheet revision 1.3 page 57 ox16pci954 oxford semiconductor ltd. 10.2.2 zone1: local configuration registers the zone1 region of eeprom contains the program value of the vendor - specific local configuration registers using one or more configuration words. registers are selected using a 7 - bit byte - offset field. this offset value is the offset from base address registers in i/o or memory space (see section 6.4 ). note: not all of the registers in the local configuration register set are writab le by eeprom. if bit2 of the header is set, zone1 configuration words follow the header declaration. the format of configuration words for the local configuration registers in zone1 are described in table 32 . bi ts description 15 ?0? = there are no more configuration words to follow in zone1. move to the next available zone or end eeprom program if no more zones are enabled in the header. ?1? = there is another configuration word to follow for the local confi guration registers. 14:8 these seven bits define the byte - offset of the local configuration register to be programmed. for example the byte - offset for lt2[23:16] is 0x0e. 7:0 8 - bit value of the register to be programmed table 32 : zone 1 data format table 33 shows which local configuration registers are writable from the eeprom. note that an attempt by the eeprom to write to any other offset locations can result in unpredictable behaviour. offset bits d escription reference 0x00 1:0 must be ?00?. 0x00 2 enable uart clock - out. lcc[2] 0x00 4:3 endian byte - lane select. lcc[4:3] 0x00 6:5 power - down filter. lcc[6:5] 0x00 7 mio2_pme enable. lcc[7] 0x04 7:0 multi - purpose io configuration. mic[7:0] 0x05 7:0 multi - purpose io configuration. mic[15:8] 0x06 7:0 multi - purpose io configuration. mic[23:16] 0x08 7:0 local bus timing parameters lt1[7:0] 0x09 7:0 local bus timing parameters lt1[15:8] 0x0a 7:0 local bus timing parameters lt1[23:16] 0x0b 7:0 loc al bus timing parameters lt1[31:24] 0x0c 7:0 local bus timing parameters lt2[7:0] 0x0d 7:0 local bus timing parameters lt2[15:8] 0x0e 3:0 must be ?0000?. 0x0e 6:4 io space block size. lt2[22:20] 0x0e 7 lower - address - cs - decode. lt2[23] 0x0f 2:0 lower - address - cs - decode. lt2[26:24] 0x0f 4:3 memory space block size in 32 - bit local bus. lt2[28:27] 0x0f 5 must be ?0?. 0x0f 6 local bus clock enable. lt2[30] 0x0f 7 bus interface type. lt2[31] 0x1e 3:0 uart interrupt mask gis[19:16] 0x1e 4 mio0/paralle l port interrupt mask gis[20] 0x1e 7:5 multi - purpose io interrupt mask. gis[23:21] 0x1f 7:0 multi - purpose io interrupt mask. gis[31:24] table 33 : eeprom - writable local configuration registers
data sheet revision 1.3 page 58 ox16pci954 oxford semiconductor ltd. 10.2.3 zone2: identification registers t he zone2 region of eeprom contains the program value for vendor id and subsystem vendor id. the format of device identification configuration words are described in table 34 . bits description 15 ?0? = there are no more zone2 ( identification) bytes to program. move to the next available zone or end eeprom program if no more zones are enabled in the header. ?1? = there is another zone2 (identification) byte to follow. 14:8 0x00 = vendor id bits [7:0]. 0x01 = vendor id bits [1 5:8]. 0x02 = subsystem vendor id [7:0]. 0x03 = subsystem vendor id [15:8]. 0x03 to 0x7f = reserved. 7:0 8 - bit value of the register to be programmed table 34 : zone 2 data format 10.2.4 zone3: pci configuration registers the zone3 reg ion of eeprom contains any changes required to the pci configuration registers (with the exception of vendor id and subsystem vendor id which are programmed in zone2). this zone is divided into two groups, each of which consists of a function header word, and one or more configuration words for that function. the function header is described in table 35 . bits description 15 ?0? = end of zone 3. ?1? = define this function header. 14:3 reserved. write zeros. 2:0 function numbe r for the following configuration word(s). ?000? = function0 (internal uarts) ?001? = function1 (local bus / parallel port) other values = reserved. table 35 : zone 3 data format (function header) the subsequent words for each function contain the address offset and a byte of programming data for the pci configuration space belonging to the function number selected by the proceeding function - header. the format of configuration words for the pci configuration registers are descri bed below. bits description 15 ?0? = this is the last configuration word in for the selected function in the function - header. ?1? = there is another word to follow for this function. 14:8 these seven bits define the byte - offset of the pci configuratio n register to be programmed. for example the byte - offset of the interrupt pin register is 0x3d. offset values are tabulated in section 6.2 . 7:0 8 - bit value of the register to be programmed table 36 : z one 3 data format (data) table 37 shows which pci configuration registers are writable from the eeprom for each function. offset bits description 0x02 7:0 device id bits 7 to 0. 0x03 7:0 device id bits 15 to 8. 0x06 3:0 mus t be ?0000?. 0x06 4 extended capabilities. 0x06 7:5 must be ?000?. 0x09 7:0 class code bits 7 to 0. 0x0a 7:0 class code bits 15 to 8. 0x0b 7:0 class code bits 23 to 16. 0x2e 7:0 subsystem id bits 7 to 0. 0x2f 7:0 subsystem id bits 15 to 8. 0x3d 7:0 interrupt pin. 0x42 7:0 power management capabilities bits 7 to 0. 0x43 7:0 power management capabilities bits 15 to 8. table 37 : eeprom - writable pci configuration registers
data sheet revision 1.3 page 59 ox16pci954 oxford semiconductor ltd. 11 o perating c onditions symbol parameter min max uni ts v dd dc supply voltage - 0.3 7.0 v v in dc input voltage - 0.3 v dd + 0.3 v i in dc input current +/ - 10 ma t stg storage temperature - 40 125 c table 38 : absolute maximum ratings symbol parameter min max units v dd dc supply vol tage 4.5 5.5 v t c temperature 0 70 c table 39 : recommended operating conditions 12 dc e lectrical c haracteristics 12.1 non - pci i/o buffers symbol parameter condition min max units v dd supply voltage commercial 4.75 5.25 v v ih input hi gh voltage ttl interface 1 ttl schmitt trig 2.0 2.0 v v il input low voltage ttl interface 1 ttl schmitt trig 0.8 0.8 v c il cap of input buffers 5.0 pf c ol cap of output buffers 10.0 pf i ih input high leakage current v in = v dd - 10 10 m a i il input low leakage current v in = v ss - 10 10 m a v oh output high voltage i oh = 1 m a v dd ? 0.05 v v oh output high voltage i oh = 4 ma 2 2.4 v v ol output low voltage i ol = 1 m a 0.05 v v ol output low voltage i ol = 4 ma 2 0.4 v i oz 3 - state output leakage current - 10 10 m a symbol parameter condition typical max units xtal = 2 mhz 35 48.1 x tal = 15 mhz 40 68.7 operating supply current in normal mode xtal = 60 mhz 55 116.6 xtal = 2 mhz 2 34.4 xtal = 15 mhz 2 39.0 i cc operating supply current in power - down mode xtal = 60 mhz 2 49.6 ma table 40 : characteristics of non - pci i/o buffers note 1: all i nput buffers are ttl with the exception of pci buffers note 2: i oh and i ol are 12 ma for pd/lbdb[7:0] and other parallel port outputs. they are 4 ma for all other non - pci outputs
data sheet revision 1.3 page 60 ox16pci954 oxford semiconductor ltd. 12.2 pci i/o buffers symbol parameter condition min max unit dc specifications v cc supply voltage 4.75 5.25 v v il input low voltage - 0.5 0.8 v v ih input high voltage 2.0 v cc + 0.5 v i il input low leakage current v in = 0.5v - 70 m a i ih input high leakage current v in = 2.7v 70 m a v ol output low voltage i out = - 2 ma 0.55 v v oh output low voltage i out = 3 ma, 6ma 2.4 v c in input pin capacitance 10 pf c clk clk pin capacitance 5 12 pf c idsel idsel pin capacitance 8 pf l pin pin inductance 10 nh ac specifications switching current 0 < v out 1.4 - 44 i oh(ac) hig h 1.4 < v out 2.4 - 44 (v out - 1.4)/0.024 ma 3.1 < v out v cc eq. a (test point) v out = 3.1 - 142 switching current v out 2.2 95 i ol(ac) low 2.2 > v out > 0.55 v out / 0.023 ma 0.71 > v out > 0 eq. b (test point) v out = 0.71 206 i cl low clamp current - 5 < v in < - 1 - 25 + (v in +1)/ 0.015 ma i hl high clamp current v cc +4 < v in < v cc +1 25+ (v in - v cc - 1)/ 0.015 ma slew r output rise slew rate 0.4v to 2.4v 1 5 v/ns slew f output fall slew rate 2.4v to 0.4v 1 5 v/ns table 41 : characteristics of pci i/o buffers eq. a : i oh = 11.9 * (v out - 5.25) * (v out + 2.45) for 3.1 < v out v cc eq. b : i ol = 78.5 * v out * (4.4 - v out ) for 0.71 > v out > 0
data sheet revision 1.3 page 61 ox16pci954 oxford semiconductor ltd. 13 ac e lectrical c haracteristics 13.1 pci bus the timings for pci pins comply with pci specification for the 5.0 volt signalling environment. 13.2 local bus by default, the local bus control sig nals change state in the cycle immediately following the reference cycle, with offsets to provide setup and hold times for common peripherals in intel mode. the tables below show these default values; however each of these can be increased or decreased by an number of pci clock cycles by adjusting the parameters in registers lt1 and lt2. symbol parameter min max units t ref irdy# falling to reference lbclk nominally 2 pci clock cycles t za reference lbclk to address valid tbd tbd ns t ard address valid to lbrd# falling tbd tbd ns t zrcs1 reference lbclk to lbcs# falling tbd tbd ns t zrcs2 reference lbclk to lbcs# rising tbd tbd ns t csrd lbcs# falling to lbrd# falling tbd tbd ns t rdcs lbrd# rising to lbcs# rising tbd tbd ns t zrd1 reference lbclk to lbr d# falling tbd tbd ns t zrd2 reference lbclk to lbrd# rising tbd tbd ns t drd data bus floating to lbrd# falling tbd tbd ns t zd1 reference lbclk to data bus floating at the start of the read transaction tbd tbd ns t zd2 reference lbclk to data bus driven by ox16pci954 at the end of the read transaction tbd tbd ns t sd data bus valid to lbrd# rising tbd tbd ns t hd data bus valid after lbrd# rising tbd tbd ns table 42 : read operation from intel - type local bus symbol parameter min max units t ref irdy# falling to reference lbclk nominally 2 pci clock cycles t za reference lbclk to address valid tbd tbd ns t awr address valid to lbwr# falling tbd tbd ns t zwcs1 reference lbclk to lbcs# falling tbd tbd ns t zwcs2 reference lbclk to lbcs# rising tbd tbd ns t cswr lbcs# falling to lbwr# falling tbd tbd ns t wrcs lbwr# rising to lbcs# rising tbd tbd ns t zwr1 reference lbclk to lbwr# falling tbd tbd ns t zwr2 reference lbclk to lbwr# rising tbd tbd ns t zdv reference lbclk to data bus v alid tbd tbd ns t zdf reference lbclk to data bus high - impedance tbd tbd ns t wrdi lbwr# rising to data bus invalid tbd tbd ns table 43 : write operation to intel - type local bus
data sheet revision 1.3 page 62 ox16pci954 oxford semiconductor ltd. symbol parameter min max units t ref irdy# falli ng to reference lbclk nominally 2 pci clock cycles t za reference lbclk to address valid tbd tbd ns t ads address valid to lbds# falling tbd tbd ns t zrds1 reference lbclk to lbds# falling tbd tbd ns t zrds2 reference lbclk to lbds# rising tbd tbd ns vt dr d data bus floating to lbds# falling tbd tbd ns t zd1 reference lbclk to data bus floating at the start of the read transaction tbd tbd ns t zd2 reference lbclk to data bus driven by ox16pci954 at the end of the read transaction tbd tbd ns t sd data bus va lid to lbds# rising tbd tbd ns t hd data bus valid after lbds# rising tbd tbd ns table 44 : read operation from motorola - type local bus symbol parameter min max units t ref irdy# falling to reference lbclk nominally 2 pci clock c ycles t za reference lbclk to address valid tbd tbd ns t ads address valid to lbds# falling tbd tbd ns t zw1 reference lbclk to lbrdwr# falling tbd tbd ns t zw2 reference lbclk to lbrdwr# rising tbd tbd ns t wds lbrdwr# falling to lbds# falling tbd tbd ns t dsw lbds# rising to lbrdwr# rising tbd tbd ns t zwds1 reference lbclk to lbds# falling tbd tbd ns t zwds2 reference lbclk to lbds# rising tbd tbd ns t zdv reference lbclk to data bus valid tbd tbd ns t zdf reference lbclk to data bus high - impedance tbd t bd ns t dsdi lbds# rising to data bus invalid tbd tbd ns table 45 : write operation to motorola - type local bus 13.3 serial ports isochronous (x1 clock) timing: symbol parameter min max units t irs sin set - up time to isochronous input clock ?rx_clk_in rising 1 tbd tbd ns t irh sin hold time after isochronous input clock ?rx_clk_in? rising 1 tbd tbd ns t its sout valid after isochronous output clock ?tx_clk_out? falling 1 tbd tbd ns table 46 : isochronous mode t iming note 1: in isochronous mode, transmitter data is available after the falling edge of the x1 clock and the receiver data is sampled using the rising edge of the x1 clock. the system designer is should ensure that mark - to - space ratio of the x1 clock i s such that the required set - up and hold timing constraint are met. one way of achieving this is to choose a crystal frequency which is twice the required data rate and then divide the clock by two using the on - board prescaler. in this case the mark - to - spa ce ratio is 50/50 for the purpose of set - up and hold calculations.
data sheet revision 1.3 page 63 ox16pci954 oxford semiconductor ltd. 14 t iming w aveforms clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 5 data wait data transfer figure 4 : pci read transaction from internal uarts clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data data transfer figure 5 : pci write transaction to internal uarts
data sheet revision 1.3 page 64 ox16pci954 oxford semiconductor ltd. t im ing w aveforms clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data data transfer figure 6 : pci read transaction from local configuration registers clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data data transfer figure 7 : pci write transaction to local configuration registers
data sheet revision 1.3 page 65 ox16pci954 oxford semiconductor ltd. t iming w aveforms t clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data data transfer data lbclk lba lbcs# lbrd# lbd lbd valid data valid data wait wait wait wait 5 n+5 n+6 n+7 1 2 valid local bus address t ref t za t ard t zrcs2 rdcs t zrd2 t zd2 t sd t hd t zd1 t drd t zrd1 t csrd t zrcs1 local bus reference cycle where: n = 0, 1, .., 9 data sampled figure 8 : pci read transaction from intel - type local bus
data sheet revision 1.3 page 66 ox16pci954 oxford semiconductor ltd. t iming w aveforms t clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data transfer lbclk lba lbcs# lbwr# lbd lbd valid local bus data wait wait wait wait 5 n+5 n+6 n+7 1 2 valid local bus address t ref t za t awr t zwcs2 wrcs t zwr2 t wrdi t zdf t zwr1 t cswr t zwcs1 data valid local bus data local bus reference cycle t zdv where: n = 0, 1, .., 9 figure 9 : pci write transaction to intel - type local bus
data sheet revision 1.3 page 67 ox16pci954 oxford semiconductor ltd. t iming w aveforms clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data data transfer data lbclk lba lbrdwr# lbds# lbd lbd valid data valid data wait wait wait wait 5 n+5 n+6 n+7 1 2 valid local bus address t ref t za t ads t zrds2 t zd2 t sd t hd t zd1 t drd t zrds1 local bus reference cycle where: n = 0, 1, .., 9 data sampled figure 10 : pci read transaction from motorola - type local bus
data sheet revision 1.3 page 68 ox16pci954 oxford semiconductor ltd. t iming w aveforms clk frame# ad[31:0] c/be[3:0]# irdy# trdy# devsel# stop# address bus cmd byte enable# 1 2 3 4 data transfer lbclk lba lbrdwr# lbds# lbd lbd valid local bus data wait wait wait wait 5 n+5 n+6 n+7 1 2 valid local bus address t ref t za t ads t zw2 t zwds2 t dsdi t zdf t zwds1 t wds t zw1 data valid local bus data local bus reference cycle t zdv where: n = 0, 1, .., 9 t dsw figure 11 : pci write transaction to motorola - type local bus
data sheet revision 1.3 page 69 ox16pci954 oxford semiconductor ltd. t iming w aveforms sin rx_clk_in sout tx_clk_out t irs t irh t its figure 12 : isochronous (x1 clock) timing waveform
data sheet revision 1.3 page 70 ox16pci954 oxford semiconductor ltd. 15 p ackage i nformation figure 13 : 160 pin thin quad flat pack (tqfp) package 16 o rdering i nformation ox16pci954 - tqc60 - a revision package type ? 160 tqfp
data sheet revision 1.3 page 71 ox16pci954 oxford semiconductor ltd. n otes this page has been intentionally left blank
data sheet revision 1.3 page 72 ox16pci954 oxford semiconductor ltd. c ontact d etails oxford semiconductor ltd. 69 milton park abingdon oxfordshire ox14 4rx united kingdom telephone: +44 (0)1235 824900 fax: +44 (0)1235 821141 sales e - mail: sales@oxsemi.com tech support e - mail: support@oxsemi.com web site: http://www.oxsemi.com d isclaimer oxford semiconductor believes the information contained in this document to be accurate and reliable. however, it is subject to change without notice. no res ponsibility is assumed by oxford semiconductor for its use, nor for infringement of patents or other rights of third parties. no part of this publication may be reproduced, or transmitted in any form or by any means without the prior consent of oxford semi conductor ltd. oxford semiconductor?s terms and conditions of sale apply at all times.

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