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Freescale Semiconductor Advance Information
Document Number: MC33976 Rev 4.0, 1/2007
Dual Gauge Driver with Configurable Response Time
The 33976 is a single-packaged, Serial Peripheral Interface (SPI) controlled, dual step motor gauge driver integrated circuit (IC). This monolithic IC consists of four dual output H-Bridge coil drivers and the associated control logic. Each pair of H-Bridge drivers is used to automatically control the speed, direction, and magnitude of current through the two coils of a two-phase instrumentation step motor, similar to an MMT-licensed AFIC 6405 or Switec MS-X15.xxx motor. The 33976 is ideal for use in automotive instrumentation systems requiring distributed and flexible step motor gauge driving. The device also eases the transition to step motors from air core motors by emulating the air core pointer movement with little additional processor bandwidth utilization. Features *MMT-Licensed Two-Phase Step Motor Compatible *Switec MS-X15.xxx Step Motor Compatible *Minimal Processor Overhead Required *Fully Integrated Pointer Movement and Position State Machine with Channel-Independent Configurable Pointer Movement *4096 Possible Steady State Pointer Positions *340 Maximum Pointer Sweep *Maximum Acceleration of *Maximum Pointer Velocity of 400/s *Analog Microstepping (12 Steps/Degree of Pointer Movement) *Pointer Calibration and Return to Zero (RTZ) *SPI-Controlled 16-Bit Word *Calibratable Internal Clock *Low Sleep Mode Current *Pb-Free Packaging Designated by Suffix Code EG
VPWR
33976
CONFIGURABLE DUAL GAUGE DRIVER
DW SUFFIX EG SUFFIX (PB-FREE) 98ASB42344B 24-PIN SOICW
ORDERING INFORMATION
Device MC33976DW/R2 - 40C to 125C MCZ33976EG/R2 24 SOICW Temperature Range (TA) Package
4500/s2
33976
VPWD 5.0 V Regulator VDD VDD SIN0+ SIN0Motor 0 COS0+ COS0RTZ RST CS SCLK SI SO GND SIN1+ SIN1Motor 1 COS1+ COS1-
MCU
Figure 1. 33976 Simplified Application Diagram
* This document contains certain information on a new product. Specifications and information herein are subject to change without notice.
(c) Freescale Semiconductor, Inc., 2007. All rights reserved.
INTERNAL BLOCK DIAGRAM
INTERNAL BLOCK DIAGRAM
VPWR
VDD
INTERNAL REGULATOR
CS SCLK SO SI
COS0 SPI SIN0
COS0+ COS0SIN0+ SIN0COS1+ COS1-
COS1
RST
LOGIC STATE MACHINE UNDERAND OVERVOLTAGE DETECT ILIM H-BRIDGE AND CONTROL
SIN1+ SIN1-
OVERTEMPERATURE DETECT
SIN1
SIGMA-DELTA ADC OSCILLATOR AGND
VDD MULTIPLEXER
RTZ
GND (8)
Figure 2. 33976 Simplified Internal Block Diagram
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PIN CONNECTIONS
PIN CONNECTIONS
COS0+ COS0SIN0+ SIN0GND GND GND GND CS SCLK SO SI
1 2 3 4 5 6 7 8 9 10 11 12
24 23 22 21 20 19 18 17 16 15 14 13
COS1+ COS1SIN1+ SIN1GND GND GND GND VPWR RST VDD RTZ
Figure 3. 33976 Pin Connections Table 1. 33976 Pin Definitions
Pin Number Pin Name (MS Motor Pin #) 1 2 3 4 5 - 8, 17- 20 9 10 11 12 13 14 15 16 COS0+ (MS #4) COS0- (MS #3) SIN0+(MS #1) SIN0- (MS #2) GND CS SCLK SO SI RTZ VDD RST VPWR (MS Motor Pin #) 21 22 23 24 SIN1- (MS #2) SIN1+ (MS #1) COS1- (MS #3) COS1+ (MS #4) Ground Input Input Output Input Output Input Input Input Output Ground Chip Select Serial Clock Serial Output Serial Input Multiplexed Output Voltage Reset Battery Voltage H-Bridge Outputs 1 Pin Function Output Formal Name H-Bridge Outputs 0 Definition Each pin is the output pin of a half bridge, designed to source or sink current.
These pins serve as the ground for the source of the low-side output transistors as well as the logic portion of the device. This pin is connected to a chip select output of a LSI IC. This pin is connected to the SCLK pin of the master device and acts as a bit clock for the SPI port. This pin is connected to the SPI Serial Data Input pin of the master device or to the SI pin of the next device in a daisy chain. This pin is connected to the SPI Serial Data Output pin of the master device from which it receives output command data. This is a multiplexed output pin for the non-driven coil, during a Return to Zero (RTZ) event. This SPI and logic power supply input will work with 5.0 V supplies. This input has an internal active pull-up. Power supply. Each of these pins is the output pin of a half bridge, designed to source or sink current.
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ELECTRICAL CHARACTERISTICS MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
MAXIMUM RATINGS
Table 2. Maximum Ratings All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage to the device.
Rating Power Supply Voltage Steady State Input Pin Voltage (1) SIN +/- COS +/- Continuous Per Output Current (2) Storage Temperature Operating Junction Temperature Thermal Resistance Junction to Ambient Junction to Lead ESD Voltage (3) Human Body Model Machine Model Peak Package Reflow Temperature During Reflow (4), (5) VESD1 VESD2 TPPRT 2000 200 Note 5 C RJA RJL 60 20 V VIN IOUTMAX TSTG TJ Symbol VPWR(SUS) -0.3 to 41 -0.3 to 7.0 40 -55 to 150 -40 to 150 V mA C C C/W Value Unit V
Notes 1. Exceeding voltage limits on Input pins may cause permanent damage to the device. 2. Output continuous output rating so long as maximum junction temperature is not exceeded. Operation at 125C ambient temperature will require maximum output current computation using package thermal resistances. 3. ESD1 testing is performed in accordance with the Human Body Model (CZAP = 100 pF, RZAP = 1500 ), ESD2 testing is performed in accordance with the Machine Model (CZAP = 200 pF, RZAP = 0 ). 4. 5. Pin soldering temperature limit is for 10 seconds maximum duration. Not designed for immersion soldering. Exceeding these limits may cause malfunction or permanent damage to the device. Freescale's Package Reflow capability meets Pb-free requirements for JEDEC standard J-STD-020C. For Peak Package Reflow Temperature and Moisture Sensitivity Levels (MSL), Go to www.freescale.com, search by part number [e.g. remove prefixes/suffixes and enter the core ID to view all orderable parts. (i.e. MC33xxxD enter 33xxx), and review parametrics.
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ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS
STATIC ELECTRICAL CHARACTERISTICS
Table 3. Static Electrical Characteristics Characteristics noted under conditions 4.75 V VDD 5.25 V, - 40C TJ 150C, GND = 0 V unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25C under nominal conditions unless otherwise noted.
Characteristic POWER INPUT Supply Voltage Range Fully Operational Limited Operational (6), (7) VPWR Supply Current Gauge 1 and 2 Outputs ON, No Output Loads VPWR Supply Current (All Outputs Disabled) Reset = Logic [0], VDD = 5.0 V Reset = Logic [0], VDD = 0 V Overvoltage Detection Level (8) Undervoltage Detection Level (9) Logic Supply Voltage Range (5.0 V Nominal Supply) Under VDD Logic Reset VDD Supply Current Sleep: Reset Logic [0] Outputs Enabled POWER OUTPUTS Microstep Output (Measured Across Coil Outputs) SIN0,1, (COS0,1, ) (refer to Table 1) ROUT = 200 , PE6 = 0 Steps 6, 18 (0, 12) Steps 5, 7, 17, 19 (1, 11, 13, 23) Steps 4, 8, 16, 20 (2, 10, 14, 22) Steps 3, 9, 15, 21 (3, 9, 15, 21) Steps 2, 10, 14, 22 (4, 8,16, 20) Steps 1, 11, 13, 23 (5, 7, 17, 19) Steps 0, 12 (6, 18) VST6 VST5 VST4 VST3 VST2 VST1 VST0 4.82 0.94 VST6 0.84 VST6 0.68 VST6 0.47 VST6 0.23 VST6 -0.1 5.3 0.97 VST6 0.87 VST6 0.71 VST6 0.50 VST6 0.26 VST6 0 6.0 1.0 VST6 0.96 VST6 0.8 VST6 0.57 VST6 0.31 VST6 0.1 V IDD(OFF) IDD(ON) - - 40 1.0 65 1.8 A mA IPWSLP1 IPWRSLP2 VPWROV VPWRUV VDD VDDUV - - 26 5.0 4.5 - 42 15 32 5.6 5.0 - 60 25 38 6.2 5.5 4.5 V V V V IPWR(ON) - 4.0 6.0 A VPWR 6.5 4.0 - - 26 26 mA V Symbol Min Typ Max Unit
Notes 6. Outputs and logic remain active; however, the larger coil voltage levels may be clipped. The reduction in drive voltage may result in a loss of position control. 7. The logic will reset at some level below the specified Limited Operational minimum. 8. Outputs will disable and must be re-enabled via the PECCR command. 9. Outputs remain active; however, the reduction in drive voltage may result in a loss of position control.
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ELECTRICAL CHARACTERISTICS STATIC ELECTRICAL CHARACTERISTICS
Table 3. Static Electrical Characteristics (continued) Characteristics noted under conditions 4.75 V VDD 5.25 V, - 40C TJ 150C, GND = 0 V unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25C under nominal conditions unless otherwise noted.
Characteristic POWER OUTPUTS (CONTINUED) Full Step Active Output (Measured Across Coil Outputs) SIN0, 1, (COS0, 1, ) (see Figure 9, page 26) Steps 1, 3 (0, 2) Microstep, Full Step Output (Measured from Coil Low Side to Ground) SIN0, 1, (COS0, 1, ), IOUT = 30 mA Output Flyback Clamp (11) Output Current Limit (Output = Vst6) Overtemperature Shutdown (10) Overtemperature Hysteresis (11) CONTROL I/O Input Logic High Voltage (12) Input Logic Low Voltage (12) Input Logic Voltage Hysteresis (10) Input Logic Pull Down Current (SI, SCLK) Input Logic Pull-Up Current (CS, RST) SO High-State Output Voltage (IOH = 1.0 mA) SO Low-State Output Voltage (IOL = -1.6 mA) SO Tri-State Leakage Current (CS 3.5 V) Input Capacitance (13) SO Tri-State Capacitance (13) ANALOG TO DIGITAL CONVERTER (RTZ ACCUMULATOR COUNT) ADC Gain (10), (14) VIH VIL VIN(HYST) IDWN IUP VSOH VSOL ISOLK CIN CSO 2.0 - - 3.0 5.0 0.8 VDD - -5.0 - - - - 100 - - - 0.2 0 4.0 - - 0.8 - 20 20 - 0.4 5.0 12 20 V V mV A A V V A pF pF VFB ILIM OTSD OTHYST 0 - 40 155 8.0 0.1 VST6 + 0.5 100 - - 0.3 VST6+ 1.0 170 180 16 V mA C C VLS 4.9 5.3 6.0 V VFS V Symbol Min Typ Max Unit
GADC
100
188
270
Counts/ V/ms
Notes 10. This parameter is guaranteed by design, but it is not production tested. 11. Not 100 percent tested. 12. VDD = 5.0 V. 13. 14. Capacitance not measured. This parameter is guaranteed by design, but it is not production tested. Reference RTZ Accumulator (Typical) on page 23
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ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS
DYNAMIC ELECTRICAL CHARACTERISTICS
Table 4. Dynamic Electrical Characteristics Characteristics noted under conditions 4.75 V VDD 5.25 V, - 40C TJ 150C, GND = 0 V unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25C under nominal conditions unless otherwise noted.
Characteristic POWER OUTPUT AND CLOCK TIMINGS SIN0,1, (COS0,1, ) Output Turn ON Delay Time (Time from Rising CS Enabling Outputs to Steady State Coil Voltages and Currents) (15) SIN0,1, (COS0,1, ) Output Turn OFF Delay Time (Time from Rising CS Disables Outputs to Steady State Coil Voltages and Currents) (15) Uncalibrated Oscillator Cycle Time Calibrated Oscillator Cycle Time Calibration Pulse = 8.0 s, PECCR D4 = Logic [0] Calibration Pulse = 8.0 s, PECCR D4 = Logic [1] Maximum Pointer Speed (16) Maximum Pointer Acceleration (16) VMAX A MAX - - ms - - 1.0 1.0 1.7 s s 1.0 0.9 - - 1.1 1.0 - - 1.2 1.1 400 4500 /s /s2 Symbol Min Typ Max Units
tDLY (ON)
1.0
ms
tDLY (OFF)
tCLU tCLC
0.65
Notes 15. Maximum specified time for the 33976 is the minimum guaranteed time needed from the microcontroller. 16. The minimum and maximum value will vary proportionally to the internal clock tolerance. These numbers are based on an ideally calibrated clock frequency of 1.0 MHz. These are not 100 percent tested.
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ELECTRICAL CHARACTERISTICS DYNAMIC ELECTRICAL CHARACTERISTICS
Table 4. Dynamic Electrical Characteristics (continued) Characteristics noted under conditions 4.75 V VDD 5.25 V, - 40C TJ 150C, GND = 0 V unless otherwise noted. Typical values noted reflect the approximate parameter means at TA = 25C under nominal conditions unless otherwise noted.
Characteristic SPI INTERFACE TIMING (17) Recommended Frequency of SPI Operation Falling Edge of CS to Rising Edge of SCLK (Required Setup Time) (18) Falling Edge of SCLK to Rising Edge of CS (Required Setup Time) (18) SI to Falling Edge of SCLK (Required Setup Time) (18) Required High State Duration of SCLK (Required Setup Time (18) Required Low State Duration of SCLK (Required Setup Time (18) Falling Edge of SCLK to SI (Required Hold Time) (18) SO Rise Time CL = 200 pF SO Fall Time CL = 200 pF SI, CS, SCLK, Incoming Signal Rise Time (19) SI, CS, SCLK, Incoming Signal Fall Time
(19) (18)
Symbol
Min
Typ
Max
Units
fSPI tLEAD tLAG tSISU tWSCLKH tWSCLKL tSI (HOLD) tRSO
- - - - - - -
1.0 50 50 25 - - 25
2.0 167 167 83 167 167 83
MHz ns ns ns ns ns ns ns
- tFSO - tRSI tFSI tWRST t CS tEN tSO(EN) tSO(DIS) tVALID - - - - - - - -
25
50 ns
25 - - - - - - 1.3
50 50 50 3.0 5.0 5.0 145 4.0 ns ns s s s ns s ns
Falling Edge of RST to Rising Edge of RST (Required Setup Time) Rising Edge of CS to Falling Edge of CS (Required Setup Time)
(18), (20) (18)
Rising Edge of RST to Falling Edge of CS (Required Setup Time) Time from Falling Edge of CS to SO Low Impedance Time from Rising Edge of CS to SO High Impedance Time from Rising Edge of SCLK to SO Data Valid 0.2 VDD SO 0.8 VDD, CL = 200 pF
(21) (22)
(23)
90
150
Notes 17. The 33976 shall meet all SPI interface timing requirements specified in the SPI Interface Timing section of this table, over the specified temperature range. Digital interface timing is based on a symmetrical 50 percent duty cycle SCLK Clock Period of 333 ns. The device shall be fully functional for slower clock speeds. Reference Figure 4 and 5. 18. The maximum setup time specified for the 33976 is the minimum time needed from the microcontroller to guarantee correct operation. 19. Rise and Fall time of incoming SI, CS, and SCLK signals suggested for design consideration to prevent the occurrence of double pulsing. 20. The value is for a 1.0 MHz calibrated internal clock. The value will change proportionally as the internal clock frequency changes. 21. Time required for output status data to be terminated at SO. 1.0 k load on SO 22. Time required for output status data to be available for use at SO. 1.0 k load on SO. 23. Time required to obtain valid data out from SO following the rise of SCLK.
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ELECTRICAL CHARACTERISTICS TIMING DIAGRAMS
TIMING DIAGRAMS
VIN
RST
0.2 VDD tWRST tEN 0.7 VDD tCS
VIL
VIH VIL
CS
0.7 VDD tLEAD 0.7 VDD tWSCLKH tRSI tLAG
VIH VIL tLEAD tWSCLKL tSI(HOLD) Valid Don't Care tFSI VIH Valid Don't Care VIL
SCLK
0.2 VDD
SI
Don't Care
0.7 VDD 0.2 VDD
Figure 4. Input Timing Switching Characteristics
tRSI 3.5 V
tFSI VOH 50% 1.0 V
SCLK
VOL
tSO(EN)
SO
Low-to-High
0.7 VDD 0.2 VDD
VOH
VOL trSO tVALID
SO
High-to-Low 0.7 VDD tSO(DIS)
tfSO 0.2 VDD
VOH
VOL
Figure 5. Valid Data Delay Time and Valid Time Waveforms
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FUNCTIONAL DESCRIPTION INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
This 33976 is a single-packaged, Serial Peripheral Interface (SPI) controlled, dual step motor gauge driver integrated circuit (IC). This monolithic IC consists of four dual output H-Bridge coil drivers and the associated control logic. Each pair of H-Bridge drivers is used to automatically control the speed, direction, and magnitude of current through the two coils of a two-phase instrumentation step motor, similar to an MMT-licensed AFIC 6405 or a Switec MS-X15.xxx motor. The 33976 is ideal for use in automotive instrumentation systems requiring distributed and flexible step motor gauge driving. The device also eases the transition to step motors from air core motors by emulating the air core pointer movement with little additional processor bandwidth utilization.
FUNCTIONAL PIN DESCRIPTION H-BRIDGE OUTPUTS 0 (COS0+, COS0-, SIN0+, SIN0-)
Each pin is the output pin of a half bridge, designed to source or sink current. The H-Bridge pins linearly drive the sine and cosine coils of two separate step motors to provide four-quadrant operation. and SO is tri-stated (high impedance). Refer to the data transfer timing diagrams in Figure 6 and Figure 7 on page 12.
SERIAL OUTPUT (SO)
The SO data pin is a tri-stateable output from the Shift register. The Status register bits are the first 16 bits shifted out. Those bits are followed by the message bits clocked in FIFO, when the device is in a daisy chain connection or being sent words that are multiples of 16 bits. Data is shifted on the rising edge of the SCLK signal. The SO pin will remain in a high impedance state until the CS pin is put into a logic low state.
GROUND (GND)
These pins serve as the ground for the source of the lowside output transistors as well as the logic portion of the device. They also help dissipate heat from the device.
CHIP SELECT (CS)
The CS pin enables communication with the master device. When this pin is in a logic [0] state, the 33976 is capable of transferring information to, and receiving information from, the master. The 33976 latches data in from the Input Shift registers to the addressed registers on the rising edge of CS. The output driver on the SO pin is enabled when CS is logic [0]. When CS is logic high, signals at the SCLK and SI pins are ignored and the SO pin is tri-stated (high impedance). CS will only be transitioned from a logic [1] state to a logic [0] state when SCLK is a logic [0]. CS has an internal pull-up (lUP) connected to the pin, as specified in the section of the Static Electrical Characteristics table entitled CONTROL I/O, which is found on page 6.
SERIAL INPUT (SI)
The SI pin is the input of the SPI. Serial input information is read on the falling edge of SCLK. A 16-bit stream of serial data is required on the SI pin, beginning with the most significant bit (MSB). Messages that are not multiples of 16 bits (e.g., daisy chained device messages) are ignored. After transmitting a 16-bit word, the CS pin must be de-asserted (logic [1]) before transmitting a new word. SI information is ignored when CS is in a logic high state.
MULTIPLEXED OUTPUT (RTZ)
This is a multiplexed output pin for the non-driven coil, during a Return to Zero (RTZ) event.
SERIAL CLOCK (SCLK)
SCLK clocks the Internal Shift registers of the 33976 device. The SI pin accepts data into the Input Shift register on the falling edge of the SCLK signal, while the Serial Output pin (SO) shifts data information out of the SO Line Driver on the rising edge of the SCLK signal. It is important that the SCLK pin be in a logic [0] state whenever the CS makes any transition. SCLK has an internal pull down (lDWN), as specified in the section of the Static Electrical Characteristics table entitled CONTROL I/O, which is found on page 6. When CS is logic [1], signals at the SCLK and SI pins are ignored
VOLTAGE (VDD)
This SPI and logic power supply input will work with 5.0 V supplies.
RESET (RST)
If the master decides to reset the device or place it into a sleep state, the RST pin is driven to a logic [0]. A logic [0] on the RST pin will force all internal logic to the known default state. This input has an internal active pull-up.
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FUNCTIONAL DESCRIPTION FUNCTIONAL PIN DESCRIPTION
BATTERY VOLTAGE (VPWR)
Power supply.
H-BRIDGE OUTPUTS 1 (SIN1-, SIN1+, COS1-, COS1+)
Each of these pins is the output pin of a half bridge, designed to source or sink current. The H-Bridge pins linearly drive the sine and cosine coils of two separate step motors to provide four-quadrant operation.
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FUNCTIONAL DEVICE OPERATION OPERATIONAL MODES
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES SPI PROTOCOL DESCRIPTION
The SPI interface has a full-duplex, three-wire synchronous, 16-bit serial synchronous interface data transfer and four I/O lines associated with it: Chip Select (CS), Serial Clock (SCLK), Serial Input (SI), and Serial Output (SO). The SI/SO pins of the 33976 follow a first in/first out (D15/D0) protocol with both input and output words transferring the most significant bit first. All inputs are compatible with 5.0 V CMOS logic levels.
TIMING DESCRIPTION
This section provides a description of the 33976 SPI behavior. To follow the explanations below, refer to Table 5 and to the timing diagrams shown in Figure 6 and Figure 7. Table 5. Data Transfer Timing
Pin
CS (1-to-0) CS (0-to-1)
Description SO pin is enabled. 33976 configuration and desired output states are transferred and executed according to the data in the Shift registers. Will change state on the rising edge of the SCLK pin signal. Will accept data on the falling edge of the SCLK pin signal.
SO SI
CS SCLK SI SO
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
OD15
OD14
OD13
OD12
OD11
OD10
OD9
OD8
OD7
OD6
OD5
OD4
OD3
OD2
OD1
OD0
Output shift register is loaded here. Note SO is tri-stated when CS is logic [1].
Figure 6. Single 16-Bit Word SPI Communication
CS
SCLK SI SO
D15 D14 D13 D12 D11 D2 D1 D0 D15* D14* D13* D4 D3 D2* D1* D0*
OD15
OD14
OD13
OD12
OD11
OD2
OD1
OD0
D15
D14
D13
OD4
OD3
D2
D1
D0
Notes 1. SO is tri-stated when CS is logic [1]. 2. D15, D14, D13, ..., and D0 refer to the first 16 bits of data into the 33976. 3. D15*, D14*, D13*, ..., and D0* refer to the most recent entry of program data into the 33976. 4. OD15, OD14, OD13, ..., and OD0 refer to the first 16 bits of fault and status data out of the 33976.
Figure 7. Multiple 16-Bit Word SPI Communication
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FUNCTIONAL DEVICE OPERATION LOGIC COMMANDS AND REGISTERS
DATA INPUT
The Input Shift register captures data at the falling edge of the SCLK clock. The SCLK clock pulses exactly 16 times only inside the transmission windows (CS in a logic [0] state). By the time the CS signal goes to logic [1] again, the contents of the Input Shift register are transferred to the appropriate internal register addressed in bits 15:13. The minimum time CS should be kept high depends on the internal clock speed, specified in the SPI INTERFACE TIMING (17) section of the Static Electrical Characteristics, found on page 6. It must be long enough so the internal clock is able to capture the data
from the Input Shift register and transfer it to the internal registers.
DATA OUTPUT
At the first rising edge of the SCLK clock, with CS at logic [0], the contents of the selected Status Word register are transferred to the Output Shift register. The first 16 bits clocked out are the status bits. If data continues to clock in before the CS transitions to a logic [1], the device begins to shift out the data previously clocked in FIFO after the CS first transitioned to logic [0].
LOGIC COMMANDS AND REGISTERS COMMUNICATION MEMORY MAPS AND REGISTER DESCRIPTIONS
The 33976 device is capable of interfacing directly with a microcontroller via the 16-bit SPI protocol specified below. The device is controlled by the microprocessor and reports back status information via the SPI. This section provides a detailed description of all registers accessible via serial interface. The various registers control the behavior of this device. A message is transmitted by the master beginning with the MSB (D15) and ending with the LSB (D0). Multiple messages can be transmitted in succession to accommodate those applications where daisy chaining is desirable, or to confirm transmitted data, as long as the messages are all multiples of 16 bits. Data is transferred through daisy-chained devices, as illustrated in Figure 7, page 12. If an attempt is made to latch in a message smaller than 16 bits wide, it is ignored. Table 6 lists the seven registers the 33976 uses to configure the device, control the state of the four H-bridge outputs, and determine the type of status information that is clocked back to the master. The registers are addressed via D15:D13 of the incoming SPI word. Table 6. Module Memory Map
Address [15:13] 000 Register Power, Enable, Calibration, and Configuration Register Maximum Velocity Register Gauge 0 Position Register Gauge 1 Position Register Return to 0 Register Return to 0 Configuration Register Ramp Selection Register Reserved for Test Name PECCR See Page Page 13
MODULE MEMORY MAP
Various registers of the 33976 SPI module are addressed by the three MSBs of the 16-bit word received serially. Functions to be controlled include: * Individual gauge drive enabling * Power-up/down * Internal clock calibration * Gauge pointer position and velocity * Gauge pointer zeroing * Air core motor movement emulation * Status information Status reporting includes: * Individual gauge overtemperature condition * Battery overvoltage * Battery undervoltage * Pointer zeroing status * Internal clock status * Confirmation of coil output changes that should result in pointer movement * Real time pointer position information * Real time pointer velocity step information * Pointer movement direction * Command pointer position status * RTZ accumulator value
001 010 011 100 101
VELR POS0R POS1R RTZR RTZCR
Page 15 Page 16 Page 16 Page 16 Page 17
REGISTER DESCRIPTIONS
The following section describes the registers, their addresses, and their impact on device operation. Address 000 -- Power, Enable, Calibration, and Configuration Register (PECCR) The Power, Enable, Calibration, and Configuration Register is illustrated in Table 7, page 14. A write to the 33976 using this register allows the master to (1) independently enable or disable the output drivers of the two-gauge controllers, (2) calibrate the internal clock, (3) disable the air core emulation, (4) select the direction of the pointer movement during pointer positioning and zeroing, (5) configure the device for the desired status information to
110 111
RMPSELR -
Page 19 -
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FUNCTIONAL DEVICE OPERATION LOGIC COMMANDS AND REGISTERS
be clocked out into the SO pin, or (6) send a null command for the purpose of reading the status bits. This register is also used to place the 33976 into a low current consumption mode. Each of the gauge drivers can be enabled by writing a logic [1] to their assigned address bits, PE0 and PE1 respectively. This feature could be used to disable a driver if it is failing or is not being used. The device can be placed into a standby current mode by writing a logic [0] to both PE0 and PE1. During this state, most current consuming circuits are biased off. When in the Standby mode, the internal clock will remain ON. The internal state machine utilizes a ROM table of step times defining the duration that the motor will spend at each microstep as it accelerates or decelerates to a commanded position. The accuracy of the acceleration and velocity of the motor is directly related to the accuracy of the internal clock. Although the accuracy of the internal clock is temperature independent, the non-calibrated tolerance is +70% to -35%. The 33976 was designed with a feature allowing the internal clock to be software calibrated to a tighter tolerance of 10%, using the CS pin and a reference time pulse provided by the microcontroller. Calibration of the internal clock is initiated by writing a logic [1] to PE3. The calibration pulse, which must be 8.0 s for an internal clock speed of 1.0 MHz, will be sent on the CS pin immediately after the SPI word is sent. No other SPI lines will be toggled. A clock calibration will be allowed only if the gauges are disabled or the pointers are not moving, as indicated by status bits MOV0 and MOV1. Additional details are provided in the Internal Clock Calibration section, beginning on page 30. Some applications may require a guaranteed maximum pointer velocity and acceleration. Guaranteeing these maximums requires that the nominal internal clock frequency fall below 1.0 MHz. The frequency range of the calibrated clock will always be below 1.0 MHz if bit PE4 is logic [0] when initiating a calibration command, followed by an 8.0 s reference pulse. The frequency will be centered at 1.0 MHz if bit PE4 is logic [1]. Some applications may require a slower calibrated clock due to a lower motor gear reduction ratio. Writing a logic [1] to bit PE2 will slow the internal oscillator by one-third. Slowing the clock accommodates a longer calibration pulse without overrunning the internal counter--a condition designed to
generate a CAL fault indication. For example, calibration for a clock frequency of 667 kHz would require a calibration pulse of 12 s. Unless the internal oscillator is slowed by writing PE2 to logic [1], a 12 s calibration pulse may overrun the counter and generate a CAL fault indication. Some applications may require faster pointer positioning than is provided with the air core motor emulation feature. Writing logic [1] to bit PE5 will disable the air core emulation for both gauges and provide an acceleration and deceleration at the maximum that the velocity position ramp can provide. If the Hold Counts need to be enabled and disabled dynamically, then the POSxR commands could also be used. Bit PE6 must always be written as a logic [0] during all PECCR writes if the device is being used to drive an MMT style motor. Similarly, this bit must always be written as a logic [1] when being used to control Switec style motors. The default Pointer Position 0 (PE7 = 0) will be the farthest counter-clockwise position. A logic [1] written to bit PE7 will change the location of the position 0, for the gauge selected by bit PE8, to the farthest clockwise position. A change in position 0 of only one, or both, of the two coils can be accomplished by using bits PE8 and PE7. Performing an RTZ will always move the pointer to position 0. Exercise care when writing to PECCR bits PE8 and PE7 in order to prevent accidental changes of the position 0 locations. Bits PE11:PE8 determine the content of the bits clocked out of the SO pin. When bit PE11 is at logic [0], the clocked out bits will provide device status. If a logic [1] is written to bit PE11, the bits clocked out of the SO pin, depending upon the state of bits PE10:PE8, provides either: * Accumulator information and detection status during the RTZ (PE10 logic [0]) * Real time pointer position location at the time CS goes low (PE10 logic [1] and PE9 logic [0]), or * The real time step position of the pointer as described in the velocity Table 30, page 28 (PE10, PE9, and PE8 logic [1]). Additional details are provided in the SO Communication section beginning on page 21. If bit PE12 is logic [1] during a PECCR command, the state of PE11:PE0 is ignored. This is referred to as the null command and can be used to read device status without affecting device operation.
Table 7. Power, Enable, Calibration, and Configuration Register (PECCR)
Address 000 Bits Read Write D12 - PE12 D11 - PE11 D10 - PE10 D9 - PE9 D8 - PE8 D7 - PE7 D6 - PE6 D5 - PE5 D4 - PE4 D3 - PE3 D2 - PE2 D1 - PE1 D0 - PE0
The bits in Table 7 are write-only.
PE12 (D12) -- Null Command for Status Read
* 0 = Disable * 1 = Enable
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PE11 (D11) -- Status Select bit. This bit selects the information clocked out of the SO pin. * 0 = Device Status (the logic states of PE10, PE9, and PE8 don't cares) * 1 = RTZ Accumulator Value, Gauge 0 or 1 Pointer position, or Gauge 0 and 1 Velocity ramp position (depending upon the logic states of PE10, PE9, and PE8) PE10 (D10) -- RTZ Accumulator or Pointer Status Select bit. This bit is recognized only when PE11 = 1. * 0 = RTZ Accumulator Value and status * 1 = Pointer Position or Speed PE9 (D9) -- Pointer Position or Pointer Speed Select bit. This bit is recognized only if PE11 and PE10 = 1. * 0 = Gauge 0 or Gauge 1 Pointer Position * 1 = Gauge 0 and Gauge 1 Pointer Speed PE8 (D8) -- Pointer Position Gauge Select bit. Also the Position 0 of the selected gauge is determined by the PE7 selection. This bit is recognized only if PE11 and PE10 = 1 and PE9 = 0. * 0 = Gauge 0 position * 1 = Gauge 1 position PE7 (D7) -- Position 0 Location Select bit. This bit determines the Position 0 of the gauge selected by PE8. RTZ direction will always be to the position 0. * 0 = Position 0 is the most CCW (counterclockwise) position * 1 = Position 0 is the most CW (clockwise) position PE6 (D6) -- Motor Type Selection bit. * 0 = MMT Style (coil phase difference = 90) * 1 = Switec Style (coil phase difference = 60) PE5 (D5) -- Air Core Motor Emulation bit. This bit is enabled or disabled (acceleration and deceleration is constant if disabled). * 0 = Enable * 1 = Disable Table 8. Maximum Velocity Register (VELR)
PE4 (D4) -- Clock Calibration Frequency Selector * 0 = Maximum f =1.0 MHz (for 8.0 s calibration pulse) * 1 = Nominal f =1.0 MHz (for 8.0 s calibration pulse) PE3 (D3) -- Clock Calibration Enable bit. This bit enables or disables the clock calibration. * 0 = Disable * 1 = Enable PE2 (D2) -- Oscillator Adjustment * 0 = tCLU * 1 = 0.66 x tCLU PE1 (D1) -- Gauge 1 Enable bit. This bit enables or disables the output driver of Gauge 1. * 0 = Disable * 1 = Enable PE0 (D0) -- Gauge 0 Enable bit. This bit enables or disables the output driver of Gauge 0. * 0 = Disable * 1 = Enable Address 001 -- Maximum Velocity Register (VELR) The Gauge Maximum Velocity Register is used to set a maximum velocity for each gauge (refer to Table 8). Bits V7:V0 contain a position value from 1- 225 that is representative of the velocity position value described in Table 30, Velocity Table, page 28. The table value becomes the maximum velocity until it is changed to another value. If a maximum value is chosen greater than the maximum velocity in the acceleration table, the maximum table value becomes the maximum velocity. If the motor is turning at a speed greater than the new maximum, the motor immediately moves down the velocity ramp until the speed falls equal to or below it. Velocity for each motor can be changed simultaneously or independently by writing V8 and/or V9 to a logic [1]. Bits V12:V10 must be at logic [0] for valid VELR commands.
Address 001 Bits Read Write D12 - 0 D11 - 0 D10 - 0 D9 - V9 D8 - V8 D7 - V7 D6 - V6 D5 - V5 D4 - V4 D3 - V3 D2 - V2 D1 - V1 D0 - V0
The bits in Table 8 are write-only.
V12:V10 (D12:D10) -- These bits must be transmitted as logic [0] for valid VELR commands V9 (D9) -- Gauge 1 Velocity. Specifies whether the maximum velocity determined in the V7: V0 field will apply to Gauge 1. * 0 = Velocity does not apply to Gauge 1 * 1 = Velocity applies to Gauge 1
V8 (D8) -- Gauge 0 Velocity. Specifies whether the maximum velocity specified in the V7: V0 field will apply to Gauge 0. * 0 = Velocity does not apply to Gauge 0 * 1 = Velocity applies to Gauge 0 V7:V0 (D7:D0) -- Maximum Velocity. Specifies the maximum velocity position from Table 30, page 28. This velocity will remain the maximum of the intended gauge until
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changed by command. Velocities can range from position 1 (00000001) to position 225 (11111111). Addresses 010 and 011 -- Gauge 0/1 Position Registers (POS0R, POS1R) SI Address 010 (Gauge 0 Position Register) and SI Address 011 (Gauge 1 Position Register) Register bits PO 11: PO0 are written to when communicating the desired pointer positions. Table 9. Gauge 0 Position Register (POS0R)
Commanded positions can range from 0 to 4095. The D12 bit is used to disable the damping (i.e., hold counts) for each respective gauge. This feature allows the user to easily turn on and off the damping that was configured with the RMPSELR. Disabling the hold counts allows the pointer to decelerate to the commanded position, as fast as possible down the velocity ramp. When disabled, the acceleration and deceleration of the pointer are symmetrical.
Address 010 Bits Read Write D12 - HE012 D11 - P0 11 D10 - P0 10 D9 - P0 9 D8 - P0 8 D7 - P0 7 D6 - P0 6 D5 - P0 5 D4 - P0 4 D3 - P0 3 D2 - P02 D1 - P01 D0 - P0 0
The bits in Table 9 are write-only.
HE0 12 (D12) -- This bit is used to disable the damping (i.e., hold counts) for Gauge 0 (1 = Damping disabled; 0 = Damping enabled).
P0 11:P0 0 (D11:D0) -- Desired pointer position of Gauge 0. Pointer positions can range from 0 (000000000000) to position 4095 (111111111111). For a step motor requiring 12 microsteps per degree of pointer movement, the maximum pointer sweep is 341.25.
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Table 10. Gauge 1 Position Register (POS1R)
Address 011 Bits Read Write D12 - HE112 D11 - P1 11 D10 - P1 10 D9 - P1 9 D8 - P1 8 D7 - P1 7 D6 - P1 6 D5 - P1 5 D4 - P1 4 D3 - P1 3 D2 - P1 2 D1 - P1 1 D0 - P1 0
The bits in Table 10 are write-only.
HE1 12 (D12) -- This bit is used to disable the damping (i.e., hold counts) for Gauge 1 (1 = Damping disabled; 0 = Damping enabled). P1 11:P1 0 (D11:D0) -- Desired pointer position of Gauge 1. Pointer positions can range from 0 (000000000000) to position 4095 (111111111111). For a step motor requiring 12 microsteps per degree of pointer movement, the maximum pointer sweep is 341.25 (4095 / 12). Address 100 -- Gauge Return to Zero Register (RTZR) Gauge Return to Zero Register (RTZR) (refer to Table 11, page 17) is written to return the gauge pointers to the zero position. During an RTZ event, the pointer is returned to zero using full steps, where only one coil is driven at any point in time. The back electromotive force (EMF) signal present on
the non-driven coil is integrated and its results are stored in an accumulator. A logic [1] written to bit RZ1 enables a Return to Zero for Gauge 0 if RZ0 is logic [0], and Gauge 1 if RZ0 is logic [1], respectively. Similarly, a logic [0] written to bit RZ1 disables a Return to Zero for Gauge 0 when RZ0 is logic [0], and Gauge 1 when RZ0 is logic [1], respectively. Bits D12:D5 and D3:D2 must be at logic [0] for valid RTZR commands. Bit RZ4 is used to enable an unconditional RTZ event. A logic [0] results in a typical RTZ event, automatically providing a Stop when a stall condition is detected. A logic [1] will result in RTZ movement, causing a Stop if a logic [0] is written to bit RZ0. This feature is useful during development and characterization of RTZ requirements.
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Table 11. Return to Zero Register (RTZR)
Address 100 Bits Read Write D12 - 0 D11 - 0 D10 - 0 D9 - 0 D8 - 0 D7 - 0 D6 - 0 D5 - 0 D4 - RZ4 D3 - 0 D2 - RZ2 D1 - RZ1 D0 - RZ0
The register bits in Table 11 are write-only.
RZ12:RZ5 (D12:D5) -- These bits must be transmitted as logic [0] for valid commands. RZ4 (D4) -- This bit is used to enable an unconditional RTZ event. * 0 = Automatic Return to Zero * 1 = Unconditional Return to Zero RZ3 (D3) -- This bit must be transmitted as logic [0] for valid commands. RZ2 (D2) -- Return to Zero Direction bit. This bit is used to properly sequence the integrator, depending upon the desired zeroing direction. * 0 = Return to Zero will occur in the CCW direction (PE7 = 0) * 1 = Return to Zero will occur in the CW direction (PE7 = 1) RZ1 (D1) -- Return to Zero Direction. This bit commands the selected gauge to return the pointer to zero position. * 0 = Return to Zero Disabled * 1 = Return to Zero Enabled RZ0 (D0) -- Gauge Select: Gauge 0/Gauge 1. This bit selects the gauge to be commanded. * 0 = Selects Gauge 0 * 1 = Selects Gauge 1 Address 101 -- Gauge Return to Zero Configuration Register Gauge Return to Zero Configuration Register (RTZCR) is used to configure the Return to Zero Event (refer to Table 12, page 18). It is written to modify (1) the step time, or rate at which the pointer moves during an RTZ event, (2) the integration blanking time, which is the time immediately following the transition of a coil from a driven state to an open state in the RTZ mode, and (3) the threshold of the RTZ integration register. The values used for this register should be selected during development to optimize the RTZ for each application. Selecting an RTZ step rate resulting in consistently successful zero detections depends on a clear understanding of the motor characteristics. Specifically, resonant frequencies exist due to the interaction between the motor and the pointer. This command allows movement of the RTZ pointer speed away from these frequencies. Also, some motors require a significant amount of time for the pointer to settle to a steady state position when moving from one full
step position to the next. Consistent and accurate integration values require the pointer be stationary at the end of the full step time. Bits RC3:RC0, RC12:RC11, and RC4 determine the time spent at each full step during an RTZ event. Bits RC3:RC0 are used to select a t ranging from 0 ms (0000) to 61.44 ms (1111) in increments of 4.096 ms (refer to Table 13, page 18). The t is multiplied by the factor M, which is defined by bits RC12:RC11. The product is then added to the blanking time, selected using bit RC4, to generate the full step time. The multiplier selected with RC12:RC11 will be 1 (00), 2 (01), or 4 (10) as illustrated in the equations below. The multiplier selected with RC12:RC11 will be 1 (00), 2 (01), or 4 (10) as illustrated in the equations below. Note that the RC12:RC11 value of 8 (11) is not recommended for use in a product design application, because of the potential for an RTZ accumulator internal overflow, due to the long time step. The blanking time that is selected with bit RC4 determines the time that is provided immediately following a full step change, before enabling the integration of the non-driven coil signal. The blanking time is either 512 s when RC4 is logic [0], or 768 s when it is logic [1].The full step time is generated using the following equations: When D3:D0 (RC3:RC0) 0000 Full Step (t) = t x M + blanking (t) (1) When D3:D0 (RC3:RC0) = 0000 Full Step (t) = blanking (t) + 2.048 ms (2) Note In equation (2), a 2.048 ms offset is added to the full step time when the RC3:RC0 = 0000. The full step time default value after a logic reset is 12.80 ms (RC12:RC11 = 00, RC4 = 0, and RC3:RC0 = 0011). If there are two full steps per degree of pointer movement, the pointer speed is 1/(FullStep x 2) deg/s. Detecting pointer movement is accomplished by integrating the EMF present in the non-driven coil during the RTZ event. The integration circuitry is implemented using a Sigma-Delta converter resulting in the placement of a value in the 15-bit RTZ accumulator at the end of each full step. The value in the RTZ accumulator represents the change in flux and is compared to a threshold. Values above the threshold indicate a pointer is moving. Values below the threshold indicate a stalled pointer, thereby resulting in the cessation of the RTZ event. The RTZ accumulator bits are signed and represented in two's complement. After a full step of integration, a sign bit of
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0 is the indicator of an accumulator exceeding the decision threshold of 0, and the pointer is assumed to still be moving. Similarly, if the sign bit is logic [1] after a full step of integration, the accumulator value is negative and the pointer is assumed to be stopped. The integrator and accumulator are initialized after each full step. If the PECCR command is written to clock out the RTZ accumulator values via the SO, the OD14 bit corresponds to the sign bit of the RTZ accumulator. Accurate pointer stall detection depends on a correctly preloaded accumulator for specific gauge, pointer, and full step combinations. Bits RC10:RC5 are used to offset the initial RTZ accumulator value, properly detecting a stalled
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motor. The initial accumulator value at the start of a full step of integration is negative. If the accumulator was correctly preloaded, a free-moving pointer will result in a positive value at the end of the integration time, and a stalled pointer will result in a negative value. The preloaded values associated with each combination of bits RC10:RC5 are illustrated in Table 14, page 19. The accumulator should be loaded with a value resulting in an accumulator MSB to a logic [1] when the motor is stalled. For the default mode, after a power-up or any reset, the 33976 device sets the accumulator value to -1, resulting in an unconditional RTZ pointer movement until it is increased.
Table 12. RTZCR SI Register Assignment
Address 101 Bits Read Write D12 - RC12 D11 - RC11 D10 - RC10 D9 - RC9 D8 - RC8 D7 - RC7 D6 - RC6 D5 - RC5 D4 - RC4 D3 - RC3 D2 - RC2 D1 - RC1 D0 - RC0
The bits in Table 12 are write-only.
RC12:RC11 (D12:D11) -- These bits, along with RC3:RC0 (D3:D0) and RC4 (D4), determine the full step time and, therefore, the rate at which the pointer will move during an RTZ event. The values of D12:D11 determine the multiplier (M) used in equation (1) (refer to page 17). RC12:RC11 = M; default value = 00 * 00 = 1 * 01 = 2 * 10 = 4 * 11 = 8 (Not to be used for design) RC10:RC5 (D10:D5) -- These bits determine the value preloaded into the RTZ integration accumulator to adjust the detection threshold. Values range from -1 (00000000) to 1009 (11111111) as shown in Table 14, the default value = 000000. RC4 (D4) -- This bit determines the RTZ blanking time (blanking (t)). The default value = 0 * 0 = 512 s * 1 = 768 s RC3:RC0 (D3:D0) -- These bits, along with RC12:RC11 (D12:D11) and RC4 (D4), determine the time variables used to calculate the full step times with equations (1) or (2) illustrated above. RC3:RC0 determines the t time. The t values range from 0 (0000) to 61.440 ms (1111) and are shown in Table 13. The default t is 0 (0011). Note Equation (2) (refer to page 17) is only used to calculate the full step time if RC3:RC0 = 0000. Use equation (1) for all other combinations of RC3:RC0.
Table 13. RTZCR Full Step Time
RC3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 RC2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 RC1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 RC0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 t (ms) 0 4.096 8.192 12.288 16.384 20.480 24.576 28.672 32.768 36.864 40.960 45.056 49.152 53.248 57.344 61.440
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Table 14. RTZCR Accumulator Offset
RC10 0 0 0 0 0 . . . 1 RC9 0 0 0 0 0 . . . 1 RC8 0 0 0 0 0 . . . 1 RC7 0 0 0 0 1 . . . 1 RC6 0 0 1 1 0 . . . 1 RC5 0 1 0 1 0 . . . 1 Preload Value (PV) 0 1 2 3 4 . . . 63 Initial Accumulator Value = (-16 x PV) -1 -1 -17 -33 -49 -65 . . . -1009
Address 110 -- Ramp Selection Register (RMPSELR) SI Address 110 Ramp Selection Register (RMPSELR) (refer to Table 15, page 20). A write to the 33976 using this register allows the master to independently modify the pointer movement response characteristics of each gauge driver. The user has three variables that can be configured, during the initialization of the device, to provide quick and responsive pointers (e.g., tachometer applications) or soft landing and less responsive pointers (e.g., speedometer or fuel indicators). These three variables are (1) the ramp zero selection RS (RS3:RS0), (2) the hold count cut-in location offset variable HCP (HCP2: HCP0), and (3) the hold count value HC, (HC3:HC0). Each of these variables is described below and an implementation example is shown in Figure 11, page 31. The state machine uses the velocity ramp (refer to Table 30, page 28) to control the acceleration, deceleration and speed of the pointer movement. During an acceleration from a stopped position, the state machine will microstep the pointer at each velocity step, starting with step 0, in succession until the desired pointer speed is reached. Similarly, as the pointer approaches the commanded position, the state machine will microstep the motor at successive velocity steps down the velocity ramp until reaching step 0. The fastest that a pointer can accelerate, decelerate or change directions is limited by the velocity ramp. For example, if a pointer is moving in the clockwise direction and is commanded to a position that is counter clockwise from the current pointer location, then the state machine must first decelerate the pointer down the ramp to the step 0 location, change directions and then accelerate up the ramp towards the commanded location. In this situation, the state machine will force movement down and then up the ramp as fast as possible by stepping at each Velocity Position only once for a direction change. The low velocity steps (e.g., Velocity Position 1 is 27 ms) are significant in that they can limit the speed with which a pointer can change direction.
Bits RS3:RS0 of the RMPSELR are used to truncate as many as 15 velocity steps off of the bottom of the velocity ramp. The value of RS determines the Initial Velocity Ramp Position: Initial Velocity Position = RS + 1 For example, writing a value of 4 to these bits truncates the velocity ramp by 4 and would result in a first and last velocity step of 5.86ms (Velocity Position 5). A pointer will change directions much faster with this abbreviated ramp than it would if using the default ramp with a Velocity Position 1 of 27 ms Most applications require a smooth dynamic pointer as the commanded position is constantly updated. Movement along the ramp at the maximum acceleration and deceleration (only one step at each velocity position) results in a choppy movement because the movement velocity range is large for small changes in position as the pointer quickly reaches commanded locations from command to command. Configuring the state machine to repeat velocity steps at several of the last few step locations, when the pointer decelerates to the commanded location, can eliminate this choppy movement. These repetitive steps are referred to as hold counts. Bits HCP2: HCP0 of the RMPSELR determine the velocity step location at which the hold counts begin during a deceleration to the commanded position. The value written to HCP2: HCP0 (HCP) is multiplied by 8 and added to the RS value. The result is the first velocity position, or the Hold Count Cut-In Point, to which the hold counts will apply during a deceleration. First Velocity Position w/ Hold Counts = HCP x 8 + RS The exception to this is when the HCP2: HCP0 value is 000. In this case, HCP = 8 and the cut-in point will be 64 steps above the RS value. The default value of the HCP = 2 or a hold count cut-in point of 16 velocity steps above the RS value.
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The value of RS also determines the last velocity position step for which the Hold Counts are applied: Last Velocity Position w/ Hold Counts = RS + 2 The number of hold counts per applicable velocity step is determined by the value written to HC3:HC0 (HC) and can range from 0 to 15 steps. This number of hold counts will be applied to each step below the Hold Count Cut-In as determined by HCP and RS. The default value of HC is 5. Note: the following relationship between the variables must be adhered to for the state machine to work properly: Table 15. Ramp Selection Register (RMPSELR)
HC x (HCP x 8 - 1) + (225 - RS) < 512 Therefore, if RS = 0 and the Hold Count Cut-In point is 64, the largest value of Hold Counts you can choose is 4. 4 * (64 - 1) + (225 - 0) = 477 The GSEL bit determines which of the two gauges the rest of the RMPSELR bits are applied to. A GSEL bit set to logic 1 will apply the RMPSELR data to Gauge 1 and, Logic 0 to Gauge 0, respectively. Configuring both gauges requires two writes to this register.
Address 101 Bits Read Write D12 - D11 - D10 - HCP2 D9 - HCP1 D8 - HCP0 D7 - HC3 D6 - HC2 D5 - HC1 D4 - HC0 D3 - RS3 D2 - RS2 D1 - RS1 D0 - RS0
GSEL 12 GSEL 11
The bits in Table 15 are write-only.
GSEL 12 (D12) -- Gauge Select bit. The value of this bit determines the gauge for which the settings apply (refer to page 17): * 1 = Gauge 1 * 0 = Gauge 0 GSEL 11 (D11) -- This bit must be transmitted as Logic 0 for valid commands. HCP2 : HPC0 (D10 : D8) -- Hold Count Cut-in Point variable. These bits determine HCP, which is then multiplied by 8, and added to the RS number, to determine the actual Hold Count Cut-In Step value. The values of HCP range from 1 to 8 as shown in Table 16. The default value is 2.
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Table 17. Hold Counts Per Step
HC3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 HC2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 HC1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 HC0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Hold Counts / Step (HC) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Table 16. First Hold Count Velocity Position
HCP2 0 0 0 0 1 1 1 1 HCP1 0 0 1 1 0 0 1 1 HCP0 0 1 0 1 0 1 0 1 Velocity Step (HCP x 8 + RS) 64 + RS 8 + RS 16 + RS 24 + RS 32 + RS 40 + RS 48 + RS 56 + RS
HC3 : HC0 (D7 : D4) -- These bits determine the number of Hold Counts that will be applied to the steps that are determined by the HCP2:HCP0 and RS3:RS0 bits. The HC values range from 0 to 15 and are shown in Table 17. The default value is 5.
RS3 : RS0 (D3 : D0) -- These bits determine the number of velocity steps that are truncated from the Velocity Position ramp. The values range from 0 to 15 and are shown in Table 18. The default value is 0.
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Table 18. Truncated Velocity Steps
RS3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 RS2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 RS1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 RS0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Zero Velocity Position # (RS) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Output register is selected and it is clocked out via the SO. If the message length was determined to be invalid, the fault information will not be cleared and will be transmitted again during the next valid SPI message. Pointer status information bits (e.g., pointer position, velocity, and commanded position status) will always reflect the real time state of the pointer. Any bits clocked out of the SO pin after the first 16 are representative of the initial message bits clocked into the SI pin since the CS pin first transitioned to a logic [0]. This feature is useful for daisy-chaining devices as well as message verification. As described above, the last valid write to bits PE11:PE8 of the PECCR command determines the nature of the status data that is clocked out of the SO pin. There are five different types of status information available: 1. Device Status (refer to Table 20, page 21) 2. RTZ Accumulator Status (refer to Table 22, page 23) 3. Gauge 0 Pointer Position Status (refer to Table 24, page 24) 4. Gauge 1 Pointer Position Status (refer to Table 26, page 24) 5. Gauge 1 and 2 Pointer Velocity Status (refer to Table 28, page 24) Once a specific status type is selected, it will not change until either the PECCR command bits PE11:PE8 (D11:D8) are written to select another or the device is reset. Each of the Status types and the PECCR bit necessary to select them are described in the following paragraphs. Device Status Information Most recent valid PECCR command resulting in the Device Status output: Table 19.
D11 0 x = Don't care. D10 x D9 x D8 x
SO Communication When the CS pin is pulled low, the internal status register, as configured with the PECCR command bits PE11:PE8, is loaded into the output register and the data is clocked out MSB (OD15) first. Following a CS transition 0 to 1, the device determines if the shifted-in message was of a valid length (a valid message length is one that is greater than 0 bits and a multiple of 16 bits) and, if so, latches the incoming data into the appropriate registers. At this time, the SO pin is tri-stated and the status register is now able to accept new status information. Fault status information will be latched and held until the Device Status Table 20. Device Status Output Register
Bits Read Write OD15 DIR1 - OD14 OD13 OD12 OD11 OD10 OD9 OV - OD8 UV - OD7 CAL - OD6 OD5 OD4 OD3 RTZ1 - OD2 RTZ0 - OD1 OT1 - OD0 OT0 -
DIR0 0POS1 0POS0 CMD1 CMD0 - - - - -
OVUV MOV1 MOV0 - - -
The bits in Table 20 are read-only bits.
DIR1 (OD15) -- This bit indicates the direction Gauge 1 pointer is moving. * 0 = Toward position 0 * 1 = Away from position 0
DIR0 (OD14) -- This bit indicates the direction Gauge 0 pointer is moving. * 0 = Toward position 0 * 1 = Away from position 0
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0POS1 (OD13) -- This bit indicates the configured Position 0 for Gauge 1. *0 = Farthest CCW *1 = Farthest CW 0POS0 (OD12) -- This bit indicates the configured Position 0 for Gauge 0. * 0 = Farthest CCW * 1 = Farthest CW CMD1 (OD11) -- This bit indicates whether Gauge 1 is at the most recently commanded position. * 0 = At commanded position * 1 = Not at commanded position CMD0 (OD10) -- This bit indicates whether Gauge 0 is at the most recently commanded position. * 0 = At commanded position * 1 = Not at commanded position OV (OD9) -- Overvoltage Indication. A logic [1] on this bit indicates VPWR voltage exceeded the upper limit of VPWROV since the last SPI communication (refer to the Static Electrical Characteristics table under POWER INPUT, page 5). An overvoltage event will automatically disable the driver outputs. Because the pointer may not be in the expected position, the master may want to re-calibrate the pointer position with an RTZ command after the voltage returns to a normal level. For an overvoltage event, both gauges must be re-enabled as quickly as this flag returns to logic [0]. The state machine will continue to operate properly as long as VDD is within the normal range. * 0 = Normal range * 1 = Battery voltage exceeded VPWROV UV (OD8) -- Undervoltage Indication. A logic [1] on this bit indicates the VPWR voltage fell below VPWRUV since the last SPI communication (refer to the Static Electrical Characteristics table under POWER INPUT, page 5). An undervoltage event is just flagged; however, at some voltage level below 4.0 V, the outputs turn OFF and the state machine resets. Because the pointer may not be in the expected position, the master may want to re-calibrate the pointer position with an RTZ command after the voltage returns to a normal level. For an undervoltage event, both gauges may need to be re-enabled as quickly as this flag returns to logic [0]. The state machine will continue to operate properly as long as VDD is within the normal range. * 0 = Normal range * 1 = Battery voltage fell below VPWRUV CAL (OD7) -- Calibrated Clock out of Specification. A logic [1] on this bit indicates the clock count calibrated to a value outside the expected range given the tolerance specified by tCLC in the Dynamic Electrical Characteristics table under POWER OUTPUT AND CLOCK TIMINGS, page 7. * 0 = Clock within spec * 1 = Clock out of spec OVUV (OD6) -- Undervoltage or Overvoltage Indication. A logic [1] on this bit indicates the VPWR voltage fell to a level
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below the VPWRUV since the last SPI communication (refer to the Static Electrical Characteristics table under POWER INPUT, page 5). An undervoltage event is just flagged, while an overvoltage event automatically disables the drive outputs. Because the pointer may not be in the expected position, the master may want to re-calibrate the pointer with an RTZ command after the voltage returns to normal level. For an overvoltage event, both gauges must be re-enabled as soon as this flag returns to logic [0]. The state machine will continue to operate properly as long as VDD is within the normal range. * 0 = Normal range * 1 = Battery voltage fell below VPWRUV or exceeded VPWROV MOV1 (OD5) -- This bit identifies Gauge 1 movement since last SPI communication. A logic [1] on this bit indicates the Gauge 1 pointer position changed since the last SPI command. This information allows the master to confirm the pointer is moving as commanded. This bit may also be used to determine if Gauge 1 is enabled or disabled. * 0 = Gauge 1 position has not changed since the last SPI command * 1 = Gauge 1 pointer position has changed since the last SPI command MOV0 (OD4) -- Gauge 0 Movement Since last SPI Communication. A logic [1] on this bit indicates the Gauge 0 pointer position has changed since the last SPI command. This information allows the master to confirm the pointer is moving as commanded. This bit may also be used to determine if Gauge 0 is enabled or disabled. * 0 = Gauge 0 position has not changed since the last SPI command * 1 = Gauge 0 pointer position has changed since the last SPI command RTZ1 (OD3) -- RTZ1 Is Enabled or Disabled. A logic [1] on this bit indicates Gauge 1 is in the process of returning to the zero position as requested with the RTZ command. This bit will continue to indicate a logic [1] until the SPI message following a detection of the zero position, or the RTZ feature is commanded OFF using the RTZ message. * 0 = Return to Zero disabled * 1 = Return to Zero enabled successfully RTZ0 (OD2) -- RTZ0 Is Enabled or Disabled. A logic [1] on this bit indicates Gauge 0 is in the process of returning to the zero position as requested with the RTZ command. This bit continues to indicate a logic [1] until the SPI message following a detection of the zero position, or the RTZ feature is commanded OFF using the RTZ message. * 0 = Return to Zero disabled * 1 = Return to Zero enabled successfully OT1 (OD1) -- Gauge 1 Junction Overtemperature. A logic [1] on this bit indicates that the coil drive circuitry dedicated to drive Gauge 1 has exceeded the maximum allowable junction temperature since the last SPI communication and that Gauge 1 has been disabled. It is recommended that the pointer be re-calibrated using the RTZ
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command after re-enabling the gauge using the PECCR command. This bit remains logic [1] until the gauge is enabled. * 0 = Temperature within range * 1 = Gauge 1 maximum allowable junction temperature condition has been reached OT0 (OD0) -- Gauge 0 Junction Overtemperature. A logic [1] on this bit indicates that the coil drive circuitry dedicated to drive Gauge 0 has exceeded the maximum allowable junction temperature since the last SPI communication and that Gauge 0 has been disabled. It is recommended that the pointer be re-calibrated using the RTZ command after re-enabling the gauge using the PECCR
command. This bit remains logic [1] until the gauge is reenabled. *0 = Temperature within range1 = Gauge 0 maximum allowable junction temperature condition is reached RTZ Accumulator Status Information Most recent valid PECCR command resulting in the RTZ Accumulator status output: Table 21.
D11 1 x = Don't care. D10 0 D9 x D8 x
Table 22. RTZ Accumulator Status Output Register
Bits Read Write OD15 RTZ - OD14 OD13 OD12 OD11 OD10 OD9 OD8 ACC8 - OD7 ACC7 - OD6 ACC6 - OD5 ACC5 - OD4 ACC4 - OD3 ACC3 - OD2 AC2C - OD1 ACC1 - OD0 ACC0 -
ACC14 ACC13 ACC12 ACC11 ACC10 ACC9 - - - - - -
The bits in Table 22 are read-only bits.
RTZ (OD15) -- RTZ Bit Is Enabled or Disabled. A logic [1] on this bit indicates that the Gauge is in the process of returning to the zero position as requested with the RTZ command. This bit will continue to indicate a logic [1] until the SPI message following a detection of the zero position, or the RTZ feature is commanded OFF using the RTZ message. * 0 = Return to Zero disabled * 1 = Return to Zero enabled successfully ACC14:ACC0 (OD14:OD0) -- These 15 bits are from the RTZ accumulator. They represent the integrated signal present on the non-driven coil during an RTZ event. These bits are logic [0] after power-on reset, or after the RST pin transitions from logic [0] to [1]. After an RTZ event, they will represent the last RTZ accumulator result before the RTZ was stopped. ACC14 is the MSB and is the sign bit used for zero detection. Negative numbers have MSB logic [1] and are coded in two's complement.
Figure 8. RTZ Accumulator (Typical) The analog-to-digital converter's linear input range covers the expected magnitude of motor back e.m.f. signals, which is usually less than 500mV. Input signals greater than this will not cause any damage (the circuit is connected to the motor H-Bridge drivers, and thus is exposed to the full magnitude of the drive voltages), but may cause some small loss of linearity. A typical plot of output vs. input is shown in Figure 8 for 4ms step times. Gauge 0 Pointer Position Status Information Most recent valid PECCR command resulting in the Gauge 0 Pointer Position status output: Table 23.
D11 1 D10 1 D9 0 D8 0
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Table 24. Gauge 0 Pointer Position Status Output Register
Bits Read Write OD15 ENB0 - OD14 DIR0 - OD13 OD12 OD11 OD10 OD9 OD8 POS8 - OD7 POS7 - OD6 POS6 - OD5 POS5 - OD4 POS4 - OD3 POS3 - OD2 POS2 - OD1 POS1 - OD0 POS0 -
DIRC0 CMD0 POS11 POS10 POS9 - - - - -
The bits in Table 24 are read-only bits.
ENB0 (OD15) -- This bit indicates whether Gauge 0 is enabled. * 0 = Disabled * 1 = Enabled DIR0 (OD14) -- This bit indicates the direction Gauge 0 is moving. * 0 = Toward position 0 * 1 = Away from position 0 DIRC0 (OD13) -- This bit is used to determine whether the direction of the most recent pointer movement is toward the last commanded position or away from it. * 0 = Direction of the pointer movement is toward the commanded position * 1 = Direction of the pointer movement is away from the commanded position Table 26. Gauge 1 Pointer Position Status Output Register
Bits Read Write OD15 ENB1 - OD14 DIR1 - OD13 OD12 OD11 OD10 OD9 OD8 POS8 -
CMD0 (OD12) -- This bit indicates whether Gauge 0 is at the most recently commanded position. * 0 = At commanded position * 1 = Not at commanded position POS11:POS0 (OD11:OD0) -- These 12 bits represent the actual position of the pointer at the time CS transitions to a logic [0]. Gauge 1 Pointer Position Status Information Most recent valid PECCR command resulting in the Gauge 1 Pointer Velocity status output: Table 25.
D11 1 D10 1 D9 0 D8 1
OD7 POS7 -
OD6 POS6 -
OD5 POS5 -
OD4 POS4 -
OD3 POS3 -
OD2 POS2 -
OD1 POS1 -
OD0 POS0 -
DIRC1 CMD1 POS11 POS10 POS9 - - - - -
The bits in Table 26 are read-only bits.
ENB1 (OD15) -- This bit indicates if Gauge 1 is enabled. * 0 = Disabled * 1 = Enabled DIR1 (OD14) -- This bit indicates the direction Gauge 1 pointer is moving. * 0 = Toward position 0 * 1 = Away from position 0 DIRC1 (OD13) -- This bit determines if the direction of the most recent pointer movement is toward, or away from, the last commanded position. * 0 = Direction of the pointer movement is toward the commanded position * 1 = Direction of the pointer movement is away from the commanded position CMD1 (OD12) -- This bit indicates if Gauge 1 is at the most recently commanded position.
* 0 = At commanded position * 1 = Not at commanded position POS11:POS0 (OD11:OD0) -- These 12 bits represent the actual position of the pointer at the time CS transitions to a logic [0]. Gauge 0 and 1 Pointer Velocity Status Information Most recent valid PECCR command resulting in the Gauge 0 and 1 Pointer Velocity status output: Table 27.
D11 1 x = Don't care. D10 1 D9 1 D8 x
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Table 28. Gauge 0 and 1 Pointer Velocity Status Output Register
Bits OD15 OD14 OD13 OD12 OD11 OD10 OD9 OD8 OD7 OD6 OD5 OD4 OD3 OD21 OD1 OD0
Read Write
1V7 -
1V6 -
1V5 -
1V4 -
1V3 -
1V2 -
1V1 -
1V0 -
0V7 -
0V6 -
0V5 -
0V4 -
0V3 -
0V2 -
0V1 -
0V0 -
The bits in Table 28 are read-only bits.
1V7:1V0 (OD15:OD8) -- These 8 bits represent the step table value that indicates the actual velocity step location (refer to Table 30, page 28) of the Gauge 1 pointer at the time that the CS transitions to a logic [0]. Note For both sets of bits,1V7:1V0 and 0V7:0V0, if the ramp is truncated with the RMPSELR, the velocity position step that will be read when the pointer is no longer moving will
be the velocity position that identifies it in the untruncated ramp (e.g., if RS = 2, then the velocity step location will be 3 when the pointer is at the commanded position). 0V7:0V0 (OD7:OD0) -- These 8 bits represent the step table value that indicates the actual velocity step location (refer to Table 30) of the Gauge 0 pointer at the time that the CS transitions to a logic [0].
STATE MACHINE OPERATION
The two-phase step motor has maximum allowable velocities and acceleration and deceleration.The purpose of the step motor state machine is to drive the motor with maximum performance while remaining within the motor's voltage, velocity, and acceleration constraints. A requirement of the state machine is to ensure the deceleration phase begins at the correct time and pointer position. When commanded, the motor will accelerate constantly to the maximum velocity, then move toward the commanded position. Eventually, the pointer will reach the calculated location where the movement has to decelerate, slowing safely to a stop at the desired position. During the deceleration phase, the motor will not exceed the maximum deceleration. During normal operation, both step motor rotors are microstepped with 24 steps per electrical revolution (see Figure 9). A complete electrical revolution results in two degrees of pointer movement. There is a second (smaller) state machine in the IC controlling these microsteps. This state machine receives clockwise or counter-clockwise index commands at intervals, stepping the motor in the appropriate direction by adjusting the current in each coil. Normalized values are provided in Table 29, page 26.
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IMAX + ICOIL 0 IMAX IMAX + ICOIL 0 IMAX
SINx
COSx
Clockwise Microsteps for PE6 = 0
IMAX Imax + + ICOIL Icoil 0 0
SINx SINx
_ Imax IMAX
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Imax IMAX
+ + ICOIL Icoil 0
COSx COSx
_ IMAX Imax
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
FIGURE 6b. CW MICROSTEPS for PE6=1 Clockwise Microsteps for PE6 = 1
Figure 9. Clockwise Microsteps Table 29. Coil Step Value
COS (Angle)* PE6 = 0 1 0.965 0.866 0.707 0.5 0.259 COS (Angle 30)* PE6 = 1 0.866 0.966 1 0.966 0.866 0.707 6 7 8 0 1 2 3 4 5 0 15 30 45 60 75 0 0.259 0.5 0.707 0.866 0.966 9 10 11 12 13 90 105 120 135 150 165 180 195 1 0.966 0.866 0.707 0.5 0.259 0 -0.259 0 -0.259 -0.5 -0.707 -0.866 -0.966 -1 -0.966 0.500 0.259 0 -0.259 -0.500 -0.707 -0.866 -0.966
Table 29. Coil Step Value
Step Angle SINE (Angle)*
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Table 29. Coil Step Value
14 15 16 17 18 19 20 21 22 23 210 225 240 255 270 285 300 315 330 345 -0.5 -0.707 -0.866 -0.966 -1 -0.966 -0.866 -0.707 -0.5 -0.259 -0.867 -0.707 -0.5 -0.259 0 0.259 0.5 0.707 0.866 0.966 -1 -0.966 -0.866 -0.707 -0.500 -0.259 0 0.259 0.500 0.707
and solving for v in terms of u, s, and t gives: v= -u The correct value of t to use in this equation is the quantized value obtained above. From these equations a set of recursive equations can be generated to give the allowed time step between motor indexes when the motor is accelerating from a stop to its maximum velocity. Starting from a position p of 0 and a velocity v of 0, these equations define the time interval between steps at each position. To drive the motor at maximum performance, index commands are given to the motor at these intervals. A table is generated giving the time step t at an index position n.
2
/t
p0 = 0 v0 = 0
* Denotes normalized values.
The motor is stepped by providing index commands at intervals. The time between steps defines the motor velocity, and the changing time defines the motor acceleration. The state machine uses a table to define the allowed time and also the maximum velocity. A useful side effect of the table is that it also allows the direct determination of the position at which the velocity should reduce to stop the motor at the desired position. The motor equations of motion are generated as follows. (The units of position are steps, and velocity and acceleration are in steps/second and steps/second.) From an initial position of 0 with an initial velocity (u), the motor position (s) at a time (t) is:
where
indicates rounding up.
vn = 2 t n - v n -1
Pn = n Note Pn = n. This means on the n th step the motor has indexed by n positions and has been accelerating steadily at the maximum allowed rate. This is critical because it also indicates the minimum distance the motor must travel while decelerating to a stop. For example, the stopping distance is also equal to the current value of n. The algorithm to drive the motor is similar to: 1. While the motor is stopped, wait until a command is received. 2. Send index pulses to the motor at an ever-increasing rate, according to the time steps in Table 30 until: a. The maximum velocity is reached, at which point the time intervals stop decreasing, or b. The distance remaining to travel is less than the current index in the table. At this point, the stopping distance is equal to the remaining distance, and to ensure it will stop at the required position, the motor must begin decelerating. An example of the velocity table for a particular motor is provided in Table 30. This motor's maximum speed is 4800 microsteps/s (at 12 microsteps/degrees), and its maximum acceleration is 54000 microsteps/s2. The table is quantized to a 1.0 MHz clock.
s = ut +
1
2
at
2
For unit steps, the time between steps is:
- u + u 2 + 2a t = a
This defines the time increment between steps when the motor is initially travelling at a velocity u. In the ROM, this time is quantized to multiples of the system clock by rounding upwards, ensuring acceleration never exceeds the allowed value. The actual velocity and acceleration is calculated from the time step actually used. Using| v2 = u2 + 2as and v = u + at
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Table 30. Velocity Table
Velocity Position 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Time Between Steps (s) 0 27217 13607 11271 7970 5858 4564 3720 3132 2701 2373 2115 1908 1737 1594 1473 1369 1278 1199 1129 1066 1010 960 916 877 842 812 784 760 737 716 697 680 Velocity (Steps/s) 0.00 36.7 73.5 88.7 125.5 170.7 219.1 268.8 319.3 370.2 421.4 472.8 524.1 575.7 627.4 678.9 730.5 782.5 834.0 885.7 938.1 990.1 1041.7 1091.7 1140.3 1187.6 1231.5 1275.5 1315.8 1356.9 1396.6 1434.7 1470.6 Velocity Position 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 Time Between Steps (s) 380 377 374 372 369 366 364 361 358 356 354 351 349 347 344 342 340 338 336 334 332 330 328 326 324 322 321 319 317 315 314 312 310 Velocity (Steps/s) 2631.6 2652.5 2673.8 2688.2 2710.0 2732.2 2747.3 2770.1 2793.3 2809.0 2824.9 2849.0 2865.3 2881.8 2907.0 2924.0 2941.2 2958.6 2976.2 2994.0 3012.0 3030.3 3048.8 3067.5 3086.4 3105.6 3115.3 3134.8 3154.6 3174.6 3184.7 3205.1 3225.8 Velocity Position 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 Time Between Steps (s) 257 256 255 254 254 253 252 251 250 249 248 248 247 246 245 244 244 243 242 241 241 240 239 238 238 237 236 235 235 234 233 233 232 Velocity (Steps/s) 3891.1 3906.3 3921.6 3937.0 3937.0 3952.6 3968.3 3984.1 4000.0 4016.1 4032.3 4032.3 4048.6 4065.0 4081.6 4098.4 4098.4 4115.2 4132.2 4149.4 4149.4 4166.7 4184.1 4201.7 4201.7 4219.4 4237.3 4255.3 4255.3 4273.5 4291.8 4291.8 4310.3
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Table 30. Velocity Table (continued)
Velocity Position 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Time Between Steps (s) 663 648 634 621 608 596 585 575 565 555 546 538 529 521 514 507 500 493 487 481 475 469 464 458 453 448 444 439 434 430 426 422 418 Velocity (Steps/s) 1508.3 1543.2 1577.3 1610.3 1644.7 1677.9 1709.4 1739.1 1769.9 1801.8 1831.5 1858.7 1890.4 1919.4 1945.5 1972.4 2000.0 2028.4 2053.4 2079.0 2105.3 2132.2 2155.2 2183.4 2207.5 2232.1 2252.3 2277.9 2304.1 2325.6 2347.4 2369.7 2392.3 Velocity Position 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 Time Between Steps (s) 309 307 306 304 303 301 300 298 297 295 294 293 291 290 289 287 286 285 284 282 281 280 279 278 277 275 274 273 272 271 270 269 268 Velocity (Steps/s) 3236.2 3257.3 3268.0 3289.5 3300.3 3322.3 3333.3 3355.7 3367.0 3389.8 3401.4 3413.0 3436.4 3448.3 3460.2 3484.3 3496.5 3508.8 3521.1 3546.1 3558.7 3571.4 3584.2 3597.1 3610.1 3636.4 3649.6 3663.0 3676.5 3690.0 3703.7 3717.5 3731.3 Velocity Position 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 Time Between Steps (s) 231 231 230 229 229 228 227 227 226 226 225 224 224 223 222 222 221 221 220 220 219 218 218 217 217 216 216 215 215 214 214 213 212 Velocity (Steps/s) 4329.0 4329.0 4347.8 4366.8 4366.8 4386.0 4405.3 4405.3 4424.8 4424.8 4444.4 4464.3 4464.3 4484.3 4504.5 4504.5 4524.9 4524.9 4545.5 4545.5 4566.2 4587.2 4587.2 4608.3 4608.3 4629.6 4629.6 4651.2 4651.2 4672.9 4672.9 4694.8 4717.0
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Table 30. Velocity Table (continued)
Velocity Position 66 67 68 69 70 71 72 73 74 75 Time Between Steps (s) 414 410 406 403 399 396 393 389 386 383 Velocity (Steps/s) 2415.5 2439.0 2463.1 2481.4 2506.3 2525.3 2544.5 2570.7 2590.7 2611.0 Velocity Position 142 143 144 145 146 147 148 149 150 151 Time Between Steps (s) 267 266 265 264 263 262 261 260 259 258 Velocity (Steps/s) 3745.3 3759.4 3773.6 3787.9 3802.3 3816.8 3831.4 3846.2 3861.0 3876.0 Velocity Position 218 219 220 221 222 223 224 225 Time Between Steps (s) 212 211 211 210 210 209 209 208 Velocity (Steps/s) 4717.0 4739.3 4739.3 4761.9 4761.9 4784.7 4784.7 4807.7
Internal Clock Calibration Timing-related functions on the 33976 (e.g., pointer velocities, acceleration, and Return To Zero Pointer speeds) depend upon a precise, consistent time reference to control the pointer accurately and reliably. Generating accurate time references on an integrated circuit can be accomplished. For example trimming can be used however, it tends to be costly due to the large amount of die area required for trim pads. Another possibility is an externally generated clock signal; however, this requires a dedicated pin on the device and controller. An alternate approach would require the use of an additional crystal or resonator, which is expensive. The internal clock in the 33976 is temperature independent and area efficient; however, it can vary by as much as 35 percent due to process variation. Using the existing SPI inputs and the precision timing reference already available to the microcontroller, the 33976 allows more accurate clock calibration to within 10 percent. Calibrating the internal 1.0 MHz clock is initiated by writing a logic [1] to PECCR bit PE3 (see Figure 10, page 30). The 8.0 s calibration pulse is then provided by the controller to
ideally result in an internal 33976 clock speed of 1.0 MHz. The pulse is sent on the CS pin immediately after the SPI word is sent. During the calibration, no other SPI lines should be toggled. At the moment the CS pin transitions from logic [1] to logic [0], an internal 7-bit counter counts the number of cycles of an internal, 8.0 MHz clock. The counter stops when the CS pin transitions from logic [0] to logic [1]. The value in the counter represents the number of cycles of the 8.0 MHz clock occurring in the 8.0 s window; it should range from 32 to 119. An offset is added to this number to help center or skew the calibrated result to generate a desired maximum or nominal frequency. The modified counter value is truncated by 4 bits to generate the calibration divisor, which should range from 4 to 15. The 8.0 MHz clock is divided by the calibration divisor, resulting in a calibrated 1.0 MHz clock. If the calibration divisor lies outside the range of 4 to 15, the 33976 flags the CAL bit in the device status register, indicating the calibration procedure was not successful. A clock calibration is allowed only if the gauges are disabled or the pointers are not moving, as indicated by status bits MOV1 and MOV0 (Table 20, page 21).
D15 SI SCLK
CS
D0
PECCR Command 8.0 s Calibration Pulse
Figure 10. Gauge Enable and Clock Calibration Example
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Some applications may require a guaranteed maximum pointer velocity and acceleration. Guaranteeing these maximums requires that the nominal internal clock frequency falls below 1.0 MHz. The frequency range of the calibrated clock will always be below 1.0 MHz if PECCR bit PE4 is logic [0] prior to initiating a calibration command, followed by an 8.0 s reference pulse. The frequency will be centered at 1.0 MHz if bit D4 is logic [1]. The 33976 can be fooled into calibrating faster or slower than the optimal frequency by sending a calibration pulse longer or shorter than the intended 8.0 s. As long as the calibration divisor remains between 4 and 15 there will be no clock calibration flag. For applications requiring a slower calibrated clock -- e.g., a motor designed with a gear ratio of 120:1 (8 microsteps/deg) -- the user will have to provide a longer calibration pulse. The device allows a SPI-selectable slowing of the internal oscillator, using the PECCR command, so that the calibration divisor safely falls within the 4-to-15 range when calibrating with a longer time reference. For example, for the 120:1 motor, the pulse would be 12 s instead of 8.0 s. The result of this slower calibration results in the longer step times necessary to generate pointer movements meeting acceleration and velocity requirements. The resolution of the pointer positioning decreases from 0.083 deg/microstep (180:1) to 0.125 deg/microstep (120:1)
while the pointer sweep range increases from approximately 340 degrees to over 500 degrees. Note Be aware that a fast calibration could result in violations of the motor acceleration and velocity maximums, resulting in missed steps. Pointer Deceleration Constant acceleration and deceleration of the pointer produces relatively choppy movements when compared to those of an air core gauge. Modifying the velocity position ramp during deceleration can create the desired damped movement. This modification is accomplished by adding repetitive steps at several of the last velocity position step values as the pointer decelerates. The 33976 allows the user to tailor the response characteristics to the application with three independent ramp characteristic variables. The RS, HCP and HC variables can be used to change the slowest velocity position steps, the number of Hold Counts, and the number of ramp positions to which the Hold Counts apply. More information is available in the RMPSEL description and in the example shown in Figure 11. If the maximum acceleration and deceleration of the pointer is desired, the Hold Counts can be disabled dynamically by either writing a logic [1] to the global Hold Count Disable bit, PECCR bit PE5, or to the HE0 or HE1 bits of the POS0R or POS1R, respectively.
D
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
ec e
el e
ra t
e
VELOCITY POSITION
For this example:
* RS = 0 * HC = 3 * HCP = 1
8 7 6 5 4 3 2 1 Position =0
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
le
First Velocity w/ Hold Counts = HCP x 8 + RS = 8 + 0 = 8
ra
te
Initial Velocity Position = RS + 1 = 0 + 1 = 1 Last Velocity w/ Hold Counts = RS + 2 = 0 + 2 = 2 Hold Counts per Step = HC = 3
8
7 6 5 4 3
Ac c
2
1
0
MICROSTEPS
Figure 11. Deceleration Ramp Return to Zero Calibration Many step motor applications require that the IC detect when the motor is stalled after commanded to return to the zero position for calibration purposes. The stalling occurs when the pointer hits the end stop on the gauge bezel, which is usually at the zero position. It is important that when the pointer reaches the end stop it immediately stops without bouncing away. The 33976 device provides the ability to automatically and independently return each of the two pointers to the zero position via the RTZR and RTZCR SPI commands. An automatic RTZ is initiated using the RZ0, RZ1, and RZ2 bits provided the RZ4 bit is a logic [0]. Unconditional RTZ movement is initiated using the RZ0, RZ1, and RZ2 bits provided the RZ4 bit is a logic [1]. During an RTZ event, all commands related to the gauge being returned are ignored until the pointer has successfully zeroed or the RTZR bit RZ1 is written to disable the event. Once an RTZ event is initiated, the device reports back via the SO pin that an RTZ is underway. The RTZCR command is used to set the RTZ pointer speed, choose an appropriate blanking time, and preload the integration accumulator with an appropriate offset. On reaching the end stop, the device reports back to the
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microcontroller via the status message that the RTZ was successful. The RTZ automatically disables, allowing other commands to be valid. In the event the master determines an RTZ sequence is not working properly (i.e., the RTZ taking too long), it can disable the command via the RTZR bit RZ1. RTZCR bits RC10:RC5 are written to preload the accumulator with a predetermined value that will assure an accurate pointer stall detection. This preloaded value is determined during application development by disabling the automatic shutdown feature of the device with the RTZR bit RZ4. This operating mode allows the master to monitor the RTZ event, using the accumulator information available via the SO if the device is configured to provide the RTZ
IMAX
Accumulator Status. The unconditional RTZ event can be turned OFF using the RTZR bit RZ1. If the Position 0 location bit is in the default logic [0] mode, then during an RTZ event the pointer is returned counterclockwise (CCW) using full steps at a constant speed determined by the RTZCR RC3:RC0 and RC12:RC11 bits during RTZ configuration (see Figure 12). Full steps are used during an RTZ so that only one coil of the motor is being driven at any time. The coil not being driven is used to determine if the pointer is moving. If the pointer is moving, the EMF signal that is present in the non-driven coil is processed by integrating the signal present on the opened pin of the coil while essentially grounding the other end.
ICOIL
0 SINE
IMAX 0 IMAX COSINE ICOIL 0 1 2 3 0
IMAX
0
1
2
3
0
Figure 12. Full Steps Counterclockwise The IC automatically prepares the non-driven coil at each step, waits for a predetermined blanking time, then processes the signal for the duration of the full step. When the pointer reaches the stop and no longer moves, the dissipating flux is detected. The processed results are placed in the RTZ accumulator, then compared to a decision threshold. If the signal exceeds the decision threshold, the pointer is assumed to be moving. If the threshold value is not exceeded, the drive sequence is stopped if RTZR bit RZ4 is logic [0]. If bit RZ4 is logic [1], the RTZ movement will continue indefinitely until the RTZR bit RZ1 is used to stop the RTZ event. A pointer that is not on a full step location or that is in magnetic alignment prior to the RTZ event may cause a false RTZ detection. More specifically, an RTZ event beginning from a non-full step position may result in an abbreviated integration value potentially interpreted as a stalled pointer. Advancing the pointer by at least 12 microsteps clockwise (if PE7 = 0) to the nearest full step position (e.g., 0, 6, 12, 18, 24, etc.) prior to initiating an RTZ ensures the magnetic fields line up and increases the chances of a successful pointer stall detection. It is important that the pointer be in a static, or commanded, position before starting the RTZ event. Because the time duration and the number of steps the pointer moves prior to reaching the commanded position can vary depending upon its status at the time a position change is communicated, the master should assure sufficient elapsed time prior to starting an RTZ. If an RTZ is desired after first enabling the outputs or after forcing a reset of the device, the pointer should first be commanded to move 12 microsteps clockwise to the nearest full step location. Because the pointer was in a static position at default, the master could determine the number of microsteps the device has taken by monitoring and counting the MOV0. MOV1 device status bit transitions to confirm the pointer is again in a static position. Alternatively, the user could monitor the device status bits CMD1 and CMD2.
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FUNCTIONAL DEVICE OPERATION LOGIC COMMANDS AND REGISTERS
It should be pointed out that the flux value, for an ideal motor with the coils perfectly aligned at 90, will vary little from full step to full step if all other variables (e.g., temperature) are held constant. The full steps are evenly spaced which results in equidistant movement as the motor is full stepped. In comparison, motors that have coils aligned at a 60 angle will result in two distinct flux values as the coils are driven in the same full step fashion. This lack of symmetry in the measured flux is due to the difference in the electrical angles between full steps. In other words, the distance that the rotor moves changes from full step to full step. This difference can be observed in Figure 9 and Table 29. In Figure 9, where PE6 = 0, the difference in microsteps between alternating full steps (one coil at maximum current while the other is at zero) is always six. In contrast, as seen in Figure 9, where PE6 = 1, the difference in microsteps between full steps of the 60 coils alternates between four and eight. These expected differences need to be taken into account when setting the RTZ threshold. Only one gauge at a time can be returned to the zero position. The gauge not returning to zero can continue to be controlled. An RTZ should not begin until the gauge to be calibrated is at a static position and its pointer is at a full step position. An attempt to calibrate a gauge while the other is in the process of an RTZ event is ignored by the device. In most applications of the RTZR command, it is possible to avoid a visually obvious sequential calibration by first bringing the pointers back close to their previous zero positions, then recalibrating them sequentially. After completion of an RTZ, the 33976 automatically assigns the zero-step position to the full step position at the end-stop location. Because the actual zero position could lie anywhere within the full step where the zero was detected, the assigned zero position could be within a window of 0.5 degree. An RTZ can be used to detect stall, even if the pointer already rests on the end stop when an RTZ sequence is initiated. However, it is recommended the pointer be advanced by at least 12 microsteps to the nearest full step prior to initiating the RTZ.
disabled after a power-up or external reset, and SO flag OD6 and OD8 are set, indicating an undervoltage event. Anytime an external reset is exerted and the default is restored, all configuration parameters (e.g., clock calibration, maximum speed, RTZ parameters, etc.) are lost and must be reloaded.
FAULT LOGIC REQUIREMENTS
The 33976 device indicates each of the following faults as they occur: *Overtemperature fault *Undervoltage VPWR *Overvoltage VPWR *Clock out of spec These fault bits remain enabled until they are clocked out of the SO pin with a valid SPI message. Overcurrent faults are not reported directly; however, it is likely an overcurrent condition will become a thermal issue and be reported. Overtemperature Fault Requirements The 33976 incorporates overtemperature protection circuitry, which shuts off the affected gauge driver when excessive temperatures are detected. In the event of a thermal overload, the affected gauge driver is automatically disabled. The overtemperature fault is flagged via the OT0 and/or OT1 device status bits. The indicating flag continues to be set until the affected gauge is successfully re-enabled, provided the junction temperature has fallen to a temperature below the hysteresis level.
OVERVOLTAGE FAULT REQUIREMENTS
The device is capable of surviving VPWR voltages within the maximum specified in Maximum Ratings table, page 4. VPWR levels resulting in an Overvoltage Shutdown condition can result in uncertain pointer positions. Therefore, the pointer position should be re-calibrated. The master will be notified of an overvoltage event via the SO pin if the device status is selected. Overvoltage detection and notification occurs regardless of whether the gauge(s) are enabled or disabled. Overcurrent Fault Requirements Output currents are limited to safe levels allowing the device to rely on thermal shutdown to protect itself. Undervoltage Fault Requirements
RTZ OUTPUT
During an RTZ event the non-driven coil is analyzed to determine the state of the motor. The 33976 multiplexes the coil voltages and provides the signal from the non-driven coil to the RTZ pin.
DEFAULT MODE
Default mode refers to the state of the 33976 after an internal or external reset prior to SPI communication. An internal reset occurs during VDD power-up or if VPWR falls below 4.0 V. An external reset is initiated by the RST pin driven to a logic [0]. With the exception of the RTZCR full step time and the RMPSEL Register values, all of the specific pin functions and internal registers will operate as though all of the addressable configuration register bits were set to logic [0]. This means, for example, all of the outputs will be
Undervoltage VPWR conditions may result in uncertain pointer positions. Therefore, the internal clock and the pointer position may require re-calibration. The state machine continues with VPWR voltage levels as low as 4.0 V; however, the coil voltages may be clipped. The master can be notified of an undervoltage event via the SO pin.
RESET (SLEEP MODE)
The device can reset internally or externally. If the VDD level falls below the VDDUV level (refer to the Static Electrical
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FUNCTIONAL DEVICE OPERATION LOGIC COMMANDS AND REGISTERS
Characteristics table under POWER INPUT, page 5), the device resets and powers up in the Default mode. Similarly, If the RST pin is driven to a logic [0], the device resets to its
default state. The device consumes the least amount of current (IDD and IPWR) when the RST pin is logic [0]. This is also referred to as the Sleep mode.
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TYPICAL APPLICATIONS
TYPICAL APPLICATIONS
The 33976 is an extremely versatile device that can be used in a variety of applications. The flexibility has been significantly improved, over that of the older MC33991 and MC33970 devices, with the addition of the Velocity Ramp configuration features that are available in the RMPSEL
6000.0
register (see Table 31). Some applications (e.g., high performance tachometers) require responsive pointers that change directions quickly. Figure 10 shows some characteristics of the ramp modifications that are possible with the RMPSELR RS bit.
5000.0
13ms 33991 33991
63ms
4000.0
Speed (usteps / s)
Ideal Acceleration (4500 deg/s^2)
3000.0
33976 (RS = 4) 33970 or 33976 Default
2000.0
GDIC MC33991 GDIC MC33970 or MC33976 default 1000.0 Ideal Acceleration (4500 deg/s^2) GDIC MC33976 ramp w/first step = 5
0.0 0 20000 40000 60000 80000 100000 120000 140000 160000 180000
Time (us) Time (s)
Figure 13. Start / Stop Response Characteristics Other applications (e.g., speedometers and fuel page 36, gives several examples of different damping characteristics that are possible with the device. Once indicators) require smooth, low speed movement. For these configured, the damping can be dynamically enabled and applications, the damping of the pointer can be optimized disabled using the HE bits of the Position registers. with the HC and HCP bits of the RMPSELR. Figure 14,
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TYPICAL APPLICATIONS
1250 1200
33970 33976
1150 1100 1050 1000 950 900 850 800
33976 Default (16, 5 HCPx8, HC)
0
0.1
0.2
0.3
0.4
Tim e (s) 64,44 64,
0.5
0.6
0.7
0.8
0.9
1
NO HOLDS
GDIC1.5 33970
32-4 32, 4
16-5 16, 5
8-4 8, 4
Figure 14. 33976 Damping Response Examples Table 31 provides a step-by-step example of configuring and using many of the features designed into the IC. This example is intended to give a generic overview how the Table 31. 33976 Setup, Configuration, and Usage Example
Step 1 Command PECCR Enable Gauges Bit PE0: Gauge 0 Bit PE1: Gauge 1 Clock Calibration Bit PE3: Enables Calibration Procedure Bit PE4: Set clock f = 1.0 MHz maximum or nominal Send 8.0 s pulse on CS to calibrate 1.0 MHz clock 2 RTZCR Set RTZ Full Step Time Bits RC3:RC0 Set RTZ Blanking Time Bit RC4 Preload RTZ Accumulator Bits RC12:RC11 and RC10:RC5 Check SO for an Out-of-Range Clock Calibration Is bit CAL logic [1]? If so, then repeat Steps 1 and 2 Table 7 (page 14), Table 20 (page 21) Table 14 (page 19) Table 12 (page 18), Table 13 (page 18) Description Reference Table and/or Figure Table 7 (page 14), Figure 10 (page 30)
device could be used. Further, it is intended to familiarize users with some of its capabilities.
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Analog Integrated Circuit Device Data Freescale Semiconductor
Position (usteps) Position (microsteps)
TYPICAL APPLICATIONS
Table 31. 33976 Setup, Configuration, and Usage Example (continued)
Step 3 4 Command POS0R POS1R Description Move pointer to position 12 prior to RTZ Move pointer to position 12 prior to RTZ Check SO to see if Gauge 0 has moved Is bit MOV0 (OD4) logic [1]? If so, then the Gauge 0 has moved to the first microstep 5 PECCR Send null command to see if gauges have moved Bit PE12 Check SO to see if Gauge 0 (Gauge 1) has moved Is bit MOV0 (OD4) (MOV1 (OD5)) logic [1]? If so, then Gauge 0 (Gauge 1) moved another microstep. Keep track of movement and if 12 steps are finished and both gauges are at a static position, then RTZ. Otherwise, repeat steps (a) and (b) Bit CMD0 (OD10) (CMD1 (OD11)) could also be monitored to determine that the pointer is static 6 RTZ Return one gauge at a time to the zero stop using RTZ command Bit RZ0 selects the gauge Bit RZ1 is used to enable or disable an RTZ Bits RZ2 is used to select the direction (along with PE7) Select the RTZ accumulator bits to clock out on the SO bits using bits PE11:PE10. These will be used if characterizing the RTZ. 7 PECCR Check the Status of the RTZ by sending the null command to monitor SO bit RTZ0, RTZ1 of Device Status SO Bit PE12 is the null command Is RTZ0 (OD2) logic [0]? If not, Gauge 0 still returning and null command should be resent 8 RTZ Return the other gauge to the zero stop. If the second gauge is driving a different pointer than the first, a new RTZCR command may be required to change the Full Step time Check the Status of the RTZ by sending the null command to monitor SO, bit RTZ1 (OD3) Bit PE12 is the null command Is RTZ1 (OD3) logic [0]? If not, Gauge 1 still returning and null command should be resent 10 VELR Change the maximum velocity of the gauge Bits V8:V9 determine which gauge(s) will change the maximum velocity Bits V7:V0 determine the maximum velocity position from Table 30, Velocity Table 11 POS0R Position Gauge 0 pointer Bits P011:P00: Desired Pointer Position Check SO for Out-of-Range VPWR Bit OVUV (OD6) logic [1]? If so, use UV (OD8) and OV (OD9) to decide whether to RTZ after valid VPWR Check SO for overtemperature Bit OT0 logic [1]? If so, enable driver again. If OT0 continues to indicate overtemperature, shut down Gauge 0 If RTZ0 returns to normal, re-establish the zero reference by RTZ command Table 9 (page 16), Table 30 (page 28) Table 7 (page 15), Table 30 (page 28) Table 11 (page 17) Table 7 (page 14), Table 22 (page 23) Table 7 (page 14), Table 20 (page 21) Table 11 (page 17) Table 7 (page 14), Table 20 (page 21) Reference Table and/or Figure Table 9 (page 16) Table 10 (page 16) Table 7 (page 14), Table 20 (page 21) Table 7 (page 14)
9
PECCR
Table 7 (page 14), Table 20 (page 21)
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TYPICAL APPLICATIONS
Table 31. 33976 Setup, Configuration, and Usage Example (continued)
Step 12 Command POS1R Position Gauge 1 pointer Bits P1 11:P1 0: Desired Pointer Position Check SO for Out-of-Range VPWR Bit OVUV logic [1]? If so, use UV (OD8) and OV (OD9) to decided whether to RTZ after valid VPWR Check SO for overtemperature Bit OT1 logic [1]? If so, enable driver again. If OT1 continues to indicate overtemperature, shut down Gauge 1. If OT1 returns to normal, re-establish the zero reference by RTZ command 13 POS0R Return the pointers close to zero position using POS0R Move pointer position at least 12 microsteps CW to the nearest full step prior to RTZ 14 POS1R Return the pointers close to zero position using POS1R Move pointer position at least 12 microsteps CW to the nearest full step position prior to RTZ Check SO to see if Gauge 0 has moved Bit MOV0 logic [1]? If so, Gauge 0 moved to the first microstep 15 PECCR Send null command to see if gauges have moved Bits PE12 Check SO to see if Gauge 0 (Gauge 1) moved Bit MOV0 (MOV1) logic [1]? If so, Gauge 0 (Gauge 1) moved another microstep. Keep track of movement. If 12 steps are finished, and both gauges are at a static position, then RTZ. Otherwise repeat steps (a) and (b) Bit CMD0 (OD10) (CMD1 (OD1)) could also be monitored to determine that the pointer is static 16 RTZ Return one gauge at a time to the zero stop using RTZ command Bit RZ0 selects the gauge Bit RZ1 is used to enable or disable an RTZ Bit RZ2 is used to select the direction (along with PE7) Select the RTZ accumulator bits clocking out on the SO bits using bits PE11:PE10. These will be used if characterizing the RTZ 17 PECCR Check the status of the RTZ by sending the null command to monitor SO bit RTZ0 Bit PE12 is the null command Is RTZ0 logic [0]? If not, Gauge 0 still returning and null command should be resent 18 RTZ Return the other gauge to the zero stop. If the second gauge is driving a different pointer than the first, a new RTZCR command may be required to change the Full Step time Check the status of the RTZ by sending the null command to monitor SO bit RTZ1 Bit PE12 is the null command Is RTZ1 logic [0]? If not, Gauge 1 still returning and null command should be resent 20 PECCR Disable both gauges and go to standby Bit PE0:PE1 are used to disable the gauges Put the device to sleep
RST pin is pulled to logic [0]
Description
Reference Table and/or Figure Table 10 (page 16), Table 30 (page 28)
Table 9 (page 16)
Table 10 (page 16)
Table 10 (page 16), Table 20 (page 21) Table 7 (page 14), Table 20 (page 21)
Table 7 (page 14), Table 11 (page 17), Table 22 (page 23)
Table 7 (page 14), Table 20 (page 21)
Table 11 (page 17), Table 14 (page 19) Table 7 (page 14), Table 20 (page 21) Table 11 (page 17) Table 7 (page 14)
19
PECCR
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PACKAGING PACKAGE DIMENSIONS
PACKAGING
PACKAGE DIMENSIONS
For the most current package revision, visit www.freescale.com and perform a keyword search using the "98A" listed below.
DW SUFFIX EG SUFFIX (PB-FREE) 24-LEAD SOICW PLASTIC PACKAGE 98ASB42344B ISSUE F
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Analog Integrated Circuit Device Data Freescale Semiconductor
39
REVISION HISTORY
REVISION HISTORY
REVISION 3.0
DATE 8/2006
DESCRIPTION OF CHANGES
* * * * * * * * * * * * * *
4.0
1/2007
Implemented Revision History page Converted to Freescale format Updated package drawing Corrected symbol labels on Microstep Output (Measured Across Coil Outputs) and Output Flyback Clamp (11) Added maximum pointer calculation on page 16 Corrected detect threshold upper range from 4081 to 1009 Changed internal clock variation from 35% to 70% Changed EMF to flux on page 31 Added MCZ33976EG/R2 to the Ordering Information block. Revised Internal Block Diagram to enhance readability Added parameter Peak Package Reflow Temperature During Reflow (4), (5) on page 4 and notes (4) and (5) Added ADC Gain (10), (14) to Static Electrical Characteristics table Made wording additions to Address 101 -- Gauge Return to Zero Configuration Register on page 17 and RC12:RC11 = M; default value = 00 on page 18 Added RTZ Accumulator (Typical) on page 23 and accompanying text
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MC33976 Rev 4.0 1/2007

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