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? 2001 microchip technology inc. ds41098c-page 1 features security ? programmable 28-bit serial number ? programmable 64-bit encryption key ? each transmission is unique ? 66-bit transmission code length ? 32-bit hopping code ? 34-bit fixed code (28-bit serial number, 4-bit button code, 2-bit status) ? encryption keys are read protected operating ? 3.5v-13v operation (2.0v min. using the step up feature) ? three button inputs ? 7 functions available ? selectable baud rate ? automatic code word completion ? battery low signal transmitted to receiver ? non-volatile synchronization data other ? simple programming interface ? on-chip eeprom ? on-chip oscillator and timing components ? button inputs have internal pull-down resistors ? minimum component count ? synchronous transmission mode ? built-in step up regulator typical applications ? the HCS201 is ideal for remote keyless entry (rke) applications. these applications include: ? automotive rke systems ? automotive alarm systems ? automotive immobilizers ? gate and garage door openers ? identity tokens ? burglar alarm systems description the HCS201 from microchip technology inc. is a code hopping encoder designed for secure remote keyless entry (rke) systems. the HCS201 utilizes the k ee l oq code hopping technology, incorporating high security, a small package outline and low cost. the HCS201 is a perfect solution for unidirectional remote keyless entry systems and access control systems. package types HCS201 block diagram the HCS201 combines a 32-bit hopping code, generated by a nonlinear encryption algorithm, with a 28-bit serial number and 6 information bits to create a 66-bit code word. the code word length eliminates the threat of code scanning and the code hopping mecha- nism makes each transmission unique, thus rendering code capture and resend schemes useless. 1 2 3 4 8 7 6 5 s0 s1 s2 v ddb v dd step data v ss pdip, soic HCS201 v ss v dd oscillator reset circuit controller power latching and switching button input port 32-bit shift register encoder eeprom data s 2 s 1 s 0 step up controller v ddb v dd step HCS201 k ee l oq ? code hopping encoder
HCS201 ds41098c-page 2 ? 2001 microchip technology inc. the crypt key, serial number and configuration data are stored in an eeprom array which is not accessible via any external connection. the eeprom data is pro- grammable but read-protected. the data can be veri- fied only after an automatic erase and programming operation. this protects against attempts to gain access to keys or manipulate synchronization values. the HCS201 provides an easy-to-use serial interface for programming the necessary keys, system parame- ters and configuration data. 1.0 system overview key terms the following is a list of key terms used throughout this data sheet. for additional information on k ee l oq and code hopping, refer to technical brief 3 (tb003). ? rke - remote keyless entry ? button status - indicates what button input(s) activated the transmission. encompasses the 4 button status bits s3, s2, s1 and s0 (figure 4-2). ? code hopping - a method by which a code, viewed externally to the system, appears to change unpredictably each time it is transmitted. ? code word - a block of data that is repeatedly transmitted upon button activation (figure 4-1). ? transmission - a data stream consisting of repeating code words (figure 8-1). ? crypt key - a unique and secret 64-bit number used to encrypt and decrypt data. in a symmetri- cal block cipher such as the k ee l oq algorithm, the encryption and decryption keys are equal and will therefore be referred to generally as the crypt key. ? encoder - a device that generates and encodes data. ? encryption algorithm - a recipe whereby data is scrambled using a crypt key. the data can only be interpreted by the respective decryption algorithm using the same crypt key. ? decoder - a device that decodes data received from an encoder. ? decryption algorithm - a recipe whereby data scrambled by an encryption algorithm can be unscrambled using the same crypt key. ? learn C learning involves the receiver calculating the transmitters appropriate crypt key, decrypting the received hopping code and storing the serial number, synchronization counter value and crypt key in eeprom. the k ee l oq product family facil- itates several learning strategies to be imple- mented on the decoder. the following are examples of what can be done. - simple learning the receiver uses a fixed crypt key, common to all components of all systems by the same manufacturer, to decrypt the received code words encrypted portion. - normal learning the receiver uses information transmitted during normal operation to derive the crypt key and decrypt the received code words encrypted portion. - secure learn the transmitter is activated through a special button combination to transmit a stored 60-bit seed value used to generate the transmitters crypt key. the receiver uses this seed value to derive the same crypt key and decrypt the received code words encrypted portion. ? manufacturers code C a unique and secret 64- bit number used to generate unique encoder crypt keys. each encoder is programmed with a crypt key that is a function of the manufacturers code. each decoder is programmed with the manufac- turer code itself. the HCS201 code hopping encoder is designed specif- ically for keyless entry systems; primarily vehicles and home garage door openers. the encoder portion of a keyless entry system is integrated into a transmitter, carried by the user and operated to gain access to a vehicle or restricted area. the HCS201 is meant to be a cost-effective yet secure solution to such systems, requiring very few external components (figure 2-1). most low-end keyless entry transmitters are given a fixed identification code that is transmitted every time a button is pushed. the number of unique identification codes in a low-end system is usually a relatively small number. these shortcomings provide an opportunity for a sophisticated thief to create a device that grabs a transmission and retransmits it later, or a device that quickly scans all possible identification codes until the correct one is found. the HCS201, on the other hand, employs the k ee l oq code hopping technology coupled with a transmission length of 66 bits to virtually eliminate the use of code grabbing or code scanning. the high security level of the HCS201 is based on the patented k ee l oq technol- ogy. a block cipher based on a block length of 32 bits and a key length of 64 bits is used. the algorithm obscures the information in such a way that even if the transmission information (before coding) differs by only one bit from that of the previous transmission, the next
? 2001 microchip technology inc. ds41098c-page 3 HCS201 coded transmission will be completely different. statis- tically, if only one bit in the 32-bit string of information changes, greater than 50 percent of the coded trans- mission bits will change. as indicated in the block diagram on page one, the HCS201 has a small eeprom array which must be loaded with several parameters before use; most often programmed by the manufacturer at the time of produc- tion. the most important of these are: ? a 28-bit serial number, typically unique for every encoder ? a crypt key ? an initial 16-bit synchronization value ? a 16-bit configuration value the crypt key generation typically inputs the transmitter serial number and 64-bit manufacturers code into the key generation algorithm (figure 1-2). the manufac- turers code is chosen by the system manufacturer and must be carefully controlled as it is a pivotal part of the overall system security. figure 1-1: creation and storage of crypt key during production the 16-bit synchronization counter is the basis behind the transmitted code word changing for each transmis- sion; it increments each time a button is pressed. due to the code hopping algorithms complexity, each incre- ment of the synchronization value results in greater than 50% of the bits changing in the transmitted code word. figure 1-2 shows how the key values in eeprom are used in the encoder. once the encoder detects a button press, it reads the button inputs and updates the syn- chronization counter. the synchronization counter and crypt key are input to the encryption algorithm and the output is 32 bits of encrypted information. this data will change with every button press, its value appearing externally to randomly hop around, hence it is referred to as the hopping portion of the code word. the 32-bit hopping code is combined with the button information and serial number to form the code word transmitted to the receiver. the code word format is explained in greater detail in section 4.0. a receiver may use any type of controller as a decoder, but it is typically a microcontroller with compatible firm- ware that allows the decoder to operate in conjunction with an HCS201 based transmitter. section 7.0 provides detail on integrating the HCS201 into a sys- tem. a transmitter must first be learned by the receiver before its use is allowed in the system. learning includes calculating the transmitters appropriate crypt key, decrypting the received hopping code and storing the serial number, synchronization counter value and crypt key in eeprom. in normal operation, each received message of valid format is evaluated. the serial number is used to deter- mine if it is from a learned transmitter. if from a learned transmitter, the message is decrypted and the synchro- nization counter is verified. finally, the button status is checked to see what operation is requested. figure 1-3 shows the relationship between some of the values stored by the receiver and the values received from the transmitter. transmitter manufacturers serial number code crypt key key generation algorithm serial number crypt key sync counter . . . HCS201 production programmer eeprom array
HCS201 ds41098c-page 4 ? 2001 microchip technology inc. figure 1-2: building the transmitted code word (encoder) figure 1-3: basic operation of receiver (decoder) note: circled numbers indicate the order of execution. button press information eeprom array 32 bits encrypted data serial number transmitted information crypt key sync counter serial number k ee l oq encryption algorithm button press information eeprom array manufacturer code 32 bits of encrypted data serial number received information decrypted synchronization counter check for match sync counter serial number k ee l oq decryption algorithm 1 3 4 check for match 2 perform function indicated by button press 5 crypt key
? 2001 microchip technology inc. ds41098c-page 5 HCS201 2.0 encoder operation as shown in the typical application circuits (figure 2-1), the HCS201 is a simple device to use. it requires only the addition of buttons and rf circuitry for use as the transmitter in your security application. a description of each pin is given in table 2-1. figure 2-1: typical circuits table 2-1: pin descriptions the HCS201 will wake-up upon detecting a button press and delay approximately 10 ms for button debounce (figure 2-2). the synchronization counter, discrimination value and button information will be encrypted to form the hopping code. the hopping code portion will change every transmission, even if the same button is pushed again. a code word that has been transmitted will not repeat for more than 64k transmissions. this provides more than 18 years of use before a code is repeated; based on 10 operations per day. overflow information sent from the encoder can be used to extend the number of unique transmissions to more than 192k. if in the transmit process it is detected that a new but- ton(s) has been pressed, a reset will immediately occur and the current code word will not be completed. please note that buttons removed will not have any effect on the code word unless no buttons remain pressed; in which case the code word will be completed and the power-down will occur. v dd b0 tx out s0 s1 s2 v ddb step v dd data v ss two button remote control b1 tx out s0 s1 s2 step v dd data v ss four button remote control b3 b2 b1 b0 note: up to 7 functions can be implemented by pressing more than one button simultaneously or by using a suitable diode array. s0 s1 s2 step v dd data v ss v ddb v ddb v dd tx out three button remote control with step up regulator v dd 2.0-6.0v external components sample values: r = 5.1 k w l = 390 uh q = 2n3904 c = 1.0 uf d = zhcs400ct (40v 0.4a zetex) (see section 5.6 for a description of the step up circuit) r l d c q pin name pin number pin description s0 1 switch input 0 s1 2 switch input 1 s2 3 switch input 2 / clock pin for programming mode v ddb 4 battery input pin, supplies power to the step up control circuitry v ss 5 ground reference connection data 6 pulse width modulation (pwm) output pin / data pin for programming mode step 7 step up regulator switch control v dd 8 positive supply voltage
HCS201 ds41098c-page 6 ? 2001 microchip technology inc. figure 2-2: encoder operation 3.0 eeprom memory organization the HCS201 contains 192 bits (12 x 16-bit words) of eeprom memory (table 3-1). this eeprom array is used to store the encryption key information, synchro- nization value, etc. further descriptions of the memory array is given in the following sections. table 3-1: eeprom memory map 3.1 key_0 - key_3 (64-bit crypt key) the 64-bit crypt key is used to create the encrypted message transmitted to the receiver. this key is calcu- lated and programmed during production using a key generation algorithm. the key generation algorithm may be different from the k ee l oq algorithm. inputs to the key generation algorithm are typically the transmit- ters serial number and the 64-bit manufacturers code. while the key generation algorithm supplied from microchip is the typical method used, a user may elect to create their own method of key generation. this may be done providing that the decoder is programmed with the same means of creating the key for decryption purposes. 3.2 sync (synchronization counter) this is the 16-bit synchronization value that is used to create the hopping code for transmission. this value will increment after every transmission. power-up reset and debounce delay (10 ms) sample inputs update sync info encrypt with load transmit register buttons added ? all buttons released ? (a button has been pressed) transmit stop no yes no yes crypt key complete code word transmission word address mnemonic description 0 key_0 64-bit encryption key (word 0) 1 key_1 64-bit encryption key (word 1) 2 key_2 64-bit encryption key (word 2) 3 key_3 64-bit encryption key (word 3) 4 sync 16-bit synchronization value 5 reserved set to 0000h 6 ser_0 device serial number (word 0) 7 ser_1 device serial number (word 1) 8 seed_0 seed value (word 0) 9 seed_1 seed value (word 1) 10 disc discrimination word 11 config config word
? 2001 microchip technology inc. ds41098c-page 7 HCS201 3.3 reserved must be initialized to 0000h. 3.4 ser_0, ser_1 (encoder serial number) ser_0 and ser_1 are the lower and upper words of the device serial number, respectively. although there are 32 bits allocated for the serial number, only the lower order 28 bits are transmitted. the serial number is meant to be unique for every transmitter. 3.5 seed_0, seed_1 (seed word) the 2-word (32-bit) seed code will be transmitted when all three buttons are pressed at the same time (see figure 4-2). this allows the system designer to imple- ment the secure learn feature or use this fixed code word as part of a different key generation/tracking pro- cess. table 3-2: discrimination word 3.6 disc (discrimination word) the discrimination value aids the post-decryption check on the decoder end. it may be any value, but in a typical system it will be programmed as the 12 least significant bits of the serial number. values other than this must be separately stored by the receiver when a transmitter is learned. the discrimination bits are part of the information that form the encrypted portion of the transmission (figure 4-2). after the receiver has decrypted a transmission, the discrimination bits are checked against the receivers stored value to verify that the decryption process was valid. if the discrimi- nation value was programmed as the 12 lsbs of the serial number then it may merely be compared to the respective bits of the received serial number; saving eeprom space. 3.7 config (configuration word) the configuration word is a 16-bit word stored in eeprom array that is used by the device to store infor- mation used during the encryption process, as well as the status of option configurations. further explana- tions of each of the bits are described in the following sections. table 3-3: configuration word 3.7.1 oscillator tuning bits (osc0 and osc3) these bits are used to tune the frequency of the HCS201 internal clock oscillator to within 10% of its nominal value over temperature and voltage. 3.7.2 low voltage trip point select (v lows ) the low voltage trip point select bit (v lows ) and the s3 setting bit (s3set) are used to determine when to send the v low signal to the receiver. * see also section 3.7.6 bit number bit description 0 discrimination bit 0 1 discrimination bit 1 2 discrimination bit 2 3 discrimination bit 3 4 discrimination bit 4 5 discrimination bit 5 6 discrimination bit 6 7 discrimination bit 7 8 discrimination bit 8 9 discrimination bit 9 10 discrimination bit 10 11 discrimination bit 11 12 not used 13 not used 14 not used 15 not used bit number bit name 0 osc0 1 osc1 2 osc2 3 osc3 4v lows 5brs 6mtx4 7 txen 8 s3set 9 xser 10 not used 11 not used 12 not used 13 not used 14 not used 15 not used table 3-4: trip point select v lows s3set* trip point 004.4 014.4 109 116.75
HCS201 ds41098c-page 8 ? 2001 microchip technology inc. 3.7.3 baud rate select bits (brs) brs selects the speed of transmission and the code word blanking. table 3-5 shows how the bit is used to select the different baud rates and section 5.5 provides detailed explanation in code word blanking. table 3-5: baudrate select 3.7.4 minimum four transmissions (mtx4) if this bit is cleared, only one code is completed if the HCS201 is activated. if this bit is set, at least four com- plete code words are transmitted, even if code word blanking is enabled. 3.7.5 transmit pulse enable (txen) if this bit is cleared, no transmission pulse is transmit- ted before a transmission. if the bit is set, a start pulse (1 t e long) is transmitted after button de-bounc- ing, before the preamble of the first code word. 3.7.6 s3 setting (s3set) this bit determines the value of s3 in the function code during a transmission and the high trip point selected by v lows in section 3.6.2. if this bit is cleared, s3 mir- rors s2 during a transmission. if the s3set bit is set, s3 in the function code (button status) is always set, independent of the value of s2. 3.7.7 extended serial number (xser) if this bit is set, a long 32-bit serial number is transmit- ted. if this bit is cleared, a standard 28-bit serial number is transmitted followed by 4 bits of the function code (button status). brs basic pulse element code words transmitted 0400 m sall 1200 m s 1 out of 2
? 2001 microchip technology inc. ds41098c-page 9 HCS201 4.0 transmitted word 4.1 code word format the HCS201 code word is made up of several parts (figure 4-1). each code word contains a 50% duty cycle preamble, a header, 32 bits of encrypted data and 34 bits of fixed data followed by a guard period before another code word can begin. refer to table 8-4 for code word timing. 4.2 code word organization the HCS201 transmits a 66-bit code word when a button is pressed. the 66-bit word is constructed from a fixed code portion and an encrypted code portion (figure 4-2). the 32 bits of encrypted data are generated from 4 button bits, 12 discrimination bits and the 16-bit sync value. the encrypted portion alone provides up to four billion changing code combinations. the 34 bits of fixed code data are made up of 2 sta- tus bits, 4 button bits and the 28-bit serial number. the fixed and encrypted sections combined increase the number of code combinations to 7.38 x 10 19 . figure 4-1: code word format figure 4-2: code word organization logic 0 logic 1 bit period preamble header encrypted portion of transmission fixed portion of transmission guard time t p t h t hop t fix t g t e t e t e 50% duty cycle 1 v low (1 bit) button status s2 s1 s0 s3 serial number (28 bits) button status s2 s1 s0 s3 disc (12 bits) sync counter (16 bits) 1 v low (1 bit) button status 1 1 1 1 serial number (28 bits) seed (32 bits) 34 bits of fixed portion 32 bits of encrypted portion 66 data bits transmitted lsb first. lsb msb msb lsb seed replaces encrypted portion when all button inputs are activated at the same time.
HCS201 ds41098c-page 10 ? 2001 microchip technology inc. 4.3 synchronous transmission mode synchronous transmission mode can be used to clock the code word out using an external clock. to enter synchronous transmission mode, the pro- gramming mode start-up sequence must be executed as shown in figure 4-3. if either s1 or s0 is set on the falling edge of s2 (or s3), the device enters synchro- nous transmission mode. in this mode, it functions as a normal transmitter, with the exception that the timing of the pwm data string is controlled externally and 16 extra bits are transmitted at the end with the code word. the button code will be the s0, s1 value at the falling edge of s2 or s3. the timing of the pwm data string is controlled by supplying a clock on s2 or s3 and should not exceed 20 khz. the code word is the same as in pwm mode with 16 reserved bits at the end of the word. the reserved bits can be ignored. when in syn- chronous transmission mode s2 or s3 should not be toggled until all internal processing has been com- pleted as shown in figure 4-4. figure 4-3: synchronous transmission mode (txen=0) figure 4-4: code word organization (synchronous transmission mode) 01,10,11 pwm s2 s[1:0] t ps t ph 1 t ph 2 t = 50ms preamble header data reserved (16 bits) padding (2 bits) button status s2 s1 s0 s3 serial number (28 bits) button status s2 s1 s0 s3 disc (12 bits) sync counter (16 bits) 82 data bits transmitted lsb first. lsb msb fixed portion encrypted portion
? 2001 microchip technology inc. ds41098c-page 11 HCS201 5.0 special features 5.1 code word completion the code word completion feature ensures that entire code words are transmitted, even if the button is released before the code word is complete. if the but- ton is held down beyond the time for one code word, multiple code words will result. if another button is acti- vated during a transmission, the active transmission will be aborted and a new transmission will begin using the new button information. 5.2 v low : voltage low indicator the v low bit is transmitted with every transmission (figure 8-4) and will be transmitted as a one if the operating voltage has dropped below the low voltage trip point. the trip point is selectable based on the battery voltage being used. see section 3.7.2 for a description of how the low voltage select option is set. this v low signal is transmitted so the receiver can give an audible signal to the user that the transmitter battery is low. 5.3 auto-shutoff the auto-shutoff function automatically stops the device from transmitting if a button inadvertently gets pressed for a long period of time. this will prevent the device from draining the battery if a button gets pressed while the transmitter is in a pocket or purse. time-out period is t to . 5.4 seed transmission in order to increase the level of security in a system, it is possible for the receiver to implement what is known as a secure learn function. this can be done by utilizing the seed value stored in eeprom, transmitted only when all three button inputs are pressed at the same time (table 5-1). instead of the normal key generation inputs being used to create the crypt key, this seed value is used. table 5-1: pin activation table 5.5 blank alternate code word federal communications commission (fcc) part 15 rules specify the limits on worst case average funda- mental power and harmonics that can be transmitted in a 100 ms window. for fcc approval purposes, it may therefore be advantageous to minimize the transmis- sion duty cycle. this can be achieved by minimizing the duty cycle of the individual bits as well as by blanking out consecutive code words. blank alternate code word (bacw) may be used to reduce the average power of a transmission by transmitting only every sec- ond code word (figure 5-1). this is a selectable feature that is determined in conjunction with the baud rate selection bit bsl0. enabling the bacw option may likewise allow the user to transmit a higher amplitude transmission as the time averaged power is reduced. bacw effectively halves the rf on time for a given transmission so the rf out- put power could theoretically be doubled while main- taining the same time averaged output power. figure 5-1: blank alternate code word (bacw) function s2 s1 s0 standby 0 000 hopping code 1 001 2 010 - --- 5 101 6 110 seed code 7 111 code word brs = 0 brs = 1 a 2a time code word code word code word amplitude
HCS201 ds41098c-page 12 ? 2001 microchip technology inc. 5.6 step up regulator the integrated step up regulator can be used to ensure the power supply voltage to the encoder and the rf circuit (v dd ), is constant independent of what the battery voltage is (v ddb ). input on v dd pin is com- pared to v step , the internal reference voltage. if v dd falls below this voltage the step output is pulsed at f step . this output can be connected to an external cir- cuit as illustrated in figure 5-2, to provide a step up voltage on the device. the step up regulator is inactive when the device is not transmitting. figure 5-2: application circuit figure 5-3: typical loading curves (figure 5-2 circuit) table 5-2: step up circuit characteristics note: power to the step up regulator is taken from the v ddb pin. while v dd is limited to a 3.5v minimum, v ddb minimum can be as low as 2.0v for the step up circuit to start operating. s0 s1 s2 step v dd data v ss v ddb v dd tx out three button remote control with step up regulator 2.0-6.0v external components sample values: r = 5.1 k w l = 390 uh q = 2n3904 c = 1.0 uf d = zhcs400ct (40v 0.4a zetex) r l d c q symbol parameters min. typ. max. units conditions f step output frequency 125 200 250 khz v step reference voltage 5.5 6.5 7.5 v v ddb = 3v note: these parameters are characterized but not tested. 0 1 2 3 4 5 6 7 8 0 5 10 15 20 load(ma) vdd(v) vddb=2v vddb=2.5v vddb=3v vddb=3.5v note: these are typical values not tested in production.
? 2001 microchip technology inc. ds41098c-page 13 HCS201 6.0 programming the HCS201 when using the HCS201 in a system, the user will have to program some parameters into the device including the serial number and the secret key before it can be used. the programming cycle allows the user to input all 192 bits in a serial data stream, which are then stored internally in eeprom. programming will be initiated by forcing the data line high, after the s2 line has been held high for the appropriate length of time line (table 6-1 and figure 6-1). after the program mode is entered, a delay must be provided to the device for the automatic bulk write cycle to complete. this will write all locations in the eeprom to an all zeros pattern. the device can then be programmed by clocking in 16 bits at a time, using s2 as the clock line and data as the data in line. after each 16-bit word is loaded, a programming delay is required for the internal program cycle to complete. this delay can take up to twc. after every 16-bit word is written to the HCS201, the HCS201 will signal that the write is complete by sending out a train of ack pulses, t ackh high, t ackl low (if the oscillator was perfectly tuned) on data. these will continue until s2 is dropped. the first pulses width should not be used for calibration. at the end of the programming cycle, the device can be verified (figure 6-2) by reading back the eeprom. reading is done by clocking the s2 line and reading the data bits on data. for security reasons, it is not possible to exe- cute a verify function without first programming the eeprom. a verify operation can only be done once, immediately following the program cycle . figure 6-1: programming waveforms figure 6-2: verify waveforms note: to ensure that the device does not acci- dentally enter programming mode, data should never be pulled high by the circuit connected to it. special care should be taken when driving pnp rf transistors. data enter program mode (data) (clock) note 1: s0 and s1 button inputs to be held to ground during the entire programming sequence. bit 0 bit 1 bit 2 bit 3 bit 14 bit 15 bit 16 bit 17 t ph 1 t pbw t ps repeat for each word (12 times) t ph 2 t clkh t clkl t wc t ds s2 data for word 1 t dh t clkl initiate data polling here write cycle complete here t a c k l t ac k h calibration pulses t p h o l d ack ack ack data (clock) (data) note: if a verify operation is to be done, then it must immediately follow the program cycle. end of programming cycle beginning of verify cycle bit 1 bit 2 bit 3 bit 15 bit 14 bit 16 bit 17 bit190 bit191 t wc data from word 0 t dv s2 bit 0 bit191 bit190 ack
HCS201 ds41098c-page 14 ? 2001 microchip technology inc. table 6-1: programming/verify timing requirements v dd = 5.0v 10%, 25 c 5 c parameter symbol min. max. units program mode setup time t ps 25.0ms hold time 1 t ph 14.0 ms hold time 2 t ph 250 m s bulk write time t pbw 4.0 ms program delay time t prog 4.0 ms program cycle time t wc 50 ms clock low time t clkl 50 m s clock high time t clkh 50 m s data setup time t ds 0 m s data hold time t dh 18 m s data out valid time t dv 30 m s hold time t phold 100 m s acknowledge low time t ackl 800 m s acknowledge high time t ackh 800 m s
? 2001 microchip technology inc. ds41098c-page 15 HCS201 7.0 integrating the HCS201 into a system use of the HCS201 in a system requires a compatible decoder. this decoder is typically a microcontroller with compatible firmware. microchip will provide (via a license agreement) firmware routines that accept transmissions from the HCS201 and decrypt the hopping code portion of the data stream. these routines provide system designers the means to develop their own decoding system. 7.1 learning a transmitter to a receiver a transmitter must first be 'learned' by a decoder before its use is allowed in the system. several learning strat- egies are possible, figure 7-1 details a typical learn sequence. core to each, the decoder must minimally store each learned transmitter's serial number and cur- rent synchronization counter value in eeprom. addi- tionally, the decoder typically stores each transmitter's unique crypt key. the maximum number of learned transmitters will therefore be relative to the available eeprom. a transmitter's serial number is transmitted in the clear but the synchronization counter only exists in the code word's encrypted portion. the decoder obtains the counter value by decrypting using the same key used to encrypt the information. the k ee l oq algorithm is a symmetrical block cipher so the encryption and decryp- tion keys are identical and referred to generally as the crypt key. the encoder receives its crypt key during manufacturing. the decoder is programmed with the ability to generate a crypt key as well as all but one required input to the key generation routine; typically the transmitter's serial number. figure 7-1 summarizes a typical learn sequence. the decoder receives and authenticates a first transmis- sion; first button press. authentication involves gener- ating the appropriate crypt key, decrypting, validating the correct key usage via the discrimination bits and buffering the counter value. a second transmission is received and authenticated. a final check verifies the counter values were sequential; consecutive button presses. if the learn sequence is successfully com- plete, the decoder stores the learned transmitter's serial number, current synchronization counter value and appropriate crypt key. from now on the crypt key will be retrieved from eeprom during normal opera- tion instead of recalculating it for each transmission received. certain learning strategies have been patented and care must be taken not to infringe. figure 7-1: typical learn sequence enter learn mode wait for reception of a valid code generate key from serial number use generated key to decrypt compare discrimination value with fixed value equal wait for reception of second valid code compare discrimination value with fixed value use generated key to decrypt equal counters encryption key serial number synchronization counter sequential ? ? ? exit learn successful store: learn unsuccessful no no no yes yes yes
HCS201 ds41098c-page 16 ? 2001 microchip technology inc. 7.2 decoder operation figure 7-2 summarizes normal decoder operation. the decoder waits until a transmission is received. the received serial number is compared to the eeprom table of learned transmitters to first determine if this transmitter's use is allowed in the system. if from a learned transmitter, the transmission is decrypted using the stored crypt key and authenticated via the discrimination bits for appropriate crypt key usage. if the decryption was valid the synchronization value is evaluated. figure 7-2: typical decoder operation 7.3 synchronization with decoder (evaluating the counter) the k ee l oq technology patent scope includes a sophisticated synchronization technique that does not require the calculation and storage of future codes. the technique securely blocks invalid transmissions while providing transparent resynchronization to transmitters inadvertently activated away from the receiver. figure 7-3 shows a 3-partition, rotating synchronization window. the size of each window is optional but the technique is fundamental. each time a transmission is authenticated, the intended function is executed and the transmission's synchronization counter value is stored in eeprom. from the currently stored counter value there is an initial "single operation" forward win- dow of 16 codes. if the difference between a received synchronization counter and the last stored counter is within 16, the intended function will be executed on the single button press and the new synchronization counter will be stored. storing the new synchronization counter value effectively rotates the entire synchroniza- tion window. a "double operation" (resynchronization) window fur- ther exists from the single operation window up to 32k codes forward of the currently stored counter value. it is referred to as "double operation" because a trans- mission with synchronization counter value in this win- dow will require an additional, sequential counter transmission prior to executing the intended function. upon receiving the sequential transmission the decoder executes the intended function and stores the synchronization counter value. this resynchronization occurs transparently to the user as it is human nature to press the button a second time if the first was unsuc- cessful. the third window is a "blocked window" ranging from the double operation window to the currently stored synchronization counter value. any transmission with synchronization counter value within this window will be ignored. this window excludes previously used, perhaps code-grabbed transmissions from accessing the system. ? transmission received does serial number match ? decrypt transmission is decryption valid ? is counter within 16 ? is counter within 32k ? update counter execute command save counter in temp location start no no no no yes yes yes yes yes no and no note: the synchronization method described in this section is only a typical implementation and because it is usually implemented in firmware, it can be altered to fit the needs of a particular system.
? 2001 microchip technology inc. ds41098c-page 17 HCS201 figure 7-3: synchronization window blocked entire window rotates to eliminate use of previously used codes single operation window window (32k codes) (16 codes) double operation (resynchronization) window (32k codes) stored synchronization counter value
HCS201 ds41098c-page 18 ? 2001 microchip technology inc. 8.0 electrical characteristics table 8-1: absolute maximum ratings table 8-2: dc characteristics symbol item rating units v dd supply voltage -0.3 to 13.5 v v in input voltage -0.3 to v dd + 0.3 v v out output voltage -0.3 to v dd + 0.3 v i out max output current 50 ma t stg storage temperature -55 to +125 c ( note 1 ) t lsol lead soldering temp 300 c ( note 1 ) note 1: stresses above those listed under absolute maximum ratings may cause permanent damage to the device. commercial (c): tamb = 0 c to +70 c industrial (i): tamb = -40 c to +85 c 3.5v < v dd < 5.0v 5.0v < v dd < 13.0v parameter sym. min. typ. 1 max. min. typ. 1 max. unit conditions operating current (avg) 2 i cc 0.20.5 1.5 2 ma ma standby current i ccs 0.1 1.0 0.1 1.0 m a auto-shutoff current 3,4 i ccs 40 75 160 300 m a high level input voltage v ih 0.55v dd v dd +0.3 2.75 v dd +0.3 v low level input voltage v il -0.3 0.15v dd -0.3 0.75 v high level output voltage v oh 0.6v dd 3.3 v v i oh = -1.0 ma v dd = 3.5v i oh = -2.0 ma v dd = 12v low level output voltage v ol 0.08v dd 0.4 v v i ol = 1.0 ma v dd = 5v i ol = 2.0 ma v dd = 12v pull-down resistance; s0-s2 r so - 2 40 60 80 40 60 80 k w v dd = 4.0v pull-down resistance; data r data 80 120 160 80 120 160 k w v dd = 4.0v note 1: typical values are at 25 c. 2: no load. 3: auto-shutoff current specification does not include the current through the input pull-down resistors. 4: these values are characterized but not tested.
? 2001 microchip technology inc. ds41098c-page 19 HCS201 figure 8-1: power-up and transmit timing table 8-3: power-up and transmit timing (2) figure 8-2: code word format standard operating conditions (unless otherwise specified): commercial(c): tamb = 0c to +70c industrial(i): tamb = -40c to +85c symbol parameter min. typ. max. unit conditions t bp time to second button press 10 + code word 26 + code word ms (note 1) t td transmit delay from button detect 12 26 ms t db debounce delay 6 20 ms t to auto-shutoff time-out period 27 s ts start pulse delay 4.5 ms note 1: t bp is the time in which a second button can be pressed without completion of the first code word (the intention was to press the combination of buttons). 2: typical values - not tested in production. button press sn detect t db output t td multiple code word transmission t to code word 1 code word 2 code word 3 code word n t bp code word 4 data input button t s logic 0 logic 1 bit period preamble header encrypted portion of transmission fixed portion of transmission guard time t p t h t hop t fix t g 50% duty cycle t bp t e t e t e
HCS201 ds41098c-page 20 ? 2001 microchip technology inc. figure 8-3: code word format: preamble/header portion figure 8-4: code word format: data portion (xser=0) table 8-4: code word transmission timing requirements v dd = +3.5 to 6.0v commercial (c): tamb = 0 c to +70 c industrial (i): tamb = -40 c to +85 c code words transmitted all 1 out of 2 symbol characteristic number of t e min. typ. max. min. typ. max. units t e basic pulse element 1 360 400 440 180 200 220 m s t bp pwm bit pulse width 3 1.08 1.2 1.32 0.54 0.6 0.66 ms t p preamble duration 23 8.64 9.2 10.56 4.32 4.6 5.28 ms t h header duration 10 3.6 4.0 4.4 1.8 2.0 2.2 ms t hop hopping code duration 96 34.56 38.4 42.24 17.28 19.2 21.12 ms t fix fixed code duration 102 36.72 40.8 44.88 18.36 20.4 22.44 ms t g guard time 39 14.04 15.6 17.16 7.02 7.8 8.58 ms ? total transmit time 271 97.56 108.4 119.24 48.78 54.2 59.62 ms ? pwm data rate ? 925 833 757 1851 1667 1515 bps note 1: the timing parameters are not tested but derived from the oscillator clock. 50% duty cycle preamble header p1 p12 23 t e 10 t e data bits bit 0 bit 1 bit 0 bit 1 header bit 30 bit 31 bit 32 bit 33 bit 58 bit 59 fixed portion encrypted portion guard lsb lsb msb msb s3 s0 s1 s2 v low rpt time serial number button code status bit 60 bit 61 bit 62 bit 63 bit 64 bit 65
? 2001 microchip technology inc. ds41098c-page 21 HCS201 9.0 packaging information 9.1 package marking information xxxxxxxx xxxxxnnn yyww 8-lead pdip (300 mil) example HCS201 xxxxxnnn 0025 8-lead soic (150 mil) example legend: xx...x customer specific information* yy year code (last 2 digits of calendar year) ww week code (week of january 1 is week 01) nnn alphanumeric traceability code note : in the event the full microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information. * standard otp marking consists of microchip part number, year code, week code, facility code, mask rev#, and assembly code. for otp marking beyond this, certain price adders apply. please check with your microchip sales office. for qtp devices, any special marking adders are included in qtp price. xxxxxxx xxxyyww nnn HCS201 xxx0025 nnn
HCS201 ds41098c-page 22 ? 2001 microchip technology inc. 9.2 package details 8-lead plastic dual in-line (p) C 300 mil (pdip) b1 b a1 a l a2 p a e eb b c e1 n d 1 2 units inches* millimeters dimension limits min nom max min nom max number of pins n 88 pitch p .100 2.54 top to seating plane a .140 .155 .170 3.56 3.94 4.32 molded package thickness a2 .115 .130 .145 2.92 3.30 3.68 base to seating plane a1 .015 0.38 shoulder to shoulder width e .300 .313 .325 7.62 7.94 8.26 molded package width e1 .240 .250 .260 6.10 6.35 6.60 overall length d .360 .373 .385 9.14 9.46 9.78 tip to seating plane l .125 .130 .135 3.18 3.30 3.43 lead thickness c .008 .012 .015 0.20 0.29 0.38 upper lead width b1 .045 .058 .070 1.14 1.46 1.78 lower lead width b .014 .018 .022 0.36 0.46 0.56 overall row spacing eb .310 .370 .430 7.87 9.40 10.92 mold draft angle top a 51015 51015 mold draft angle bottom b 51015 51015 * controlling parameter notes: dimensions d and e1 do not include mold flash or protrusions. mold flash or protrusions shall not exceed jedec equivalent: ms-001 drawing no. c04-018 .010 (0.254mm) per side. significant characteristic
? 2001 microchip technology inc. ds41098c-page 23 HCS201 8-lead plastic small outline (sn) C narrow, 150 mil (soic) foot angle f 048048 15 12 0 15 12 0 b mold draft angle bottom 15 12 0 15 12 0 a mold draft angle top 0.51 0.42 0.33 .020 .017 .013 b lead width 0.25 0.23 0.20 .010 .009 .008 c lead thickness 0.76 0.62 0.48 .030 .025 .019 l foot length 0.51 0.38 0.25 .020 .015 .010 h chamfer distance 5.00 4.90 4.80 .197 .193 .189 d overall length 3.99 3.91 3.71 .157 .154 .146 e1 molded package width 6.20 6.02 5.79 .244 .237 .228 e overall width 0.25 0.18 0.10 .010 .007 .004 a1 standoff 1.55 1.42 1.32 .061 .056 .052 a2 molded package thickness 1.75 1.55 1.35 .069 .061 .053 a overall height 1.27 .050 p pitch 8 8 n number of pins max nom min max nom min dimension limits millimeters inches* units 2 1 d n p b e e1 h l b c 45 f a2 a a a1 * controlling parameter notes: dimensions d and e1 do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010 (0.254mm) per side. jedec equivalent: ms-012 drawing no. c04-057 significant characteristic
HCS201 ds41098c-page 24 ? 2001 microchip technology inc. on-line support microchip provides on-line support on the microchip world wide web (www) site. the web site is used by microchip as a means to make files and information easily available to customers. to view the site, the user must have access to the internet and a web browser, such as netscape or microsoft explorer. files are also available for ftp download from our ftp site. connecting to the microchip internet web site the microchip web site is available by using your favorite internet browser to attach to: www.microchip.com the file transfer site is available by using an ftp ser- vice to connect to: ftp://ftp.microchip.com the web site and file transfer site provide a variety of services. users may download files for the latest development tools, data sheets, application notes, user's guides, articles and sample programs. a vari- ety of microchip specific business information is also available, including listings of microchip sales offices, distributors and factory representatives. other data available for consideration is: ? latest microchip press releases ? technical support section with frequently asked questions ? design tips ? device errata ? job postings ? microchip consultant program member listing ? links to other useful web sites related to microchip products ? conferences for products, development systems, technical information and more ? listing of seminars and events systems information and upgrade hot line the systems information and upgrade line provides system users a listing of the latest versions of all of microchip's development systems software products. plus, this line provides information on how customers can receive any currently available upgrade kits.the hot line numbers are: 1-800-755-2345 for u.s. and most of canada, and 1-480-792-7302 for the rest of the world.
? 2001 microchip technology inc. ds41098c-page 25 HCS201 reader response it is our intention to provide you with the best documentation possible to ensure successful use of your microchip prod- uct. if you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please fax your comments to the technical publications manager at (480) 792-7578. please list the following information, and use this outline to provide us with your comments about this data sheet. to : technical publications manager re: reader response total pages sent from: name company address city / state / zip / country telephone: (_______) _________ - _________ application (optional): would you like a reply? y n device: literature number: questions: fax: (______) _________ - _________ ds41098c HCS201 1. what are the best features of this document? 2. how does this document meet your hardware and software development needs? 3. do you find the organization of this data sheet easy to follow? if not, why? 4. what additions to the data sheet do you think would enhance the structure and subject? 5. what deletions from the data sheet could be made without affecting the overall usefulness? 6. is there any incorrect or misleading information (what and where)? 7. how would you improve this document? 8. how would you improve our software, systems, and silicon products?
HCS201 ds41098c-page 26 ? 2001 microchip technology inc. notes:
2001 microchip technology inc. ds41098c - page 27 information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. it is your responsibility to ensure that your application meets with your specifications. no representation or warranty is given and no liability is assumed by microchip technology incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. use of microchips products as critical com- ponents in life support systems is not authorized except with express written approval by microchip. no licenses are con- veyed, implicitly or otherwise, under any intellectual property rights. trademarks the microchip name and logo, the microchip logo, filterlab, k ee l oq , mplab, pic, picmicro, picmaster, picstart, pro mate, seeval and the embedded control solutions company are registered trademarks of microchip technology incorporated in the u.s.a. and other countries. dspic, economonitor, fansense, flexrom, fuzzylab, in-circuit serial programming, icsp, icepic, microid, microport, migratable memory, mpasm, mplib, mplink, mpsim, mxdev, picc, picdem, picdem.net, rfpic, select mode and total endurance are trademarks of microchip technology incorporated in the u.s.a. serialized quick turn programming (sqtp) is a service mark of microchip technology incorporated in the u.s.a. all other trademarks mentioned herein are property of their respective companies. ? 2001, microchip technology incorporated, printed in the u.s.a., all rights reserved. printed on recycled paper. microchip received qs-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in chandler and tempe, arizona in july 1999. the companys quality system processes and procedures are qs-9000 compliant for its picmicro ? 8-bit mcus, k ee l oq ? code hopping devices, serial eeproms and microperipheral products. in addition, microchips quality system for the design and manufacture of development systems is iso 9001 certified. microchips secure data products are covered by some or all of the following patents: code hopping encoder patents issued in europe, u.s.a., and r.s.a. u.s.a.: 5,517,187; europe: 0459781; r.s.a.: za93/4726 secure learning patents issued in the u.s.a. and r.s.a. u.s.a.: 5,686,904; r.s.a.: 95/5429
ds41098c-page 28 ? 2001 microchip technology inc. americas corporate office 2355 west chandler blvd. chandler, az 85224-6199 tel: 480-792-7200 fax: 480-792-7277 technical support: 480-792-7627 web address: http://www.microchip.com rocky mountain 2355 west chandler blvd. chandler, az 85224-6199 tel: 480-792-7966 fax: 480-792-7456 atlanta 500 sugar mill road, suite 200b atlanta, ga 30350 tel: 770-640-0034 fax: 770-640-0307 boston 2 lan drive, suite 120 westford, ma 01886 tel: 978-692-3848 fax: 978-692-3821 chicago 333 pierce road, suite 180 itasca, il 60143 tel: 630-285-0071 fax: 630-285-0075 dallas 4570 westgrove drive, suite 160 addison, tx 75001 tel: 972-818-7423 fax: 972-818-2924 dayton two prestige place, suite 130 miamisburg, oh 45342 tel: 937-291-1654 fax: 937-291-9175 detroit tri-atria office building 32255 northwestern highway, suite 190 farmington hills, mi 48334 tel: 248-538-2250 fax: 248-538-2260 kokomo 2767 s. albright road kokomo, indiana 46902 tel: 765-864-8360 fax: 765-864-8387 los angeles 18201 von karman, suite 1090 irvine, ca 92612 tel: 949-263-1888 fax: 949-263-1338 new york 150 motor parkway, suite 202 hauppauge, ny 11788 tel: 631-273-5305 fax: 631-273-5335 san jose microchip technology inc. 2107 north first street, suite 590 san jose, ca 95131 tel: 408-436-7950 fax: 408-436-7955 toronto 6285 northam drive, suite 108 mississauga, ontario l4v 1x5, canada tel: 905-673-0699 fax: 905-673-6509 asia/pacific australia microchip technology australia pty ltd suite 22, 41 rawson street epping 2121, nsw australia tel: 61-2-9868-6733 fax: 61-2-9868-6755 china - beijing microchip technology consulting (shanghai) co., ltd., beijing liaison office unit 915 bei hai wan tai bldg. no. 6 chaoyangmen beidajie beijing, 100027, no. china tel: 86-10-85282100 fax: 86-10-85282104 china - chengdu microchip technology consulting (shanghai) co., ltd., chengdu liaison office rm. 2401, 24th floor, ming xing financial tower no. 88 tidu street chengdu 610016, china tel: 86-28-6766200 fax: 86-28-6766599 china - fuzhou microchip technology consulting (shanghai) co., ltd., fuzhou liaison office rm. 531, north building fujian foreign trade center hotel 73 wusi road fuzhou 350001, china tel: 86-591-7557563 fax: 86-591-7557572 china - shanghai microchip technology consulting (shanghai) co., ltd. room 701, bldg. b far east international plaza no. 317 xian xia road shanghai, 200051 tel: 86-21-6275-5700 fax: 86-21-6275-5060 china - shenzhen microchip technology consulting (shanghai) co., ltd., shenzhen liaison office rm. 1315, 13/f, shenzhen kerry centre, renminnan lu shenzhen 518001, china tel: 86-755-2350361 fax: 86-755-2366086 hong kong microchip technology hongkong ltd. unit 901-6, tower 2, metroplaza 223 hing fong road kwai fong, n.t., hong kong tel: 852-2401-1200 fax: 852-2401-3431 india microchip technology inc. india liaison office divyasree chambers 1 floor, wing a (a3/a4) no. 11, oshaugnessey road bangalore, 560 025, india tel: 91-80-2290061 fax: 91-80-2290062 japan microchip technology japan k.k. benex s-1 6f 3-18-20, shinyokohama kohoku-ku, yokohama-shi kanagawa, 222-0033, japan tel: 81-45-471- 6166 fax: 81-45-471-6122 korea microchip technology korea 168-1, youngbo bldg. 3 floor samsung-dong, kangnam-ku seoul, korea 135-882 tel: 82-2-554-7200 fax: 82-2-558-5934 singapore microchip technology singapore pte ltd. 200 middle road #07-02 prime centre singapore, 188980 tel: 65-334-8870 fax: 65-334-8850 taiwan microchip technology taiwan 11f-3, no. 207 tung hua north road taipei, 105, taiwan tel: 886-2-2717-7175 fax: 886-2-2545-0139 europe denmark microchip technology nordic aps regus business centre lautrup hoj 1-3 ballerup dk-2750 denmark tel: 45 4420 9895 fax: 45 4420 9910 france microchip technology sarl parc dactivite du moulin de massy 43 rue du saule trapu batiment a - ler etage 91300 massy, france tel: 33-1-69-53-63-20 fax: 33-1-69-30-90-79 germany microchip technology gmbh gustav-heinemann ring 125 d-81739 munich, germany tel: 49-89-627-144 0 fax: 49-89-627-144-44 italy microchip technology srl centro direzionale colleoni palazzo taurus 1 v. le colleoni 1 20041 agrate brianza milan, italy tel: 39-039-65791-1 fax: 39-039-6899883 united kingdom arizona microchip technology ltd. 505 eskdale road winnersh triangle wokingham berkshire, england rg41 5tu tel: 44 118 921 5869 fax: 44-118 921-5820 10/01/01 w orldwide s ales and s ervice

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