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| max66020 iso/iec 14443 type b-compliant 1kb memory fob ________________________________________________________________ maxim integrated products 1 19-5540; rev 0; 12/10 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. general description the max66020 combines 1024 bits of user eeprom, a64-bit unique identifier (uid), and a 13.56mhz rf inter- face (iso/iec 14443 type b, parts 2-4) in a plastic key fob. the memory is organized as 16 blocks of 8 bytes plus two more blocks for data and control registers. four adjacent user eeprom blocks form a memory page (pages 0 to 3). memory protection features are write protection and eprom emulation, which the user can set for each individual memory page. memory access is accomplished through the block transmission protocol (iso/iec 14443-4), where requests and responses are exchanged through i-blocks once a device is in the active state. the data rate can be as high as 847.5kbps. the reader must support a frame size of 19 bytes. the device supports an application family identifier (afi) and a card identifier (cid). iso/iec 14443 functions not supported are chaining, frame-waiting time extension, and power indication. applications driver identification (fleet application)access control asset tracking features ? fully compliant iso/iec 14443 (parts 2-4) type binterface ? 13.56mhz ?khz carrier frequency ? 1024-bit user eeprom with block lock feature,write-cycle counter, and optional eprom- emulation mode ? 64-bit uid ? read and write (64-bit block) ? supports afi and cid function ? 10ms maximum programming time ? to fob: 10% ask modulation at 105.9kbps,211.9kbps, 423.75kbps, or 847.5kbps ? from fob: load modulation using bpskmodulated subcarrier at 105.9kbps, 211.9kbps, 423.75kbps, or 847.5kbps ? 200,000 write/erase cycles (minimum) ? 40-year data retention (minimum) ? powered entirely through the rf field ? operating temperature: -25? to +50? ordering information + denotes a lead(pb)-free/rohs-compliant package. part temp range pin-package max66020k-000aa+ -25c to +50c key fob ic load switched load magnetic coupling antenna rx_in tx_out transmitter 13.56mhz reader max66020 typical operating circuit key fob mechanical drawing appears at end of data sheet. evaluation kit available downloaded from: http:///
max66020 iso/iec 14443 type b-compliant 1kb memory fob 2 _______________________________________________________________________________________ absolute maximum ratingselectrical characteristics (t a = -25? to +50?.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. note 1: system requirement. note 2: measured from the time at which the incident field is present with strength greater than or equal to h (min) to the time at which the max66020? internal power-on reset signal is deasserted and the device is ready to receive a command frame.not characterized or production tested; guaranteed by simulation only. maximum incident magnetic field strength ..........141.5db?/m operating temperature range ...........................-25? to +50? relative humidity ..............................................(water resistant) storage temperature range ...............................-25? to +50? parameter symbol conditions min typ max units eeprom programming time t prog 9 10 ms endurance n cycle at +25c 200,000 cycles data retention t ret 40 years rf interface carrier frequency f c (note 1) 13.553 13.560 13.567 mhz operating magnetic field strength h at +25c (note 1) 123.5 137.5 dba/m power-up time t por (note 2) 1.0 ms downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob _______________________________________________________________________________________ 3 detailed description the max66020 combines 1024 bits of user eeprom,128 bits of user and control registers, a 64-bit uid, and a 13.56mhz rf interface (iso/iec 14443 type b, parts 2-4) in a single key fob. the memory is organized as 18 blocks of 8 bytes each. four adjacent user eeprom blocks form a memory page (pages 0 to 3). memory protection features include write protection and eprom emulation, which the user can set for each individual memory page. the memory of the max66020 is accessed through the iso/iec 14443-4 block transmis- sion protocol, where requests and responses are exchanged through i-blocks once a device is in the active state. the reader must support a frame size of at least 19 bytes. the data rate can be as high as 847.5kbps. the max66020 supports afi and cid. functions not supported are chaining, frame-waiting time extension, and power indication. applications of the max66020 include driver identification (fleet appli- cation), access control, and asset tracking. overview figure 1 shows the relationships between the majorcontrol and memory sections of the max66020. the device has three main data components: 64-bit uid, four 256-bit pages of user eeprom, and two 8-byte blocks of user and control registers. figure 2 shows thehierarchical structure of the iso/iec 14443 type b- compliant access protocol. the master must first apply network function commands to put the max66020 into the active state before the memory and control func- tions become accessible. the protocol required for these network function commands is described in the network function commands section. once the max66020 is in the active state, the master can issue any one of the available memory and control function commands. upon completion of such a command, the max66020 returns to the active state and the master can issue another memory and control function com- mand or deselect the device, which returns it to the halt state. the protocol for these memory and control function commands is described in the memory and control function commands section. all data is read and written least significant bit (lsb) first, starting withthe least significant byte (lsb). parasite power as a wireless device, the max66020 is not connectedto any power source. it gets the energy for operation from the surrounding rf field, which needs to have a minimum strength as specified in the electrical characteristics table. rf front- end voltage regulator internalsupply memory and function control iso 14443 frame formatting and error detection uid register block user eeprom f c data modulation figure 1. block diagram downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 4 _______________________________________________________________________________________ available commands: data field affected: request (reqb) wakeup (wupb) slot-marker halt (hltb) select (attrib) deselect (deselect) afi, administrative dataafi, administrative data (administrative data) pupi pupi, administrative data (administrative data) network function commands get system informationwrite single block lock block read single block read single block with block security status custom read block write afi lock afi get uid 64-bit uid, afi, constantsdata of selected memory block, applicable protection control register protection control register selected memory block selected memory block, applicable protection control register selected memory block, integrity bytes afi byte afi-lock byte 64-bit uid memory and control function commands command level: max66020 figure 2. hierarchical structure of iso/iec 14443 type b protocol msb lsb 64 57 56 49 48 45 44 37 36 1 e0h 2bh 0h feature code (02h) 36-bit ic serial number figure 3. 64-bit uid unique identification number (uid) each max66020 contains a factory-programmed andlocked identification number that is 64 bits long (figure 3). the lower 36 bits are the serial number of the chip. the next 8 bits store the device feature code, which is 02h. bits 45 to 48 are 0h. the code in bit locations 49 to 56 identifies the chip manufacturer, according to iso/iec 7816-6/am1. this code is 2bh for maxim. the code in the upper 8 bits is e0h. the uid is read accessible through the get uid and get system information commands. the lower 32 bits of the uid are transmitted in the pupi field of the atqb response to the reqb, wupb, or slot-marker command. by default, the upper 32 bits of the uid are factory programmed into the application data field, which is transmitted as part of the atqb response.this way the master receives the complete uid in the first response from the slave. see the network function commands section for details. detailed memory description the memory of the max66020 is organized as 18blocks of 8 bytes each. figure 4 shows the memory map. the first 16 blocks (block numbers 00h to 0fh in hexadecimal counting) are the user eeprom, the area for application-specific data. four adjacent blocks are referred to as a page. blocks 00h to 03h are page 0, blocks 04h to 07h are page 1, blocks 08h to 0bh are page 2, and blocks 0ch to 0fh are page 3. downloaded from: http:/// block 10h provides storage for user-programmableparameters that are defined by the iso/iec 14443 stan- dard. these are application data field and afi. the remaining bytes (u1, u2, u3) are not defined by the communication standard; the application software can use them, e.g., for proprietary markings. block 11h con- tains control bytes that determine the operation of the individual pages (eprom-emulation mode, write protec- tion of individual blocks), or to write protect the applica- tion data field, the afi, and u1. the s-lock byte, if programmed to a suitable code, only protects itself from future changes. the self-protection feature can be used to permanently mark the fob as being ?pecial,?as defined by the application. table 1 illustrates the rela-tionship between the controlling register in block 11h and the memory area affected. tables 2 and 3 specify the code assignments to achieve the protection. besides the storage for 8 data bytes, each memory block has 2 integrity bytes, which are not memory mapped. the integrity bytes function as a max66020- maintained, 16-bit write-cycle counter. having reached its maximum value of 65,535, the write-cycle counter stops incrementing, but does not prevent additional write cycles to the memory block. the integrity bytes can be read through the custom read block command. max66020 iso/iec 14443 type b-compliant 1kb memory fob _______________________________________________________________________________________ 5 data byte number (sequence left to right as written to or read from device) integrity bytes block number 0 1 2 3 4 5 6 7 lsb msb 00h page 0 user eeprom r/(w) write-cycle counter 01h page 0 user eeprom r/(w) write-cycle counter 02h page 0 user eeprom r/(w) write-cycle counter 03h page 0 user eeprom r/(w) write-cycle counter 04h page 1 user eeprom r/(w) write-cycle counter 05h page 1 user eeprom r/(w) write-cycle counter 06h page 1 user eeprom r/(w) write-cycle counter 07h page 1 user eeprom r/(w) write-cycle counter 08h page 2 user eeprom r/(w) write-cycle counter 09h page 2 user eeprom r/(w) write-cycle counter 0ah page 2 user eeprom r/(w) write-cycle counter 0bh page 2 user eeprom r/(w) write-cycle counter 0ch page 3 user eeprom r/(w) write-cycle counter 0dh page 3 user eeprom r/(w) write-cycle counter 0eh page 3 user eeprom r/(w) write-cycle counter 0fh page 3 user eeprom r/(w) write-cycle counter 10h iso/iec 14443 application data field afi u1 u2 u3 write-cy cle counter 11h bp1 bp2 bp3 bp4 adf-lock afi-lock u1-lock s-lock write-cycle counter figure 4. memory map downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 6 _______________________________________________________________________________________ affected memory area controlling register* blocks 00h to 03h blocks 04h to 07h blocks 08h to 0bh blocks 0ch to 0fh application data field afi u1 s-lock bp1 e, w bp2 e, w bp3 e, w bp4 e, w adf-lock w afi-lock w u1-lock w s-lock w table 1. memory protection matrix code description e erpom-emulation mode w write protection legend (table 1): code description 00000000b (00h) unlocked (factory default) 00001010b (0ah) eprom-emulation mode (irreversible) bp1: blocks 00h to 03h bp2: blocks 04h to 07h bp3: blocks 08h to 0bh bp4: blocks 0ch to 0fh 1010 max66020 iso/iec 14443 type b-compliant 1kb memory fob _______________________________________________________________________________________ 7 iso/iec 14443 type b communication concept the communication between the master and themax66020 (slave) is based on the exchange of data packets. the master initiates every transaction; only one side (master or slaves) transmits information at any time. data packets are composed of characters, which always begin with a start bit and typically end with one or more stop bits (figure 5). the least significant data bit is transmitted first. data characters have 8 bits. each data packet begins with a start-of-frame (sof) character and ends with an end-of-frame (eof) charac- ter. the eof/sof characters have 9 all-zero data bits (figure 6). the sof has 2 stop bits, after which data characters are transmitted. a data packet with at least 3 bytes between sof and eof is called a frame (figure 7). the last two data characters of an iso/iec 14443 type b frame are an inverted 16-bit crc of the preceding data characters generated according to the crc-16-ccitt polynomial. this crc is transmitted with the lsb first. for more details on the crc-16-ccitt, refer to iso/iec 14443-3, annex b. with network function commands, the command code, parameters, and response are embedded between sof and crc. with memory function commands, com- mand code, and parameters are placed into the infor- mation field of i-blocks (see the block types section), which in turn are embedded between sof and eof. for transmission, the frame information is modulated on a carrier frequency, which is 13.56mhz for iso/iec 14443 . the subsequent paragraphs are a concise description of the required modulation and coding. for full details including sof/eof and subcarrier on/off timing, refer to iso/iec 14443-3, sections 7.1 and 7.2. the path from master to slave uses amplitude modula- tion with a modulation index between 8% and 14% (figure 8). in this direction, a start bit and logic 0 bit correspond to a modulated carrier; stop bit and logic 1 bit correspond to the unmodulated carrier. eof ends with an unmodulated carrier instead of stop bits. the path from slave to master uses an 847.5khz sub- carrier, which is modulated using binary phase-shift key(bpsk) modulation. depending on the data rate, the transmission of a single bit takes eight, four, two, or one subcarrier cycles. the slave generates the subcarrier only when needed; i.e., starting shortly before an sof and ending shortly after an eof. the standard defines the phase of the subcarrier before the sof as 0 refer- ence, which corresponds to logic 1. the phase of the subcarrier changes by 180 whenever there is a binary transition in the character to be transmitted (figure 9). the first phase transition represents a change from logic 1 to logic 0, which coincides with the beginning of the sof. the bpsk modulated subcarrier is used to modulate the load on the fob? antenna (figure 10). start 10 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 8 lsb msb stop figure 5. iso/iec 14443 data character format start 10 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 9 stop/idle bit 8 figure 6. iso/iec 14443 sof/eof character format sof one or more data characters crc (lsb) crc (msb) eof time figure 7. iso/iec 14443 frame format downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 8 _______________________________________________________________________________________ data to be transmitted indicates 180 phase change (polarity reversal) or 11 0 847khz subcarrier bpsk modulation transmission of a single bit power-up default = eight cycles of 847khz (9.44 s) can be reduced to four, two, or one subcarrier cycles for communication in the active state. figure 9. uplink: bpsk modulation of the 847.5khz subcarrier a b carrier amplitude t 11 1 1 00 modulation index m = = 0.08 to 0.14 a - b a + b figure 8. downlink: 8% to 14% amplitude modulation downloaded from: http:/// iso/iec 14443 block transmission protocol before the master can send a data packet to access the memory, the max66020 must be in the active state. the protocol to put the max66020 into the active state is explained in the network function commands sec- tion. while in the active state, the communication between the master and the max66020 follows the block transmission protocol as specified in section 7 of iso/iec 14443-4. such a block (figure 11) consists of three parts: the prologue field, the information field, and the epilogue field. the prologue can contain up to 3 bytes, called the protocol control byte (pcb), card iden- tifier (cid), and the node address (nad). epilogue is another name for the 16-bit crc that precedes the eof. the information field is the general location for data. block types the standard defines three types of blocks: i-block,r-block, and s-block. figures 12, 13, and 14 show the applicable pcb bit assignments. the i-block is the main tool to access the memory. for i-blocks, bit 2 must be 1 and bit 6, bit 7, and bit 8 must be 0. bit 5, marked as ch, is used to indicate chaining, a function that is not used or supported by the max66020. therefore, bit 5 must always be 0. bit 4, marked as cid, is used by the master to indicate whether the prologue field contains a cid byte. the max66020 processes blocks with and without cid as defined in the standard. the master must include the cid byte if bit 4 is 1. bit 3, marked as nad, is used to indicate whether the prologue field contains an nad byte, a feature not supported by the max66020. therefore, bit 3 must always be 0. bit 1, marked as #, is max66020 iso/iec 14443 type b-compliant 1kb memory fob _______________________________________________________________________________________ 9 transmission of a single bit shown as eight cycles of the 847khz subcarrier data**depending on the initial phase, the data polarity may be inverse. 10 1 figure 10. uplink: load modulation of the rf field by the bpsk modulated subcarrier prologue field information field epilogue field pcb cid nad (data) crc (lsb) crc (msb) 1 byte 1 byte 1 byte 0 or more bytes 1 byte 1 byte figure 11. iso/iec 14443-4 type b block format bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb 0 0 0 ch cid nad 1 # figure 12. bit assignments for i-block pcb bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb 1 0 1 an cid 0 1 # figure 13. bit assignments for r-block pcb downloaded from: http:/// max66020 the block number field. the block number is used toensure that the response received relates to the request sent. this function is important in the error han- dling, which is illustrated in annex b of iso/iec 14443- 4. the rules that govern the numbering and handling of blocks are found in sections 7.5.3 and 7.5.4 of iso/iec 14443-4. the max66020 ignores i-blocks that have bit 5 or bit 3 set to 1. for r-blocks, the states of bit 2, bit 3, bit 6, bit 7, and bit 8 are fixed and must be transmitted as shown in figure 13. the function of bit 1 (block number) and bit 4 (cid indicator) is the same as for i-blocks. bit 5, marked as an, is used to acknowledge (if transmitted as 0) or not to acknowledge (if transmitted as 1) the reception of the last frame for recovery from certain error conditions. the max66020 fully supports the func- tion of the r-block as defined in the standard. for details and the applicable rules, refer to sections 7.5.3 and 7.5.4 and annex b of iso/iec 14443-4. for s-blocks, the states of bit 1, bit 2, bit 3, and bit 7 and bit 8 are fixed and must be transmitted as shown in figure 14. the function of bit 4 (cid indicator) is the same as for i-blocks. bit 5 and bit 6, when 00b, specify whether the s-block represents a deselect command. if bit 5 and bit 6 are 11b, the s-block represents a frame- waiting time extension (wtx) request, a feature to tell the master that the response is going to take longer thanspecified by the frame-waiting time (fwt) (see the atqb response section). however, the max66020 does not use this feature and consequently, the only useof the s-block is to transition the device from the active state to the halt state using the deselect command (see the network function commands section). card identifier figure 15 shows the bit assignment within the cardidentifier byte. the purpose of bits 4 to 1 is to select one of multiple slave devices that the master has ele- vated to the active state. the cid is assigned to a slave through param 4 of the attrib command (see the network function commands section). while in active state, a compliant slave only processes blocks that contain a matching cid and blocks without cid if the assigned cid is all zeros. if the master includes a cid, then the slave? response also includes a cid byte. blocks with a nonmatching cids are ignored. according to the standard, the slave can use bits 8 and 7 to inform the master whether power-level indication is supported, and, if yes, whether sufficient power is avail- able for full functionality. since the max66020 does not support power-level indication, the power-level bits are always 00b. when the master transmits a cid byte, the power-level bits must be 00b. information field since the max66020 does not generate wtx requests,the information field (figure 11) is found only with i-blocks. the length of the information field is calculated by counting the number of bytes of the whole block minus length of prologue and epilogue field. the iso/iec 14443 standard does not define any rules for the contents of the information field. the max66020 assumes that the first byte it receives in the information field is a command code followed by 0 or more com- mand-specific parameters. when responding to an i-block, the first byte of the information field indicates success (code 00h) followed by command-specific data or failure (code 01h) followed by one error code. memory and control function commands the commands described in this section are transmit-ted using the block transmission protocol. the data of a block (from prologue to epilogue) is embedded between sof and eof, as shown in figure 16. the cid field (shaded) is optional. if the request contains a cid, the response also contains a cid. iso/iec 14443 type b-compliant 1kb memory fob 10 ______________________________________________________________________________________ bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb 1 1 cid 0 1 0 figure 14. bit assignments for s-block pcb bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb 0 0 00 (power level) (fixed) card identifier value figure 15. bit assignments for cid byte in i-blocks pcb cid sof information field crc (msb) crc (lsb) eof figure 16. frame format for block transmission protocol downloaded from: http:/// the command descriptions in this section only showthe information field of the i-blocks used to transmit requests and responses. since the max66020 neither supports chaining nor generates wtx requests, when it receives an i-block, the max66020 responds with an i-block. the block number in the i-block response is the same as in the i-block request. error indication depending on the complexity of a function, variouserror conditions can occur. in case of an error, the response to a request begins with a 01h byte followed by one error code. table 4 shows a matrix of commands and potential errors. if there was no error, the information field of the response begins with 00h followed by command- specific data, as specified in the detailed commanddescription. if the max66020 does not recognize a command, it does not generate a response. detailed command descriptions get system information this command allows the master to retrieve technicalinformation about the max66020. in the response, the least significant uid byte is transmitted first. the response is adapted from iso 15693-3, section 10. the ic reference code indicates the die revision in hexa- decimal format, such as a1h, a2h, b1h, etc. to receive the system information, issue a request with the com- mand code 2bh in the request information field. max66020 iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 11 failing commands error description error code get sstem information write single block lock block read single block read single block with block securit status custom read block write afi lock afi get uid invalid block number 10h already locked 11h write access failed because block is locked 12h table 4. error code matrix indicator info flags uid u1 afi number of blocks memory block size ic reference 00h 0fh (8 bytes) (1 byte) (1 byte) 12h 07h (1 byte) response information field for the get system information command (no error) downloaded from: http:/// write single block the normal way to write data to the device is throughwrite single block. this command uses one command- specific parameter, which is the memory block number. valid block numbers are 00h to 11h. writing a block takes t prog . if this command is processed without any error, the response information field consists of an indi-cator byte with the code 00h. the response is transmit- ted after the memory is updated. depending on the protection settings of the memory location to be updated, the max66020 manipulates data as it arrives in a buffer. upon receiving a write single block command for a write-protected location, e.g., a self-locking nibble or byte in memory block 11h, the buffer is loaded with the data already in memory, rather than the data transmitted in the request. similarly, if the target memory block is in eprom mode, the buffer is loaded with the bitwise logical and of the transmitted data and data already in memory. in all other cases, the data sent by the master arrives in thebuffer unaltered. lock block this command permanently locks (write protects) theselected block and reports the success of the operation in the response. locking a block takes t prog . if this command is processed without any error, the responseinformation field consists of an indicator byte with the code 00h. the response is transmitted after the protec- tion byte is updated. the block protection can alterna- tively be achieved by directly writing to memory block 11. before using the lock block command, the final block data should be defined and written to the device. read single block this command allows for retrieving the data of a singlememory block. this command uses one command-spe- cific parameter, which is the memory block number. valid block numbers are 00h to 11h. max66020 iso/iec 14443 type b-compliant 1kb memory fob 12 ______________________________________________________________________________________ command block number new block data 21h (1 byte) (8 bytes) request information field for the write single block command command block number 22h (1 byte) request information field for the lock block command command block number 20h (1 byte) indicator memory data 00h (8 bytes) request information field for the read single block command response information field for the read single block command (no error) downloaded from: http:/// max66020 read single block with block security status this command allows for retrieving the security statusof a memory block followed by the memory block? data. this command uses one command-specific para- meter, which is the memory block number. valid block numbers are 00h to 11h. custom read block this command allows for retrieving the data of a singleblock, followed by the block? integrity bytes. this com- mand uses one command-specific parameter, which is the memory block number. valid block numbers are 00h to 11h. command block number a4h (1 byte) indicator memory data integrity bytes 00h (8 bytes) (2 bytes) request information field for the read single block with block security status command command block number b0h (1 byte) response information field for the read single block with block security status command (no error) request information field for the custom read block command response information field for the custom read block command (no error) indicator security status (see codes below) memory data 00h (1 byte) (8 bytes) 00h = the memory block is not protected. 01h = the memory block is write protected. iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 13 downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 14 ______________________________________________________________________________________ write afi this command writes the afi byte and reports the suc-cess of the operation in the response. the afi byte can alternatively be defined by writing to the proper loca- tion in memory block 10h using the write single block command. if this command is processed without any error, the response information field consists of an indi- cator byte with the code 00h. lock afi this command permanently locks (write protects) theafi byte and reports the success of the operation in the response. before using the lock afi command, the afi byte should be written to the device using the write afi command. the afi byte can alternatively be locked by writing the afi-lock byte in memory block 11h to aah, using the write single block command. to lock the afi, issue a request with the command code 28h in the request information field. if this command is processed without any error, the response information field con- sists of an indicator byte with the code 00h. get uid this command allows the master to retrieve thedevice? unique identification number, uid. in the response, the least significant uid byte is transmitted first. to read the uid, issue a request with the com- mand code 30h in the request information field. iso/iec 14443-3 type b initialization and anticollision protocol before an iso/iec 14443-compliant rf device givesaccess to its memory, a communication path between the master and the rf device must be established. initially, the master has no information whether there are any rf devices in the field of its antenna. to find out whether there are one or more rf devices compli- ant to a known standard in the field, the master uses a standard-specific initialization and anticollision proto- col. the iso/iec 14443 type b protocol defines six states: power-off, idle, waiting for slot- marker, ready, halt, and active. figure 17 shows these states and the conditions under which a slave transitions between states. for most cases, let- ters surrounded by small circles reference the condi- tion under which a transition occurs. the conditions are explained in the legend to figure 17. table 5 explains terms that are used in the anticollision proto- col and in the network function command description. command afi value 27h (1 byte) indicator uid 00h (8 bytes) request information field for the write afi command response information field for the get uid command (no error) downloaded from: http:/// max66020 idle ready power-off waiting for slot-marker* active halt any other command in field any other command or case out of field (from any state) any other command response legend: *when entering ?waiting for slot-marker,? each tag selects a random number r in the range of 1 to ?number of slots.? deselect (special case of a block transmission protocol function) atqb response 1 a a b s a b s s b ms 1 1 1 4 3 2 attrib response 2 hltb response 3 deselect response 4 any other command or case any other command or case attrib with matching pupi hltb withmatching pupi executive block transmission protocol function figure 17. iso/iec 14443 type b state transitions diagram name description result a (afi mismatch) reqb/wupb with nonmatching afi a wupb with nonmatching afi return to idle b (bypass sm) reqb/wupb with matching afi and [(n = 1) or [r = 1)] b wupb with matching afi and [(n = 1) or [r = 1)] transition directly to ready s (slot-marker) reqb/wupb with matching afi and (n 1) and (r 1) wupb with matching afi and (n 1) and (r 1) wait for matching slot number ms (matching slot) slot-marker command with slot number = r transition to ready with matching slot-marker conditions legend: iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 15 downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 16 ______________________________________________________________________________________ term description active one of the slaves six states. in this state, the memor y and control function commands and deselect apply. adc application data coding. 2-bit field of the 3rd protocol info byt e of the atqb response. afi application family identifier. 1-byte field used in the reqb /wupb request to preselect slaves. atqb answer to request, type b. response to reqb, wupb, and sl ot-marker command. attrib slave selection command, type b. used to transition a slave from ready to the active state. bpsk binary phase-shift keying modulation cid card identifier. 4-bit temporary identification number assigned to a slave through the attrib command, used in conjunction with the block transmission protocol. eof end of frame deselect slave deselection command. transitions the slave from the acti ve state to the halt state. fc carrier frequency = 13.56mhz fo frame option. 2-bit field of the 3rd protocol info byte of the atqb response. fs subcarrier frequency = f c /16 = 847.5khz fwi frame-waiting time integer. 4-bit field of the 3rd protocol info b yte of the atqb response. fwt frame-waiting time. calculated from fwi. halt one of the slaves six states. the master puts a slave in this state to park it. hltb halt command, type b idle one of the slaves six states. in this state, the slave has power and is waiting for action. inf information field for higher layer protocol (per iso/iec 14443-4) mbli maximum buffer length index of slave (per iso/iec 14443-4). 4-bit fiel d of the first protocol info byte of the atqb response. n number of anticollision slots (or response probability per slot) nad node address (per iso/iec 14443-4) power-off one of the slaves six states. in this state, the slave has no power and consequently cannot do anything. pupi pseudo unique identifier. 4-byte field of the atqb response. r 4-bit random number chosen by a slave when processing the reqb or wup b command ready one of the slaves six states; official name is ready-declared substate. in this state, the slave has identified itself and is waiting for transition to active (m emory and control functions) or halt (parking). reqb request command, type b. used to probe the rf field for the pres ence of slave devices. rf radio frequency s slot number. 4-bit field sent to slave with slot-marker comm and. slot-marker command used in the time-slot approach to identify sl aves in the rf field sof start of frame tr0 guard time per iso/iec 14443-2 tr1 synchronization time per iso/iec 14443-2 waiting for slot-marker one of the slaves six states; official name is ready-requeste d substate. in this state, the slave is waiting to be called by its random number r to transition to read y. wupb wake-up command, type b. similar to reqb, required to wake up s laves in the halt state. table 5. iso/iec 14443 type b technical terms downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 17 iso/iec 14443 type b states and transitions power-off state this state applies if the slave is outside the master? rf field. a slave transitions to the power-off state when leaving the power-delivering rf field. when entering the rf field, the slave automatically transitions to the idle state. idle state the purpose of the idle state is to have the slave pop- ulation ready to participate in the anticollision protocol. when transitioning to the idle state, the slave does not generate any response. to maintain this state, the slave must continuously receive sufficient power from the master? rf field to prevent transitioning into the power-off state. while in the idle state, the slave lis- tens to the commands that the master sends, but reacts only on the reqb and wupb commands, provided that they include a matching afi value. if the master sends a command with a nonmatching afi byte (conditions a and a), a transition to idle is also possible from the halt state, the ready state, and the waiting for slot-marker state. from idle, a slave can transition to the higher states ready (condition b) or waiting for slot-marker (condition s). for details, see the reqb/wupb command description in the network function commands section. waiting for slot-marker state (ready requested substate) the waiting for slot-marker state is used in the time-slot anticollision approach. a slave can transition to waiting for slot-marker from the idle, halt, or ready state upon receiving a reqb or wupb com- mand with a matching afi (conditions s and s), provid- ed that both the number of slots specified in the reqb/wupb command and the random number that the slave has chosen are different from 1. to maintain this state, the slave must continuously receive sufficient power from the master? rf field to prevent transitioning into the power-off state. a slave in the waiting for slot-marker state listens to the commands that the master sends, but reacts only on the reqb, wupb, and slot-marker commands. from waiting for slot-marker, a slave can transition to the higher state ready under condition b (bypassing the slot- marker), or ms (matching slot, slot-marker com- mand with a slot number that matches the random number r). condition a (afi mismatch) returns the slave to the idle state. ready state (ready declared substate) the ready state applies to a slave that has met the cri- teria in the anticollision protocol to send an atqb response. a slave can transition to ready from idle or halt (conditions b and b) or from waiting for slot-marker (conditions b and ms). when transition- ing to the ready state, the slave transmits an atqb response. to maintain this state, the slave must contin- uously receive sufficient power from the master? rf field to prevent transitioning into the power-off state. a slave in the ready state listens to the commands that the master sends, but reacts only on the reqb, wupb, attrib and hltb commands. from ready, a slave can transition to active (attrib command with matching pupi), halt (hltb command with matching pupi), or idle (condition a). halt state the halt state is used to silence slaves that have been identified and shall no longer participate in the anticollion protocol. this state is also used to park slaves after communication in the active state was completed. a slave transitions to the halt state either from ready (hltb command with matching pupi) or from active (deselect command with matching cid). when transitioning to the halt state, the slave transmits a response that confirms the transition. to maintain this state, the slave must continuously receive sufficient power from the master? rf field to prevent transitioning into the power-off state. the normal way out of the halt state is through the wupb com- mand. from halt, a slave can transition to idle (con- dition a), ready (condition b), or waiting for slot-marker (condition s). active state the active state enables the slave to process com- mands sent through the block transmission protocol. when entering the active state, the slave confirms the transition with a response. the only way for a slave to transition to the active state is from the ready state (attrib command with a matching pupi). in the attrib command, the master assigns a 4-bit cid that is used to address one of multiple slaves that could all be in the active state. to maintain this state, the slave must continuously receive sufficient power from the master? rf field to prevent transitioning into the power-off state. the normal way out of the active state is through the deselect command, which transi- tions the slave to the halt state. downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 18 ______________________________________________________________________________________ network function commands to transition slaves devices between states, theiso/iec 14443 type b standard defines six network function commands, called reqb, wupb, slot- marker, hltb, attrib, and deselect. the master issues the commands in the form of request frames and the slaves respond by transmitting response frames. with network function commands, command code, parameters and response are embedded between sof and crc. this section describes the format of the response and request frames and the coding of the data fields inside the frames as detailed as necessary to operate the max66020. not all of the fields and cases that the standard defines are relevant for the max66020. for a full description of those fields refer to the iso/iec 14443-3, section 7. reqb/wupb command the request command, type b (reqb) and the wakeup command, type b (wupb) are the general tools for the master to probe the rf field for the presence of slave devices and to preselect them for action based on the value of the application family identifier (afi). an iso/iec 14443 type b-compliant slave watches for these commands while in the idle state, waiting for slot- marker state, and ready state. in the halt state, the slave only acts upon receiving a wupb command. the reqb or wupb command is transmitted as a frame, as shown in figure 18. besides the command code, the request includes two parameters, afi and param. the response to reqb/wupb is named atqb. see the atqb response section for details. the iso/iec 14443 standard defines rules for theassignment of the afi codes and the behavior of the slaves when receiving a reqb/wupb request. if the request specifies an afi of 00h, a slave must process the command regardless of its actual afi value. if the least significant nibble of the afi in the request is 0000b, the slave must process the command only if the most significant nibble of the afi sent by the master matches the most significant nibble of the slave? afi. for all other afi values, the slave processes the com- mand only if the afi in the request and the slave match. the afi code can be programmed and locked by the user. for details see the memory and control function commands section. the bit assignments of the param byte are shown infigure 19. bits 5 to 8 are reserved and must be trans- mitted as 0. bit 4, if 0, indicates that the request is a reqb command; bit 4, if 1, defines a wupb command. bits 1, 2, and 3 specify the number of slots (n) to be used in the anticollision protocol. table 6 shows the codes. in the case of n = 1, the slot-marker com- mand does not apply and all slaves with a matching afi transition to the ready state. with multiple slaves in the field, this leads to a data collision, since the response frames are transmitted simultaneously. if n is larger than 1, each slave in the field selects its own 4-bit random number, r, in the range of 1 to n. a slave that happens command sof afi crc param eof 05h (1 byte) (2 bytes) (1 byte) figure 18. reqb/wupb request frame bit 8 bit 7 bit 6 bit 5 bit 4 reqb/wupb bit 3 bit 2 bit 1 msb lsb 0 0 00 (fixed) n figure 19. bit assignments for param byte bit 3 bit 2 bit 1 n 0 0 0 1 0 0 1 2 0 1 0 4 0 1 1 8 1 0 0 16 1 0 1 (reserved) 1 1 x (reserved) table 6. number of slots codes downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 19 to choose r = 1 responds to the reqb/wupb request.the larger n is the lower the probability of colliding response frames; however, if n is 16 and there is only a single slave in the field, it can take up to 15 slot- marker commands to get a response. the method to identify all slaves in the field relying solely on the ran- dom number r and the reqb/wupb command is called the ?robabilistic approach.?for mode informa- tion about the anticollision process, see the anticollision examples section. slot-marker command instead of relying on the fact that a participating slavechooses a new random number for every reqb/wupb command, in the ?ime-slot approach?the master calls the slaves by their random number r using the slot- marker command. before this can be done, the mas- ter must have issued the reqb/wupb command with a number of slots (n) value greater than 1. the master can send up to (n - 1) slot-marker commands. figure 20 shows the format of the slot-marker request frame. the afi field is not needed since the slaves have already been preselected through the pre- ceding reqb/wupb request. the response to the slot-marker command is called atqb. see the atqb response section for details. the bits marked as ?nnn?specify the slot number asdefined in the table 7. any sequence of the allowable slot numbers is permitted. atqb response the response for both the reqb/wupb and the slot- marker command is called atqb, which stands for ?nswer to request, type b.?figure 21 shows the for- mat of the atqb response. the pupi field (pseudo- unique identifier) is used by the master to address a slave for transitioning to the active or halt state. the data reported as pupi is the least significant 4 bytes of the 64-bit uid. the application data field reports user- defined data that is relevant for distinguishing otherwise equal slaves in the rf field. application data is the first 4 bytes of memory block 10h. by default, the applica- tion data field is factory programmed to reflect the most significant 4 bytes of the 64-bit uid. this allows the master to obtain the full 64-bit uid in the first response from the slave. however, since this field is not factory locked, it may be written to any value. the protocol info field provides the master with admin- istrative information, such as data rate, frame size, iso/iec 14443-4 compliance, frame waiting time, and whether the slave supports cid and nad in the iso/iec 14443-4 block transmission protocol. figure 22 command sof crc eof nnnn0101b (2 bytes) figure 20. slot-marker request frame indicator sof crc eof 50h application data (4 bytes) (2 bytes) protocol info (3 bytes) pupi (4 bytes) figure 21. atqb response frame bit 8 bit 7 bit 6 bit 5 slot number 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 1 1 1 0 15 1 1 1 1 16 table 7. slot numbering downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 20 ______________________________________________________________________________________ shows where this information is located in the protocolinfo field and what the values are. the bit-rate capability of the max66020 ranges from 105.9kbps to 847.5kbps in both directions (request and response); request and response bit rate need not be the same. the maximum frame size (upper nibble of the 2nd byte) of any request/response specifies 24 bytes. the largest frame that occurs with the max66020 is 19 bytes (get system information response). the protocol type (lower nibble of the 2nd byte) specifies that the max66020 supports the iso/iec 14443-4 block trans- mission protocol. the fwi code 0110b specifies a frame waiting time of 19.3ms. note that a slave may respond long before the maximum frame waiting time is expired. the adc code 00b specifies that the max66020 uses proprietary coding for the application data field. the fo code 01b implies that the max66020 supports cid, but does not support the nad field in the iso/iec 14443-4 block transmission protocol. hltb command the hltb command is the only network function com- mand to silence a slave by parking it in the halt state. if, based on the atqb response, the master does not want to further communicate with the slave, the master issues the hltb command. figures 23 and 24 show the format of the hltb request frame and the corre- sponding response frame. the data to be used in the pupi field must match the pupi information that the slave has transmitted in the atqb response. while in the halt state, the slave only responds to the wupb request. attrib command the attrib command is the only way to select a slaveand make it process commands that are transmitted according to the iso/iec 14443 block transmission pro- tocol. if, based on the atqb response, the master wants to communicate with the slave, the master must put the slave into the active state using the slave selection command attrib. the normal way for the master to move a slave out of the active state is by sending a deselect command, which uses an s-block to convey a network function command. figure 25 shows the format of the attrib request frame. the data to be used in the pupi field must match the pupi information that the slave has transmit- ted in the atqb response. param 1 tells the slave how much time the master needs to switch from transmit to receive (tr0), how much time the master needs to syn- chronize to the slave? subcarrier (tr1), and whether the master is capable of receiving response frames without sof and/or eof. the max66020 ignores the data of param 1. to ease requirements for iso/iec 14443 type b readers, the max66020 has tr0 and tr1 fixed at 128/fs (151?; fs is the subcarrier frequency of 847.5khz) and always begins and ends its responses with sof and eof, respectively. 1st byte 2nd byte 3rd byte, upper nibble 3rd byte, bit 4, bit 3 3rd byte, bit 2, bit 1 bit rate cability maximum frame size, protocol type fwi ad c fo 77h 11h 0110b 00b 01b figure 22. protocol info field details command sof crc eof 1dh (2 bytes) pupi (4 bytes) param 1 (1 byte) param 2 (1 byte) param 3 01h param 4 (1 byte) hlinf ( 0 bytes) figure 25. attrib request frame command sof crc eof 50h (2 bytes) pupi (4 bytes) figure 23. hltb request frame indicator sof crc eof 00h (2 bytes) figure 24. hltb response frame downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 21 param 2 informs the slave about the data rate that shall be used for communication in the active state and the maximum frame size that the master can receive. figure 26 shows the bit assignments for the param 2 byte. the max66020 supports the data rates of 105.9kbps (code 00b), 211.9kbps (code 01b), 423.75kbps (code 10b), and 847.5kbps (code 11b). the master can choose different data rates for request and response. since it does not support chaining, the max66020 ignores the frame size capability and assumes that the master can receive frames as large as specified in the atqb response. the lower nibble of param 3 is used to confirm the pro- tocol type as specified in the lower nibble of the second byte of the atqb protocol info. since iso/iec 14443-3 sets the upper nibble of param 3 to 0000b, the param 3value to be used for the max66020 in the attrib request is 01h. param 4 assigns the slave the cid number that is used with the block transmission protocol to address one of several slaves in the active state. figure 27 shows the param 4 bit assignments. since the max66020 sup- ports the cid field, the master can assign any number in the range from 0 to 14. according to iso/iec 14443- 3, code 15 is reserved. the attrib request frame contains one optional field, called higher layer information (hlinf). this field can be used to include data as in the information field of the iso/iec 14443 type b block transmission protocol (see figure 11). if such data is present and the slave sup- ports the hlinf field, then the slave processes the hlinf data and returns the result in its response to the attrib request. typically, the attrib request is trans- mitted without hlinf field. the only hlinf data that the max66020 accepts and processes is the get uid com- mand, code 30h. if the attrib request has a matching pupi and a valid crc, the slave transmits an attrib response frame, as shown in figure 28. the upper nibble of the indicator, also referred to as mbli, is 0000b, telling that the slave does not provide any information on its internal input buffer size; the lower nibble returns the card identifier value that the master has just assigned to the slave. the hl response field is optional. there are three cases to be distinguished: a) if there was no hlinf field in the attrib request, then there is no hl response field in the response. b) if there was a get uid command code (30h) in the hlinf field of the attrib request, then the hl response field is identical to the get uid response information field (i.e., 00h followed by the 8-byte uid). c) if the code in the hlinf field of the attrib request was different from 30h, then the response frame does not contain an hl response field. deselect command the deselect command is used to transition the slave from the active to the halt state after the master has completed the communication with the slave. there are two versions of the deselect request frame, one without cid and one with cid. figure 29 shows both versions. figure 27 shows the cid format. logically, the deselect command is a special case of the s-block of the block transmission protocol, as defined in part 4 of the iso/iec 14443 standard. the max66020 responds to a deselect command if the bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb xxxx response data rate (uplink) receiver frame size capability response data rate (downlink) figure 26. bit assignments for param 2 byte bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 msb lsb 0 (fixed) card identifier value (cid) 0 00 figure 27. bit assignments for param 4 byte sof frame without cid crc eof (2 bytes) command c2h sof frame with cid crc eof (2 bytes) cid (1 byte) command cah figure 29. deselect request and response frames indicator sof crc eof mbli, cid (2 bytes) hl response ( 0 bytes) figure 28. attrib response frame downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 22 ______________________________________________________________________________________ cid in the request and the cid in the device match. if the deselect request does not include a cid, the max66020 only responds to the request if its cid is 0000b. the response frame to the deselect command is identical to the request frame. the slave returns the same data that it had received, confirming that the slave addressed in the request has been transitioned to the halt sate. anticollision examples probabilistic anticollision the master starts the anticollision process by issuing anreqb or wupb command. the wupb command involves any slave in the field with a matching afi code. the reqb command performs the same function, but is ignored by slaves in the halt state. both commands include the parameter n, which according to table 6 is used to set the probability of an atqb response to 1/n. if n = 1, all participating slaves respond with the atqb response. if n is greater than one, then each slave selects a random number r in the range of 1 to n. if a slave happens to choose r = 1, then it responds with atqb. if r is greater than 1, then the slave waits for another reqb or wupb command, which causes the participating slaves to choose a new random number r. the atqb response contains a field named pupi, which is used to direct commands to a specific slave during the anticollision process. when the master receives an atqb response, it should issue a matching hltb command to halt the slave or issue a matching attrib command to assign a cid and place the slave in the active state. if this is not done, the slaves con- tinue to participate in the anticollision process. a slave in the active state ignores all reqb, wupb, slot- marker, attrib, and hltb commands, but responds to the deselect command. an atqb response received with a crc error indicatesa collision because two or more slaves have responded at the same time. with probabilistic anticollision, the master must issue another reqb command to cause the slaves in the field that are not in the halt or active state to select a new random number r. if one of the slaves has chosen r = 1, it responds with atqb. a reqb without atqb response does not guaran- tee that all slaves in the field have been identified. figure 30 shows an example of the time-slot anticolli- sion, assuming that there are four slaves in idle state in the field. the process begins with the master sending an reqb request with n = 1, which forces all slaves to respond with atqb, resulting in a collision. knowing that slaves are present, the master now sends reqb with n = 8. this causes all slaves to select a random number in the range of 1 to 8. only the slave that has chosen r = 1 responds, which is slave c in the example. knowing that there are more slaves in the field, the master continues issuing reqb commands, which in the example, even- tually identifies all slaves. due to its statistical nature, probabilistic anticollision is less likely to find every slave in the field than the time-slot anticollision. time-slot anticollision the master starts the anticollision process by issuingan reqb or wupb command. the wupb command involves any slave in the field with a matching afi code. the reqb command performs the same function, but is ignored by slaves in the halt state. both commands include the parameter n, which according to table 6 specifies the number of slots to be used in the anticolli- sion protocol. if n = 1, all participating slaves respond with the atqb response. if n is greater than one, then each slave selects a random number r in the range of 1 to n. if a slave happens to choose r = 1, then it responds with atqb. if r is greater than 1, then the slave waits for a testing for slaves attempt 1 attempt 2 attempt 3 attempt 4 attempt 5 attempt 6 master reqb (n = 1) reqb (n = 8) reqb (n = 8) reqb (n = 8) reqb (n = 8) reqb (n = 8) reqb (n = 8) slave a atqb (r = 3) (r = 7) (r = 1) atqb (r = 3) (r = 6) (r = 8) slave b atqb (r = 6) (r = 4) (r = 8) (r = 8) (r = 5) (r = 1) atqb slave c atqb (r = 1) atqb (r = 8) (r = 2) (r = 4) (r = 3) (r = 4) slave d atqb (r = 2) (r = 1) atqb (r = 5) (r = 8) (r = 4) (r = 2) figure 30. probabilistic anticollision example downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob ______________________________________________________________________________________ 23 slot-marker command with a slot number that is equal to r and then responds with atqb. the master must try all slot numbers from 2 to n to ensure that no slave is missed. the atqb response contains a field named pupi, which is used to direct commands to a specific slave during the anticollision process. when the master receives an atqb response, it should issue a matching hltb command to halt the slave, or issue a matching attrib command to assign a cid and place the slave in the active state. a slave in the active state ignores all reqb, wupb, slot-marker, attrib, and hltb commands, but responds to the deselect command. an atqb response received with a crc error indicates a collision because two or more slaves have responded at the same time. typically the master continues issuing slot-marker commands to test for slaves with ran- dom numbers r different from 1. if additional collisions were encountered, the master must issue a new reqb command, causing each slave in the field that is not in the halt or active state to select a new random num- ber r. the anticollision process then continues in this manner until all slaves in the field have been identified and put either into the halt or active state. figure 31 shows an example of the time-slot anticolli- sion, assuming that there are four slaves in idle state in the field. the process begins with the master send- ing an reqb request with n = 1, which forces all slaves to respond with atqb, resulting in a collision. knowingthat slaves are present, the master now sends reqb with n = 8. this causes all slaves to select a random number in the range of 1 to 8. this does not prevent two slaves from choosing the same value for r, but the higher n is, the less likely this is to occur. in the exam- ple, slave c has chosen r = 1 and responds right after reqb. the master now sends a slot-marker com- mand with slot number 2 (sm2), which causes slave d to respond. the master continues testing all slots, and, if a slave with matching r is present, receives an atqb. in case the master detects a collision in a slot, the slaves identified in the remaining slots need to be put in the halt or active state first, before another anticollision process is started. note that there is no need for the master to test the slots in numerical order, as in the example. crc generation the iso/iec 14443 standard uses a 16-bit crc, gener-ated according to the crc-16-ccitt polynomial func- tion: x 16 + x 12 + x 5 + 1 (figure 32). this crc is used for error detection in request and response data pack-ets and is always communicated in the inverted form. after all data bytes are shifted into the crc generator, the state of the 16 flip-flops is parallel-copied to a shift register and shifted out for transmission with the lsb first. for more details on this crc refer to iso/iec 14443-3, annex b, crc_b encoding. testing for slaves slot 1 slot 2 slot 3 slot 4 slot 5 slot 6 slot 7 slot 8 master reqb (n = 1) reqb (n = 8) sm2 sm3 sm4 sm5 sm6 sm7 sm8 slave a atqb (r = 3) atqb slave b atqb (r = 6) atqb slave c atqb (r = 1) atqb slave d atqb (r = 2) atqb figure 31. time-slot anticollision example downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob 24 ______________________________________________________________________________________ max66020k-000aa+ top viewside view 54mm 28mm 7.7mm 1.6mm key fob mechanical drawing figure 32. crc-16-ccitt generator 1st stage msb lsb 2nd stage 7th stage 8th stage 6th stage x 0 x 1 3rd stage 4th stage 5th stage x 2 x 3 x 4 polynomial = x 16 + x 12 + x 5 + 1 input data x 5 x 6 11th stage x 11 9th stage 10th stage x 9 x 10 12th stage 15th stage 14th stage 13th stage x 12 x 13 x 14 x 7 16th stage x 16 x 15 x 8 downloaded from: http:/// max66020 iso/iec 14443 type b-compliant 1kb memory fob maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 25 2010 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 12/10 initial release downloaded from: http:/// |
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