cvs.zerfleddert.de Git - proxmark3-svn/blob - armsrc/iso14443b.c

   1 //-----------------------------------------------------------------------------
   2 // Jonathan Westhues, split Nov 2006
   3 //
   4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   5 // at your option, any later version. See the LICENSE.txt file for the text of
   6 // the license.
   7 //-----------------------------------------------------------------------------
   8 // Routines to support ISO 14443B. This includes both the reader software and
   9 // the `fake tag' modes.
  10 //-----------------------------------------------------------------------------
  11
  12 #include "proxmark3.h"
  13 #include "apps.h"
  14 #include "util.h"
  15 #include "string.h"
  16
  17 #include "iso14443crc.h"
  18
  19 #define RECEIVE_SAMPLES_TIMEOUT 2000
  20 #define ISO14443B_DMA_BUFFER_SIZE 256
  21
  22 // PCB Block number for APDUs
  23 static uint8_t pcb_blocknum = 0;
  24
  25 //=============================================================================
  26 // An ISO 14443 Type B tag. We listen for commands from the reader, using
  27 // a UART kind of thing that's implemented in software. When we get a
  28 // frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
  29 // If it's good, then we can do something appropriate with it, and send
  30 // a response.
  31 //=============================================================================
  32
  33 //-----------------------------------------------------------------------------
  34 // Code up a string of octets at layer 2 (including CRC, we don't generate
  35 // that here) so that they can be transmitted to the reader. Doesn't transmit
  36 // them yet, just leaves them ready to send in ToSend[].
  37 //-----------------------------------------------------------------------------
  38 static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
  39 {
  40         int i;
  41
  42         ToSendReset();
  43
  44         // Transmit a burst of ones, as the initial thing that lets the
  45         // reader get phase sync. This (TR1) must be > 80/fs, per spec,
  46         // but tag that I've tried (a Paypass) exceeds that by a fair bit,
  47         // so I will too.
  48         for(i = 0; i < 20; i++) {
  49                 ToSendStuffBit(1);
  50                 ToSendStuffBit(1);
  51                 ToSendStuffBit(1);
  52                 ToSendStuffBit(1);
  53         }
  54
  55         // Send SOF.
  56         for(i = 0; i < 10; i++) {
  57                 ToSendStuffBit(0);
  58                 ToSendStuffBit(0);
  59                 ToSendStuffBit(0);
  60                 ToSendStuffBit(0);
  61         }
  62         for(i = 0; i < 2; i++) {
  63                 ToSendStuffBit(1);
  64                 ToSendStuffBit(1);
  65                 ToSendStuffBit(1);
  66                 ToSendStuffBit(1);
  67         }
  68
  69         for(i = 0; i < len; i++) {
  70                 int j;
  71                 uint8_t b = cmd[i];
  72
  73                 // Start bit
  74                 ToSendStuffBit(0);
  75                 ToSendStuffBit(0);
  76                 ToSendStuffBit(0);
  77                 ToSendStuffBit(0);
  78
  79                 // Data bits
  80                 for(j = 0; j < 8; j++) {
  81                         if(b & 1) {
  82                                 ToSendStuffBit(1);
  83                                 ToSendStuffBit(1);
  84                                 ToSendStuffBit(1);
  85                                 ToSendStuffBit(1);
  86                         } else {
  87                                 ToSendStuffBit(0);
  88                                 ToSendStuffBit(0);
  89                                 ToSendStuffBit(0);
  90                                 ToSendStuffBit(0);
  91                         }
  92                         b >>= 1;
  93                 }
  94
  95                 // Stop bit
  96                 ToSendStuffBit(1);
  97                 ToSendStuffBit(1);
  98                 ToSendStuffBit(1);
  99                 ToSendStuffBit(1);
 100         }
 101
 102         // Send EOF.
 103         for(i = 0; i < 10; i++) {
 104                 ToSendStuffBit(0);
 105                 ToSendStuffBit(0);
 106                 ToSendStuffBit(0);
 107                 ToSendStuffBit(0);
 108         }
 109         for(i = 0; i < 2; i++) {
 110                 ToSendStuffBit(1);
 111                 ToSendStuffBit(1);
 112                 ToSendStuffBit(1);
 113                 ToSendStuffBit(1);
 114         }
 115
 116         // Convert from last byte pos to length
 117         ToSendMax++;
 118 }
 119
 120 //-----------------------------------------------------------------------------
 121 // The software UART that receives commands from the reader, and its state
 122 // variables.
 123 //-----------------------------------------------------------------------------
 124 static struct {
 125         enum {
 126                 STATE_UNSYNCD,
 127                 STATE_GOT_FALLING_EDGE_OF_SOF,
 128                 STATE_AWAITING_START_BIT,
 129                 STATE_RECEIVING_DATA
 130         }       state;
 131         uint16_t    shiftReg;
 132         int     bitCnt;
 133         int     byteCnt;
 134         int     byteCntMax;
 135         int     posCnt;
 136         uint8_t   *output;
 137 } Uart;
 138
 139 /* Receive & handle a bit coming from the reader.
 140  *
 141  * This function is called 4 times per bit (every 2 subcarrier cycles).
 142  * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
 143  *
 144  * LED handling:
 145  * LED A -> ON once we have received the SOF and are expecting the rest.
 146  * LED A -> OFF once we have received EOF or are in error state or unsynced
 147  *
 148  * Returns: true if we received a EOF
 149  *          false if we are still waiting for some more
 150  */
 151 static RAMFUNC int Handle14443bUartBit(uint8_t bit)
 152 {
 153         switch(Uart.state) {
 154                 case STATE_UNSYNCD:
 155                         if(!bit) {
 156                                 // we went low, so this could be the beginning
 157                                 // of an SOF
 158                                 Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
 159                                 Uart.posCnt = 0;
 160                                 Uart.bitCnt = 0;
 161                         }
 162                         break;
 163
 164                 case STATE_GOT_FALLING_EDGE_OF_SOF:
 165                         Uart.posCnt++;
 166                         if(Uart.posCnt == 2) {  // sample every 4 1/fs in the middle of a bit
 167                                 if(bit) {
 168                                         if(Uart.bitCnt > 9) {
 169                                                 // we've seen enough consecutive
 170                                                 // zeros that it's a valid SOF
 171                                                 Uart.posCnt = 0;
 172                                                 Uart.byteCnt = 0;
 173                                                 Uart.state = STATE_AWAITING_START_BIT;
 174                                                 LED_A_ON(); // Indicate we got a valid SOF
 175                                         } else {
 176                                                 // didn't stay down long enough
 177                                                 // before going high, error
 178                                                 Uart.state = STATE_UNSYNCD;
 179                                         }
 180                                 } else {
 181                                         // do nothing, keep waiting
 182                                 }
 183                                 Uart.bitCnt++;
 184                         }
 185                         if(Uart.posCnt >= 4) Uart.posCnt = 0;
 186                         if(Uart.bitCnt > 12) {
 187                                 // Give up if we see too many zeros without
 188                                 // a one, too.
 189                                 LED_A_OFF();
 190                                 Uart.state = STATE_UNSYNCD;
 191                         }
 192                         break;
 193
 194                 case STATE_AWAITING_START_BIT:
 195                         Uart.posCnt++;
 196                         if(bit) {
 197                                 if(Uart.posCnt > 50/2) {        // max 57us between characters = 49 1/fs, max 3 etus after low phase of SOF = 24 1/fs
 198                                         // stayed high for too long between
 199                                         // characters, error
 200                                         Uart.state = STATE_UNSYNCD;
 201                                 }
 202                         } else {
 203                                 // falling edge, this starts the data byte
 204                                 Uart.posCnt = 0;
 205                                 Uart.bitCnt = 0;
 206                                 Uart.shiftReg = 0;
 207                                 Uart.state = STATE_RECEIVING_DATA;
 208                         }
 209                         break;
 210
 211                 case STATE_RECEIVING_DATA:
 212                         Uart.posCnt++;
 213                         if(Uart.posCnt == 2) {
 214                                 // time to sample a bit
 215                                 Uart.shiftReg >>= 1;
 216                                 if(bit) {
 217                                         Uart.shiftReg |= 0x200;
 218                                 }
 219                                 Uart.bitCnt++;
 220                         }
 221                         if(Uart.posCnt >= 4) {
 222                                 Uart.posCnt = 0;
 223                         }
 224                         if(Uart.bitCnt == 10) {
 225                                 if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
 226                                 {
 227                                         // this is a data byte, with correct
 228                                         // start and stop bits
 229                                         Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
 230                                         Uart.byteCnt++;
 231
 232                                         if(Uart.byteCnt >= Uart.byteCntMax) {
 233                                                 // Buffer overflowed, give up
 234                                                 LED_A_OFF();
 235                                                 Uart.state = STATE_UNSYNCD;
 236                                         } else {
 237                                                 // so get the next byte now
 238                                                 Uart.posCnt = 0;
 239                                                 Uart.state = STATE_AWAITING_START_BIT;
 240                                         }
 241                                 } else if (Uart.shiftReg == 0x000) {
 242                                         // this is an EOF byte
 243                                         LED_A_OFF(); // Finished receiving
 244                                         Uart.state = STATE_UNSYNCD;
 245                                         if (Uart.byteCnt != 0) {
 246                                                 return TRUE;
 247                                         }
 248                                 } else {
 249                                         // this is an error
 250                                         LED_A_OFF();
 251                                         Uart.state = STATE_UNSYNCD;
 252                                 }
 253                         }
 254                         break;
 255
 256                 default:
 257                         LED_A_OFF();
 258                         Uart.state = STATE_UNSYNCD;
 259                         break;
 260         }
 261
 262         return FALSE;
 263 }
 264
 265
 266 static void UartReset()
 267 {
 268         Uart.byteCntMax = MAX_FRAME_SIZE;
 269         Uart.state = STATE_UNSYNCD;
 270         Uart.byteCnt = 0;
 271         Uart.bitCnt = 0;
 272 }
 273
 274
 275 static void UartInit(uint8_t *data)
 276 {
 277         Uart.output = data;
 278         UartReset();
 279 }
 280
 281
 282 //-----------------------------------------------------------------------------
 283 // Receive a command (from the reader to us, where we are the simulated tag),
 284 // and store it in the given buffer, up to the given maximum length. Keeps
 285 // spinning, waiting for a well-framed command, until either we get one
 286 // (returns TRUE) or someone presses the pushbutton on the board (FALSE).
 287 //
 288 // Assume that we're called with the SSC (to the FPGA) and ADC path set
 289 // correctly.
 290 //-----------------------------------------------------------------------------
 291 static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
 292 {
 293         // Set FPGA mode to "simulated ISO 14443B tag", no modulation (listen
 294         // only, since we are receiving, not transmitting).
 295         // Signal field is off with the appropriate LED
 296         LED_D_OFF();
 297         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
 298
 299         // Now run a `software UART' on the stream of incoming samples.
 300         UartInit(received);
 301
 302         for(;;) {
 303                 WDT_HIT();
 304
 305                 if(BUTTON_PRESS()) return FALSE;
 306
 307                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
 308                         uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
 309                         for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
 310                                 if(Handle14443bUartBit(b & mask)) {
 311                                         *len = Uart.byteCnt;
 312                                         return TRUE;
 313                                 }
 314                         }
 315                 }
 316         }
 317
 318         return FALSE;
 319 }
 320
 321 //-----------------------------------------------------------------------------
 322 // Main loop of simulated tag: receive commands from reader, decide what
 323 // response to send, and send it.
 324 //-----------------------------------------------------------------------------
 325 void SimulateIso14443bTag(void)
 326 {
 327         // the only commands we understand is WUPB, AFI=0, Select All, N=1:
 328         static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // WUPB
 329         // ... and REQB, AFI=0, Normal Request, N=1:
 330         static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF }; // REQB
 331         // ... and HLTB
 332         static const uint8_t cmd3[] = { 0x50, 0xff, 0xff, 0xff, 0xff }; // HLTB
 333         // ... and ATTRIB
 334         static const uint8_t cmd4[] = { 0x1D, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; // ATTRIB
 335
 336         // ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
 337         // supports only 106kBit/s in both directions, max frame size = 32Bytes,
 338         // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
 339         static const uint8_t response1[] = {
 340                 0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
 341                 0x00, 0x21, 0x85, 0x5e, 0xd7
 342         };
 343         // response to HLTB and ATTRIB
 344         static const uint8_t response2[] = {0x00, 0x78, 0xF0};
 345
 346
 347         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 348
 349         clear_trace();
 350         set_tracing(TRUE);
 351
 352         const uint8_t *resp;
 353         uint8_t *respCode;
 354         uint16_t respLen, respCodeLen;
 355
 356         // allocate command receive buffer
 357         BigBuf_free();
 358         uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
 359
 360         uint16_t len;
 361         uint16_t cmdsRecvd = 0;
 362
 363         // prepare the (only one) tag answer:
 364         CodeIso14443bAsTag(response1, sizeof(response1));
 365         uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
 366         memcpy(resp1Code, ToSend, ToSendMax);
 367         uint16_t resp1CodeLen = ToSendMax;
 368
 369         // prepare the (other) tag answer:
 370         CodeIso14443bAsTag(response2, sizeof(response2));
 371         uint8_t *resp2Code = BigBuf_malloc(ToSendMax);
 372         memcpy(resp2Code, ToSend, ToSendMax);
 373         uint16_t resp2CodeLen = ToSendMax;
 374
 375         // We need to listen to the high-frequency, peak-detected path.
 376         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 377         FpgaSetupSsc();
 378
 379         cmdsRecvd = 0;
 380
 381         for(;;) {
 382
 383                 if(!GetIso14443bCommandFromReader(receivedCmd, &len)) {
 384                         Dbprintf("button pressed, received %d commands", cmdsRecvd);
 385                         break;
 386                 }
 387
 388                 if (tracing) {
 389                         uint8_t parity[MAX_PARITY_SIZE];
 390                         LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
 391                 }
 392
 393                 // Good, look at the command now.
 394                 if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
 395                         || (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0) ) {
 396                         resp = response1;
 397                         respLen = sizeof(response1);
 398                         respCode = resp1Code;
 399                         respCodeLen = resp1CodeLen;
 400                 } else if ( (len == sizeof(cmd3) && receivedCmd[0] == cmd3[0])
 401                         || (len == sizeof(cmd4) && receivedCmd[0] == cmd4[0]) ) {
 402                         resp = response2;
 403                         respLen = sizeof(response2);
 404                         respCode = resp2Code;
 405                         respCodeLen = resp2CodeLen;
 406                 } else {
 407                         Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
 408                         // And print whether the CRC fails, just for good measure
 409                         uint8_t b1, b2;
 410                         if (len >= 3){ // if crc exists
 411                                 ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
 412                                 if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
 413                                         // Not so good, try again.
 414                                         DbpString("+++CRC fail");
 415
 416                                 } else {
 417                                         DbpString("CRC passes");
 418                                 }
 419                         }
 420                         //get rid of compiler warning
 421                         respCodeLen = 0;
 422                         resp = response1;
 423                         respLen = 0;
 424                         respCode = resp1Code;
 425                         //don't crash at new command just wait and see if reader will send other new cmds.
 426                         //break;
 427                 }
 428
 429                 cmdsRecvd++;
 430
 431                 if(cmdsRecvd > 0x30) {
 432                         DbpString("many commands later...");
 433                         break;
 434                 }
 435
 436                 if(respCodeLen <= 0) continue;
 437
 438                 // Modulate BPSK
 439                 // Signal field is off with the appropriate LED
 440                 LED_D_OFF();
 441                 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
 442                 AT91C_BASE_SSC->SSC_THR = 0xff;
 443                 FpgaSetupSsc();
 444
 445                 // Transmit the response.
 446                 uint16_t i = 0;
 447                 for(;;) {
 448                         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
 449                                 uint8_t b = respCode[i];
 450
 451                                 AT91C_BASE_SSC->SSC_THR = b;
 452
 453                                 i++;
 454                                 if(i > respCodeLen) {
 455                                         break;
 456                                 }
 457                         }
 458                         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
 459                                 volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
 460                                 (void)b;
 461                         }
 462                 }
 463
 464                 // trace the response:
 465                 if (tracing) {
 466                         uint8_t parity[MAX_PARITY_SIZE];
 467                         LogTrace(resp, respLen, 0, 0, parity, FALSE);
 468                 }
 469
 470         }
 471 }
 472
 473 //=============================================================================
 474 // An ISO 14443 Type B reader. We take layer two commands, code them
 475 // appropriately, and then send them to the tag. We then listen for the
 476 // tag's response, which we leave in the buffer to be demodulated on the
 477 // PC side.
 478 //=============================================================================
 479
 480 static struct {
 481         enum {
 482                 DEMOD_UNSYNCD,
 483                 DEMOD_PHASE_REF_TRAINING,
 484                 DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
 485                 DEMOD_GOT_FALLING_EDGE_OF_SOF,
 486                 DEMOD_AWAITING_START_BIT,
 487                 DEMOD_RECEIVING_DATA
 488         }       state;
 489         int     bitCount;
 490         int     posCount;
 491         int     thisBit;
 492 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
 493         int     metric;
 494         int     metricN;
 495 */
 496         uint16_t    shiftReg;
 497         uint8_t   *output;
 498         int     len;
 499         int     sumI;
 500         int     sumQ;
 501 } Demod;
 502
 503 /*
 504  * Handles reception of a bit from the tag
 505  *
 506  * This function is called 2 times per bit (every 4 subcarrier cycles).
 507  * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 4,72us
 508  *
 509  * LED handling:
 510  * LED C -> ON once we have received the SOF and are expecting the rest.
 511  * LED C -> OFF once we have received EOF or are unsynced
 512  *
 513  * Returns: true if we received a EOF
 514  *          false if we are still waiting for some more
 515  *
 516  */
 517 static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 518 {
 519         int v;
 520
 521 // The soft decision on the bit uses an estimate of just the
 522 // quadrant of the reference angle, not the exact angle.
 523 #define MAKE_SOFT_DECISION() { \
 524                 if(Demod.sumI > 0) { \
 525                         v = ci; \
 526                 } else { \
 527                         v = -ci; \
 528                 } \
 529                 if(Demod.sumQ > 0) { \
 530                         v += cq; \
 531                 } else { \
 532                         v -= cq; \
 533                 } \
 534         }
 535
 536 #define SUBCARRIER_DETECT_THRESHOLD     8
 537
 538 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by abs(ci) + abs(cq)
 539 /* #define CHECK_FOR_SUBCARRIER() { \
 540                 v = ci; \
 541                 if(v < 0) v = -v; \
 542                 if(cq > 0) { \
 543                         v += cq; \
 544                 } else { \
 545                         v -= cq; \
 546                 } \
 547         }
 548  */
 549 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
 550 #define CHECK_FOR_SUBCARRIER() { \
 551                 if(ci < 0) { \
 552                         if(cq < 0) { /* ci < 0, cq < 0 */ \
 553                                 if (cq < ci) { \
 554                                         v = -cq - (ci >> 1); \
 555                                 } else { \
 556                                         v = -ci - (cq >> 1); \
 557                                 } \
 558                         } else {        /* ci < 0, cq >= 0 */ \
 559                                 if (cq < -ci) { \
 560                                         v = -ci + (cq >> 1); \
 561                                 } else { \
 562                                         v = cq - (ci >> 1); \
 563                                 } \
 564                         } \
 565                 } else { \
 566                         if(cq < 0) { /* ci >= 0, cq < 0 */ \
 567                                 if (-cq < ci) { \
 568                                         v = ci - (cq >> 1); \
 569                                 } else { \
 570                                         v = -cq + (ci >> 1); \
 571                                 } \
 572                         } else {        /* ci >= 0, cq >= 0 */ \
 573                                 if (cq < ci) { \
 574                                         v = ci + (cq >> 1); \
 575                                 } else { \
 576                                         v = cq + (ci >> 1); \
 577                                 } \
 578                         } \
 579                 } \
 580         }
 581
 582         switch(Demod.state) {
 583                 case DEMOD_UNSYNCD:
 584                         CHECK_FOR_SUBCARRIER();
 585                         if(v > SUBCARRIER_DETECT_THRESHOLD) {   // subcarrier detected
 586                                 Demod.state = DEMOD_PHASE_REF_TRAINING;
 587                                 Demod.sumI = ci;
 588                                 Demod.sumQ = cq;
 589                                 Demod.posCount = 1;
 590                                 }
 591                         break;
 592
 593                 case DEMOD_PHASE_REF_TRAINING:
 594                         if(Demod.posCount < 8) {
 595                                 CHECK_FOR_SUBCARRIER();
 596                                 if (v > SUBCARRIER_DETECT_THRESHOLD) {
 597                                         // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
 598                                         // note: synchronization time > 80 1/fs
 599                                         Demod.sumI += ci;
 600                                         Demod.sumQ += cq;
 601                                         Demod.posCount++;
 602                                 } else {                // subcarrier lost
 603                                         Demod.state = DEMOD_UNSYNCD;
 604                                 }
 605                         } else {
 606                                 Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
 607                         }
 608                         break;
 609
 610                 case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
 611                         MAKE_SOFT_DECISION();
 612                         if(v < 0) {     // logic '0' detected
 613                                 Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
 614                                 Demod.posCount = 0;     // start of SOF sequence
 615                         } else {
 616                                 if(Demod.posCount > 200/4) {    // maximum length of TR1 = 200 1/fs
 617                                         Demod.state = DEMOD_UNSYNCD;
 618                                 }
 619                         }
 620                         Demod.posCount++;
 621                         break;
 622
 623                 case DEMOD_GOT_FALLING_EDGE_OF_SOF:
 624                         Demod.posCount++;
 625                         MAKE_SOFT_DECISION();
 626                         if(v > 0) {
 627                                 if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
 628                                         Demod.state = DEMOD_UNSYNCD;
 629                                 } else {
 630                                         LED_C_ON(); // Got SOF
 631                                         Demod.state = DEMOD_AWAITING_START_BIT;
 632                                         Demod.posCount = 0;
 633                                         Demod.len = 0;
 634 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
 635                                         Demod.metricN = 0;
 636                                         Demod.metric = 0;
 637 */
 638                                 }
 639                         } else {
 640                                 if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
 641                                         Demod.state = DEMOD_UNSYNCD;
 642                                         LED_C_OFF();
 643                                 }
 644                         }
 645                         break;
 646
 647                 case DEMOD_AWAITING_START_BIT:
 648                         Demod.posCount++;
 649                         MAKE_SOFT_DECISION();
 650                         if(v > 0) {
 651                                 if(Demod.posCount > 3*2) {              // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs
 652                                         Demod.state = DEMOD_UNSYNCD;
 653                                         LED_C_OFF();
 654                                 }
 655                         } else {                                                        // start bit detected
 656                                 Demod.bitCount = 0;
 657                                 Demod.posCount = 1;                             // this was the first half
 658                                 Demod.thisBit = v;
 659                                 Demod.shiftReg = 0;
 660                                 Demod.state = DEMOD_RECEIVING_DATA;
 661                         }
 662                         break;
 663
 664                 case DEMOD_RECEIVING_DATA:
 665                         MAKE_SOFT_DECISION();
 666                         if(Demod.posCount == 0) {                       // first half of bit
 667                                 Demod.thisBit = v;
 668                                 Demod.posCount = 1;
 669                         } else {                                                        // second half of bit
 670                                 Demod.thisBit += v;
 671
 672 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
 673                                 if(Demod.thisBit > 0) {
 674                                         Demod.metric += Demod.thisBit;
 675                                 } else {
 676                                         Demod.metric -= Demod.thisBit;
 677                                 }
 678                                 (Demod.metricN)++;
 679 */
 680
 681                                 Demod.shiftReg >>= 1;
 682                                 if(Demod.thisBit > 0) { // logic '1'
 683                                         Demod.shiftReg |= 0x200;
 684                                 }
 685
 686                                 Demod.bitCount++;
 687                                 if(Demod.bitCount == 10) {
 688                                         uint16_t s = Demod.shiftReg;
 689                                         if((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'
 690                                                 uint8_t b = (s >> 1);
 691                                                 Demod.output[Demod.len] = b;
 692                                                 Demod.len++;
 693                                                 Demod.state = DEMOD_AWAITING_START_BIT;
 694                                         } else {
 695                                                 Demod.state = DEMOD_UNSYNCD;
 696                                                 LED_C_OFF();
 697                                                 if(s == 0x000) {
 698                                                         // This is EOF (start, stop and all data bits == '0'
 699                                                         return TRUE;
 700                                                 }
 701                                         }
 702                                 }
 703                                 Demod.posCount = 0;
 704                         }
 705                         break;
 706
 707                 default:
 708                         Demod.state = DEMOD_UNSYNCD;
 709                         LED_C_OFF();
 710                         break;
 711         }
 712
 713         return FALSE;
 714 }
 715
 716
 717 static void DemodReset()
 718 {
 719         // Clear out the state of the "UART" that receives from the tag.
 720         Demod.len = 0;
 721         Demod.state = DEMOD_UNSYNCD;
 722         Demod.posCount = 0;
 723         memset(Demod.output, 0x00, MAX_FRAME_SIZE);
 724 }
 725
 726
 727 static void DemodInit(uint8_t *data)
 728 {
 729         Demod.output = data;
 730         DemodReset();
 731 }
 732
 733
 734 /*
 735  *  Demodulate the samples we received from the tag, also log to tracebuffer
 736  *  quiet: set to 'TRUE' to disable debug output
 737  */
 738 static void GetSamplesFor14443bDemod(int n, bool quiet)
 739 {
 740         int max = 0;
 741         bool gotFrame = FALSE;
 742         int lastRxCounter, ci, cq, samples = 0;
 743
 744         // Allocate memory from BigBuf for some buffers
 745         // free all previous allocations first
 746         BigBuf_free();
 747
 748         // The response (tag -> reader) that we're receiving.
 749         uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
 750
 751         // The DMA buffer, used to stream samples from the FPGA
 752         int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
 753
 754         // Set up the demodulator for tag -> reader responses.
 755         DemodInit(receivedResponse);
 756
 757         // Setup and start DMA.
 758         FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
 759
 760         int8_t *upTo = dmaBuf;
 761         lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
 762
 763         // Signal field is ON with the appropriate LED:
 764         LED_D_ON();
 765         // And put the FPGA in the appropriate mode
 766         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
 767
 768         for(;;) {
 769                 int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
 770                 if(behindBy > max) max = behindBy;
 771
 772                 while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1)) > 2) {
 773                         ci = upTo[0];
 774                         cq = upTo[1];
 775                         upTo += 2;
 776                         if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
 777                                 upTo = dmaBuf;
 778                                 AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
 779                                 AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
 780                         }
 781                         lastRxCounter -= 2;
 782                         if(lastRxCounter <= 0) {
 783                                 lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
 784                         }
 785
 786                         samples += 2;
 787
 788                         if(Handle14443bSamplesDemod(ci, cq)) {
 789                                 gotFrame = TRUE;
 790                                 break;
 791                         }
 792                 }
 793
 794                 if(samples > n || gotFrame) {
 795                         break;
 796                 }
 797         }
 798
 799         AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
 800
 801         if (!quiet) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.len = %d, Demod.sumI = %d, Demod.sumQ = %d", max, samples, gotFrame, Demod.len, Demod.sumI, Demod.sumQ);
 802         //Tracing
 803         if (tracing && Demod.len > 0) {
 804                 uint8_t parity[MAX_PARITY_SIZE];
 805                 LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
 806         }
 807 }
 808
 809
 810 //-----------------------------------------------------------------------------
 811 // Transmit the command (to the tag) that was placed in ToSend[].
 812 //-----------------------------------------------------------------------------
 813 static void TransmitFor14443b(void)
 814 {
 815         int c;
 816
 817         FpgaSetupSsc();
 818
 819         while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
 820                 AT91C_BASE_SSC->SSC_THR = 0xff;
 821         }
 822
 823         // Signal field is ON with the appropriate Red LED
 824         LED_D_ON();
 825         // Signal we are transmitting with the Green LED
 826         LED_B_ON();
 827         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
 828
 829         for(c = 0; c < 10;) {
 830                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
 831                         AT91C_BASE_SSC->SSC_THR = 0xff;
 832                         c++;
 833                 }
 834                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
 835                         volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
 836                         (void)r;
 837                 }
 838                 WDT_HIT();
 839         }
 840
 841         c = 0;
 842         for(;;) {
 843                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
 844                         AT91C_BASE_SSC->SSC_THR = ToSend[c];
 845                         c++;
 846                         if(c >= ToSendMax) {
 847                                 break;
 848                         }
 849                 }
 850                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
 851                         volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
 852                         (void)r;
 853                 }
 854                 WDT_HIT();
 855         }
 856         LED_B_OFF(); // Finished sending
 857 }
 858
 859
 860 //-----------------------------------------------------------------------------
 861 // Code a layer 2 command (string of octets, including CRC) into ToSend[],
 862 // so that it is ready to transmit to the tag using TransmitFor14443b().
 863 //-----------------------------------------------------------------------------
 864 static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 865 {
 866         int i, j;
 867         uint8_t b;
 868
 869         ToSendReset();
 870
 871         // Establish initial reference level
 872         for(i = 0; i < 40; i++) {
 873                 ToSendStuffBit(1);
 874         }
 875         // Send SOF
 876         for(i = 0; i < 10; i++) {
 877                 ToSendStuffBit(0);
 878         }
 879
 880         for(i = 0; i < len; i++) {
 881                 // Stop bits/EGT
 882                 ToSendStuffBit(1);
 883                 ToSendStuffBit(1);
 884                 // Start bit
 885                 ToSendStuffBit(0);
 886                 // Data bits
 887                 b = cmd[i];
 888                 for(j = 0; j < 8; j++) {
 889                         if(b & 1) {
 890                                 ToSendStuffBit(1);
 891                         } else {
 892                                 ToSendStuffBit(0);
 893                         }
 894                         b >>= 1;
 895                 }
 896         }
 897         // Send EOF
 898         ToSendStuffBit(1);
 899         for(i = 0; i < 10; i++) {
 900                 ToSendStuffBit(0);
 901         }
 902         for(i = 0; i < 8; i++) {
 903                 ToSendStuffBit(1);
 904         }
 905
 906         // And then a little more, to make sure that the last character makes
 907         // it out before we switch to rx mode.
 908         for(i = 0; i < 24; i++) {
 909                 ToSendStuffBit(1);
 910         }
 911
 912         // Convert from last character reference to length
 913         ToSendMax++;
 914 }
 915
 916
 917 /**
 918   Convenience function to encode, transmit and trace iso 14443b comms
 919   **/
 920 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 921 {
 922         CodeIso14443bAsReader(cmd, len);
 923         TransmitFor14443b();
 924         if (tracing) {
 925                 uint8_t parity[MAX_PARITY_SIZE];
 926                 LogTrace(cmd,len, 0, 0, parity, TRUE);
 927         }
 928 }
 929
 930 /* Sends an APDU to the tag
 931  * TODO: check CRC and preamble
 932  */
 933 int iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *response)
 934 {
 935         uint8_t message_frame[message_length + 4];
 936         // PCB
 937         message_frame[0] = 0x0A | pcb_blocknum;
 938         pcb_blocknum ^= 1;
 939         // CID
 940         message_frame[1] = 0;
 941         // INF
 942         memcpy(message_frame + 2, message, message_length);
 943         // EDC (CRC)
 944         ComputeCrc14443(CRC_14443_B, message_frame, message_length + 2, &message_frame[message_length + 2], &message_frame[message_length + 3]);
 945         // send
 946         CodeAndTransmit14443bAsReader(message_frame, message_length + 4);
 947         // get response
 948         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT*100, TRUE);
 949         if(Demod.len < 3)
 950         {
 951                 return 0;
 952         }
 953         // TODO: Check CRC
 954         // copy response contents
 955         if(response != NULL)
 956         {
 957                 memcpy(response, Demod.output, Demod.len);
 958         }
 959         return Demod.len;
 960 }
 961
 962 /* Perform the ISO 14443 B Card Selection procedure
 963  * Currently does NOT do any collision handling.
 964  * It expects 0-1 cards in the device's range.
 965  * TODO: Support multiple cards (perform anticollision)
 966  * TODO: Verify CRC checksums
 967  */
 968 int iso14443b_select_card()
 969 {
 970         // WUPB command (including CRC)
 971         // Note: WUPB wakes up all tags, REQB doesn't wake up tags in HALT state
 972         static const uint8_t wupb[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
 973         // ATTRIB command (with space for CRC)
 974         uint8_t attrib[] = { 0x1D, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00};
 975
 976         // first, wake up the tag
 977         CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
 978         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 979         // ATQB too short?
 980         if (Demod.len < 14)
 981         {
 982                 return 2;
 983         }
 984
 985     // select the tag
 986     // copy the PUPI to ATTRIB
 987     memcpy(attrib + 1, Demod.output + 1, 4);
 988     /* copy the protocol info from ATQB (Protocol Info -> Protocol_Type) into
 989     ATTRIB (Param 3) */
 990     attrib[7] = Demod.output[10] & 0x0F;
 991     ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
 992     CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));
 993     GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 994     // Answer to ATTRIB too short?
 995     if(Demod.len < 3)
 996         {
 997                 return 2;
 998         }
 999         // reset PCB block number
1000         pcb_blocknum = 0;
1001         return 1;
1002 }
1003
1004 // Set up ISO 14443 Type B communication (similar to iso14443a_setup)
1005 void iso14443b_setup() {
1006         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1007         // Set up the synchronous serial port
1008         FpgaSetupSsc();
1009         // connect Demodulated Signal to ADC:
1010         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1011
1012         // Signal field is on with the appropriate LED
1013     LED_D_ON();
1014         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
1015
1016         // Start the timer
1017         StartCountSspClk();
1018
1019         DemodReset();
1020         UartReset();
1021 }
1022
1023 //-----------------------------------------------------------------------------
1024 // Read a SRI512 ISO 14443B tag.
1025 //
1026 // SRI512 tags are just simple memory tags, here we're looking at making a dump
1027 // of the contents of the memory. No anticollision algorithm is done, we assume
1028 // we have a single tag in the field.
1029 //
1030 // I tried to be systematic and check every answer of the tag, every CRC, etc...
1031 //-----------------------------------------------------------------------------
1032 void ReadSTMemoryIso14443b(uint32_t dwLast)
1033 {
1034         uint8_t i = 0x00;
1035
1036         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1037         // Make sure that we start from off, since the tags are stateful;
1038         // confusing things will happen if we don't reset them between reads.
1039         LED_D_OFF();
1040         FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1041         SpinDelay(200);
1042
1043         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1044         FpgaSetupSsc();
1045
1046         // Now give it time to spin up.
1047         // Signal field is on with the appropriate LED
1048         LED_D_ON();
1049         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
1050         SpinDelay(200);
1051
1052         clear_trace();
1053         set_tracing(TRUE);
1054
1055         // First command: wake up the tag using the INITIATE command
1056         uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};
1057         CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
1058         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1059
1060         if (Demod.len == 0) {
1061                 DbpString("No response from tag");
1062                 return;
1063         } else {
1064                 Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
1065                                 Demod.output[0], Demod.output[1], Demod.output[2]);
1066         }
1067
1068         // There is a response, SELECT the uid
1069         DbpString("Now SELECT tag:");
1070         cmd1[0] = 0x0E; // 0x0E is SELECT
1071         cmd1[1] = Demod.output[0];
1072         ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
1073         CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
1074         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1075         if (Demod.len != 3) {
1076                 Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
1077                 return;
1078         }
1079         // Check the CRC of the answer:
1080         ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
1081         if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
1082                 DbpString("CRC Error reading select response.");
1083                 return;
1084         }
1085         // Check response from the tag: should be the same UID as the command we just sent:
1086         if (cmd1[1] != Demod.output[0]) {
1087                 Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
1088                 return;
1089         }
1090
1091         // Tag is now selected,
1092         // First get the tag's UID:
1093         cmd1[0] = 0x0B;
1094         ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
1095         CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
1096         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1097         if (Demod.len != 10) {
1098                 Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
1099                 return;
1100         }
1101         // The check the CRC of the answer (use cmd1 as temporary variable):
1102         ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
1103         if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
1104                 Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
1105                                 (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
1106                 // Do not return;, let's go on... (we should retry, maybe ?)
1107         }
1108         Dbprintf("Tag UID (64 bits): %08x %08x",
1109                         (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
1110                         (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
1111
1112         // Now loop to read all 16 blocks, address from 0 to last block
1113         Dbprintf("Tag memory dump, block 0 to %d", dwLast);
1114         cmd1[0] = 0x08;
1115         i = 0x00;
1116         dwLast++;
1117         for (;;) {
1118                 if (i == dwLast) {
1119                         DbpString("System area block (0xff):");
1120                         i = 0xff;
1121                 }
1122                 cmd1[1] = i;
1123                 ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
1124                 CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
1125                 GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1126                 if (Demod.len != 6) { // Check if we got an answer from the tag
1127                         DbpString("Expected 6 bytes from tag, got less...");
1128                         return;
1129                 }
1130                 // The check the CRC of the answer (use cmd1 as temporary variable):
1131                 ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
1132                 if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
1133                         Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
1134                                         (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
1135                         // Do not return;, let's go on... (we should retry, maybe ?)
1136                 }
1137                 // Now print out the memory location:
1138                 Dbprintf("Address=%02x, Contents=%08x, CRC=%04x", i,
1139                                 (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
1140                                 (Demod.output[4]<<8)+Demod.output[5]);
1141                 if (i == 0xff) {
1142                         break;
1143                 }
1144                 i++;
1145         }
1146 }
1147
1148
1149 //=============================================================================
1150 // Finally, the `sniffer' combines elements from both the reader and
1151 // simulated tag, to show both sides of the conversation.
1152 //=============================================================================
1153
1154 //-----------------------------------------------------------------------------
1155 // Record the sequence of commands sent by the reader to the tag, with
1156 // triggering so that we start recording at the point that the tag is moved
1157 // near the reader.
1158 //-----------------------------------------------------------------------------
1159 /*
1160  * Memory usage for this function, (within BigBuf)
1161  * Last Received command (reader->tag) - MAX_FRAME_SIZE
1162  * Last Received command (tag->reader) - MAX_FRAME_SIZE
1163  * DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
1164  * Demodulated samples received - all the rest
1165  */
1166 void RAMFUNC SnoopIso14443b(void)
1167 {
1168         // We won't start recording the frames that we acquire until we trigger;
1169         // a good trigger condition to get started is probably when we see a
1170         // response from the tag.
1171         int triggered = TRUE;                   // TODO: set and evaluate trigger condition
1172
1173         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1174         BigBuf_free();
1175
1176         clear_trace();
1177         set_tracing(TRUE);
1178
1179         // The DMA buffer, used to stream samples from the FPGA
1180         int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
1181         int lastRxCounter;
1182         int8_t *upTo;
1183         int ci, cq;
1184         int maxBehindBy = 0;
1185
1186         // Count of samples received so far, so that we can include timing
1187         // information in the trace buffer.
1188         int samples = 0;
1189
1190         DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
1191         UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
1192
1193         // Print some debug information about the buffer sizes
1194         Dbprintf("Snooping buffers initialized:");
1195         Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
1196         Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
1197         Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
1198         Dbprintf("  DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);
1199
1200         // Signal field is off, no reader signal, no tag signal
1201         LEDsoff();
1202
1203         // And put the FPGA in the appropriate mode
1204         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
1205         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1206
1207         // Setup for the DMA.
1208         FpgaSetupSsc();
1209         upTo = dmaBuf;
1210         lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
1211         FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
1212         uint8_t parity[MAX_PARITY_SIZE];
1213
1214         bool TagIsActive = FALSE;
1215         bool ReaderIsActive = FALSE;
1216
1217         // And now we loop, receiving samples.
1218         for(;;) {
1219                 int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
1220                                                                 (ISO14443B_DMA_BUFFER_SIZE-1);
1221                 if(behindBy > maxBehindBy) {
1222                         maxBehindBy = behindBy;
1223                 }
1224
1225                 if(behindBy < 2) continue;
1226
1227                 ci = upTo[0];
1228                 cq = upTo[1];
1229                 upTo += 2;
1230                 lastRxCounter -= 2;
1231                 if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
1232                         upTo = dmaBuf;
1233                         lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
1234                         AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
1235                         AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
1236                         WDT_HIT();
1237                         if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
1238                                 Dbprintf("blew circular buffer! behindBy=%d", behindBy);
1239                                 break;
1240                         }
1241                         if(!tracing) {
1242                                 DbpString("Reached trace limit");
1243                                 break;
1244                         }
1245                         if(BUTTON_PRESS()) {
1246                                 DbpString("cancelled");
1247                                 break;
1248                         }
1249                 }
1250
1251                 samples += 2;
1252
1253                 if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
1254                         if(Handle14443bUartBit(ci & 0x01)) {
1255                                 if(triggered && tracing) {
1256                                         LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
1257                                 }
1258                                 /* And ready to receive another command. */
1259                                 UartReset();
1260                                 /* And also reset the demod code, which might have been */
1261                                 /* false-triggered by the commands from the reader. */
1262                                 DemodReset();
1263                         }
1264                         if(Handle14443bUartBit(cq & 0x01)) {
1265                                 if(triggered && tracing) {
1266                                         LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
1267                                 }
1268                                 /* And ready to receive another command. */
1269                                 UartReset();
1270                                 /* And also reset the demod code, which might have been */
1271                                 /* false-triggered by the commands from the reader. */
1272                                 DemodReset();
1273                         }
1274                         ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
1275                 }
1276
1277                 if(!ReaderIsActive) {                                           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
1278                         if(Handle14443bSamplesDemod(ci | 0x01, cq | 0x01)) {
1279
1280                                 //Use samples as a time measurement
1281                                 if(tracing)
1282                                 {
1283                                         uint8_t parity[MAX_PARITY_SIZE];
1284                                         LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
1285                                 }
1286                                 triggered = TRUE;
1287
1288                                 // And ready to receive another response.
1289                                 DemodReset();
1290                         }
1291                         TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
1292                 }
1293
1294         }
1295
1296         FpgaDisableSscDma();
1297         LEDsoff();
1298         AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
1299         DbpString("Snoop statistics:");
1300         Dbprintf("  Max behind by: %i", maxBehindBy);
1301         Dbprintf("  Uart State: %x", Uart.state);
1302         Dbprintf("  Uart ByteCnt: %i", Uart.byteCnt);
1303         Dbprintf("  Uart ByteCntMax: %i", Uart.byteCntMax);
1304         Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
1305 }
1306
1307
1308 /*
1309  * Send raw command to tag ISO14443B
1310  * @Input
1311  * datalen     len of buffer data
1312  * recv        bool when true wait for data from tag and send to client
1313  * powerfield  bool leave the field on when true
1314  * data        buffer with byte to send
1315  *
1316  * @Output
1317  * none
1318  *
1319  */
1320 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
1321 {
1322         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
1323         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
1324         FpgaSetupSsc();
1325
1326         if (datalen){
1327                 set_tracing(TRUE);
1328
1329                 CodeAndTransmit14443bAsReader(data, datalen);
1330
1331                 if(recv) {
1332                         GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
1333                         uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
1334                         cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
1335                 }
1336         }
1337
1338         if(!powerfield) {
1339                 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
1340                 LED_D_OFF();
1341         }
1342 }
1343