Merge pull request #114 from pwpiwi/iso14443b_fix
authorpwpiwi <pwpiwi@users.noreply.github.com>
Tue, 23 Jun 2015 05:14:52 +0000 (07:14 +0200)
committerpwpiwi <pwpiwi@users.noreply.github.com>
Tue, 23 Jun 2015 05:14:52 +0000 (07:14 +0200)
fixing iso14443b (issue #103): fix bug introduced during Bigbuf rework

13 files changed:
armsrc/Makefile
armsrc/appmain.c
armsrc/apps.h
armsrc/iso14443.c [deleted file]
armsrc/iso14443b.c [new file with mode: 0644]
client/cmdhf.c
client/cmdhf14b.c
client/hid-flasher/usb_cmd.h
client/lualibs/commands.lua
fpga/fpga_hf.bit
fpga/fpga_hf.v
fpga/hi_read_rx_xcorr.v
include/usb_cmd.h

index 899b03075af35d1d51a0d61f318d1028959ae09f..502ab958c8aa3f6b3ab2ea35f3823122bcf4294c 100644 (file)
@@ -17,7 +17,7 @@ APP_CFLAGS    = -DWITH_LF -DWITH_ISO15693 -DWITH_ISO14443a -DWITH_ISO14443b -DWITH_
 SRC_LF = lfops.c hitag2.c lfsampling.c
 SRC_ISO15693 = iso15693.c iso15693tools.c
 SRC_ISO14443a = epa.c iso14443a.c mifareutil.c mifarecmd.c mifaresniff.c
-SRC_ISO14443b = iso14443.c
+SRC_ISO14443b = iso14443b.c
 SRC_CRAPTO1 = crapto1.c crypto1.c des.c aes.c 
 SRC_CRC = iso14443crc.c crc.c crc16.c crc32.c 
 
index c226c726398dd822b85f287aadb8d47be421e7e3..fb3c0f18ce22a5ccfdbc68599da9091ebf9a398f 100644 (file)
@@ -250,55 +250,6 @@ void MeasureAntennaTuningHf(void)
 }
 
 
-void SimulateTagHfListen(void)
-{
-       // ToDo: historically this used the free buffer, which was 2744 Bytes long. 
-       // There might be a better size to be defined:
-       #define HF_14B_SNOOP_BUFFER_SIZE 2744
-       uint8_t *dest = BigBuf_malloc(HF_14B_SNOOP_BUFFER_SIZE);
-       uint8_t v = 0;
-       int i;
-       int p = 0;
-
-       // We're using this mode just so that I can test it out; the simulated
-       // tag mode would work just as well and be simpler.
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
-
-       // We need to listen to the high-frequency, peak-detected path.
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-
-       FpgaSetupSsc();
-
-       i = 0;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0xff;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       uint8_t r = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-
-                       v <<= 1;
-                       if(r & 1) {
-                               v |= 1;
-                       }
-                       p++;
-
-                       if(p >= 8) {
-                               dest[i] = v;
-                               v = 0;
-                               p = 0;
-                               i++;
-
-                               if(i >= HF_14B_SNOOP_BUFFER_SIZE) {
-                                       break;
-                               }
-                       }
-               }
-       }
-       DbpString("simulate tag (now type bitsamples)");
-}
-
 void ReadMem(int addr)
 {
        const uint8_t *data = ((uint8_t *)addr);
@@ -782,20 +733,17 @@ void UsbPacketReceived(uint8_t *packet, int len)
 #endif
 
 #ifdef WITH_ISO14443b
-               case CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_14443:
-                       AcquireRawAdcSamplesIso14443(c->arg[0]);
-                       break;
                case CMD_READ_SRI512_TAG:
-                       ReadSTMemoryIso14443(0x0F);
+                       ReadSTMemoryIso14443b(0x0F);
                        break;
                case CMD_READ_SRIX4K_TAG:
-                       ReadSTMemoryIso14443(0x7F);
+                       ReadSTMemoryIso14443b(0x7F);
                        break;
-               case CMD_SNOOP_ISO_14443:
-                       SnoopIso14443();
+               case CMD_SNOOP_ISO_14443B:
+                       SnoopIso14443b();
                        break;
-               case CMD_SIMULATE_TAG_ISO_14443:
-                       SimulateIso14443Tag();
+               case CMD_SIMULATE_TAG_ISO_14443B:
+                       SimulateIso14443bTag();
                        break;
                case CMD_ISO_14443B_COMMAND:
                        SendRawCommand14443B(c->arg[0],c->arg[1],c->arg[2],c->d.asBytes);
@@ -911,10 +859,6 @@ void UsbPacketReceived(uint8_t *packet, int len)
                        break;
 #endif
 
-               case CMD_SIMULATE_TAG_HF_LISTEN:
-                       SimulateTagHfListen();
-                       break;
-
                case CMD_BUFF_CLEAR:
                        BigBuf_Clear();
                        break;
index 6360b664b82f49528570d2ec00b1f88a93cbd258..542f3a650d92f87f09ee712476e0bc45e1590069 100644 (file)
@@ -141,10 +141,10 @@ void EM4xReadWord(uint8_t Address, uint32_t Pwd, uint8_t PwdMode);
 void EM4xWriteWord(uint32_t Data, uint8_t Address, uint32_t Pwd, uint8_t PwdMode);
 
 /// iso14443.h
-void SimulateIso14443Tag(void);
-void AcquireRawAdcSamplesIso14443(uint32_t parameter);
-void ReadSTMemoryIso14443(uint32_t);
-void RAMFUNC SnoopIso14443(void);
+void SimulateIso14443bTag(void);
+void AcquireRawAdcSamplesIso14443b(uint32_t parameter);
+void ReadSTMemoryIso14443b(uint32_t);
+void RAMFUNC SnoopIso14443b(void);
 void SendRawCommand14443B(uint32_t, uint32_t, uint8_t, uint8_t[]);
 
 /// iso14443a.h
diff --git a/armsrc/iso14443.c b/armsrc/iso14443.c
deleted file mode 100644 (file)
index c202e31..0000000
+++ /dev/null
@@ -1,1245 +0,0 @@
-//-----------------------------------------------------------------------------
-// Jonathan Westhues, split Nov 2006
-//
-// This code is licensed to you under the terms of the GNU GPL, version 2 or,
-// at your option, any later version. See the LICENSE.txt file for the text of
-// the license.
-//-----------------------------------------------------------------------------
-// Routines to support ISO 14443. This includes both the reader software and
-// the `fake tag' modes. At the moment only the Type B modulation is
-// supported.
-//-----------------------------------------------------------------------------
-
-#include "proxmark3.h"
-#include "apps.h"
-#include "util.h"
-#include "string.h"
-
-#include "iso14443crc.h"
-
-//static void GetSamplesFor14443(int weTx, int n);
-
-/*#define DEMOD_TRACE_SIZE 4096
-#define READER_TAG_BUFFER_SIZE 2048
-#define TAG_READER_BUFFER_SIZE 2048
-#define DEMOD_DMA_BUFFER_SIZE 1024
-*/
-
-#define RECEIVE_SAMPLES_TIMEOUT 2000
-
-//=============================================================================
-// An ISO 14443 Type B tag. We listen for commands from the reader, using
-// a UART kind of thing that's implemented in software. When we get a
-// frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
-// If it's good, then we can do something appropriate with it, and send
-// a response.
-//=============================================================================
-
-//-----------------------------------------------------------------------------
-// Code up a string of octets at layer 2 (including CRC, we don't generate
-// that here) so that they can be transmitted to the reader. Doesn't transmit
-// them yet, just leaves them ready to send in ToSend[].
-//-----------------------------------------------------------------------------
-static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
-{
-       int i;
-
-       ToSendReset();
-
-       // Transmit a burst of ones, as the initial thing that lets the
-       // reader get phase sync. This (TR1) must be > 80/fs, per spec,
-       // but tag that I've tried (a Paypass) exceeds that by a fair bit,
-       // so I will too.
-       for(i = 0; i < 20; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
-
-       // Send SOF.
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 2; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
-
-       for(i = 0; i < len; i++) {
-               int j;
-               uint8_t b = cmd[i];
-
-               // Start bit
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-
-               // Data bits
-               for(j = 0; j < 8; j++) {
-                       if(b & 1) {
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                       } else {
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                       }
-                       b >>= 1;
-               }
-
-               // Stop bit
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
-
-       // Send SOF.
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
-
-       // Convert from last byte pos to length
-       ToSendMax++;
-
-       // Add a few more for slop
-       ToSendMax += 2;
-}
-
-//-----------------------------------------------------------------------------
-// The software UART that receives commands from the reader, and its state
-// variables.
-//-----------------------------------------------------------------------------
-static struct {
-       enum {
-               STATE_UNSYNCD,
-               STATE_GOT_FALLING_EDGE_OF_SOF,
-               STATE_AWAITING_START_BIT,
-               STATE_RECEIVING_DATA,
-               STATE_ERROR_WAIT
-       }       state;
-       uint16_t    shiftReg;
-       int     bitCnt;
-       int     byteCnt;
-       int     byteCntMax;
-       int     posCnt;
-       uint8_t   *output;
-} Uart;
-
-/* Receive & handle a bit coming from the reader.
- *
- * LED handling:
- * LED A -> ON once we have received the SOF and are expecting the rest.
- * LED A -> OFF once we have received EOF or are in error state or unsynced
- *
- * Returns: true if we received a EOF
- *          false if we are still waiting for some more
- */
-static int Handle14443UartBit(int bit)
-{
-       switch(Uart.state) {
-               case STATE_UNSYNCD:
-                       LED_A_OFF();
-                       if(!bit) {
-                               // we went low, so this could be the beginning
-                               // of an SOF
-                               Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
-                               Uart.posCnt = 0;
-                               Uart.bitCnt = 0;
-                       }
-                       break;
-
-               case STATE_GOT_FALLING_EDGE_OF_SOF:
-                       Uart.posCnt++;
-                       if(Uart.posCnt == 2) {
-                               if(bit) {
-                                       if(Uart.bitCnt >= 10) {
-                                               // we've seen enough consecutive
-                                               // zeros that it's a valid SOF
-                                               Uart.posCnt = 0;
-                                               Uart.byteCnt = 0;
-                                               Uart.state = STATE_AWAITING_START_BIT;
-                                               LED_A_ON(); // Indicate we got a valid SOF
-                                       } else {
-                                               // didn't stay down long enough
-                                               // before going high, error
-                                               Uart.state = STATE_ERROR_WAIT;
-                                       }
-                               } else {
-                                       // do nothing, keep waiting
-                               }
-                               Uart.bitCnt++;
-                       }
-                       if(Uart.posCnt >= 4) Uart.posCnt = 0;
-                       if(Uart.bitCnt > 14) {
-                               // Give up if we see too many zeros without
-                               // a one, too.
-                               Uart.state = STATE_ERROR_WAIT;
-                       }
-                       break;
-
-               case STATE_AWAITING_START_BIT:
-                       Uart.posCnt++;
-                       if(bit) {
-                               if(Uart.posCnt > 25) {
-                                       // stayed high for too long between
-                                       // characters, error
-                                       Uart.state = STATE_ERROR_WAIT;
-                               }
-                       } else {
-                               // falling edge, this starts the data byte
-                               Uart.posCnt = 0;
-                               Uart.bitCnt = 0;
-                               Uart.shiftReg = 0;
-                               Uart.state = STATE_RECEIVING_DATA;
-                               LED_A_ON(); // Indicate we're receiving
-                       }
-                       break;
-
-               case STATE_RECEIVING_DATA:
-                       Uart.posCnt++;
-                       if(Uart.posCnt == 2) {
-                               // time to sample a bit
-                               Uart.shiftReg >>= 1;
-                               if(bit) {
-                                       Uart.shiftReg |= 0x200;
-                               }
-                               Uart.bitCnt++;
-                       }
-                       if(Uart.posCnt >= 4) {
-                               Uart.posCnt = 0;
-                       }
-                       if(Uart.bitCnt == 10) {
-                               if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
-                               {
-                                       // this is a data byte, with correct
-                                       // start and stop bits
-                                       Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
-                                       Uart.byteCnt++;
-
-                                       if(Uart.byteCnt >= Uart.byteCntMax) {
-                                               // Buffer overflowed, give up
-                                               Uart.posCnt = 0;
-                                               Uart.state = STATE_ERROR_WAIT;
-                                       } else {
-                                               // so get the next byte now
-                                               Uart.posCnt = 0;
-                                               Uart.state = STATE_AWAITING_START_BIT;
-                                       }
-                               } else if(Uart.shiftReg == 0x000) {
-                                       // this is an EOF byte
-                                       LED_A_OFF(); // Finished receiving
-                                       return TRUE;
-                               } else {
-                                       // this is an error
-                                       Uart.posCnt = 0;
-                                       Uart.state = STATE_ERROR_WAIT;
-                               }
-                       }
-                       break;
-
-               case STATE_ERROR_WAIT:
-                       // We're all screwed up, so wait a little while
-                       // for whatever went wrong to finish, and then
-                       // start over.
-                       Uart.posCnt++;
-                       if(Uart.posCnt > 10) {
-                               Uart.state = STATE_UNSYNCD;
-                       }
-                       break;
-
-               default:
-                       Uart.state = STATE_UNSYNCD;
-                       break;
-       }
-
-       // This row make the error blew circular buffer in hf 14b snoop
-       //if (Uart.state == STATE_ERROR_WAIT) LED_A_OFF(); // Error
-
-       return FALSE;
-}
-
-//-----------------------------------------------------------------------------
-// Receive a command (from the reader to us, where we are the simulated tag),
-// and store it in the given buffer, up to the given maximum length. Keeps
-// spinning, waiting for a well-framed command, until either we get one
-// (returns TRUE) or someone presses the pushbutton on the board (FALSE).
-//
-// Assume that we're called with the SSC (to the FPGA) and ADC path set
-// correctly.
-//-----------------------------------------------------------------------------
-static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
-{
-       uint8_t mask;
-       int i, bit;
-
-       // Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
-       // only, since we are receiving, not transmitting).
-       // Signal field is off with the appropriate LED
-       LED_D_OFF();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
-
-
-       // Now run a `software UART' on the stream of incoming samples.
-       Uart.output = received;
-       Uart.byteCntMax = maxLen;
-       Uart.state = STATE_UNSYNCD;
-
-       for(;;) {
-               WDT_HIT();
-
-               if(BUTTON_PRESS()) return FALSE;
-
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x00;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-
-                       mask = 0x80;
-                       for(i = 0; i < 8; i++, mask >>= 1) {
-                               bit = (b & mask);
-                               if(Handle14443UartBit(bit)) {
-                                       *len = Uart.byteCnt;
-                                       return TRUE;
-                               }
-                       }
-               }
-       }
-}
-
-//-----------------------------------------------------------------------------
-// Main loop of simulated tag: receive commands from reader, decide what
-// response to send, and send it.
-//-----------------------------------------------------------------------------
-void SimulateIso14443Tag(void)
-{
-       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
-       static const uint8_t response1[] = {
-               0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
-               0x00, 0x21, 0x85, 0x5e, 0xd7
-       };
-
-       uint8_t *resp;
-       int respLen;
-
-       uint8_t *resp1 = BigBuf_get_addr() + 800;
-       int resp1Len;
-
-       uint8_t *receivedCmd = BigBuf_get_addr();
-       int len;
-
-       int i;
-
-       int cmdsRecvd = 0;
-
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       memset(receivedCmd, 0x44, 400);
-
-       CodeIso14443bAsTag(response1, sizeof(response1));
-       memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
-
-       // We need to listen to the high-frequency, peak-detected path.
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       FpgaSetupSsc();
-
-       cmdsRecvd = 0;
-
-       for(;;) {
-               uint8_t b1, b2;
-
-               if(!GetIso14443CommandFromReader(receivedCmd, &len, 100)) {
-               Dbprintf("button pressed, received %d commands", cmdsRecvd);
-               break;
-               }
-
-               // Good, look at the command now.
-
-               if(len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len)==0) {
-                       resp = resp1; respLen = resp1Len;
-               } else {
-                       Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
-                       // And print whether the CRC fails, just for good measure
-                       ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
-                       if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
-                               // Not so good, try again.
-                               DbpString("+++CRC fail");
-                       } else {
-                               DbpString("CRC passes");
-                       }
-                       break;
-               }
-
-               memset(receivedCmd, 0x44, 32);
-
-               cmdsRecvd++;
-
-               if(cmdsRecvd > 0x30) {
-                       DbpString("many commands later...");
-                       break;
-               }
-
-               if(respLen <= 0) continue;
-
-               // Modulate BPSK
-               // Signal field is off with the appropriate LED
-               LED_D_OFF();
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
-               AT91C_BASE_SSC->SSC_THR = 0xff;
-               FpgaSetupSsc();
-
-               // Transmit the response.
-               i = 0;
-               for(;;) {
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                               uint8_t b = resp[i];
-
-                               AT91C_BASE_SSC->SSC_THR = b;
-
-                               i++;
-                               if(i > respLen) {
-                                       break;
-                               }
-                       }
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                               (void)b;
-                       }
-               }
-       }
-}
-
-//=============================================================================
-// An ISO 14443 Type B reader. We take layer two commands, code them
-// appropriately, and then send them to the tag. We then listen for the
-// tag's response, which we leave in the buffer to be demodulated on the
-// PC side.
-//=============================================================================
-
-static struct {
-       enum {
-               DEMOD_UNSYNCD,
-               DEMOD_PHASE_REF_TRAINING,
-               DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
-               DEMOD_GOT_FALLING_EDGE_OF_SOF,
-               DEMOD_AWAITING_START_BIT,
-               DEMOD_RECEIVING_DATA,
-               DEMOD_ERROR_WAIT
-       }       state;
-       int     bitCount;
-       int     posCount;
-       int     thisBit;
-       int     metric;
-       int     metricN;
-       uint16_t    shiftReg;
-       uint8_t   *output;
-       int     len;
-       int     sumI;
-       int     sumQ;
-} Demod;
-
-/*
- * Handles reception of a bit from the tag
- *
- * LED handling:
- * LED C -> ON once we have received the SOF and are expecting the rest.
- * LED C -> OFF once we have received EOF or are unsynced
- *
- * Returns: true if we received a EOF
- *          false if we are still waiting for some more
- *
- */
-static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
-{
-       int v;
-
-       // The soft decision on the bit uses an estimate of just the
-       // quadrant of the reference angle, not the exact angle.
-#define MAKE_SOFT_DECISION() { \
-               if(Demod.sumI > 0) { \
-                       v = ci; \
-               } else { \
-                       v = -ci; \
-               } \
-               if(Demod.sumQ > 0) { \
-                       v += cq; \
-               } else { \
-                       v -= cq; \
-               } \
-       }
-
-       switch(Demod.state) {
-               case DEMOD_UNSYNCD:
-                       v = ci;
-                       if(v < 0) v = -v;
-                       if(cq > 0) {
-                               v += cq;
-                       } else {
-                               v -= cq;
-                       }
-                       if(v > 40) {
-                               Demod.posCount = 0;
-                               Demod.state = DEMOD_PHASE_REF_TRAINING;
-                               Demod.sumI = 0;
-                               Demod.sumQ = 0;
-                       }
-                       break;
-
-               case DEMOD_PHASE_REF_TRAINING:
-                       if(Demod.posCount < 8) {
-                               Demod.sumI += ci;
-                               Demod.sumQ += cq;
-                       } else if(Demod.posCount > 100) {
-                               // error, waited too long
-                               Demod.state = DEMOD_UNSYNCD;
-                       } else {
-                               MAKE_SOFT_DECISION();
-                               if(v < 0) {
-                                       Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
-                                       Demod.posCount = 0;
-                               }
-                       }
-                       Demod.posCount++;
-                       break;
-
-               case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
-                       MAKE_SOFT_DECISION();
-                       if(v < 0) {
-                               Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
-                               Demod.posCount = 0;
-                       } else {
-                               if(Demod.posCount > 100) {
-                                       Demod.state = DEMOD_UNSYNCD;
-                               }
-                       }
-                       Demod.posCount++;
-                       break;
-
-               case DEMOD_GOT_FALLING_EDGE_OF_SOF:
-                       MAKE_SOFT_DECISION();
-                       if(v > 0) {
-                               if(Demod.posCount < 12) {
-                                       Demod.state = DEMOD_UNSYNCD;
-                               } else {
-                                       LED_C_ON(); // Got SOF
-                                       Demod.state = DEMOD_AWAITING_START_BIT;
-                                       Demod.posCount = 0;
-                                       Demod.len = 0;
-                                       Demod.metricN = 0;
-                                       Demod.metric = 0;
-                               }
-                       } else {
-                               if(Demod.posCount > 100) {
-                                       Demod.state = DEMOD_UNSYNCD;
-                               }
-                       }
-                       Demod.posCount++;
-                       break;
-
-               case DEMOD_AWAITING_START_BIT:
-                       MAKE_SOFT_DECISION();
-                       if(v > 0) {
-                               if(Demod.posCount > 10) {
-                                       Demod.state = DEMOD_UNSYNCD;
-                               }
-                       } else {
-                               Demod.bitCount = 0;
-                               Demod.posCount = 1;
-                               Demod.thisBit = v;
-                               Demod.shiftReg = 0;
-                               Demod.state = DEMOD_RECEIVING_DATA;
-                       }
-                       break;
-
-               case DEMOD_RECEIVING_DATA:
-                       MAKE_SOFT_DECISION();
-                       if(Demod.posCount == 0) {
-                               Demod.thisBit = v;
-                               Demod.posCount = 1;
-                       } else {
-                               Demod.thisBit += v;
-
-                               if(Demod.thisBit > 0) {
-                                       Demod.metric += Demod.thisBit;
-                               } else {
-                                       Demod.metric -= Demod.thisBit;
-                               }
-                               (Demod.metricN)++;
-
-                               Demod.shiftReg >>= 1;
-                               if(Demod.thisBit > 0) {
-                                       Demod.shiftReg |= 0x200;
-                               }
-
-                               Demod.bitCount++;
-                               if(Demod.bitCount == 10) {
-                                       uint16_t s = Demod.shiftReg;
-                                       if((s & 0x200) && !(s & 0x001)) {
-                                               uint8_t b = (s >> 1);
-                                               Demod.output[Demod.len] = b;
-                                               Demod.len++;
-                                               Demod.state = DEMOD_AWAITING_START_BIT;
-                                       } else if(s == 0x000) {
-                                               // This is EOF
-                                               LED_C_OFF();
-                                               Demod.state = DEMOD_UNSYNCD;
-                                               return TRUE;
-                                       } else {
-                                               Demod.state = DEMOD_UNSYNCD;
-                                       }
-                               }
-                               Demod.posCount = 0;
-                       }
-                       break;
-
-               default:
-                       Demod.state = DEMOD_UNSYNCD;
-                       break;
-       }
-
-       if (Demod.state == DEMOD_UNSYNCD) LED_C_OFF(); // Not synchronized...
-       return FALSE;
-}
-static void DemodReset()
-{
-       // Clear out the state of the "UART" that receives from the tag.
-       Demod.len = 0;
-       Demod.state = DEMOD_UNSYNCD;
-       memset(Demod.output, 0x00, MAX_FRAME_SIZE);
-}
-static void DemodInit(uint8_t *data)
-{
-       Demod.output = data;
-       DemodReset();
-}
-
-static void UartReset()
-{
-       Uart.byteCntMax = MAX_FRAME_SIZE;
-       Uart.state = STATE_UNSYNCD;
-       Uart.byteCnt = 0;
-       Uart.bitCnt = 0;
-}
-static void UartInit(uint8_t *data)
-{
-       Uart.output = data;
-       UartReset();
-}
-
-/*
- *  Demodulate the samples we received from the tag, also log to tracebuffer
- *  weTx: set to 'TRUE' if we behave like a reader
- *        set to 'FALSE' if we behave like a snooper
- *  quiet: set to 'TRUE' to disable debug output
- */
-static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
-{
-       int max = 0;
-       int gotFrame = FALSE;
-       int lastRxCounter, ci, cq, samples = 0;
-
-       // Allocate memory from BigBuf for some buffers
-       // free all previous allocations first
-       BigBuf_free();
-       
-       // The response (tag -> reader) that we're receiving.
-       uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
-       
-       // The DMA buffer, used to stream samples from the FPGA
-       uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
-
-       // Set up the demodulator for tag -> reader responses.
-       DemodInit(receivedResponse);
-
-       // Setup and start DMA.
-       FpgaSetupSscDma(dmaBuf, DMA_BUFFER_SIZE);
-
-       uint8_t *upTo= dmaBuf;
-       lastRxCounter = DMA_BUFFER_SIZE;
-
-       // Signal field is ON with the appropriate LED:
-       if (weTx) LED_D_ON(); else LED_D_OFF();
-       // And put the FPGA in the appropriate mode
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               (weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
-
-       for(;;) {
-               int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
-               if(behindBy > max) max = behindBy;
-
-               while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (DMA_BUFFER_SIZE-1))
-                                       > 2)
-               {
-                       ci = upTo[0];
-                       cq = upTo[1];
-                       upTo += 2;
-                       if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
-                               upTo = dmaBuf;
-                               AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
-                               AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-                       }
-                       lastRxCounter -= 2;
-                       if(lastRxCounter <= 0) {
-                               lastRxCounter += DMA_BUFFER_SIZE;
-                       }
-
-                       samples += 2;
-
-                       if(Handle14443SamplesDemod(ci, cq)) {
-                               gotFrame = 1;
-                       }
-               }
-
-               if(samples > n) {
-                       break;
-               }
-       }
-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-       if (!quiet) Dbprintf("%x %x %x", max, gotFrame, Demod.len);
-       //Tracing
-       if (tracing && Demod.len > 0) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               GetParity(Demod.output, Demod.len, parity);
-               LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
-       }
-}
-
-//-----------------------------------------------------------------------------
-// Read the tag's response. We just receive a stream of slightly-processed
-// samples from the FPGA, which we will later do some signal processing on,
-// to get the bits.
-//-----------------------------------------------------------------------------
-/*static void GetSamplesFor14443(int weTx, int n)
-{
-       uint8_t *dest = (uint8_t *)BigBuf;
-       int c;
-
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               (weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
-
-       c = 0;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
-
-                       dest[c++] = (uint8_t)b;
-
-                       if(c >= n) {
-                               break;
-                       }
-               }
-       }
-}*/
-
-//-----------------------------------------------------------------------------
-// Transmit the command (to the tag) that was placed in ToSend[].
-//-----------------------------------------------------------------------------
-static void TransmitFor14443(void)
-{
-       int c;
-
-       FpgaSetupSsc();
-
-       while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-               AT91C_BASE_SSC->SSC_THR = 0xff;
-       }
-
-       // Signal field is ON with the appropriate Red LED
-       LED_D_ON();
-       // Signal we are transmitting with the Green LED
-       LED_B_ON();
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
-
-       for(c = 0; c < 10;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0xff;
-                       c++;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
-               }
-               WDT_HIT();
-       }
-
-       c = 0;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
-                       c++;
-                       if(c >= ToSendMax) {
-                               break;
-                       }
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
-               }
-               WDT_HIT();
-       }
-       LED_B_OFF(); // Finished sending
-}
-
-//-----------------------------------------------------------------------------
-// Code a layer 2 command (string of octets, including CRC) into ToSend[],
-// so that it is ready to transmit to the tag using TransmitFor14443().
-//-----------------------------------------------------------------------------
-static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
-{
-       int i, j;
-       uint8_t b;
-
-       ToSendReset();
-
-       // Establish initial reference level
-       for(i = 0; i < 40; i++) {
-               ToSendStuffBit(1);
-       }
-       // Send SOF
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-       }
-
-       for(i = 0; i < len; i++) {
-               // Stop bits/EGT
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               // Start bit
-               ToSendStuffBit(0);
-               // Data bits
-               b = cmd[i];
-               for(j = 0; j < 8; j++) {
-                       if(b & 1) {
-                               ToSendStuffBit(1);
-                       } else {
-                               ToSendStuffBit(0);
-                       }
-                       b >>= 1;
-               }
-       }
-       // Send EOF
-       ToSendStuffBit(1);
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 8; i++) {
-               ToSendStuffBit(1);
-       }
-
-       // And then a little more, to make sure that the last character makes
-       // it out before we switch to rx mode.
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
-       }
-
-       // Convert from last character reference to length
-       ToSendMax++;
-}
-
-//-----------------------------------------------------------------------------
-// Read an ISO 14443 tag. We send it some set of commands, and record the
-// responses.
-// The command name is misleading, it actually decodes the reponse in HEX
-// into the output buffer (read the result using hexsamples, not hisamples)
-//
-// obsolete function only for test
-//-----------------------------------------------------------------------------
-void AcquireRawAdcSamplesIso14443(uint32_t parameter)
-{
-       uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
-
-       SendRawCommand14443B(sizeof(cmd1),1,1,cmd1);
-}
-
-/**
-  Convenience function to encode, transmit and trace iso 14443b comms
-  **/
-static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
-{
-       CodeIso14443bAsReader(cmd, len);
-       TransmitFor14443();
-       if (tracing) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               GetParity(cmd, len, parity);
-               LogTrace(cmd,len, 0, 0, parity, TRUE);
-       }
-}
-
-//-----------------------------------------------------------------------------
-// Read a SRI512 ISO 14443 tag.
-//
-// SRI512 tags are just simple memory tags, here we're looking at making a dump
-// of the contents of the memory. No anticollision algorithm is done, we assume
-// we have a single tag in the field.
-//
-// I tried to be systematic and check every answer of the tag, every CRC, etc...
-//-----------------------------------------------------------------------------
-void ReadSTMemoryIso14443(uint32_t dwLast)
-{
-       clear_trace();
-       set_tracing(TRUE);
-
-       uint8_t i = 0x00;
-
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       // Make sure that we start from off, since the tags are stateful;
-       // confusing things will happen if we don't reset them between reads.
-       LED_D_OFF();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
-
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       FpgaSetupSsc();
-
-       // Now give it time to spin up.
-       // Signal field is on with the appropriate LED
-       LED_D_ON();
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
-       SpinDelay(200);
-
-       // First command: wake up the tag using the INITIATE command
-       uint8_t cmd1[] = { 0x06, 0x00, 0x97, 0x5b};
-
-       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
-
-       if (Demod.len == 0) {
-       DbpString("No response from tag");
-       return;
-       } else {
-       Dbprintf("Randomly generated UID from tag (+ 2 byte CRC): %x %x %x",
-               Demod.output[0], Demod.output[1],Demod.output[2]);
-       }
-       // There is a response, SELECT the uid
-       DbpString("Now SELECT tag:");
-       cmd1[0] = 0x0E; // 0x0E is SELECT
-       cmd1[1] = Demod.output[0];
-       ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
-       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
-       if (Demod.len != 3) {
-       Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
-       return;
-       }
-       // Check the CRC of the answer:
-       ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
-       if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
-       DbpString("CRC Error reading select response.");
-       return;
-       }
-       // Check response from the tag: should be the same UID as the command we just sent:
-       if (cmd1[1] != Demod.output[0]) {
-       Dbprintf("Bad response to SELECT from Tag, aborting: %x %x", cmd1[1], Demod.output[0]);
-       return;
-       }
-       // Tag is now selected,
-       // First get the tag's UID:
-       cmd1[0] = 0x0B;
-       ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
-       CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
-       if (Demod.len != 10) {
-       Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
-       return;
-       }
-       // The check the CRC of the answer (use cmd1 as temporary variable):
-       ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
-                  if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
-       Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
-               (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
-       // Do not return;, let's go on... (we should retry, maybe ?)
-       }
-       Dbprintf("Tag UID (64 bits): %08x %08x",
-       (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
-       (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
-
-       // Now loop to read all 16 blocks, address from 0 to last block
-       Dbprintf("Tag memory dump, block 0 to %d",dwLast);
-       cmd1[0] = 0x08;
-       i = 0x00;
-       dwLast++;
-       for (;;) {
-                  if (i == dwLast) {
-                       DbpString("System area block (0xff):");
-                       i = 0xff;
-               }
-               cmd1[1] = i;
-               ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
-               CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-
-//         LED_A_ON();
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//         LED_A_OFF();
-               if (Demod.len != 6) { // Check if we got an answer from the tag
-               DbpString("Expected 6 bytes from tag, got less...");
-               return;
-               }
-               // The check the CRC of the answer (use cmd1 as temporary variable):
-               ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
-                       if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
-               Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
-                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
-               // Do not return;, let's go on... (we should retry, maybe ?)
-               }
-               // Now print out the memory location:
-               Dbprintf("Address=%x, Contents=%x, CRC=%x", i,
-               (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
-               (Demod.output[4]<<8)+Demod.output[5]);
-               if (i == 0xff) {
-               break;
-               }
-               i++;
-       }
-}
-
-
-//=============================================================================
-// Finally, the `sniffer' combines elements from both the reader and
-// simulated tag, to show both sides of the conversation.
-//=============================================================================
-
-//-----------------------------------------------------------------------------
-// Record the sequence of commands sent by the reader to the tag, with
-// triggering so that we start recording at the point that the tag is moved
-// near the reader.
-//-----------------------------------------------------------------------------
-/*
- * Memory usage for this function, (within BigBuf)
- * 0-4095 : Demodulated samples receive (4096 bytes) - DEMOD_TRACE_SIZE
- * 4096-6143 : Last Received command, 2048 bytes (reader->tag) - READER_TAG_BUFFER_SIZE
- * 6144-8191 : Last Received command, 2048 bytes(tag->reader) - TAG_READER_BUFFER_SIZE
- * 8192-9215 : DMA Buffer, 1024 bytes (samples) - DEMOD_DMA_BUFFER_SIZE
- */
-void RAMFUNC SnoopIso14443(void)
-{
-       // We won't start recording the frames that we acquire until we trigger;
-       // a good trigger condition to get started is probably when we see a
-       // response from the tag.
-       int triggered = TRUE;
-
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BigBuf_free();
-
-       clear_trace();
-       set_tracing(TRUE);
-
-       // The DMA buffer, used to stream samples from the FPGA
-       uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
-       int lastRxCounter;
-       uint8_t *upTo;
-       int ci, cq;
-       int maxBehindBy = 0;
-
-       // Count of samples received so far, so that we can include timing
-       // information in the trace buffer.
-       int samples = 0;
-
-       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
-       UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
-
-       // Print some debug information about the buffer sizes
-       Dbprintf("Snooping buffers initialized:");
-       Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
-       Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
-       Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
-       Dbprintf("  DMA: %i bytes", DMA_BUFFER_SIZE);
-
-       // Signal field is off with the appropriate LED
-       LED_D_OFF();
-
-       // And put the FPGA in the appropriate mode
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               FPGA_HF_READER_RX_XCORR_SNOOP);
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-
-       // Setup for the DMA.
-       FpgaSetupSsc();
-       upTo = dmaBuf;
-       lastRxCounter = DMA_BUFFER_SIZE;
-       FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
-       uint8_t parity[MAX_PARITY_SIZE];
-       LED_A_ON();
-               
-       // And now we loop, receiving samples.
-       for(;;) {
-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
-                                                               (DMA_BUFFER_SIZE-1);
-               if(behindBy > maxBehindBy) {
-                       maxBehindBy = behindBy;
-                       if(behindBy > (9*DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
-                               Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
-                               break;
-                       }
-               }
-               if(behindBy < 2) continue;
-
-               ci = upTo[0];
-               cq = upTo[1];
-               upTo += 2;
-               lastRxCounter -= 2;
-               if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
-                       upTo = dmaBuf;
-                       lastRxCounter += DMA_BUFFER_SIZE;
-                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
-                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-               }
-
-               samples += 2;
-
-               if(Handle14443UartBit(ci & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
-                       }
-                       if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
-
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
-               }
-               if(Handle14443UartBit(cq & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
-                       }
-                       if(Uart.byteCnt==0) Dbprintf("[2] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
-
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
-               }
-
-               if(Handle14443SamplesDemod(ci, cq)) {
-
-                       //Use samples as a time measurement
-                       if(tracing)
-                       {
-                               uint8_t parity[MAX_PARITY_SIZE];
-                               GetParity(Demod.output, Demod.len, parity);
-                               LogTrace(Demod.output,Demod.len,samples, samples,parity,FALSE);
-                       }
-                       triggered = TRUE;
-                       LED_A_OFF();
-                       LED_B_ON();
-
-                       // And ready to receive another response.
-                       DemodReset();
-               }
-               WDT_HIT();
-
-               if(!tracing) {
-                       DbpString("Reached trace limit");
-                       break;
-               }
-
-               if(BUTTON_PRESS()) {
-                       DbpString("cancelled");
-                       break;
-               }
-       }
-       FpgaDisableSscDma();
-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-       DbpString("Snoop statistics:");
-       Dbprintf("  Max behind by: %i", maxBehindBy);
-       Dbprintf("  Uart State: %x", Uart.state);
-       Dbprintf("  Uart ByteCnt: %i", Uart.byteCnt);
-       Dbprintf("  Uart ByteCntMax: %i", Uart.byteCntMax);
-       Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
-}
-
-/*
- * Send raw command to tag ISO14443B
- * @Input
- * datalen     len of buffer data
- * recv        bool when true wait for data from tag and send to client
- * powerfield  bool leave the field on when true
- * data        buffer with byte to send
- *
- * @Output
- * none
- *
- */
-
-void SendRawCommand14443B(uint32_t datalen, uint32_t recv,uint8_t powerfield, uint8_t data[])
-{
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       if(!powerfield)
-       {
-               // Make sure that we start from off, since the tags are stateful;
-               // confusing things will happen if we don't reset them between reads.
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               LED_D_OFF();
-               SpinDelay(200);
-       }
-
-       if(!GETBIT(GPIO_LED_D))
-       {
-               SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-               FpgaSetupSsc();
-
-               // Now give it time to spin up.
-               // Signal field is on with the appropriate LED
-               LED_D_ON();
-               FpgaWriteConfWord(
-                       FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
-               SpinDelay(200);
-       }
-
-       CodeAndTransmit14443bAsReader(data, datalen);
-
-       if(recv)
-       {
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-               uint16_t iLen = MIN(Demod.len,USB_CMD_DATA_SIZE);
-               cmd_send(CMD_ACK,iLen,0,0,Demod.output,iLen);
-       }
-       if(!powerfield)
-       {
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               LED_D_OFF();
-       }
-}
-
diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
new file mode 100644 (file)
index 0000000..416c31f
--- /dev/null
@@ -0,0 +1,1218 @@
+//-----------------------------------------------------------------------------
+// Jonathan Westhues, split Nov 2006
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// Routines to support ISO 14443B. This includes both the reader software and
+// the `fake tag' modes.
+//-----------------------------------------------------------------------------
+
+#include "proxmark3.h"
+#include "apps.h"
+#include "util.h"
+#include "string.h"
+
+#include "iso14443crc.h"
+
+#define RECEIVE_SAMPLES_TIMEOUT 2000
+#define ISO14443B_DMA_BUFFER_SIZE 256
+
+//=============================================================================
+// An ISO 14443 Type B tag. We listen for commands from the reader, using
+// a UART kind of thing that's implemented in software. When we get a
+// frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
+// If it's good, then we can do something appropriate with it, and send
+// a response.
+//=============================================================================
+
+//-----------------------------------------------------------------------------
+// Code up a string of octets at layer 2 (including CRC, we don't generate
+// that here) so that they can be transmitted to the reader. Doesn't transmit
+// them yet, just leaves them ready to send in ToSend[].
+//-----------------------------------------------------------------------------
+static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
+{
+       int i;
+
+       ToSendReset();
+
+       // Transmit a burst of ones, as the initial thing that lets the
+       // reader get phase sync. This (TR1) must be > 80/fs, per spec,
+       // but tag that I've tried (a Paypass) exceeds that by a fair bit,
+       // so I will too.
+       for(i = 0; i < 20; i++) {
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+       }
+
+       // Send SOF.
+       for(i = 0; i < 10; i++) {
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+       }
+       for(i = 0; i < 2; i++) {
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+       }
+
+       for(i = 0; i < len; i++) {
+               int j;
+               uint8_t b = cmd[i];
+
+               // Start bit
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+
+               // Data bits
+               for(j = 0; j < 8; j++) {
+                       if(b & 1) {
+                               ToSendStuffBit(1);
+                               ToSendStuffBit(1);
+                               ToSendStuffBit(1);
+                               ToSendStuffBit(1);
+                       } else {
+                               ToSendStuffBit(0);
+                               ToSendStuffBit(0);
+                               ToSendStuffBit(0);
+                               ToSendStuffBit(0);
+                       }
+                       b >>= 1;
+               }
+
+               // Stop bit
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+       }
+
+       // Send EOF.
+       for(i = 0; i < 10; i++) {
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+               ToSendStuffBit(0);
+       }
+       for(i = 0; i < 2; i++) {
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+       }
+
+       // Convert from last byte pos to length
+       ToSendMax++;
+}
+
+//-----------------------------------------------------------------------------
+// The software UART that receives commands from the reader, and its state
+// variables.
+//-----------------------------------------------------------------------------
+static struct {
+       enum {
+               STATE_UNSYNCD,
+               STATE_GOT_FALLING_EDGE_OF_SOF,
+               STATE_AWAITING_START_BIT,
+               STATE_RECEIVING_DATA
+       }       state;
+       uint16_t    shiftReg;
+       int     bitCnt;
+       int     byteCnt;
+       int     byteCntMax;
+       int     posCnt;
+       uint8_t   *output;
+} Uart;
+
+/* Receive & handle a bit coming from the reader.
+ *
+ * This function is called 4 times per bit (every 2 subcarrier cycles).
+ * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
+ *
+ * LED handling:
+ * LED A -> ON once we have received the SOF and are expecting the rest.
+ * LED A -> OFF once we have received EOF or are in error state or unsynced
+ *
+ * Returns: true if we received a EOF
+ *          false if we are still waiting for some more
+ */
+static RAMFUNC int Handle14443bUartBit(uint8_t bit)
+{
+       switch(Uart.state) {
+               case STATE_UNSYNCD:
+                       if(!bit) {
+                               // we went low, so this could be the beginning
+                               // of an SOF
+                               Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
+                               Uart.posCnt = 0;
+                               Uart.bitCnt = 0;
+                       }
+                       break;
+
+               case STATE_GOT_FALLING_EDGE_OF_SOF:
+                       Uart.posCnt++;
+                       if(Uart.posCnt == 2) {  // sample every 4 1/fs in the middle of a bit
+                               if(bit) {
+                                       if(Uart.bitCnt > 9) {
+                                               // we've seen enough consecutive
+                                               // zeros that it's a valid SOF
+                                               Uart.posCnt = 0;
+                                               Uart.byteCnt = 0;
+                                               Uart.state = STATE_AWAITING_START_BIT;
+                                               LED_A_ON(); // Indicate we got a valid SOF
+                                       } else {
+                                               // didn't stay down long enough
+                                               // before going high, error
+                                               Uart.state = STATE_UNSYNCD;
+                                       }
+                               } else {
+                                       // do nothing, keep waiting
+                               }
+                               Uart.bitCnt++;
+                       }
+                       if(Uart.posCnt >= 4) Uart.posCnt = 0;
+                       if(Uart.bitCnt > 12) {
+                               // Give up if we see too many zeros without
+                               // a one, too.
+                               LED_A_OFF();
+                               Uart.state = STATE_UNSYNCD;
+                       }
+                       break;
+
+               case STATE_AWAITING_START_BIT:
+                       Uart.posCnt++;
+                       if(bit) {
+                               if(Uart.posCnt > 50/2) {        // max 57us between characters = 49 1/fs, max 3 etus after low phase of SOF = 24 1/fs
+                                       // stayed high for too long between
+                                       // characters, error
+                                       Uart.state = STATE_UNSYNCD;
+                               }
+                       } else {
+                               // falling edge, this starts the data byte
+                               Uart.posCnt = 0;
+                               Uart.bitCnt = 0;
+                               Uart.shiftReg = 0;
+                               Uart.state = STATE_RECEIVING_DATA;
+                       }
+                       break;
+
+               case STATE_RECEIVING_DATA:
+                       Uart.posCnt++;
+                       if(Uart.posCnt == 2) {
+                               // time to sample a bit
+                               Uart.shiftReg >>= 1;
+                               if(bit) {
+                                       Uart.shiftReg |= 0x200;
+                               }
+                               Uart.bitCnt++;
+                       }
+                       if(Uart.posCnt >= 4) {
+                               Uart.posCnt = 0;
+                       }
+                       if(Uart.bitCnt == 10) {
+                               if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
+                               {
+                                       // this is a data byte, with correct
+                                       // start and stop bits
+                                       Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
+                                       Uart.byteCnt++;
+
+                                       if(Uart.byteCnt >= Uart.byteCntMax) {
+                                               // Buffer overflowed, give up
+                                               LED_A_OFF();
+                                               Uart.state = STATE_UNSYNCD;
+                                       } else {
+                                               // so get the next byte now
+                                               Uart.posCnt = 0;
+                                               Uart.state = STATE_AWAITING_START_BIT;
+                                       }
+                               } else if (Uart.shiftReg == 0x000) {
+                                       // this is an EOF byte
+                                       LED_A_OFF(); // Finished receiving
+                                       Uart.state = STATE_UNSYNCD;
+                                       if (Uart.byteCnt != 0) {
+                                               return TRUE;
+                                       }
+                               } else {
+                                       // this is an error
+                                       LED_A_OFF();
+                                       Uart.state = STATE_UNSYNCD;
+                               }
+                       }
+                       break;
+
+               default:
+                       LED_A_OFF();
+                       Uart.state = STATE_UNSYNCD;
+                       break;
+       }
+
+       return FALSE;
+}
+
+
+static void UartReset()
+{
+       Uart.byteCntMax = MAX_FRAME_SIZE;
+       Uart.state = STATE_UNSYNCD;
+       Uart.byteCnt = 0;
+       Uart.bitCnt = 0;
+}
+
+
+static void UartInit(uint8_t *data)
+{
+       Uart.output = data;
+       UartReset();
+}
+
+
+//-----------------------------------------------------------------------------
+// Receive a command (from the reader to us, where we are the simulated tag),
+// and store it in the given buffer, up to the given maximum length. Keeps
+// spinning, waiting for a well-framed command, until either we get one
+// (returns TRUE) or someone presses the pushbutton on the board (FALSE).
+//
+// Assume that we're called with the SSC (to the FPGA) and ADC path set
+// correctly.
+//-----------------------------------------------------------------------------
+static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
+{
+       // Set FPGA mode to "simulated ISO 14443B tag", no modulation (listen
+       // only, since we are receiving, not transmitting).
+       // Signal field is off with the appropriate LED
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+
+       // Now run a `software UART' on the stream of incoming samples.
+       UartInit(received);
+
+       for(;;) {
+               WDT_HIT();
+
+               if(BUTTON_PRESS()) return FALSE;
+
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
+                               if(Handle14443bUartBit(b & mask)) {
+                                       *len = Uart.byteCnt;
+                                       return TRUE;
+                               }
+                       }
+               }
+       }
+       
+       return FALSE;
+}
+
+//-----------------------------------------------------------------------------
+// Main loop of simulated tag: receive commands from reader, decide what
+// response to send, and send it.
+//-----------------------------------------------------------------------------
+void SimulateIso14443bTag(void)
+{
+       // the only commands we understand is REQB, AFI=0, Select All, N=0:
+       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+       // ... and REQB, AFI=0, Normal Request, N=0:
+       static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF };
+
+       // ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
+       // supports only 106kBit/s in both directions, max frame size = 32Bytes,
+       // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
+       static const uint8_t response1[] = {
+               0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
+               0x00, 0x21, 0x85, 0x5e, 0xd7
+       };
+
+       clear_trace();
+       set_tracing(TRUE);
+
+       const uint8_t *resp;
+       uint8_t *respCode;
+       uint16_t respLen, respCodeLen;
+
+       // allocate command receive buffer
+       BigBuf_free();
+       uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
+
+       uint16_t len;
+       uint16_t cmdsRecvd = 0;
+
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+
+       // prepare the (only one) tag answer:
+       CodeIso14443bAsTag(response1, sizeof(response1));
+       uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
+       memcpy(resp1Code, ToSend, ToSendMax); 
+       uint16_t resp1CodeLen = ToSendMax;
+
+       // We need to listen to the high-frequency, peak-detected path.
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc();
+
+       cmdsRecvd = 0;
+
+       for(;;) {
+
+               if(!GetIso14443bCommandFromReader(receivedCmd, &len)) {
+                       Dbprintf("button pressed, received %d commands", cmdsRecvd);
+                       break;
+               }
+
+               if (tracing) {
+                       uint8_t parity[MAX_PARITY_SIZE];
+                       LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
+               }
+
+               // Good, look at the command now.
+               if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
+                       || (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0) ) {
+                       resp = response1; 
+                       respLen = sizeof(response1);
+                       respCode = resp1Code; 
+                       respCodeLen = resp1CodeLen;
+               } else {
+                       Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
+                       // And print whether the CRC fails, just for good measure
+                       uint8_t b1, b2;
+                       ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
+                       if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
+                               // Not so good, try again.
+                               DbpString("+++CRC fail");
+                       } else {
+                               DbpString("CRC passes");
+                       }
+                       break;
+               }
+
+               cmdsRecvd++;
+
+               if(cmdsRecvd > 0x30) {
+                       DbpString("many commands later...");
+                       break;
+               }
+
+               if(respCodeLen <= 0) continue;
+
+               // Modulate BPSK
+               // Signal field is off with the appropriate LED
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
+               AT91C_BASE_SSC->SSC_THR = 0xff;
+               FpgaSetupSsc();
+
+               // Transmit the response.
+               uint16_t i = 0;
+               for(;;) {
+                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                               uint8_t b = respCode[i];
+
+                               AT91C_BASE_SSC->SSC_THR = b;
+
+                               i++;
+                               if(i > respCodeLen) {
+                                       break;
+                               }
+                       }
+                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                               volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                               (void)b;
+                       }
+               }
+               
+               // trace the response:
+               if (tracing) {
+                       uint8_t parity[MAX_PARITY_SIZE];
+                       LogTrace(resp, respLen, 0, 0, parity, FALSE);
+               }
+                       
+       }
+}
+
+//=============================================================================
+// An ISO 14443 Type B reader. We take layer two commands, code them
+// appropriately, and then send them to the tag. We then listen for the
+// tag's response, which we leave in the buffer to be demodulated on the
+// PC side.
+//=============================================================================
+
+static struct {
+       enum {
+               DEMOD_UNSYNCD,
+               DEMOD_PHASE_REF_TRAINING,
+               DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
+               DEMOD_GOT_FALLING_EDGE_OF_SOF,
+               DEMOD_AWAITING_START_BIT,
+               DEMOD_RECEIVING_DATA
+       }       state;
+       int     bitCount;
+       int     posCount;
+       int     thisBit;
+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
+       int     metric;
+       int     metricN;
+*/
+       uint16_t    shiftReg;
+       uint8_t   *output;
+       int     len;
+       int     sumI;
+       int     sumQ;
+} Demod;
+
+/*
+ * Handles reception of a bit from the tag
+ *
+ * This function is called 2 times per bit (every 4 subcarrier cycles).
+ * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 4,72us
+ *
+ * LED handling:
+ * LED C -> ON once we have received the SOF and are expecting the rest.
+ * LED C -> OFF once we have received EOF or are unsynced
+ *
+ * Returns: true if we received a EOF
+ *          false if we are still waiting for some more
+ *
+ */
+static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
+{
+       int v;
+
+// The soft decision on the bit uses an estimate of just the
+// quadrant of the reference angle, not the exact angle.
+#define MAKE_SOFT_DECISION() { \
+               if(Demod.sumI > 0) { \
+                       v = ci; \
+               } else { \
+                       v = -ci; \
+               } \
+               if(Demod.sumQ > 0) { \
+                       v += cq; \
+               } else { \
+                       v -= cq; \
+               } \
+       }
+
+#define SUBCARRIER_DETECT_THRESHOLD    8
+
+// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by abs(ci) + abs(cq)
+/* #define CHECK_FOR_SUBCARRIER() { \
+               v = ci; \
+               if(v < 0) v = -v; \
+               if(cq > 0) { \
+                       v += cq; \
+               } else { \
+                       v -= cq; \
+               } \
+       }               
+ */
+// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
+#define CHECK_FOR_SUBCARRIER() { \
+               if(ci < 0) { \
+                       if(cq < 0) { /* ci < 0, cq < 0 */ \
+                               if (cq < ci) { \
+                                       v = -cq - (ci >> 1); \
+                               } else { \
+                                       v = -ci - (cq >> 1); \
+                               } \
+                       } else {        /* ci < 0, cq >= 0 */ \
+                               if (cq < -ci) { \
+                                       v = -ci + (cq >> 1); \
+                               } else { \
+                                       v = cq - (ci >> 1); \
+                               } \
+                       } \
+               } else { \
+                       if(cq < 0) { /* ci >= 0, cq < 0 */ \
+                               if (-cq < ci) { \
+                                       v = ci - (cq >> 1); \
+                               } else { \
+                                       v = -cq + (ci >> 1); \
+                               } \
+                       } else {        /* ci >= 0, cq >= 0 */ \
+                               if (cq < ci) { \
+                                       v = ci + (cq >> 1); \
+                               } else { \
+                                       v = cq + (ci >> 1); \
+                               } \
+                       } \
+               } \
+       }
+       
+       switch(Demod.state) {
+               case DEMOD_UNSYNCD:
+                       CHECK_FOR_SUBCARRIER();
+                       if(v > SUBCARRIER_DETECT_THRESHOLD) {   // subcarrier detected
+                               Demod.state = DEMOD_PHASE_REF_TRAINING;
+                               Demod.sumI = ci;
+                               Demod.sumQ = cq;
+                               Demod.posCount = 1;
+                               }
+                       break;
+
+               case DEMOD_PHASE_REF_TRAINING:
+                       if(Demod.posCount < 8) {
+                               CHECK_FOR_SUBCARRIER();
+                               if (v > SUBCARRIER_DETECT_THRESHOLD) {
+                                       // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
+                                       // note: synchronization time > 80 1/fs
+                                       Demod.sumI += ci;
+                                       Demod.sumQ += cq;
+                                       Demod.posCount++;
+                               } else {                // subcarrier lost
+                                       Demod.state = DEMOD_UNSYNCD;
+                               }
+                       } else {
+                               Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
+                       }
+                       break;
+
+               case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
+                       MAKE_SOFT_DECISION();
+                       if(v < 0) {     // logic '0' detected
+                               Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
+                               Demod.posCount = 0;     // start of SOF sequence
+                       } else {
+                               if(Demod.posCount > 200/4) {    // maximum length of TR1 = 200 1/fs
+                                       Demod.state = DEMOD_UNSYNCD;
+                               }
+                       }
+                       Demod.posCount++;
+                       break;
+
+               case DEMOD_GOT_FALLING_EDGE_OF_SOF:
+                       Demod.posCount++;
+                       MAKE_SOFT_DECISION();
+                       if(v > 0) {
+                               if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
+                                       Demod.state = DEMOD_UNSYNCD;
+                               } else {
+                                       LED_C_ON(); // Got SOF
+                                       Demod.state = DEMOD_AWAITING_START_BIT;
+                                       Demod.posCount = 0;
+                                       Demod.len = 0;
+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
+                                       Demod.metricN = 0;
+                                       Demod.metric = 0;
+*/
+                               }
+                       } else {
+                               if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
+                                       Demod.state = DEMOD_UNSYNCD;
+                                       LED_C_OFF();
+                               }
+                       }
+                       break;
+
+               case DEMOD_AWAITING_START_BIT:
+                       Demod.posCount++;
+                       MAKE_SOFT_DECISION();
+                       if(v > 0) {
+                               if(Demod.posCount > 3*2) {              // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs
+                                       Demod.state = DEMOD_UNSYNCD;
+                                       LED_C_OFF();
+                               }
+                       } else {                                                        // start bit detected
+                               Demod.bitCount = 0;
+                               Demod.posCount = 1;                             // this was the first half
+                               Demod.thisBit = v;
+                               Demod.shiftReg = 0;
+                               Demod.state = DEMOD_RECEIVING_DATA;
+                       }
+                       break;
+
+               case DEMOD_RECEIVING_DATA:
+                       MAKE_SOFT_DECISION();
+                       if(Demod.posCount == 0) {                       // first half of bit
+                               Demod.thisBit = v;
+                               Demod.posCount = 1;
+                       } else {                                                        // second half of bit
+                               Demod.thisBit += v;
+
+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
+                               if(Demod.thisBit > 0) {
+                                       Demod.metric += Demod.thisBit;
+                               } else {
+                                       Demod.metric -= Demod.thisBit;
+                               }
+                               (Demod.metricN)++;
+*/                             
+
+                               Demod.shiftReg >>= 1;
+                               if(Demod.thisBit > 0) { // logic '1'
+                                       Demod.shiftReg |= 0x200;
+                               }
+
+                               Demod.bitCount++;
+                               if(Demod.bitCount == 10) {
+                                       uint16_t s = Demod.shiftReg;
+                                       if((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'
+                                               uint8_t b = (s >> 1);
+                                               Demod.output[Demod.len] = b;
+                                               Demod.len++;
+                                               Demod.state = DEMOD_AWAITING_START_BIT;
+                                       } else {
+                                               Demod.state = DEMOD_UNSYNCD;
+                                               LED_C_OFF();
+                                               if(s == 0x000) {
+                                                       // This is EOF (start, stop and all data bits == '0'
+                                                       return TRUE;
+                                               }
+                                       }
+                               }
+                               Demod.posCount = 0;
+                       }
+                       break;
+
+               default:
+                       Demod.state = DEMOD_UNSYNCD;
+                       LED_C_OFF();
+                       break;
+       }
+
+       return FALSE;
+}
+
+
+static void DemodReset()
+{
+       // Clear out the state of the "UART" that receives from the tag.
+       Demod.len = 0;
+       Demod.state = DEMOD_UNSYNCD;
+       Demod.posCount = 0;
+       memset(Demod.output, 0x00, MAX_FRAME_SIZE);
+}
+
+
+static void DemodInit(uint8_t *data)
+{
+       Demod.output = data;
+       DemodReset();
+}
+
+
+/*
+ *  Demodulate the samples we received from the tag, also log to tracebuffer
+ *  quiet: set to 'TRUE' to disable debug output
+ */
+static void GetSamplesFor14443bDemod(int n, bool quiet)
+{
+       int max = 0;
+       bool gotFrame = FALSE;
+       int lastRxCounter, ci, cq, samples = 0;
+
+       // Allocate memory from BigBuf for some buffers
+       // free all previous allocations first
+       BigBuf_free();
+       
+       // The response (tag -> reader) that we're receiving.
+       uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
+       
+       // The DMA buffer, used to stream samples from the FPGA
+       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
+
+       // Set up the demodulator for tag -> reader responses.
+       DemodInit(receivedResponse);
+
+       // Setup and start DMA.
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
+
+       int8_t *upTo = dmaBuf;
+       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+
+       // Signal field is ON with the appropriate LED:
+       LED_D_ON();
+       // And put the FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+
+       for(;;) {
+               int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
+               if(behindBy > max) max = behindBy;
+
+               while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1)) > 2) {
+                       ci = upTo[0];
+                       cq = upTo[1];
+                       upTo += 2;
+                       if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
+                               upTo = dmaBuf;
+                               AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
+                               AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
+                       }
+                       lastRxCounter -= 2;
+                       if(lastRxCounter <= 0) {
+                               lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+                       }
+
+                       samples += 2;
+
+                       if(Handle14443bSamplesDemod(ci, cq)) {
+                               gotFrame = TRUE;
+                               break;
+                       }
+               }
+
+               if(samples > n || gotFrame) {
+                       break;
+               }
+       }
+
+       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+
+       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);
+       //Tracing
+       if (tracing && Demod.len > 0) {
+               uint8_t parity[MAX_PARITY_SIZE];
+               LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
+       }
+}
+
+
+//-----------------------------------------------------------------------------
+// Transmit the command (to the tag) that was placed in ToSend[].
+//-----------------------------------------------------------------------------
+static void TransmitFor14443b(void)
+{
+       int c;
+
+       FpgaSetupSsc();
+
+       while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+               AT91C_BASE_SSC->SSC_THR = 0xff;
+       }
+
+       // Signal field is ON with the appropriate Red LED
+       LED_D_ON();
+       // Signal we are transmitting with the Green LED
+       LED_B_ON();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
+
+       for(c = 0; c < 10;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = 0xff;
+                       c++;
+               }
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
+                       (void)r;
+               }
+               WDT_HIT();
+       }
+
+       c = 0;
+       for(;;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
+                       c++;
+                       if(c >= ToSendMax) {
+                               break;
+                       }
+               }
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
+                       (void)r;
+               }
+               WDT_HIT();
+       }
+       LED_B_OFF(); // Finished sending
+}
+
+
+//-----------------------------------------------------------------------------
+// Code a layer 2 command (string of octets, including CRC) into ToSend[],
+// so that it is ready to transmit to the tag using TransmitFor14443b().
+//-----------------------------------------------------------------------------
+static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
+{
+       int i, j;
+       uint8_t b;
+
+       ToSendReset();
+
+       // Establish initial reference level
+       for(i = 0; i < 40; i++) {
+               ToSendStuffBit(1);
+       }
+       // Send SOF
+       for(i = 0; i < 10; i++) {
+               ToSendStuffBit(0);
+       }
+
+       for(i = 0; i < len; i++) {
+               // Stop bits/EGT
+               ToSendStuffBit(1);
+               ToSendStuffBit(1);
+               // Start bit
+               ToSendStuffBit(0);
+               // Data bits
+               b = cmd[i];
+               for(j = 0; j < 8; j++) {
+                       if(b & 1) {
+                               ToSendStuffBit(1);
+                       } else {
+                               ToSendStuffBit(0);
+                       }
+                       b >>= 1;
+               }
+       }
+       // Send EOF
+       ToSendStuffBit(1);
+       for(i = 0; i < 10; i++) {
+               ToSendStuffBit(0);
+       }
+       for(i = 0; i < 8; i++) {
+               ToSendStuffBit(1);
+       }
+
+       // And then a little more, to make sure that the last character makes
+       // it out before we switch to rx mode.
+       for(i = 0; i < 24; i++) {
+               ToSendStuffBit(1);
+       }
+
+       // Convert from last character reference to length
+       ToSendMax++;
+}
+
+
+/**
+  Convenience function to encode, transmit and trace iso 14443b comms
+  **/
+static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
+{
+       CodeIso14443bAsReader(cmd, len);
+       TransmitFor14443b();
+       if (tracing) {
+               uint8_t parity[MAX_PARITY_SIZE];
+               LogTrace(cmd,len, 0, 0, parity, TRUE);
+       }
+}
+
+
+//-----------------------------------------------------------------------------
+// Read a SRI512 ISO 14443B tag.
+//
+// SRI512 tags are just simple memory tags, here we're looking at making a dump
+// of the contents of the memory. No anticollision algorithm is done, we assume
+// we have a single tag in the field.
+//
+// I tried to be systematic and check every answer of the tag, every CRC, etc...
+//-----------------------------------------------------------------------------
+void ReadSTMemoryIso14443b(uint32_t dwLast)
+{
+       clear_trace();
+       set_tracing(TRUE);
+
+       uint8_t i = 0x00;
+
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       // Make sure that we start from off, since the tags are stateful;
+       // confusing things will happen if we don't reset them between reads.
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelay(200);
+
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc();
+
+       // Now give it time to spin up.
+       // Signal field is on with the appropriate LED
+       LED_D_ON();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+       SpinDelay(200);
+
+       // First command: wake up the tag using the INITIATE command
+       uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};
+       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+
+       if (Demod.len == 0) {
+               DbpString("No response from tag");
+               return;
+       } else {
+               Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
+                               Demod.output[0], Demod.output[1], Demod.output[2]);
+       }
+
+       // There is a response, SELECT the uid
+       DbpString("Now SELECT tag:");
+       cmd1[0] = 0x0E; // 0x0E is SELECT
+       cmd1[1] = Demod.output[0];
+       ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
+       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       if (Demod.len != 3) {
+               Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
+               return;
+       }
+       // Check the CRC of the answer:
+       ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
+       if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
+               DbpString("CRC Error reading select response.");
+               return;
+       }
+       // Check response from the tag: should be the same UID as the command we just sent:
+       if (cmd1[1] != Demod.output[0]) {
+               Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
+               return;
+       }
+
+       // Tag is now selected,
+       // First get the tag's UID:
+       cmd1[0] = 0x0B;
+       ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
+       CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       if (Demod.len != 10) {
+               Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
+               return;
+       }
+       // The check the CRC of the answer (use cmd1 as temporary variable):
+       ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
+       if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
+               Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
+                               (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
+               // Do not return;, let's go on... (we should retry, maybe ?)
+       }
+       Dbprintf("Tag UID (64 bits): %08x %08x",
+                       (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
+                       (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
+
+       // Now loop to read all 16 blocks, address from 0 to last block
+       Dbprintf("Tag memory dump, block 0 to %d", dwLast);
+       cmd1[0] = 0x08;
+       i = 0x00;
+       dwLast++;
+       for (;;) {
+               if (i == dwLast) {
+                       DbpString("System area block (0xff):");
+                       i = 0xff;
+               }
+               cmd1[1] = i;
+               ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
+               CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
+               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+               if (Demod.len != 6) { // Check if we got an answer from the tag
+                       DbpString("Expected 6 bytes from tag, got less...");
+                       return;
+               }
+               // The check the CRC of the answer (use cmd1 as temporary variable):
+               ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
+               if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
+                       Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
+                                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
+                       // Do not return;, let's go on... (we should retry, maybe ?)
+               }
+               // Now print out the memory location:
+               Dbprintf("Address=%02x, Contents=%08x, CRC=%04x", i,
+                               (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
+                               (Demod.output[4]<<8)+Demod.output[5]);
+               if (i == 0xff) {
+                       break;
+               }
+               i++;
+       }
+}
+
+
+//=============================================================================
+// Finally, the `sniffer' combines elements from both the reader and
+// simulated tag, to show both sides of the conversation.
+//=============================================================================
+
+//-----------------------------------------------------------------------------
+// Record the sequence of commands sent by the reader to the tag, with
+// triggering so that we start recording at the point that the tag is moved
+// near the reader.
+//-----------------------------------------------------------------------------
+/*
+ * Memory usage for this function, (within BigBuf)
+ * Last Received command (reader->tag) - MAX_FRAME_SIZE
+ * Last Received command (tag->reader) - MAX_FRAME_SIZE
+ * DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
+ * Demodulated samples received - all the rest
+ */
+void RAMFUNC SnoopIso14443b(void)
+{
+       // We won't start recording the frames that we acquire until we trigger;
+       // a good trigger condition to get started is probably when we see a
+       // response from the tag.
+       int triggered = TRUE;                   // TODO: set and evaluate trigger condition
+
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       BigBuf_free();
+
+       clear_trace();
+       set_tracing(TRUE);
+
+       // The DMA buffer, used to stream samples from the FPGA
+       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
+       int lastRxCounter;
+       int8_t *upTo;
+       int ci, cq;
+       int maxBehindBy = 0;
+
+       // Count of samples received so far, so that we can include timing
+       // information in the trace buffer.
+       int samples = 0;
+
+       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
+       UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
+
+       // Print some debug information about the buffer sizes
+       Dbprintf("Snooping buffers initialized:");
+       Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
+       Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
+       Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
+       Dbprintf("  DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);
+
+       // Signal field is off, no reader signal, no tag signal
+       LEDsoff();
+
+       // And put the FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Setup for the DMA.
+       FpgaSetupSsc();
+       upTo = dmaBuf;
+       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
+       uint8_t parity[MAX_PARITY_SIZE];
+
+       bool TagIsActive = FALSE;
+       bool ReaderIsActive = FALSE;
+       
+       // And now we loop, receiving samples.
+       for(;;) {
+               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
+                                                               (ISO14443B_DMA_BUFFER_SIZE-1);
+               if(behindBy > maxBehindBy) {
+                       maxBehindBy = behindBy;
+               }
+
+               if(behindBy < 2) continue;
+
+               ci = upTo[0];
+               cq = upTo[1];
+               upTo += 2;
+               lastRxCounter -= 2;
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
+                       upTo = dmaBuf;
+                       lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
+                       WDT_HIT();
+                       if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
+                               Dbprintf("blew circular buffer! behindBy=%d", behindBy);
+                               break;
+                       }
+                       if(!tracing) {
+                               DbpString("Reached trace limit");
+                               break;
+                       }
+                       if(BUTTON_PRESS()) {
+                               DbpString("cancelled");
+                               break;
+                       }
+               }
+
+               samples += 2;
+
+               if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
+                       if(Handle14443bUartBit(ci & 0x01)) {
+                               if(triggered && tracing) {
+                                       LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
+                               }
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();
+                       }
+                       if(Handle14443bUartBit(cq & 0x01)) {
+                               if(triggered && tracing) {
+                                       LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
+                               }
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();
+                       }
+                       ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
+               }
+
+               if(!ReaderIsActive) {                                           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
+                       if(Handle14443bSamplesDemod(ci | 0x01, cq | 0x01)) {
+
+                               //Use samples as a time measurement
+                               if(tracing)
+                               {
+                                       uint8_t parity[MAX_PARITY_SIZE];
+                                       LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
+                               }
+                               triggered = TRUE;
+
+                               // And ready to receive another response.
+                               DemodReset();
+                       }
+                       TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
+               }
+
+       }
+
+       FpgaDisableSscDma();
+       LEDsoff();
+       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+       DbpString("Snoop statistics:");
+       Dbprintf("  Max behind by: %i", maxBehindBy);
+       Dbprintf("  Uart State: %x", Uart.state);
+       Dbprintf("  Uart ByteCnt: %i", Uart.byteCnt);
+       Dbprintf("  Uart ByteCntMax: %i", Uart.byteCntMax);
+       Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
+}
+
+
+/*
+ * Send raw command to tag ISO14443B
+ * @Input
+ * datalen     len of buffer data
+ * recv        bool when true wait for data from tag and send to client
+ * powerfield  bool leave the field on when true
+ * data        buffer with byte to send
+ *
+ * @Output
+ * none
+ *
+ */
+void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
+{
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc();
+
+       set_tracing(TRUE);
+       
+       CodeAndTransmit14443bAsReader(data, datalen);
+
+       if(recv) {
+               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+               uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
+               cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
+       }
+       
+       if(!powerfield) {
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               LED_D_OFF();
+       }
+}
+
index 16f7bb0f39f661c180723bd0c52bd1306407f8bd..fc6127c2d2dadef666eea5bb3fa0f007bacb73a0 100644 (file)
@@ -378,7 +378,7 @@ uint16_t printTraceLine(uint16_t tracepos, uint16_t traceLen, uint8_t *trace, ui
                        oddparity ^= (((frame[j] & 0xFF) >> k) & 0x01);
                }
                uint8_t parityBits = parityBytes[j>>3];
-               if (isResponse && (oddparity != ((parityBits >> (7-(j&0x0007))) & 0x01))) {
+               if (protocol != ISO_14443B && isResponse && (oddparity != ((parityBits >> (7-(j&0x0007))) & 0x01))) {
                        snprintf(line[j/16]+(( j % 16) * 4),110, "%02x! ", frame[j]);
 
                } else {
index 525ffcc63d1d62a79c14c1845ff8099fe3390b06..496267cd47a55da826aadb888d5516cddb474db8 100644 (file)
 
 static int CmdHelp(const char *Cmd);
 
-int CmdHF14BDemod(const char *Cmd)
-{
-  int i, j, iold;
-  int isum, qsum;
-  int outOfWeakAt;
-  bool negateI, negateQ;
-
-  uint8_t data[256];
-  int dataLen = 0;
-
-  // As received, the samples are pairs, correlations against I and Q
-  // square waves. So estimate angle of initial carrier (or just
-  // quadrant, actually), and then do the demod.
-
-  // First, estimate where the tag starts modulating.
-  for (i = 0; i < GraphTraceLen; i += 2) {
-    if (abs(GraphBuffer[i]) + abs(GraphBuffer[i + 1]) > 40) {
-      break;
-    }
-  }
-  if (i >= GraphTraceLen) {
-    PrintAndLog("too weak to sync");
-    return 0;
-  }
-  PrintAndLog("out of weak at %d", i);
-  outOfWeakAt = i;
-
-  // Now, estimate the phase in the initial modulation of the tag
-  isum = 0;
-  qsum = 0;
-  for (; i < (outOfWeakAt + 16); i += 2) {
-    isum += GraphBuffer[i + 0];
-    qsum += GraphBuffer[i + 1];
-  }
-  negateI = (isum < 0);
-  negateQ = (qsum < 0);
-
-  // Turn the correlation pairs into soft decisions on the bit.
-  j = 0;
-  for (i = 0; i < GraphTraceLen / 2; i++) {
-    int si = GraphBuffer[j];
-    int sq = GraphBuffer[j + 1];
-    if (negateI) si = -si;
-    if (negateQ) sq = -sq;
-    GraphBuffer[i] = si + sq;
-    j += 2;
-  }
-  GraphTraceLen = i;
-
-  i = outOfWeakAt / 2;
-  while (GraphBuffer[i] > 0 && i < GraphTraceLen)
-    i++;
-  if (i >= GraphTraceLen) goto demodError;
-
-  iold = i;
-  while (GraphBuffer[i] < 0 && i < GraphTraceLen)
-    i++;
-  if (i >= GraphTraceLen) goto demodError;
-  if ((i - iold) > 23) goto demodError;
-
-  PrintAndLog("make it to demod loop");
-
-  for (;;) {
-    iold = i;
-    while (GraphBuffer[i] >= 0 && i < GraphTraceLen)
-      i++;
-    if (i >= GraphTraceLen) goto demodError;
-    if ((i - iold) > 6) goto demodError;
-
-    uint16_t shiftReg = 0;
-    if (i + 20 >= GraphTraceLen) goto demodError;
-
-    for (j = 0; j < 10; j++) {
-      int soft = GraphBuffer[i] + GraphBuffer[i + 1];
-
-      if (abs(soft) < (abs(isum) + abs(qsum)) / 20) {
-        PrintAndLog("weak bit");
-      }
-
-      shiftReg >>= 1;
-      if(GraphBuffer[i] + GraphBuffer[i+1] >= 0) {
-        shiftReg |= 0x200;
-      }
-
-      i+= 2;
-    }
-
-    if ((shiftReg & 0x200) && !(shiftReg & 0x001))
-    {
-      // valid data byte, start and stop bits okay
-      PrintAndLog("   %02x", (shiftReg >> 1) & 0xff);
-      data[dataLen++] = (shiftReg >> 1) & 0xff;
-      if (dataLen >= sizeof(data)) {
-        return 0;
-      }
-    } else if (shiftReg == 0x000) {
-      // this is EOF
-      break;
-    } else {
-      goto demodError;
-    }
-  }
-
-  uint8_t first, second;
-  ComputeCrc14443(CRC_14443_B, data, dataLen-2, &first, &second);
-  PrintAndLog("CRC: %02x %02x (%s)\n", first, second,
-    (first == data[dataLen-2] && second == data[dataLen-1]) ?
-      "ok" : "****FAIL****");
-
-  RepaintGraphWindow();
-  return 0;
-
-demodError:
-  PrintAndLog("demod error");
-  RepaintGraphWindow();
-  return 0;
-}
-
 int CmdHF14BList(const char *Cmd)
 {
        PrintAndLog("Deprecated command, use 'hf list 14b' instead");
 
        return 0;
 }
-int CmdHF14BRead(const char *Cmd)
-{
-  UsbCommand c = {CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_14443, {strtol(Cmd, NULL, 0), 0, 0}};
-  SendCommand(&c);
-  return 0;
-}
-
-int CmdHF14Sim(const char *Cmd)
-{
-  UsbCommand c={CMD_SIMULATE_TAG_ISO_14443};
-  SendCommand(&c);
-  return 0;
-}
 
-int CmdHFSimlisten(const char *Cmd)
+int CmdHF14BSim(const char *Cmd)
 {
-  UsbCommand c = {CMD_SIMULATE_TAG_HF_LISTEN};
+  UsbCommand c={CMD_SIMULATE_TAG_ISO_14443B};
   SendCommand(&c);
   return 0;
 }
 
 int CmdHF14BSnoop(const char *Cmd)
 {
-  UsbCommand c = {CMD_SNOOP_ISO_14443};
+  UsbCommand c = {CMD_SNOOP_ISO_14443B};
   SendCommand(&c);
   return 0;
 }
@@ -288,7 +157,7 @@ int CmdHF14BCmdRaw (const char *cmd) {
         if (WaitForResponseTimeout(CMD_ACK,&resp,1000)) {
             recv = resp.d.asBytes;
             PrintAndLog("received %i octets",resp.arg[0]);
-            if(!resp.arg[0])
+            if(resp.arg[0] == 0)
                 return 0;
             hexout = (char *)malloc(resp.arg[0] * 3 + 1);
             if (hexout != NULL) {
@@ -298,11 +167,13 @@ int CmdHF14BCmdRaw (const char *cmd) {
                 }
                 PrintAndLog("%s", hexout);
                 free(hexout);
-                ComputeCrc14443(CRC_14443_B, recv, resp.arg[0]-2, &first, &second);
-                if(recv[resp.arg[0]-2]==first && recv[resp.arg[0]-1]==second) {
-                    PrintAndLog("CRC OK");
-                } else {
-                    PrintAndLog("CRC failed");
+                               if (resp.arg[0] > 2) {
+                                       ComputeCrc14443(CRC_14443_B, recv, resp.arg[0]-2, &first, &second);
+                                       if(recv[resp.arg[0]-2]==first && recv[resp.arg[0]-1]==second) {
+                                               PrintAndLog("CRC OK");
+                                       } else {
+                                               PrintAndLog("CRC failed");
+                                       }
                 }
             } else {
                 PrintAndLog("malloc failed your client has low memory?");
@@ -385,12 +256,9 @@ int CmdHF14BWrite( const char *Cmd){
 static command_t CommandTable[] = 
 {
   {"help",        CmdHelp,        1, "This help"},
-  {"demod",       CmdHF14BDemod,  1, "Demodulate ISO14443 Type B from tag"},
   {"list",        CmdHF14BList,   0, "[Deprecated] List ISO 14443b history"},
-  {"read",        CmdHF14BRead,   0, "Read HF tag (ISO 14443)"},
-  {"sim",         CmdHF14Sim,     0, "Fake ISO 14443 tag"},
-  {"simlisten",   CmdHFSimlisten, 0, "Get HF samples as fake tag"},
-  {"snoop",       CmdHF14BSnoop,  0, "Eavesdrop ISO 14443"},
+  {"sim",         CmdHF14BSim,    0, "Fake ISO 14443B tag"},
+  {"snoop",       CmdHF14BSnoop,  0, "Eavesdrop ISO 14443B"},
   {"sri512read",  CmdSri512Read,  0, "Read contents of a SRI512 tag"},
   {"srix4kread",  CmdSrix4kRead,  0, "Read contents of a SRIX4K tag"},
   {"raw",         CmdHF14BCmdRaw, 0, "Send raw hex data to tag"},
index c5b91f99783830e3274d54169aa4ae4a289f02bb..b3a7f4ec94c3e3663fc3db40fb9de301dbb1d065 100644 (file)
@@ -89,7 +89,6 @@ typedef struct {
 
 // For the 13.56 MHz tags
 #define CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_15693                             0x0300
-#define CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_14443                             0x0301
 #define CMD_READ_SRI512_TAG                                               0x0303
 #define CMD_READ_SRIX4K_TAG                                               0x0304
 #define CMD_READER_ISO_15693                                              0x0310
@@ -105,9 +104,8 @@ typedef struct {
 #define CMD_SIMULATE_HITAG                                                0x0371
 #define CMD_READER_HITAG                                                  0x0372
 
-#define CMD_SIMULATE_TAG_HF_LISTEN                                        0x0380
-#define CMD_SIMULATE_TAG_ISO_14443                                        0x0381
-#define CMD_SNOOP_ISO_14443                                               0x0382
+#define CMD_SIMULATE_TAG_ISO_14443B                                       0x0381
+#define CMD_SNOOP_ISO_14443B                                              0x0382
 #define CMD_SNOOP_ISO_14443a                                              0x0383
 #define CMD_SIMULATE_TAG_ISO_14443a                                       0x0384
 #define CMD_READER_ISO_14443a                                             0x0385
index 678c745ec65cc2afd8b0583ed99ec3d74489c80f..4c7bc638319d39066227f769c4ee662720a58707 100644 (file)
@@ -59,7 +59,6 @@ local _commands = {
 
        --// For the 13.56 MHz tags
        CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_15693 =                              0x0300,
-       CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_14443 =                              0x0301,
        CMD_READ_SRI512_TAG =                                                0x0303,
        CMD_READ_SRIX4K_TAG =                                                0x0304,
        CMD_READER_ISO_15693 =                                               0x0310,
@@ -76,9 +75,8 @@ local _commands = {
        CMD_SIMULATE_HITAG =                                                 0x0371,
        CMD_READER_HITAG =                                                   0x0372,
 
-       CMD_SIMULATE_TAG_HF_LISTEN =                                         0x0380,
-       CMD_SIMULATE_TAG_ISO_14443 =                                         0x0381,
-       CMD_SNOOP_ISO_14443 =                                                0x0382,
+       CMD_SIMULATE_TAG_ISO_14443B =                                        0x0381,
+       CMD_SNOOP_ISO_14443B =                                               0x0382,
        CMD_SNOOP_ISO_14443a =                                               0x0383,
        CMD_SIMULATE_TAG_ISO_14443a =                                        0x0384,
        CMD_READER_ISO_14443a =                                              0x0385,
index 20fb2bd4401254d899d6273451bfccbd827f562b..50c7eef97c8b98461b7d8be9e4e643dd85910241 100644 (file)
Binary files a/fpga/fpga_hf.bit and b/fpga/fpga_hf.bit differ
index a2100df65f5212761b03b1f4ba1e7a53d8d67ca0..8a465e75c5304452b598d5d28d5f2f4ae16f8c6f 100644 (file)
@@ -73,9 +73,6 @@ wire hi_read_rx_xcorr_848 = conf_word[0];
 // and whether to drive the coil (reader) or just short it (snooper)
 wire hi_read_rx_xcorr_snoop = conf_word[1];
 
-// Divide the expected subcarrier frequency for hi_read_rx_xcorr by 4
-wire hi_read_rx_xcorr_quarter = conf_word[2];
-
 // For the high-frequency simulated tag: what kind of modulation to use.
 wire [2:0] hi_simulate_mod_type = conf_word[2:0];
 
@@ -102,7 +99,7 @@ hi_read_rx_xcorr hrxc(
        hrxc_ssp_frame, hrxc_ssp_din, ssp_dout, hrxc_ssp_clk,
        cross_hi, cross_lo,
        hrxc_dbg,
-       hi_read_rx_xcorr_848, hi_read_rx_xcorr_snoop, hi_read_rx_xcorr_quarter
+       hi_read_rx_xcorr_848, hi_read_rx_xcorr_snoop
 );
 
 hi_simulate hs(
index dece2db3195844ce9ce2d371d09a1ff7df0069bf..afaf7cb6fb17ae0a1f5687a9b48601ead3d65c23 100644 (file)
@@ -10,7 +10,7 @@ module hi_read_rx_xcorr(
     ssp_frame, ssp_din, ssp_dout, ssp_clk,
     cross_hi, cross_lo,
     dbg,
-    xcorr_is_848, snoop, xcorr_quarter_freq
+    xcorr_is_848, snoop
 );
     input pck0, ck_1356meg, ck_1356megb;
     output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
@@ -20,58 +20,24 @@ module hi_read_rx_xcorr(
     output ssp_frame, ssp_din, ssp_clk;
     input cross_hi, cross_lo;
     output dbg;
-    input xcorr_is_848, snoop, xcorr_quarter_freq;
+    input xcorr_is_848, snoop;
 
 // Carrier is steady on through this, unless we're snooping.
 assign pwr_hi = ck_1356megb & (~snoop);
 assign pwr_oe1 = 1'b0;
-assign pwr_oe2 = 1'b0;
 assign pwr_oe3 = 1'b0;
 assign pwr_oe4 = 1'b0;
 
-reg ssp_clk;
-reg ssp_frame;
+wire adc_clk = ck_1356megb;
 
 reg fc_div_2;
-always @(posedge ck_1356meg)
-    fc_div_2 = ~fc_div_2;
-
-reg fc_div_4;
-always @(posedge fc_div_2)
-    fc_div_4 = ~fc_div_4;
-
-reg fc_div_8;
-always @(posedge fc_div_4)
-    fc_div_8 = ~fc_div_8;
-
-reg adc_clk;
-
-always @(xcorr_is_848 or xcorr_quarter_freq or ck_1356meg)
-    if(~xcorr_quarter_freq)
-    begin
-           if(xcorr_is_848)
-               // The subcarrier frequency is fc/16; we will sample at fc, so that 
-               // means the subcarrier is 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 ...
-               adc_clk <= ck_1356meg;
-           else
-               // The subcarrier frequency is fc/32; we will sample at fc/2, and
-               // the subcarrier will look identical.
-               adc_clk <= fc_div_2;
-    end
-    else
-    begin
-           if(xcorr_is_848)
-               // The subcarrier frequency is fc/64
-               adc_clk <= fc_div_4;
-           else
-               // The subcarrier frequency is fc/128
-               adc_clk <= fc_div_8;
-       end
+always @(negedge ck_1356megb)
+    fc_div_2 <= fc_div_2 + 1;
 
 // When we're a reader, we just need to do the BPSK demod; but when we're an
 // eavesdropper, we also need to pick out the commands sent by the reader,
 // using AM. Do this the same way that we do it for the simulated tag.
-reg after_hysteresis, after_hysteresis_prev;
+reg after_hysteresis, after_hysteresis_prev, after_hysteresis_prev_prev;
 reg [11:0] has_been_low_for;
 always @(negedge adc_clk)
 begin
@@ -97,12 +63,24 @@ end
 // Let us report a correlation every 4 subcarrier cycles, or 4*16 samples,
 // so we need a 6-bit counter.
 reg [5:0] corr_i_cnt;
-reg [5:0] corr_q_cnt;
 // And a couple of registers in which to accumulate the correlations.
-reg signed [15:0] corr_i_accum;
-reg signed [15:0] corr_q_accum;
+// we would add at most 32 times adc_d, the result can be held in 13 bits. 
+// Need one additional bit because it can be negative as well
+reg signed [13:0] corr_i_accum;
+reg signed [13:0] corr_q_accum;
 reg signed [7:0] corr_i_out;
 reg signed [7:0] corr_q_out;
+// clock and frame signal for communication to ARM
+reg ssp_clk;
+reg ssp_frame;
+
+
+always @(negedge adc_clk)
+begin
+       if (xcorr_is_848 | fc_div_2)
+               corr_i_cnt <= corr_i_cnt + 1;
+end            
+               
 
 // ADC data appears on the rising edge, so sample it on the falling edge
 always @(negedge adc_clk)
@@ -110,24 +88,24 @@ begin
     // These are the correlators: we correlate against in-phase and quadrature
     // versions of our reference signal, and keep the (signed) result to
     // send out later over the SSP.
-    if(corr_i_cnt == 7'd63)
+    if(corr_i_cnt == 6'd0)
     begin
         if(snoop)
         begin
-            corr_i_out <= {corr_i_accum[12:6], after_hysteresis_prev};
-            corr_q_out <= {corr_q_accum[12:6], after_hysteresis};
+                       // Send only 7 most significant bits of tag signal (signed), LSB is reader signal:
+            corr_i_out <= {corr_i_accum[13:7], after_hysteresis_prev_prev};
+            corr_q_out <= {corr_q_accum[13:7], after_hysteresis_prev};
+                       after_hysteresis_prev_prev <= after_hysteresis;
         end
         else
         begin
-            // Only correlations need to be delivered.
+            // 8 most significant bits of tag signal
             corr_i_out <= corr_i_accum[13:6];
             corr_q_out <= corr_q_accum[13:6];
         end
 
         corr_i_accum <= adc_d;
         corr_q_accum <= adc_d;
-        corr_q_cnt <= 4;
-        corr_i_cnt <= 0;
     end
     else
     begin
@@ -136,18 +114,16 @@ begin
         else
             corr_i_accum <= corr_i_accum + adc_d;
 
-        if(corr_q_cnt[3])
-            corr_q_accum <= corr_q_accum - adc_d;
-        else
+        if(corr_i_cnt[3] == corr_i_cnt[2])                     // phase shifted by pi/2
             corr_q_accum <= corr_q_accum + adc_d;
+        else
+            corr_q_accum <= corr_q_accum - adc_d;
 
-        corr_i_cnt <= corr_i_cnt + 1;
-        corr_q_cnt <= corr_q_cnt + 1;
     end
 
     // The logic in hi_simulate.v reports 4 samples per bit. We report two
     // (I, Q) pairs per bit, so we should do 2 samples per pair.
-    if(corr_i_cnt == 6'd31)
+    if(corr_i_cnt == 6'd32)
         after_hysteresis_prev <= after_hysteresis;
 
     // Then the result from last time is serialized and send out to the ARM.
@@ -168,7 +144,9 @@ begin
         end
     end
 
-    if(corr_i_cnt[5:2] == 4'b000 || corr_i_cnt[5:2] == 4'b1000)
+       // set ssp_frame signal for corr_i_cnt = 0..3 and corr_i_cnt = 32..35
+       // (send two frames with 8 Bits each)
+    if(corr_i_cnt[5:2] == 4'b0000 || corr_i_cnt[5:2] == 4'b1000)
         ssp_frame = 1'b1;
     else
         ssp_frame = 1'b0;
@@ -181,5 +159,6 @@ assign dbg = corr_i_cnt[3];
 
 // Unused.
 assign pwr_lo = 1'b0;
+assign pwr_oe2 = 1'b0;
 
 endmodule
index 357395d43f3103eb01a66144648dbd2e97d001e9..132e1805d31c8fb6fd5c987ec5d01033f6c67dcf 100644 (file)
@@ -100,7 +100,6 @@ typedef struct{
 
 // For the 13.56 MHz tags
 #define CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_15693                             0x0300
-#define CMD_ACQUIRE_RAW_ADC_SAMPLES_ISO_14443                             0x0301
 #define CMD_READ_SRI512_TAG                                               0x0303
 #define CMD_READ_SRIX4K_TAG                                               0x0304
 #define CMD_ISO_14443B_COMMAND                                            0x0305
@@ -118,9 +117,8 @@ typedef struct{
 #define CMD_SIMULATE_HITAG                                                0x0371
 #define CMD_READER_HITAG                                                  0x0372
 
-#define CMD_SIMULATE_TAG_HF_LISTEN                                        0x0380
-#define CMD_SIMULATE_TAG_ISO_14443                                        0x0381
-#define CMD_SNOOP_ISO_14443                                               0x0382
+#define CMD_SIMULATE_TAG_ISO_14443B                                       0x0381
+#define CMD_SNOOP_ISO_14443B                                              0x0382
 #define CMD_SNOOP_ISO_14443a                                              0x0383
 #define CMD_SIMULATE_TAG_ISO_14443a                                       0x0384
 #define CMD_READER_ISO_14443a                                             0x0385
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