usb communication (device side) housekeeping

[proxmark3-svn] / armsrc / iso14443b.c

diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index 82e5dd6a1c1bba44a33814b62b06be2d1e047093..5a335e25afab1d27076665cbc36a0ea047e82932 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -1,5 +1,6 @@
 //-----------------------------------------------------------------------------
 // Jonathan Westhues, split Nov 2006
 //-----------------------------------------------------------------------------
 // Jonathan Westhues, split Nov 2006

+// piwi 2018

 //
 // 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
 //
 // 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


@@ -9,15 +10,19 @@
 // the `fake tag' modes.
 //-----------------------------------------------------------------------------
 
 // the `fake tag' modes.
 //-----------------------------------------------------------------------------
 

+#include "iso14443b.h"
+

 #include "proxmark3.h"
 #include "apps.h"
 #include "proxmark3.h"
 #include "apps.h"

+#include "cmd.h"

 #include "util.h"
 #include "string.h"
 #include "util.h"
 #include "string.h"

-

 #include "iso14443crc.h"
 #include "iso14443crc.h"

+#include "fpgaloader.h"
+#include "BigBuf.h"

 
 

-#define RECEIVE_SAMPLES_TIMEOUT 2000
-#define ISO14443B_DMA_BUFFER_SIZE 256
+#define RECEIVE_SAMPLES_TIMEOUT 64 // TR0 max is 256/fs = 256/(848kHz) = 302us or 64 samples from FPGA
+#define ISO14443B_DMA_BUFFER_SIZE 128

 
 // PCB Block number for APDUs
 static uint8_t pcb_blocknum = 0;
 
 // PCB Block number for APDUs
 static uint8_t pcb_blocknum = 0;


@@ -243,7 +248,7 @@ static RAMFUNC int Handle14443bUartBit(uint8_t bit)
                                        LED_A_OFF(); // Finished receiving
                                        Uart.state = STATE_UNSYNCD;
                                        if (Uart.byteCnt != 0) {
                                        LED_A_OFF(); // Finished receiving
                                        Uart.state = STATE_UNSYNCD;
                                        if (Uart.byteCnt != 0) {

-                                               return TRUE;
+                                               return true;

                                        }
                                } else {
                                        // this is an error
                                        }
                                } else {
                                        // this is an error


@@ -259,7 +264,7 @@ static RAMFUNC int Handle14443bUartBit(uint8_t bit)
                        break;
        }
 
                        break;
        }
 

-       return FALSE;
+       return false;

 }
 
 
 }
 
 


@@ -283,7 +288,7 @@ static void UartInit(uint8_t *data)
 // 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
 // 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).
+// (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.
 //
 // Assume that we're called with the SSC (to the FPGA) and ADC path set
 // correctly.


@@ -302,20 +307,20 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
        for(;;) {
                WDT_HIT();
 
        for(;;) {
                WDT_HIT();
 

-               if(BUTTON_PRESS()) return FALSE;
+               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;
 
                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 true;

                                }
                        }
                }
        }
 
                                }
                        }
                }
        }
 

-       return FALSE;
+       return false;

 }
 
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------


@@ -324,6 +329,7 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
 //-----------------------------------------------------------------------------
 void SimulateIso14443bTag(void)
 {
 //-----------------------------------------------------------------------------
 void SimulateIso14443bTag(void)
 {

+       LED_A_ON();

        // the only commands we understand is WUPB, AFI=0, Select All, N=1:
        static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // WUPB
        // ... and REQB, AFI=0, Normal Request, N=1:
        // the only commands we understand is WUPB, AFI=0, Select All, N=1:
        static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // WUPB
        // ... and REQB, AFI=0, Normal Request, N=1:


@@ -347,7 +353,7 @@ void SimulateIso14443bTag(void)
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        clear_trace();
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        clear_trace();

-       set_tracing(TRUE);
+       set_tracing(true);

 
        const uint8_t *resp;
        uint8_t *respCode;
 
        const uint8_t *resp;
        uint8_t *respCode;


@@ -374,7 +380,7 @@ void SimulateIso14443bTag(void)
 
        // We need to listen to the high-frequency, peak-detected path.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // We need to listen to the high-frequency, peak-detected path.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);

 
        cmdsRecvd = 0;
 
 
        cmdsRecvd = 0;
 


@@ -385,10 +391,7 @@ void SimulateIso14443bTag(void)
                        break;
                }
 
                        break;
                }
 

-               if (tracing) {
-                       uint8_t parity[MAX_PARITY_SIZE];
-                       LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
-               }
+               LogTrace(receivedCmd, len, 0, 0, NULL, true);

 
                // Good, look at the command now.
                if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
 
                // Good, look at the command now.
                if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)


@@ -440,7 +443,7 @@ void SimulateIso14443bTag(void)
                LED_D_OFF();
                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
                AT91C_BASE_SSC->SSC_THR = 0xff;
                LED_D_OFF();
                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
                AT91C_BASE_SSC->SSC_THR = 0xff;

-               FpgaSetupSsc();
+               FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);

 
                // Transmit the response.
                uint16_t i = 0;
 
                // Transmit the response.
                uint16_t i = 0;


@@ -462,12 +465,12 @@ void SimulateIso14443bTag(void)
                }
 
                // trace the response:
                }
 
                // trace the response:

-               if (tracing) {
-                       uint8_t parity[MAX_PARITY_SIZE];
-                       LogTrace(resp, respLen, 0, 0, parity, FALSE);
-               }
+               LogTrace(resp, respLen, 0, 0, NULL, false);

 
        }
 
        }

+       
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_A_OFF();

 }
 
 //=============================================================================
 }
 
 //=============================================================================


@@ -535,54 +538,11 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 
 #define SUBCARRIER_DETECT_THRESHOLD    8
 
 
 #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)))
 // 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); \
-                               } \
-                       } \
-               } \
-       }
-
+#define AMPLITUDE(ci,cq) (MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2))

        switch(Demod.state) {
                case DEMOD_UNSYNCD:
        switch(Demod.state) {
                case DEMOD_UNSYNCD:

-                       CHECK_FOR_SUBCARRIER();
-                       if(v > SUBCARRIER_DETECT_THRESHOLD) {   // subcarrier detected
+                       if(AMPLITUDE(ci,cq) > SUBCARRIER_DETECT_THRESHOLD) {    // subcarrier detected

                                Demod.state = DEMOD_PHASE_REF_TRAINING;
                                Demod.sumI = ci;
                                Demod.sumQ = cq;
                                Demod.state = DEMOD_PHASE_REF_TRAINING;
                                Demod.sumI = ci;
                                Demod.sumQ = cq;


@@ -592,8 +552,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 
                case DEMOD_PHASE_REF_TRAINING:
                        if(Demod.posCount < 8) {
 
                case DEMOD_PHASE_REF_TRAINING:
                        if(Demod.posCount < 8) {

-                               CHECK_FOR_SUBCARRIER();
-                               if (v > SUBCARRIER_DETECT_THRESHOLD) {
+                               if (AMPLITUDE(ci,cq) > 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;
                                        // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
                                        // note: synchronization time > 80 1/fs
                                        Demod.sumI += ci;


@@ -628,9 +587,10 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF
                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF

-                                       Demod.state = DEMOD_AWAITING_START_BIT;

                                        Demod.posCount = 0;
                                        Demod.posCount = 0;

+                                       Demod.bitCount = 0;

                                        Demod.len = 0;
                                        Demod.len = 0;

+                                       Demod.state = DEMOD_AWAITING_START_BIT;

 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
                                        Demod.metricN = 0;
                                        Demod.metric = 0;
 /* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
                                        Demod.metricN = 0;
                                        Demod.metric = 0;


@@ -647,13 +607,16 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                case DEMOD_AWAITING_START_BIT:
                        Demod.posCount++;
                        MAKE_SOFT_DECISION();
                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;
+                       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

                                        LED_C_OFF();
                                        LED_C_OFF();

+                                       if (Demod.bitCount == 0 && Demod.len == 0) { // received SOF only, this is valid for iClass/Picopass
+                                               return true;
+                                       } else {
+                                               Demod.state = DEMOD_UNSYNCD;
+                                       }

                                }
                        } else {                                                        // start bit detected
                                }
                        } else {                                                        // start bit detected

-                               Demod.bitCount = 0;

                                Demod.posCount = 1;                             // this was the first half
                                Demod.thisBit = v;
                                Demod.shiftReg = 0;
                                Demod.posCount = 1;                             // this was the first half
                                Demod.thisBit = v;
                                Demod.shiftReg = 0;


@@ -663,7 +626,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 
                case DEMOD_RECEIVING_DATA:
                        MAKE_SOFT_DECISION();
 
                case DEMOD_RECEIVING_DATA:
                        MAKE_SOFT_DECISION();

-                       if(Demod.posCount == 0) {                       // first half of bit
+                       if (Demod.posCount == 0) {                      // first half of bit

                                Demod.thisBit = v;
                                Demod.posCount = 1;
                        } else {                                                        // second half of bit
                                Demod.thisBit = v;
                                Demod.posCount = 1;
                        } else {                                                        // second half of bit


@@ -679,24 +642,25 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 */
 
                                Demod.shiftReg >>= 1;
 */
 
                                Demod.shiftReg >>= 1;

-                               if(Demod.thisBit > 0) { // logic '1'
+                               if (Demod.thisBit > 0) {        // logic '1'

                                        Demod.shiftReg |= 0x200;
                                }
 
                                Demod.bitCount++;
                                        Demod.shiftReg |= 0x200;
                                }
 
                                Demod.bitCount++;

-                               if(Demod.bitCount == 10) {
+                               if (Demod.bitCount == 10) {

                                        uint16_t s = Demod.shiftReg;
                                        uint16_t s = Demod.shiftReg;

-                                       if((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'
+                                       if ((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'

                                                uint8_t b = (s >> 1);
                                                Demod.output[Demod.len] = b;
                                                Demod.len++;
                                                uint8_t b = (s >> 1);
                                                Demod.output[Demod.len] = b;
                                                Demod.len++;

+                                               Demod.bitCount = 0;

                                                Demod.state = DEMOD_AWAITING_START_BIT;
                                        } else {
                                                Demod.state = DEMOD_UNSYNCD;
                                                LED_C_OFF();
                                                Demod.state = DEMOD_AWAITING_START_BIT;
                                        } else {
                                                Demod.state = DEMOD_UNSYNCD;
                                                LED_C_OFF();

-                                               if(s == 0x000) {
+                                               if (s == 0x000) {

                                                        // This is EOF (start, stop and all data bits == '0'
                                                        // This is EOF (start, stop and all data bits == '0'

-                                                       return TRUE;
+                                                       return true;

                                                }
                                        }
                                }
                                                }
                                        }
                                }


@@ -710,7 +674,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                        break;
        }
 
                        break;
        }
 

-       return FALSE;
+       return false;

 }
 
 
 }
 
 


@@ -733,14 +697,15 @@ static void DemodInit(uint8_t *data)
 
 /*
  *  Demodulate the samples we received from the tag, also log to tracebuffer
 
 /*
  *  Demodulate the samples we received from the tag, also log to tracebuffer

- *  quiet: set to 'TRUE' to disable debug output
+ *  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;
-
+static int GetSamplesFor14443bDemod(int timeout, bool quiet) {
+       int ret = 0;
+       int maxBehindBy = 0;
+       bool gotFrame = false;
+       int lastRxCounter, samples = 0;
+       int8_t ci, cq;
+       

        // Allocate memory from BigBuf for some buffers
        // free all previous allocations first
        BigBuf_free();
        // Allocate memory from BigBuf for some buffers
        // free all previous allocations first
        BigBuf_free();


@@ -749,61 +714,72 @@ static void GetSamplesFor14443bDemod(int n, bool quiet)
        uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
 
        // The DMA buffer, used to stream samples from the FPGA
        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);
+       uint16_t *dmaBuf = (uint16_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE * sizeof(uint16_t));

 
        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse);
 
 
        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse);
 

+       // wait for last transfer to complete
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY))
+

        // Setup and start DMA.
        // Setup and start DMA.

+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
 
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
 

-       int8_t *upTo = dmaBuf;
+       uint16_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
        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);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_848_KHZ | FPGA_HF_READER_MODE_RECEIVE_IQ);

 
        for(;;) {
 
        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;
-                       }
+               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1);
+               if(behindBy > maxBehindBy) {
+                       maxBehindBy = behindBy;
+               }

 
 

-                       samples += 2;
+               if(behindBy < 1) continue;

 
 

-                       if(Handle14443bSamplesDemod(ci, cq)) {
-                               gotFrame = TRUE;
-                               break;
-                       }
+               ci = *upTo >> 8;
+               cq = *upTo;
+               upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {               // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning
+                       lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;  // DMA Next Counter registers
+               }
+               samples++;
+
+               if (Handle14443bSamplesDemod(ci, cq)) {
+                       ret = Demod.len;
+                       gotFrame = true;
+                       break;

                }
 
                }
 

-               if(samples > n || gotFrame) {
+               if(samples > timeout && Demod.state < DEMOD_PHASE_REF_TRAINING) {
+                       ret = -1;
+                       LED_C_OFF();

                        break;
                }
        }
 
                        break;
                }
        }
 

-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+       FpgaDisableSscDma();
+
+       if (!quiet) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.len = %d, Demod.sumI = %d, Demod.sumQ = %d", maxBehindBy, samples, gotFrame, Demod.len, Demod.sumI, Demod.sumQ);

 
 

-       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);
+       if (ret < 0) {
+               return ret;

        }
        }

+       //Tracing
+       LogTrace(Demod.output, Demod.len, 0, 0, NULL, false);
+
+       return ret;

 }
 
 
 }
 
 


@@ -812,48 +788,21 @@ static void GetSamplesFor14443bDemod(int n, bool quiet)
 //-----------------------------------------------------------------------------
 static void TransmitFor14443b(void)
 {
 //-----------------------------------------------------------------------------
 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
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_SHALLOW_MOD);

        LED_B_ON();
        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;
+       for(int c = 0; c < ToSendMax; c++) {
+               uint8_t data = ToSend[c];
+               for (int i = 0; i < 8; i++) {
+                       uint16_t send_word = (data & 0x80) ? 0x0000 : 0xffff;
+                       while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
+                       AT91C_BASE_SSC->SSC_THR = send_word;
+                       while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
+                       AT91C_BASE_SSC->SSC_THR = send_word;
+                       data <<= 1;

                }
                WDT_HIT();
        }
                }
                WDT_HIT();
        }

-       LED_B_OFF(); // Finished sending
+       LED_B_OFF();

 }
 
 
 }
 
 


@@ -868,19 +817,14 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 
        ToSendReset();
 
 
        ToSendReset();
 

-       // Establish initial reference level
-       for(i = 0; i < 40; i++) {
-               ToSendStuffBit(1);
-       }

        // Send SOF
        for(i = 0; i < 10; i++) {
                ToSendStuffBit(0);
        }
        // Send SOF
        for(i = 0; i < 10; i++) {
                ToSendStuffBit(0);
        }

+       ToSendStuffBit(1);
+       ToSendStuffBit(1);

 
        for(i = 0; i < len; i++) {
 
        for(i = 0; i < len; i++) {

-               // Stop bits/EGT
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);

                // Start bit
                ToSendStuffBit(0);
                // Data bits
                // Start bit
                ToSendStuffBit(0);
                // Data bits


@@ -893,19 +837,18 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
                        }
                        b >>= 1;
                }
                        }
                        b >>= 1;
                }

+               // Stop bit
+               ToSendStuffBit(1);

        }
        }

+

        // Send EOF
        // Send EOF

-       ToSendStuffBit(1);

        for(i = 0; i < 10; i++) {
                ToSendStuffBit(0);
        }
        for(i = 0; i < 10; i++) {
                ToSendStuffBit(0);
        }

-       for(i = 0; i < 8; i++) {
-               ToSendStuffBit(1);
-       }
+       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++) {
+       // ensure that last byte is filled up
+       for(i = 0; i < 8; i++) {

                ToSendStuffBit(1);
        }
 
                ToSendStuffBit(1);
        }
 


@@ -921,17 +864,14 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 {
        CodeIso14443bAsReader(cmd, len);
        TransmitFor14443b();
 {
        CodeIso14443bAsReader(cmd, len);
        TransmitFor14443b();

-       if (tracing) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               LogTrace(cmd,len, 0, 0, parity, TRUE);
-       }
+       LogTrace(cmd,len, 0, 0, NULL, true);

 }
 
 /* Sends an APDU to the tag
  * TODO: check CRC and preamble
  */
 }
 
 /* Sends an APDU to the tag
  * TODO: check CRC and preamble
  */

-int iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *response)
-{
+int iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *response) {
+       LED_A_ON();

        uint8_t message_frame[message_length + 4];
        // PCB
        message_frame[0] = 0x0A | pcb_blocknum;
        uint8_t message_frame[message_length + 4];
        // PCB
        message_frame[0] = 0x0A | pcb_blocknum;


@@ -945,18 +885,19 @@ int iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *respo
        // send
        CodeAndTransmit14443bAsReader(message_frame, message_length + 4);
        // get response
        // send
        CodeAndTransmit14443bAsReader(message_frame, message_length + 4);
        // get response

-       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT*100, TRUE);
-       if(Demod.len < 3)
-       {
+       int ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+       FpgaDisableTracing();
+       if (ret < 3) {
+               LED_A_OFF();

                return 0;
        }
        // TODO: Check CRC
        // copy response contents
                return 0;
        }
        // TODO: Check CRC
        // copy response contents

-       if(response != NULL)
-       {
+       if (response != NULL) {

                memcpy(response, Demod.output, Demod.len);
        }
                memcpy(response, Demod.output, Demod.len);
        }

-       return Demod.len;
+       LED_A_OFF();
+       return ret;

 }
 
 /* Perform the ISO 14443 B Card Selection procedure
 }
 
 /* Perform the ISO 14443 B Card Selection procedure


@@ -975,10 +916,9 @@ int iso14443b_select_card()
 
        // first, wake up the tag
        CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
 
        // first, wake up the tag
        CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));

-       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       int ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

        // ATQB too short?
        // ATQB too short?

-       if (Demod.len < 14)
-       {
+       if (ret < 14) {

                return 2;
        }
 
                return 2;
        }
 


@@ -990,10 +930,9 @@ int iso14443b_select_card()
     attrib[7] = Demod.output[10] & 0x0F;
     ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
     CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));
     attrib[7] = Demod.output[10] & 0x0F;
     ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
     CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));

-    GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+    ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

     // Answer to ATTRIB too short?
     // Answer to ATTRIB too short?

-    if(Demod.len < 3)
-       {
+    if (ret < 3) {

                return 2;
        }
        // reset PCB block number
                return 2;
        }
        // reset PCB block number


@@ -1005,16 +944,13 @@ int iso14443b_select_card()
 void iso14443b_setup() {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Set up the synchronous serial port
 void iso14443b_setup() {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        // Set up the synchronous serial port

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

        // connect Demodulated Signal to ADC:
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Signal field is on with the appropriate LED
     LED_D_ON();
        // connect Demodulated Signal to ADC:
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Signal field is on with the appropriate LED
     LED_D_ON();

-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
-
-       // Start the timer
-       StartCountSspClk();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_SHALLOW_MOD);

 
        DemodReset();
        UartReset();
 
        DemodReset();
        UartReset();


@@ -1031,6 +967,7 @@ void iso14443b_setup() {
 //-----------------------------------------------------------------------------
 void ReadSTMemoryIso14443b(uint32_t dwLast)
 {
 //-----------------------------------------------------------------------------
 void ReadSTMemoryIso14443b(uint32_t dwLast)
 {

+       LED_A_ON();

        uint8_t i = 0x00;
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        uint8_t i = 0x00;
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);


@@ -1041,24 +978,26 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        SpinDelay(200);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        SpinDelay(200);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

 
        // Now give it time to spin up.
        // Signal field is on with the appropriate LED
        LED_D_ON();
 
        // 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);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_SHALLOW_MOD);

        SpinDelay(200);
 
        clear_trace();
        SpinDelay(200);
 
        clear_trace();

-       set_tracing(TRUE);
+       set_tracing(true);

 
        // First command: wake up the tag using the INITIATE command
        uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
 
        // 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);
+       int ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

 
 

-       if (Demod.len == 0) {
+       if (ret < 0) {
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                DbpString("No response from tag");
                DbpString("No response from tag");

+               LEDsoff();

                return;
        } else {
                Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
                return;
        } else {
                Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",


@@ -1071,20 +1010,26 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));

-       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

        if (Demod.len != 3) {
        if (Demod.len != 3) {

+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
                Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);

+               LEDsoff();

                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]) {
                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]) {

+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                DbpString("CRC Error reading select response.");
                DbpString("CRC Error reading select response.");

+               LEDsoff();

                return;
        }
        // Check response from the tag: should be the same UID as the command we just sent:
        if (cmd1[1] != Demod.output[0]) {
                return;
        }
        // Check response from the tag: should be the same UID as the command we just sent:
        if (cmd1[1] != Demod.output[0]) {

+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
                Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);

+               LEDsoff();

                return;
        }
 
                return;
        }
 


@@ -1093,9 +1038,11 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        cmd1[0] = 0x0B;
        ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
        CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
        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) {
+       ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+       if (ret != 10) {
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
                Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);

+               LEDsoff();

                return;
        }
        // The check the CRC of the answer (use cmd1 as temporary variable):
                return;
        }
        // The check the CRC of the answer (use cmd1 as temporary variable):


@@ -1122,14 +1069,16 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
                cmd1[1] = i;
                ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
                CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
                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
+               ret = GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+               if (ret != 6) { // Check if we got an answer from the tag
+                       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

                        DbpString("Expected 6 bytes from tag, got less...");
                        DbpString("Expected 6 bytes from tag, got less...");

+                       LEDsoff();

                        return;
                }
                // The check the CRC of the answer (use cmd1 as temporary variable):
                ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
                        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]) {
+               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 ?)
                        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 ?)


@@ -1143,6 +1092,9 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
                }
                i++;
        }
                }
                i++;
        }

+       
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LEDsoff();

 }
 
 
 }
 
 


@@ -1165,22 +1117,18 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
  */
 void RAMFUNC SnoopIso14443b(void)
 {
  */
 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
-
+       LED_A_ON();

        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        BigBuf_free();
 
        clear_trace();
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        BigBuf_free();
 
        clear_trace();

-       set_tracing(TRUE);
+       set_tracing(true);

 
        // The DMA buffer, used to stream samples from the FPGA
 
        // The DMA buffer, used to stream samples from the FPGA

-       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
+       uint16_t *dmaBuf = (uint16_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE * sizeof(uint16_t));

        int lastRxCounter;
        int lastRxCounter;

-       int8_t *upTo;
-       int ci, cq;
+       uint16_t *upTo;
+       int8_t ci, cq;

        int maxBehindBy = 0;
 
        // Count of samples received so far, so that we can include timing
        int maxBehindBy = 0;
 
        // Count of samples received so far, so that we can include timing


@@ -1197,64 +1145,63 @@ void RAMFUNC SnoopIso14443b(void)
        Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
        Dbprintf("  DMA: %i bytes", ISO14443B_DMA_BUFFER_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();
+       // Signal field is off
+       LED_D_OFF();

 
        // And put the FPGA in the appropriate mode
 
        // 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);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_848_KHZ | FPGA_HF_READER_MODE_SNOOP_IQ);

        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Setup for the DMA.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // Setup for the DMA.

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

        upTo = dmaBuf;
        lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
        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;
+       bool TagIsActive = false;
+       bool ReaderIsActive = false;
+       // 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
+       // reader command
+       bool triggered = false;

 
        // And now we loop, receiving samples.
        for(;;) {
 
        // And now we loop, receiving samples.
        for(;;) {

-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
-                                                               (ISO14443B_DMA_BUFFER_SIZE-1);
+               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1);

                if(behindBy > maxBehindBy) {
                        maxBehindBy = behindBy;
                }
 
                if(behindBy > maxBehindBy) {
                        maxBehindBy = behindBy;
                }
 

-               if(behindBy < 2) continue;
+               if(behindBy < 1) continue;

 
 

-               ci = upTo[0];
-               cq = upTo[1];
-               upTo += 2;
-               lastRxCounter -= 2;
-               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
-                       upTo = dmaBuf;
+               ci = *upTo>>8;
+               cq = *upTo;
+               upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {               // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning again

                        lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
                        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");
+                       if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { 
+                               Dbprintf("About to blow circular buffer - aborted! behindBy=%d", behindBy);

                                break;
                        }
                                break;
                        }

+               }
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;  // DMA Next Counter registers
+                       WDT_HIT();

                        if(BUTTON_PRESS()) {
                                DbpString("cancelled");
                                break;
                        }
                }
 
                        if(BUTTON_PRESS()) {
                                DbpString("cancelled");
                                break;
                        }
                }
 

-               samples += 2;
+               samples++;

 
                if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
                        if(Handle14443bUartBit(ci & 0x01)) {
 
                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);
-                               }
+                               triggered = true;
+                               LogTrace(Uart.output, Uart.byteCnt, samples, samples, NULL, true);

                                /* And ready to receive another command. */
                                UartReset();
                                /* And also reset the demod code, which might have been */
                                /* And ready to receive another command. */
                                UartReset();
                                /* And also reset the demod code, which might have been */


@@ -1262,9 +1209,8 @@ void RAMFUNC SnoopIso14443b(void)
                                DemodReset();
                        }
                        if(Handle14443bUartBit(cq & 0x01)) {
                                DemodReset();
                        }
                        if(Handle14443bUartBit(cq & 0x01)) {

-                               if(triggered && tracing) {
-                                       LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
-                               }
+                               triggered = true;
+                               LogTrace(Uart.output, Uart.byteCnt, samples, samples, NULL, true);

                                /* And ready to receive another command. */
                                UartReset();
                                /* And also reset the demod code, which might have been */
                                /* And ready to receive another command. */
                                UartReset();
                                /* And also reset the demod code, which might have been */


@@ -1274,17 +1220,10 @@ void RAMFUNC SnoopIso14443b(void)
                        ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
                }
 
                        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)) {
-
+               if (!ReaderIsActive && triggered) {                                             // no need to try decoding tag data if the reader is sending or not yet triggered
+                       if (Handle14443bSamplesDemod(ci/2, cq/2) >= 0) {

                                //Use samples as a time measurement
                                //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;
-
+                               LogTrace(Demod.output, Demod.len, samples, samples, NULL, false);

                                // And ready to receive another response.
                                DemodReset();
                        }
                                // And ready to receive another response.
                                DemodReset();
                        }


@@ -1294,14 +1233,13 @@ void RAMFUNC SnoopIso14443b(void)
        }
 
        FpgaDisableSscDma();
        }
 
        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());
        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());

+       LEDsoff();

 }
 
 
 }
 
 


@@ -1319,25 +1257,36 @@ void RAMFUNC SnoopIso14443b(void)
  */
 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {
  */
 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {

+       LED_A_ON();

        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+
+       // switch field on and give tag some time to power up
+       LED_D_ON();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_SHALLOW_MOD);
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
+       SpinDelay(10);

 
        if (datalen){
 
        if (datalen){

-               set_tracing(TRUE);
+               set_tracing(true);

                
                CodeAndTransmit14443bAsReader(data, datalen);
 
                
                CodeAndTransmit14443bAsReader(data, datalen);
 

-               if(recv) {
-                       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+               if (recv) {
+                       int ret = GetSamplesFor14443bDemod(5*RECEIVE_SAMPLES_TIMEOUT, true);
+                       FpgaDisableTracing();

                        uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
                        uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);

-                       cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
+                       cmd_send(CMD_ACK, ret, 0, 0, Demod.output, iLen);

                }
                }

+
+               FpgaDisableTracing();

        }
 
        }
 

-       if(!powerfield) {
+       if (!powerfield) {

                FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                LED_D_OFF();
        }
                FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
                LED_D_OFF();
        }

+       
+       LED_A_OFF();

 }
 
 }