FIX: 'data print' - now don't crash the client when demodbuffer is empty

[proxmark3-svn] / armsrc / iso14443b.c

diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index be43d47e2cbb8317741acd756573d10f37f0b5c1..ed035d3a5e29d780a248da43ea2ca14dbee41e69 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -11,7 +11,8 @@
 #include "iso14443b.h"
 
 #ifndef FWT_TIMEOUT_14B
 #include "iso14443b.h"
 
 #ifndef FWT_TIMEOUT_14B

-# define FWT_TIMEOUT_14B 60000
+// defaults to 2000ms
+# define FWT_TIMEOUT_14B 35312

 #endif
 #ifndef ISO14443B_DMA_BUFFER_SIZE
 # define ISO14443B_DMA_BUFFER_SIZE 256
 #endif
 #ifndef ISO14443B_DMA_BUFFER_SIZE
 # define ISO14443B_DMA_BUFFER_SIZE 256


@@ -37,29 +38,19 @@
 // 4sample
 #define SEND4STUFFBIT(x) ToSendStuffBit(x);ToSendStuffBit(x);ToSendStuffBit(x);ToSendStuffBit(x);
 //#define SEND4STUFFBIT(x) ToSendStuffBit(x);
 // 4sample
 #define SEND4STUFFBIT(x) ToSendStuffBit(x);ToSendStuffBit(x);ToSendStuffBit(x);ToSendStuffBit(x);
 //#define SEND4STUFFBIT(x) ToSendStuffBit(x);

+ // iceman, this threshold value,  what makes 8 a good amplituted for this IQ values? 
+#ifndef SUBCARRIER_DETECT_THRESHOLD
+# define SUBCARRIER_DETECT_THRESHOLD   8
+#endif

 
 

+static void iso14b_set_timeout(uint32_t timeout);
+static void iso14b_set_maxframesize(uint16_t size);

 static void switch_off(void);
 
 // the block number for the ISO14443-4 PCB  (used with APDUs)
 static uint8_t pcb_blocknum = 0;
 static void switch_off(void);
 
 // the block number for the ISO14443-4 PCB  (used with APDUs)
 static uint8_t pcb_blocknum = 0;

-

 static uint32_t iso14b_timeout = FWT_TIMEOUT_14B;
 static uint32_t iso14b_timeout = FWT_TIMEOUT_14B;

-// param timeout is in ftw_ 
-void iso14b_set_timeout(uint32_t timeout) {
-       // 9.4395us = 1etu.
-       // clock is about 1.5 us
-       iso14b_timeout = timeout;
-       if(MF_DBGLEVEL >= 2) Dbprintf("ISO14443B Timeout set to %ld fwt", iso14b_timeout);
-}

 
 

-static void switch_off(void){  
-       if (MF_DBGLEVEL > 3) Dbprintf("switch_off");
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(100);
-       FpgaDisableSscDma();
-       set_tracing(FALSE);
-       LEDsoff();      
-}

 
 //=============================================================================
 // An ISO 14443 Type B tag. We listen for commands from the reader, using
 
 //=============================================================================
 // An ISO 14443 Type B tag. We listen for commands from the reader, using


@@ -150,6 +141,44 @@ static void DemodInit(uint8_t *data) {
        //      memset(Demod.output, 0x00, MAX_FRAME_SIZE); 
 }
 
        //      memset(Demod.output, 0x00, MAX_FRAME_SIZE); 
 }
 

+
+/*
+* 9.4395 us = 1 ETU  and clock is about 1.5 us
+* 13560000Hz 
+* 1000ms/s
+* timeout in ETUs (time to transfer 1 bit, 9.4395 us)
+*
+* Formula to calculate FWT (in ETUs) by timeout (in ms):
+* fwt = 13560000 * 1000 / (8*16) * timeout; 
+* Sample:  3sec == 3000ms
+*  13560000 * 1000 / (8*16) * 3000  == 
+*    13560000000 / 384000 = 35312 FWT
+* @param timeout is in frame wait time, fwt, measured in ETUs
+*/ 
+static void iso14b_set_timeout(uint32_t timeout) {
+       #define MAX_TIMEOUT 40542464    // 13560000Hz * 1000ms / (2^32-1) * (8*16)
+       if(timeout > MAX_TIMEOUT)
+               timeout = MAX_TIMEOUT;
+
+       iso14b_timeout = timeout;
+       if(MF_DBGLEVEL >= 3) Dbprintf("ISO14443B Timeout set to %ld fwt", iso14b_timeout);
+}
+static void iso14b_set_maxframesize(uint16_t size) {
+       if (size > 256)
+               size = MAX_FRAME_SIZE;
+       
+       Uart.byteCntMax = size;
+       if(MF_DBGLEVEL >= 3) Dbprintf("ISO14443B Max frame size set to %d bytes", Uart.byteCntMax);
+}
+static void switch_off(void){  
+       if (MF_DBGLEVEL > 3) Dbprintf("switch_off");
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelay(100);
+       FpgaDisableSscDma();
+       set_tracing(FALSE);
+       LEDsoff();      
+}
+

 void AppendCrc14443b(uint8_t* data, int len) {
        ComputeCrc14443(CRC_14443_B, data, len, data+len, data+len+1);
 }
 void AppendCrc14443b(uint8_t* data, int len) {
        ComputeCrc14443(CRC_14443_B, data, len, data+len, data+len+1);
 }


@@ -187,16 +216,19 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
        *  -TO VERIFY THIS BELOW-
        * The mode FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK which we use to simulate tag
        * works like this:  
        *  -TO VERIFY THIS BELOW-
        * The mode FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK which we use to simulate tag
        * works like this:  

-       * - A 1-bit input to the FPGA becomes 8 pulses at 847.5kHz (9.44µS)
-       * - A 0-bit input to the FPGA becomes an unmodulated time of 9.44µS
-       *
+       * - A 1-bit input to the FPGA becomes 8 pulses at 847.5kHz (1.18µS / pulse) == 9.44us
+       * - A 0-bit input to the FPGA becomes an unmodulated time of 1.18µS  or does it become 8 nonpulses for 9.44us

        *
        *

+       * FPGA doesn't seem to work with ETU.  It seems to work with pulse / duration instead.

        * 
        * Card sends data ub 847.e kHz subcarrier
        * 
        * Card sends data ub 847.e kHz subcarrier

-       * 848k = 9.44µS  = 128 fc
-       * 424k = 18.88µS = 256 fc
-       * 212k = 37.76µS = 512 fc
-       * 106k = 75.52µS = 1024 fc
+       * subcar |duration| FC division
+       * -------+--------+------------
+       * 106kHz | 9.44µS | FC/128
+       * 212kHz | 4.72µS | FC/64
+       * 424kHz | 2.36µS | FC/32
+       * 848kHz | 1.18µS | FC/16
+       * -------+--------+------------

        *
        *  Reader data transmission:
        *   - no modulation ONES
        *
        *  Reader data transmission:
        *   - no modulation ONES


@@ -208,7 +240,7 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
        *  Card data transmission
        *   - TR1
        *   - SOF
        *  Card data transmission
        *   - TR1
        *   - SOF

-       *   - data  (each bytes is:  1startbit,8bits, 1stopbit)
+       *   - data  (each bytes is:  1startbit, 8bits, 1stopbit)

        *   - CRC_B
        *   - EOF
        *
        *   - CRC_B
        *   - EOF
        *


@@ -251,13 +283,14 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
                // Data bits
                b = cmd[i];
                for(j = 0; j < 8; ++j) {
                // Data bits
                b = cmd[i];
                for(j = 0; j < 8; ++j) {

-                       if(b & 1) { 
-                               SEND4STUFFBIT(1); 
-                               //ToSendStuffBit(1);
-                       } else {
-                               SEND4STUFFBIT(0);
-                               //ToSendStuffBit(0);
-                       }
+                       // if(b & 1) { 
+                               // SEND4STUFFBIT(1); 
+                               // //ToSendStuffBit(1);
+                       // } else {
+                               // SEND4STUFFBIT(0);
+                               // //ToSendStuffBit(0);
+                       // }
+                       SEND4STUFFBIT( b & 1 );

                        b >>= 1;
                }
 
                        b >>= 1;
                }
 


@@ -298,9 +331,9 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
  *          false if we are still waiting for some more
  */
 static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
  *          false if we are still waiting for some more
  */
 static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {

-       switch(Uart.state) {
+       switch (Uart.state) {

                case STATE_UNSYNCD:
                case STATE_UNSYNCD:

-                       if(!bit) {
+                       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;
                                // we went low, so this could be the beginning of an SOF
                                Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
                                Uart.posCnt = 0;


@@ -310,9 +343,9 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
 
                case STATE_GOT_FALLING_EDGE_OF_SOF:
                        Uart.posCnt++;
 
                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) {
+                       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;
                                                // we've seen enough consecutive
                                                // zeros that it's a valid SOF
                                                Uart.posCnt = 0;


@@ -320,8 +353,7 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
                                                Uart.state = STATE_AWAITING_START_BIT;
                                                LED_A_ON(); // Indicate we got a valid SOF
                                        } else {
                                                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
+                                               // didn't stay down long enough before going high, error

                                                Uart.state = STATE_UNSYNCD;
                                        }
                                } else {
                                                Uart.state = STATE_UNSYNCD;
                                        }
                                } else {


@@ -329,10 +361,9 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
                                }
                                Uart.bitCnt++;
                        }
                                }
                                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.
+                       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;
                        }
                                LED_A_OFF();
                                Uart.state = STATE_UNSYNCD;
                        }


@@ -340,10 +371,9 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
 
                case STATE_AWAITING_START_BIT:
                        Uart.posCnt++;
 
                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
+                       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 {
                                        Uart.state = STATE_UNSYNCD;
                                }
                        } else {


@@ -357,26 +387,26 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
 
                case STATE_RECEIVING_DATA:
                        Uart.posCnt++;
 
                case STATE_RECEIVING_DATA:
                        Uart.posCnt++;

-                       if(Uart.posCnt == 2) {
+                       if (Uart.posCnt == 2) {

                                // time to sample a bit
                                Uart.shiftReg >>= 1;
                                // time to sample a bit
                                Uart.shiftReg >>= 1;

-                               if(bit) {
+                               if (bit) {

                                        Uart.shiftReg |= 0x200;
                                }
                                Uart.bitCnt++;
                        }
                                        Uart.shiftReg |= 0x200;
                                }
                                Uart.bitCnt++;
                        }

-                       if(Uart.posCnt >= 4) {
+                       if (Uart.posCnt >= 4) {

                                Uart.posCnt = 0;
                        }
                                Uart.posCnt = 0;
                        }

-                       if(Uart.bitCnt == 10) {
-                               if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
+                       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++;
 
                                {
                                        // 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) {
+                                       if (Uart.byteCnt >= Uart.byteCntMax) {

                                                // Buffer overflowed, give up
                                                LED_A_OFF();
                                                Uart.state = STATE_UNSYNCD;
                                                // Buffer overflowed, give up
                                                LED_A_OFF();
                                                Uart.state = STATE_UNSYNCD;


@@ -389,9 +419,9 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
                                        // this is an EOF byte
                                        LED_A_OFF(); // Finished receiving
                                        Uart.state = STATE_UNSYNCD;
                                        // this is an EOF byte
                                        LED_A_OFF(); // Finished receiving
                                        Uart.state = STATE_UNSYNCD;

-                                       if (Uart.byteCnt != 0) {
-                                       return TRUE;
-                                       }
+                                       if (Uart.byteCnt != 0)
+                                               return TRUE;
+                                       

                                } else {
                                        // this is an error
                                        LED_A_OFF();
                                } else {
                                        // this is an error
                                        LED_A_OFF();


@@ -405,7 +435,6 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
                        Uart.state = STATE_UNSYNCD;
                        break;
        }
                        Uart.state = STATE_UNSYNCD;
                        break;
        }

-

        return FALSE;
 }
 
        return FALSE;
 }
 


@@ -427,7 +456,7 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len) {
                
        StartCountSspClk();
        
                
        StartCountSspClk();
        

-       volatile uint8_t b;
+       volatile uint8_t b = 0;

 
        // clear receiving shift register and holding register
        // What does this loop do? Is it TR1?
 
        // clear receiving shift register and holding register
        // What does this loop do? Is it TR1?


@@ -441,7 +470,6 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len) {
        // Now run a `software UART' on the stream of incoming samples.
        UartInit(received);
 
        // Now run a `software UART' on the stream of incoming samples.
        UartInit(received);
 

-       b = 0;

        uint8_t mask;
        while( !BUTTON_PRESS() ) {
                WDT_HIT();
        uint8_t mask;
        while( !BUTTON_PRESS() ) {
                WDT_HIT();


@@ -464,15 +492,14 @@ void ClearFpgaShiftingRegisters(void){
        volatile uint8_t b;
 
        // clear receiving shift register and holding register
        volatile uint8_t b;
 
        // clear receiving shift register and holding register

-       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};

 
        b = AT91C_BASE_SSC->SSC_RHR; (void) b;
 
 
        b = AT91C_BASE_SSC->SSC_RHR; (void) b;
 

-       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};

 
        b = AT91C_BASE_SSC->SSC_RHR; (void) b;
 
        b = AT91C_BASE_SSC->SSC_RHR; (void) b;

-       
-               
+                       

        // wait for the FPGA to signal fdt_indicator == 1 (the FPGA is ready to queue new data in its delay line)
        for (uint8_t j = 0; j < 5; j++) {       // allow timeout - better late than never
                while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
        // wait for the FPGA to signal fdt_indicator == 1 (the FPGA is ready to queue new data in its delay line)
        for (uint8_t j = 0; j < 5; j++) {       // allow timeout - better late than never
                while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));


@@ -716,13 +743,9 @@ void SimulateIso14443bTag(uint32_t pupi) {
  *          false if we are still waiting for some more
  *
  */
  *          false if we are still waiting for some more
  *
  */

- // iceman, this threshold value,  what makes 8 a good amplituted for this IQ values? 
-#ifndef SUBCARRIER_DETECT_THRESHOLD
-# define SUBCARRIER_DETECT_THRESHOLD   6
-#endif
-

 static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
 static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {

-       int v = 0, myI = 0, myQ = 0;
+       int v = 0, myI = ABS(ci), myQ = ABS(cq);
+

 // 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() { \
 // 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() { \


@@ -774,8 +797,6 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
 
 //note: couldn't we just use MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2) from common.h - marshmellow
 #define CHECK_FOR_SUBCARRIER() { \
 
 //note: couldn't we just use MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2) from common.h - marshmellow
 #define CHECK_FOR_SUBCARRIER() { \

-               myI = ABS(ci); \
-               myQ = ABS(cq); \

                v = MAX(myI, myQ) + (MIN(myI, myQ) >> 1); \
        }
 
                v = MAX(myI, myQ) + (MIN(myI, myQ) >> 1); \
        }
 


@@ -783,9 +804,9 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                case DEMOD_UNSYNCD:
 
                        CHECK_FOR_SUBCARRIER();
                case DEMOD_UNSYNCD:
 
                        CHECK_FOR_SUBCARRIER();

-
+               

                        // subcarrier detected
                        // subcarrier detected

-                       if(v > SUBCARRIER_DETECT_THRESHOLD) {
+                       if (v > SUBCARRIER_DETECT_THRESHOLD) {

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


@@ -794,7 +815,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                        break;
 
                case DEMOD_PHASE_REF_TRAINING:
                        break;
 
                case DEMOD_PHASE_REF_TRAINING:

-                       if(Demod.posCount < 8) {
+                       if (Demod.posCount < 8) {

 
                                CHECK_FOR_SUBCARRIER();
                                
 
                                CHECK_FOR_SUBCARRIER();
                                


@@ -817,7 +838,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                        
                        MAKE_SOFT_DECISION();
                        
                        
                        MAKE_SOFT_DECISION();
                        

-                       if(v < 0) {     // logic '0' detected
+                       if (v < 0) {    // logic '0' detected

                                Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
                                Demod.posCount = 0;     // start of SOF sequence
                        } else {
                                Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
                                Demod.posCount = 0;     // start of SOF sequence
                        } else {


@@ -832,13 +853,13 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                        
                        MAKE_SOFT_DECISION();
                        
                        
                        MAKE_SOFT_DECISION();
                        

-                       if(v > 0) {
+                       if (v > 0) {

                                // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
                                // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges

-                               if(Demod.posCount < 8*2) { 
+                               if (Demod.posCount < 8*2) { 

                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF
                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF

-                                       Demod.startTime = GetCountSspClk();
+                                       //Demod.startTime = GetCountSspClk();

                                        Demod.state = DEMOD_AWAITING_START_BIT;
                                        Demod.posCount = 0;
                                        Demod.len = 0;
                                        Demod.state = DEMOD_AWAITING_START_BIT;
                                        Demod.posCount = 0;
                                        Demod.len = 0;


@@ -884,7 +905,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                                Demod.thisBit += v;
                                Demod.shiftReg >>= 1;
 
                                Demod.thisBit += v;
                                Demod.shiftReg >>= 1;
 

-                               // logic '1'
+                               // OR in a logic '1'

                                if (Demod.thisBit > 0)  Demod.shiftReg |= 0x200;
 
                                ++Demod.bitCount;
                                if (Demod.thisBit > 0)  Demod.shiftReg |= 0x200;
 
                                ++Demod.bitCount;


@@ -895,18 +916,19 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                                        uint16_t s = Demod.shiftReg;
                                        
                                        // stop bit == '1', start bit == '0'
                                        uint16_t s = Demod.shiftReg;
                                        
                                        // stop bit == '1', start bit == '0'

-                                       if((s & 0x200) && !(s & 0x001)) { 
-                                               uint8_t b = (s >> 1);
-                                               Demod.output[Demod.len] = b;
+                                       if ((s & 0x200) && (s & 0x001) == 0 ) { 
+                                               // left shift to drop the startbit
+                                               Demod.output[Demod.len] =  (s >> 1) & 0xFF;

                                                ++Demod.len;
                                                Demod.state = DEMOD_AWAITING_START_BIT;
                                        } else {
                                                ++Demod.len;
                                                Demod.state = DEMOD_AWAITING_START_BIT;
                                        } else {

+                                               // this one is a bit hard,  either its a correc byte or its unsynced.

                                                Demod.state = DEMOD_UNSYNCD;
                                                Demod.state = DEMOD_UNSYNCD;

-                                               Demod.endTime = GetCountSspClk();
+                                               //Demod.endTime = GetCountSspClk();

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

-                                               if(s == 0) return TRUE;
+                                               if (s == 0) return TRUE;

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


@@ -929,7 +951,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
 static void GetTagSamplesFor14443bDemod() {
        bool gotFrame = FALSE, finished = FALSE;
        int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
 static void GetTagSamplesFor14443bDemod() {
        bool gotFrame = FALSE, finished = FALSE;
        int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;

-       int ci = 0, cq = 0, samples = 0;
+       int ci = 0, cq = 0;

        uint32_t time_0 = 0, time_stop = 0;
 
        BigBuf_free();
        uint32_t time_0 = 0, time_stop = 0;
 
        BigBuf_free();


@@ -963,8 +985,6 @@ static void GetTagSamplesFor14443bDemod() {
                ci = upTo[0] >> 1;
                cq = upTo[1] >> 1;
                upTo += 2;
                ci = upTo[0] >> 1;
                cq = upTo[1] >> 1;
                upTo += 2;

-               samples += 2;
-

                lastRxCounter -= 2;
 
                // restart DMA buffer to receive again.
                lastRxCounter -= 2;
 
                // restart DMA buffer to receive again.


@@ -976,7 +996,6 @@ static void GetTagSamplesFor14443bDemod() {
                }
 
                // https://github.com/Proxmark/proxmark3/issues/103
                }
 
                // https://github.com/Proxmark/proxmark3/issues/103

-               //gotFrame =  Handle14443bTagSamplesDemod(ci & 0xfe, cq & 0xfe);

                gotFrame =  Handle14443bTagSamplesDemod(ci, cq);
                time_stop = GetCountSspClk() - time_0;
 
                gotFrame =  Handle14443bTagSamplesDemod(ci, cq);
                time_stop = GetCountSspClk() - time_0;
 


@@ -984,21 +1003,23 @@ static void GetTagSamplesFor14443bDemod() {
        }
        
        FpgaDisableSscDma();
        }
        
        FpgaDisableSscDma();

-
+       
+       if ( upTo ) upTo = NULL;
+       

        if (MF_DBGLEVEL >= 3) {
        if (MF_DBGLEVEL >= 3) {

-               Dbprintf("time_stop = %u PDC_RCR = %u", time_stop,  AT91C_BASE_PDC_SSC->PDC_RCR);
-               Dbprintf("#Samples = %d, Demod.state = %d, Demod.len = %u",
-                       samples,                        
+               Dbprintf("Demod.state = %d, Demod.len = %u,  PDC_RCR = %u",     

                        Demod.state,
                        Demod.state,

-                       Demod.len
+                       Demod.len,
+                       AT91C_BASE_PDC_SSC->PDC_RCR

                );
        }
        
                );
        }
        

+       // print the last batch of IQ values from FPGA

        if (MF_DBGLEVEL == 4)
                Dbhexdump(ISO14443B_DMA_BUFFER_SIZE, (uint8_t *)dmaBuf, FALSE); 
        
        if ( Demod.len > 0 )
        if (MF_DBGLEVEL == 4)
                Dbhexdump(ISO14443B_DMA_BUFFER_SIZE, (uint8_t *)dmaBuf, FALSE); 
        
        if ( Demod.len > 0 )

-               LogTrace(Demod.output, Demod.len, Demod.startTime, Demod.endTime, NULL, FALSE);
+               LogTrace(Demod.output, Demod.len, time_0, time_stop, NULL, FALSE);

 }
 
 
 }
 
 


@@ -1055,8 +1076,7 @@ static void TransmitFor14443b_AsReader(void) {
 // Code a layer 2 command (string of octets, including CRC) into ToSend[],
 // so that it is ready to transmit to the tag using TransmitFor14443b().
 //-----------------------------------------------------------------------------
 // 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)
-{
+static void CodeIso14443bAsReader(const uint8_t *cmd, int len) {

        /*
        *  Reader data transmission:
        *   - no modulation ONES
        /*
        *  Reader data transmission:
        *   - no modulation ONES


@@ -1092,14 +1112,24 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
                ToSendStuffBit(0);
                // Data bits
                b = cmd[i];             
                ToSendStuffBit(0);
                // Data bits
                b = cmd[i];             

-               if (  b & 1 )    ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>1) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>2) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>3) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>4) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>5) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>6) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
-               if ( (b>>7) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);             
+               // if (  b & 1 )    ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>1) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>2) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>3) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>4) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>5) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>6) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);
+               // if ( (b>>7) & 1) ToSendStuffBit(1); else ToSendStuffBit(0);  
+
+               ToSendStuffBit(  b & 1); 
+               ToSendStuffBit( (b>>1) & 1);            
+               ToSendStuffBit( (b>>2) & 1); 
+               ToSendStuffBit( (b>>3) & 1); 
+               ToSendStuffBit( (b>>4) & 1); 
+               ToSendStuffBit( (b>>5) & 1); 
+               ToSendStuffBit( (b>>6) & 1);            
+               ToSendStuffBit( (b>>7) & 1); 
+               

                // Stop bit
                ToSendStuffBit(1);
                // EGT extra guard time
                // Stop bit
                ToSendStuffBit(1);
                // EGT extra guard time


@@ -1125,19 +1155,19 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 }
 
 
 }
 
 

-/**
-  Convenience function to encode, transmit and trace iso 14443b comms
-  **/
+/*
+*  Convenience function to encode, transmit and trace iso 14443b comms
+*/

 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len) {
 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len) {

+
+       uint32_t time_start = GetCountSspClk();

        
        CodeIso14443bAsReader(cmd, len);
        
        CodeIso14443bAsReader(cmd, len);

-       
-       uint32_t time_start = GetCountSspClk();

 
        TransmitFor14443b_AsReader();
 
        TransmitFor14443b_AsReader();

-       
+

        if(trigger) LED_A_ON();
        if(trigger) LED_A_ON();

-       
+

        LogTrace(cmd, len, time_start, GetCountSspClk()-time_start, NULL, TRUE);
 }
 
        LogTrace(cmd, len, time_start, GetCountSspClk()-time_start, NULL, TRUE);
 }
 


@@ -1283,10 +1313,23 @@ uint8_t iso14443b_select_card(iso14b_card_select_t *card )
     ComputeCrc14443(CRC_14443_B, Demod.output, Demod.len-2, &crc[0], &crc[1]);
        if ( crc[0] != Demod.output[1] || crc[1] != Demod.output[2] ) 
                return 3;
     ComputeCrc14443(CRC_14443_B, Demod.output, Demod.len-2, &crc[0], &crc[1]);
        if ( crc[0] != Demod.output[1] || crc[1] != Demod.output[2] ) 
                return 3;

-       
-       // CID
+

        if (card) { 
        if (card) { 

+       
+               // CID

                card->cid = Demod.output[0];
                card->cid = Demod.output[0];

+
+               // MAX FRAME
+               uint16_t maxFrame = card->atqb[5] >> 4;
+               if (maxFrame < 5)               maxFrame = 8 * maxFrame + 16;
+               else if (maxFrame == 5) maxFrame = 64;
+               else if (maxFrame == 6) maxFrame = 96;
+               else if (maxFrame == 7) maxFrame = 128;
+               else if (maxFrame == 8) maxFrame = 256;
+               else maxFrame = 257;
+               iso14b_set_maxframesize(maxFrame);
+               
+               // FWT 

                uint8_t fwt = card->atqb[6] >> 4;
                if ( fwt < 16 ){
                        uint32_t fwt_time = (302 << fwt);
                uint8_t fwt = card->atqb[6] >> 4;
                if ( fwt < 16 ){
                        uint32_t fwt_time = (302 << fwt);


@@ -1517,16 +1560,13 @@ static void iso1444b_setup_snoop(void){
 void RAMFUNC SnoopIso14443b(void) {
 
        uint32_t time_0 = 0, time_start = 0, time_stop = 0;
 void RAMFUNC SnoopIso14443b(void) {
 
        uint32_t time_0 = 0, time_start = 0, time_stop = 0;

-       
+       int ci = 0, cq = 0;
+       int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+

        // 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.
        // 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     
-       int ci, cq;
-       int maxBehindBy = 0;
-       //int behindBy  = 0;
-       int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
-       
+       bool triggered = TRUE;                  // TODO: set and evaluate trigger condition             

        bool TagIsActive = FALSE;
        bool ReaderIsActive = FALSE;
 
        bool TagIsActive = FALSE;
        bool ReaderIsActive = FALSE;
 


@@ -1549,26 +1589,10 @@ void RAMFUNC SnoopIso14443b(void) {
        for(;;) {
 
                WDT_HIT();
        for(;;) {
 
                WDT_HIT();

-               
-               /* iceman: the & (and) should do what?
-                       ISO14443B_DMA_BUFFER_SIZE = 256
-                       Should it be a "mod 255" ?
-                       
-                (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1);
-                
-               */
-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & RECEIVE_MASK;

 
 

-               if ( behindBy > maxBehindBy )
-                       maxBehindBy = behindBy;
-               
-               // this one needs the inner loop from tr
-               if ( behindBy < 2 ) continue;
-               

                ci = upTo[0];
                cq = upTo[1];
                ci = upTo[0];
                cq = upTo[1];

-               upTo += 2;
-               
+               upTo += 2;              

                lastRxCounter -= 2;
                
                if (upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
                lastRxCounter -= 2;
                
                if (upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {


@@ -1576,21 +1600,14 @@ void RAMFUNC SnoopIso14443b(void) {
                        lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
                        AT91C_BASE_PDC_SSC->PDC_RNCR = 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();
-                       
-                       // TODO: understand whether we can increase/decrease as we want or not?
-                       if ( behindBy > ( 9 * ISO14443B_DMA_BUFFER_SIZE/10) ) { 
-                               Dbprintf("blew circular buffer! behindBy = %d", behindBy);
-                               break;
-                       }
-                       
-                       if(!tracing) {
-                               DbpString("Trace full");
+               
+                       if (!tracing) {
+                               if (MF_DBGLEVEL >= 2) DbpString("Trace full");

                                break;
                        }
                                
                                break;
                        }
                                

-                       if(BUTTON_PRESS()) {
-                               DbpString("cancelled");
+                       if (BUTTON_PRESS()) {
+                               if (MF_DBGLEVEL >= 2) DbpString("cancelled");

                                break;
                        }
                }
                                break;
                        }
                }


@@ -1623,11 +1640,11 @@ void RAMFUNC SnoopIso14443b(void) {
                                if (triggered)
                                        LogTrace(Uart.output, Uart.byteCnt, time_start, time_stop, NULL, TRUE);
 
                                if (triggered)
                                        LogTrace(Uart.output, Uart.byteCnt, time_start, time_stop, NULL, 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();
+                               /* 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();

                        } else {
                                time_start = GetCountSspClk() - time_0;
                        }
                        } else {
                                time_start = GetCountSspClk() - time_0;
                        }


@@ -1635,10 +1652,11 @@ void RAMFUNC SnoopIso14443b(void) {
                        LED_A_OFF();
                }
                
                        LED_A_OFF();
                }
                

-               if(!ReaderIsActive) {
+               if (!ReaderIsActive) {

                        // no need to try decoding tag data if the reader is sending - and we cannot afford the time
                        // is this | 0x01 the error?   & 0xfe  in https://github.com/Proxmark/proxmark3/issues/103
                        // no need to try decoding tag data if the reader is sending - and we cannot afford the time
                        // is this | 0x01 the error?   & 0xfe  in https://github.com/Proxmark/proxmark3/issues/103

-                       if(Handle14443bTagSamplesDemod(ci & 0xFE, cq & 0xFE)) {
+                       // LSB is a fpga signal bit.
+                       if (Handle14443bTagSamplesDemod(ci >> 1, cq >> 1)) {

                                
                                time_stop = GetCountSspClk() - time_0;
                                
                                
                                time_stop = GetCountSspClk() - time_0;
                                


@@ -1658,12 +1676,11 @@ void RAMFUNC SnoopIso14443b(void) {
        switch_off(); // Snoop
        
        DbpString("Snoop statistics:");
        switch_off(); // Snoop
        
        DbpString("Snoop statistics:");

-       Dbprintf("  Max behind by: %i", maxBehindBy);

        Dbprintf("  Uart State: %x  ByteCount: %i  ByteCountMax: %i", Uart.state,  Uart.byteCnt,  Uart.byteCntMax);
        Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
 
        // free mem refs.
        Dbprintf("  Uart State: %x  ByteCount: %i  ByteCountMax: %i", Uart.state,  Uart.byteCnt,  Uart.byteCntMax);
        Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
 
        // free mem refs.

-       if ( upTo )   upTo = NULL;
+       if ( upTo ) upTo = NULL;

        
        // Uart.byteCntMax  should be set with ATQB value..
 }
        
        // Uart.byteCntMax  should be set with ATQB value..
 }