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FIX: strange bug in "lf em em410xwatch" , which the client crasches when it reads...
[proxmark3-svn] / armsrc / iso14443b.c
diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index e45402bc41171c90711bffbb8fa8b214c0d210a6..ed035d3a5e29d780a248da43ea2ca14dbee41e69 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -10,37 +10,47 @@
 //-----------------------------------------------------------------------------
 #include "iso14443b.h"
 
 //-----------------------------------------------------------------------------
 #include "iso14443b.h"
 
-#define RECEIVE_SAMPLES_TIMEOUT 50000
-#define ISO14443B_DMA_BUFFER_SIZE 256
+#ifndef FWT_TIMEOUT_14B
+// defaults to 2000ms
+# define FWT_TIMEOUT_14B 35312
+#endif
+#ifndef ISO14443B_DMA_BUFFER_SIZE
+# define ISO14443B_DMA_BUFFER_SIZE 256
+#endif
+#ifndef RECEIVE_MASK
+# define RECEIVE_MASK  (ISO14443B_DMA_BUFFER_SIZE-1)
+#endif
 
 // Guard Time (per 14443-2)
 
 // Guard Time (per 14443-2)
-#define TR0 0  
+#ifndef TR0
+# define TR0 0
+#endif
+
 // Synchronization time (per 14443-2)
 // Synchronization time (per 14443-2)
-#define TR1 0
+#ifndef TR1
+# define TR1 0
+#endif
 // Frame Delay Time PICC to PCD  (per 14443-3 Amendment 1)
 // Frame Delay Time PICC to PCD  (per 14443-3 Amendment 1)
-#define TR2 0
+#ifndef TR2
+# define TR2 0
+#endif
+
+// 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 = RECEIVE_SAMPLES_TIMEOUT;
-// 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
@@ -131,8 +141,46 @@ 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) {
 void AppendCrc14443b(uint8_t* data, int len) {
-       ComputeCrc14443(CRC_14443_B,data,len,data+len,data+len+1);
+       ComputeCrc14443(CRC_14443_B, data, len, data+len, data+len+1);
 }
 
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------
@@ -168,16 +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
@@ -189,7 +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
        *
@@ -200,9 +251,6 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
        *
        */
        
        *
        */
        
-       // ToSendStuffBit,  40 calls
-       // 1 ETU = 1startbit, 1stopbit, 8databits == 10bits.
-       // 1 ETU = 10 * 4 == 40 stuffbits ( ETU_TAG_BIT )
        int i,j;
        uint8_t b;
        
        int i,j;
        uint8_t b;
        
@@ -218,80 +266,52 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
 
        // Send SOF.
        // 10-11 ETU * 4times samples ZEROS
 
        // Send SOF.
        // 10-11 ETU * 4times samples ZEROS
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
+       for(i = 0; i < 10; i++) { SEND4STUFFBIT(0); }
+       //for(i = 0; i < 10; i++) { ToSendStuffBit(0); }
        
        // 2-3 ETU * 4times samples ONES
        
        // 2-3 ETU * 4times samples ONES
-       for(i = 0; i < 3; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
+       for(i = 0; i < 3; i++)  { SEND4STUFFBIT(1); }
+       //for(i = 0; i < 3; i++)  { ToSendStuffBit(1); }
        
        // data
        for(i = 0; i < len; ++i) {
                
                // Start bit
        
        // data
        for(i = 0; i < len; ++i) {
                
                // Start bit
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
+               SEND4STUFFBIT(0);
+               //ToSendStuffBit(0);
 
                // 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) {
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                       } else {
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                       }
+                       // if(b & 1) { 
+                               // SEND4STUFFBIT(1); 
+                               // //ToSendStuffBit(1);
+                       // } else {
+                               // SEND4STUFFBIT(0);
+                               // //ToSendStuffBit(0);
+                       // }
+                       SEND4STUFFBIT( b & 1 );
                        b >>= 1;
                }
 
                // Stop bit
                        b >>= 1;
                }
 
                // Stop bit
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
+               SEND4STUFFBIT(1);
+               //ToSendStuffBit(1);
                
                // Extra Guard bit
                // For PICC it ranges 0-18us (1etu = 9us)
                
                // Extra Guard bit
                // For PICC it ranges 0-18us (1etu = 9us)
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
+               SEND4STUFFBIT(1);
+               //ToSendStuffBit(1);
        }
 
        // Send EOF.
        // 10-11 ETU * 4 sample rate = ZEROS
        }
 
        // Send EOF.
        // 10-11 ETU * 4 sample rate = ZEROS
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
+       for(i = 0; i < 10; i++) { SEND4STUFFBIT(0); }
+       //for(i = 0; i < 10; i++) { ToSendStuffBit(0); }
        
        // why this?
        
        // why this?
-       for(i = 0; i < 40; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
+       for(i = 0; i < 40; i++) { SEND4STUFFBIT(1); }
+       //for(i = 0; i < 40; i++) { ToSendStuffBit(1); }
        
        // Convert from last byte pos to length
        ++ToSendMax;
        
        // Convert from last byte pos to length
        ++ToSendMax;
@@ -311,11 +331,10 @@ 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) {
-                               // we went low, so this could be the beginning
-                               // of an SOF
+                       if (!bit) {
+                               // we went low, so this could be the beginning of an SOF
                                Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
                                Uart.posCnt = 0;
                                Uart.bitCnt = 0;
                                Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
                                Uart.posCnt = 0;
                                Uart.bitCnt = 0;
@@ -324,9 +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;
@@ -334,8 +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 {
@@ -343,10 +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;
                        }
@@ -354,10 +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 {
@@ -371,26 +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;
@@ -403,9 +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();
@@ -419,7 +435,6 @@ static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
                        Uart.state = STATE_UNSYNCD;
                        break;
        }
                        Uart.state = STATE_UNSYNCD;
                        break;
        }
-
        return FALSE;
 }
 
        return FALSE;
 }
 
@@ -438,21 +453,31 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len) {
        // Signal field is off with the appropriate LED
        LED_D_OFF();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
        // Signal field is off with the appropriate LED
        LED_D_OFF();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
-       
+               
        StartCountSspClk();
        
        StartCountSspClk();
        
+       volatile uint8_t b = 0;
+
+       // clear receiving shift register and holding register
+       // What does this loop do? Is it TR1?
+       for(uint8_t c = 0; c < 10;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = 0xFF;
+                       ++c;
+               }
+       }
+       
        // 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);
-       uint8_t b = 0;
-       for(;;) {
-               WDT_HIT();
 
 
-               if(BUTTON_PRESS()) return FALSE;
+       uint8_t mask;
+       while( !BUTTON_PRESS() ) {
+               WDT_HIT();
 
 
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                       for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
-                               if(Handle14443bReaderUartBit(b & mask)) {
+               if ( AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY ) {
+                       b = (uint8_t) AT91C_BASE_SSC->SSC_RHR;
+                       for ( mask = 0x80; mask != 0; mask >>= 1) {
+                               if ( Handle14443bReaderUartBit(b & mask)) {
                                        *len = Uart.byteCnt;
                                        return TRUE;
                                }
                                        *len = Uart.byteCnt;
                                        return TRUE;
                                }
@@ -462,30 +487,77 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len) {
        return FALSE;
 }
 
        return FALSE;
 }
 
+void ClearFpgaShiftingRegisters(void){
+
+       volatile uint8_t b;
+
+       // clear receiving shift register and holding register
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};
+
+       b = AT91C_BASE_SSC->SSC_RHR; (void) b;
+
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};
+
+       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));
+               if (AT91C_BASE_SSC->SSC_RHR) break;
+       }
+       
+       // Clear TXRDY:
+       //AT91C_BASE_SSC->SSC_THR = 0xFF;
+}
+
+void WaitForFpgaDelayQueueIsEmpty( uint16_t delay ){
+       // Ensure that the FPGA Delay Queue is empty before we switch to TAGSIM_LISTEN again:
+       uint8_t fpga_queued_bits = delay >> 3;  // twich /8 ??   >>3, 
+       for (uint8_t i = 0; i <= fpga_queued_bits/8 + 1; ) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = 0xFF;
+                       i++;
+               }
+       }
+}
+
+static void TransmitFor14443b_AsTag( uint8_t *response, uint16_t len) {
+
+       volatile uint32_t b;
+       
+       // Signal field is off with the appropriate LED
+       LED_D_OFF();
+       //uint16_t fpgasendQueueDelay = 0;
+       
+       // Modulate BPSK
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
+       SpinDelay(40);
+       
+       ClearFpgaShiftingRegisters();
+       
+       FpgaSetupSsc();
+
+       // Transmit the response.
+       for(uint16_t i = 0; i < len;) {
+               if(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                       AT91C_BASE_SSC->SSC_THR = response[++i];
+               }
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       b = AT91C_BASE_SSC->SSC_RHR;
+                       (void)b;
+               }                       
+       }
+       
+       //WaitForFpgaDelayQueueIsEmpty(fpgasendQueueDelay);
+       AT91C_BASE_SSC->SSC_THR = 0xFF;         
+}      
 //-----------------------------------------------------------------------------
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------
-void SimulateIso14443bTag(void) {
-       // the only commands we understand is WUPB, AFI=0, Select All, N=1:
-       static const uint8_t cmd1[] = { ISO14443B_REQB, 0x00, 0x08, 0x39, 0x73 }; // WUPB
-       // ... and REQB, AFI=0, Normal Request, N=1:
-       static const uint8_t cmd2[] = { ISO14443B_REQB, 0x00, 0x00, 0x71, 0xFF }; // REQB
-       // ... and HLTB
-       static const uint8_t cmd3[] = { ISO14443B_HALT, 0xff, 0xff, 0xff, 0xff }; // HLTB
-       // ... and ATTRIB
-       static const uint8_t cmd4[] = { ISO14443B_ATTRIB, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; // ATTRIB
+void SimulateIso14443bTag(uint32_t pupi) {
 
 
-       // ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
-       // supports only 106kBit/s in both directions, max frame size = 32Bytes,
-       // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
-       static const uint8_t response1[] = {
-               0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
-               0x00, 0x21, 0x85, 0x5e, 0xd7
-       };
-       // response to HLTB and ATTRIB
-       static const uint8_t response2[] = {0x00, 0x78, 0xF0};
-                               
+       ///////////// setup device.
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        // allocate command receive buffer
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        // allocate command receive buffer
@@ -493,125 +565,160 @@ void SimulateIso14443bTag(void) {
        BigBuf_Clear_ext(false);
        clear_trace(); //sim
        set_tracing(TRUE);
        BigBuf_Clear_ext(false);
        clear_trace(); //sim
        set_tracing(TRUE);
-
-       const uint8_t *resp;
-       uint8_t *respCode;
-       uint16_t respLen, respCodeLen, len, cmdsRecvd = 0;
-       uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
-       
-       // prepare the (only one) tag answer:
-       CodeIso14443bAsTag(response1, sizeof(response1));
-       uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
-       memcpy(resp1Code, ToSend, ToSendMax); 
-       uint16_t resp1CodeLen = ToSendMax;
-       PrintToSendBuffer();
-       DbpString("Printing Resp1Code:");
-       Dbhexdump(resp1CodeLen, resp1Code, 0);
-       
-       // prepare the (other) tag answer:
-       CodeIso14443bAsTag(response2, sizeof(response2));
-       uint8_t *resp2Code = BigBuf_malloc(ToSendMax);
-       memcpy(resp2Code, ToSend, ToSendMax); 
-       uint16_t resp2CodeLen = ToSendMax;
-       PrintToSendBuffer();
-       
-       // We need to listen to the high-frequency, peak-detected path.
+       
+       // connect Demodulated Signal to ADC:
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Set up the synchronous serial port
        FpgaSetupSsc();
        FpgaSetupSsc();
+       /////////////
 
 
-       uint32_t time_0 =0;
-       uint32_t t2r_time =0;
-       uint32_t r2t_time =0;
-       cmdsRecvd = 0;
+       uint16_t len, cmdsReceived = 0;
+       int cardSTATE = SIM_NOFIELD;
+       int vHf = 0;    // in mV
+       // uint32_t time_0 = 0;
+       // uint32_t t2r_time = 0;
+       // uint32_t r2t_time = 0;
+       uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);   
+       
+       // the only commands we understand is WUPB, AFI=0, Select All, N=1:
+//     static const uint8_t cmdWUPB[] = { ISO14443B_REQB, 0x00, 0x08, 0x39, 0x73 }; // WUPB
+       // ... and REQB, AFI=0, Normal Request, N=1:
+//     static const uint8_t cmdREQB[] = { ISO14443B_REQB, 0x00, 0x00, 0x71, 0xFF }; // REQB
+       // ... and ATTRIB
+//     static const uint8_t cmdATTRIB[] = { ISO14443B_ATTRIB, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; // ATTRIB
 
 
-       for(;;) {
+       // ... if not PUPI/UID is supplied we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
+       // supports only 106kBit/s in both directions, max frame size = 32Bytes,
+       // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
+       uint8_t respATQB[] = {  0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 
+                                                       0x22, 0x00, 0x21, 0x85, 0x5e, 0xd7 };
+                                                       
+       // response to HLTB and ATTRIB
+       static const uint8_t respOK[] = {0x00, 0x78, 0xF0};
 
 
-               if (!GetIso14443bCommandFromReader(receivedCmd, &len)) {
-                       Dbprintf("button pressed, received %d commands", cmdsRecvd);
-                       break;
-               }
-               r2t_time = GetCountSspClk();
+       // ...PUPI/UID supplied from user. Adjust ATQB response accordingly
+       if ( pupi > 0 ) {
+               uint8_t len = sizeof(respATQB);
+               num_to_bytes(pupi, 4, respATQB+1);
+               ComputeCrc14443(CRC_14443_B, respATQB, 12, &respATQB[len-2], &respATQB[len-1]);
+       }
 
 
-               if (tracing) 
-                       LogTrace(receivedCmd, len, (r2t_time - time_0), (r2t_time - time_0), NULL, TRUE);       
-                       
+       // prepare "ATQB" tag answer (encoded):
+       CodeIso14443bAsTag(respATQB, sizeof(respATQB));
+       uint8_t *encodedATQB = BigBuf_malloc(ToSendMax);
+       uint16_t encodedATQBLen = ToSendMax;
+       memcpy(encodedATQB, ToSend, ToSendMax); 
 
 
-               // Good, look at the command now.
-               if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
-                       || (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0) ) {
-                       resp = response1; 
-                       respLen = sizeof(response1);
-                       respCode = resp1Code; 
-                       respCodeLen = resp1CodeLen;
-               } else if ( (len == sizeof(cmd3) && receivedCmd[0] == cmd3[0])
-                       || (len == sizeof(cmd4) && receivedCmd[0] == cmd4[0]) ) {
-                       resp = response2; 
-                       respLen = sizeof(response2);
-                       respCode = resp2Code; 
-                       respCodeLen = resp2CodeLen;
-               } else {
-                       Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
-
-                       // And print whether the CRC fails, just for good measure
-                       uint8_t b1, b2;
-                       if (len >= 3){ // if crc exists
-                               ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
-                               if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1])
-                                       DbpString("+++CRC fail");
-                               else
-                                       DbpString("CRC passes");
-                       }
-                       //get rid of compiler warning
-                       respCodeLen = 0;
-                       resp = response1;
-                       respLen = 0;
-                       respCode = resp1Code;
-                       //don't crash at new command just wait and see if reader will send other new cmds.
-                       //break;
-               }
+       
+       // prepare "OK" tag answer (encoded):
+       CodeIso14443bAsTag(respOK, sizeof(respOK));
+       uint8_t *encodedOK = BigBuf_malloc(ToSendMax);
+       uint16_t encodedOKLen = ToSendMax;      
+       memcpy(encodedOK, ToSend, ToSendMax); 
+       
+       // Simulation loop
+       while (!BUTTON_PRESS() && !usb_poll_validate_length()) {
+               WDT_HIT();
 
 
-               ++cmdsRecvd;
+               // find reader field
+               if (cardSTATE == SIM_NOFIELD) {
+                       vHf = (MAX_ADC_HF_VOLTAGE * AvgAdc(ADC_CHAN_HF)) >> 10;
+                       if ( vHf > MF_MINFIELDV ) {
+                               cardSTATE = SIM_IDLE; 
+                               LED_A_ON();
+                       }
+               } 
+               if (cardSTATE == SIM_NOFIELD) continue;
 
 
-               if(cmdsRecvd > 1000) {
-                       DbpString("1000 commands later...");
+               // Get reader command
+               if (!GetIso14443bCommandFromReader(receivedCmd, &len)) {
+                       Dbprintf("button pressed, received %d commands", cmdsReceived);
                        break;
                }
 
                        break;
                }
 
-               if(respCodeLen <= 0) continue;
-
-               // Modulate BPSK
-               // Signal field is off with the appropriate LED
-               LED_D_OFF();
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
-
-               AT91C_BASE_SSC->SSC_THR = 0xff;
-
-               FpgaSetupSsc();
-
-               // Transmit the response.
-               uint16_t i = 0;
-               volatile uint8_t b;
-               for(;;) {
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-
-                               AT91C_BASE_SSC->SSC_THR = respCode[i];
-                               i++;
-                               if(i > respCodeLen)
-                                       break;
-                       }
-                       
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                               (void)b;
+               // ISO14443-B protocol states:
+               // REQ or WUP request in ANY state 
+               // WUP in HALTED state
+               if (len == 5 ) {
+                               if ( (receivedCmd[0] == ISO14443B_REQB && (receivedCmd[2] & 0x8)== 0x8 && cardSTATE == SIM_HALTED) ||
+                     receivedCmd[0] == ISO14443B_REQB ){
+                               LogTrace(receivedCmd, len, 0, 0, NULL, TRUE);                                             
+                               cardSTATE = SIM_SELECTING;
                        }
                }
                
                        }
                }
                
-               t2r_time = GetCountSspClk();
+               /*
+               * How should this flow go?
+               *  REQB or WUPB
+               *   send response  ( waiting for Attrib)
+               *  ATTRIB
+               *   send response  ( waiting for commands 7816) 
+               *  HALT
+                   send halt response ( waiting for wupb )
+               */
                
                
-               if (tracing)
-                       LogTrace(resp, respLen, (t2r_time-time_0), (t2r_time-time_0), NULL, FALSE);
+               switch (cardSTATE) {
+                       case SIM_NOFIELD:
+                       case SIM_HALTED:
+                       case SIM_IDLE: {
+                               LogTrace(receivedCmd, len, 0, 0, NULL, TRUE);   
+                               break;
+                       }
+                       case SIM_SELECTING: {
+                               TransmitFor14443b_AsTag( encodedATQB, encodedATQBLen );
+                               LogTrace(respATQB, sizeof(respATQB), 0, 0, NULL, FALSE);
+                               cardSTATE = SIM_WORK;
+                               break;
+                       }
+                       case SIM_HALTING: {
+                               TransmitFor14443b_AsTag( encodedOK, encodedOKLen );
+                               LogTrace(respOK, sizeof(respOK), 0, 0, NULL, FALSE);
+                               cardSTATE = SIM_HALTED;
+                               break;
+                       }
+                       case SIM_ACKNOWLEDGE: {
+                               TransmitFor14443b_AsTag( encodedOK, encodedOKLen );
+                               LogTrace(respOK, sizeof(respOK), 0, 0, NULL, FALSE);
+                               cardSTATE = SIM_IDLE;                   
+                               break;
+                       }
+                       case SIM_WORK: {
+                               if ( len == 7 && receivedCmd[0] == ISO14443B_HALT ) {
+                                       cardSTATE = SIM_HALTED;
+                               } else if ( len == 11 && receivedCmd[0] == ISO14443B_ATTRIB ) {
+                                       cardSTATE = SIM_ACKNOWLEDGE;
+                               } else {
+                                       // Todo:
+                                       // - SLOT MARKER
+                                       // - ISO7816
+                                       // - emulate with a memory dump
+                                       Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsReceived);
+
+                                       // CRC Check
+                                       uint8_t b1, b2;
+                                       if (len >= 3){ // if crc exists
+                                               ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
+                                               if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1])
+                                                       DbpString("+++CRC fail");
+                                               else
+                                                       DbpString("CRC passes");
+                                       }
+                                       cardSTATE = SIM_IDLE; 
+                               }
+                               break;
+                       }
+                       default: break;
+               }
+                       
+               ++cmdsReceived;
+               // iceman, could add a switch to turn this on/off (if off, no logging?)
+               if(cmdsReceived > 1000) {
+                       DbpString("14B Simulate, 1000 commands later...");
+                       break;
+               }
        }
        }
-       
+       if (MF_DBGLEVEL >= 1) Dbprintf("Emulator stopped. Tracing: %d  trace length: %d ", tracing, BigBuf_get_traceLen());
        switch_off(); //simulate
 }
 
        switch_off(); //simulate
 }
 
@@ -636,12 +743,9 @@ void SimulateIso14443bTag(void) {
  *          false if we are still waiting for some more
  *
  */
  *          false if we are still waiting for some more
  *
  */
-#ifndef SUBCARRIER_DETECT_THRESHOLD
-# define SUBCARRIER_DETECT_THRESHOLD   8
-#endif
-
 static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
 static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
-       int v=0;// , myI, 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() { \
@@ -659,7 +763,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
 
 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by 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)))
 
 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by 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() { \
+#define CHECK_FOR_SUBCARRIER_old() { \
                if(ci < 0) { \
                        if(cq < 0) { /* ci < 0, cq < 0 */ \
                                if (cq < ci) { \
                if(ci < 0) { \
                        if(cq < 0) { /* ci < 0, cq < 0 */ \
                                if (cq < ci) { \
@@ -692,19 +796,17 @@ 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
        }
 
 //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_un() { \
-               myI = ABS(ci); \
-               myQ = ABS(cq); \
-               v = MAX(myI,myQ) + (MIN(myI,myQ) >> 1); \
+#define CHECK_FOR_SUBCARRIER() { \
+               v = MAX(myI, myQ) + (MIN(myI, myQ) >> 1); \
        }
 
        switch(Demod.state) {
                case DEMOD_UNSYNCD:
 
                        CHECK_FOR_SUBCARRIER();
        }
 
        switch(Demod.state) {
                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;
@@ -713,7 +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();
                                
@@ -736,12 +838,12 @@ 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 {
                                // maximum length of TR1 = 200 1/fs
                                Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
                                Demod.posCount = 0;     // start of SOF sequence
                        } else {
                                // maximum length of TR1 = 200 1/fs
-                               if(Demod.posCount > 25*2) Demod.state = DEMOD_UNSYNCD;
+                               if(Demod.posCount > 26*2) Demod.state = DEMOD_UNSYNCD;
                        }
                        ++Demod.posCount;
                        break;
                        }
                        ++Demod.posCount;
                        break;
@@ -751,20 +853,20 @@ 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 < 9*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;
                                }
                        } else {
                                // low phase of SOF too long (> 12 etu)
                                        Demod.state = DEMOD_AWAITING_START_BIT;
                                        Demod.posCount = 0;
                                        Demod.len = 0;
                                }
                        } else {
                                // low phase of SOF too long (> 12 etu)
-                               if (Demod.posCount > 12*2) { 
+                               if (Demod.posCount > 14*2) { 
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
@@ -777,7 +879,7 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                        MAKE_SOFT_DECISION();
                        
                        if (v > 0) {
                        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
+                               if(Demod.posCount > 2*2) {              // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
@@ -803,28 +905,30 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
                                Demod.thisBit += v;
                                Demod.shiftReg >>= 1;
 
                                Demod.thisBit += v;
                                Demod.shiftReg >>= 1;
 
-                               // logic '1'
-                               if(Demod.thisBit > 0)  Demod.shiftReg |= 0x200;
+                               // OR in a logic '1'
+                               if (Demod.thisBit > 0)  Demod.shiftReg |= 0x200;
 
                                ++Demod.bitCount;
                                
 
                                ++Demod.bitCount;
                                
-                               if(Demod.bitCount == 10) {
+                               // 1 start 8 data 1 stop = 10
+                               if (Demod.bitCount == 10) {
                                        
                                        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;
@@ -844,10 +948,10 @@ static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
  *  Demodulate the samples we received from the tag, also log to tracebuffer
  *  quiet: set to 'TRUE' to disable debug output
  */
  *  Demodulate the samples we received from the tag, also log to tracebuffer
  *  quiet: set to 'TRUE' to disable debug output
  */
-static void GetTagSamplesFor14443bDemod(bool quiet) {
-       bool gotFrame = FALSE;
+static void GetTagSamplesFor14443bDemod() {
+       bool gotFrame = FALSE, finished = FALSE;
        int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
        int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
-       int max = 0, 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();
@@ -864,66 +968,58 @@ static void GetTagSamplesFor14443bDemod(bool quiet) {
                if (MF_DBGLEVEL > 1) Dbprintf("FpgaSetupSscDma failed. Exiting"); 
                return;
        }
                if (MF_DBGLEVEL > 1) Dbprintf("FpgaSetupSscDma failed. Exiting"); 
                return;
        }
-       
-       time_0 = GetCountSspClk();
-       
+
        // And put the FPGA in the appropriate mode
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
        // And put the FPGA in the appropriate mode
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
-       
-       while( !BUTTON_PRESS() ) {
-               WDT_HIT();
 
 
-               int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
-               if(behindBy > max) max = behindBy;
+       // get current clock
+       time_0 = GetCountSspClk();
+       
+       // rx counter - dma counter? (how much?) & (mod) mask > 2. (since 2bytes at the time is read)
+       while ( !finished ) {
 
 
-               // rx counter - dma counter? (how much?) & (mod) dma buff / 2.  (since 2bytes at the time is read)
-               while(((lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1)) > 2) {
+               LED_A_INV();
+               WDT_HIT();
 
 
-                       ci = upTo[0];
-                       cq = upTo[1];
-                       upTo += 2;
-                       samples += 2;
-                       
-                       // restart DMA buffer to receive again.
-                       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;
+               // LSB is a fpga signal bit.
+               ci = upTo[0] >> 1;
+               cq = upTo[1] >> 1;
+               upTo += 2;
+               lastRxCounter -= 2;
 
 
-                       // is this | 0x01 the error?   & 0xfe  in https://github.com/Proxmark/proxmark3/issues/103
-                       //gotFrame =  Handle14443bTagSamplesDemod(ci & 0xfe, cq & 0xfe);
-                       gotFrame =  Handle14443bTagSamplesDemod(ci, cq);
-                       if ( gotFrame ) break;
-                       LED_A_INV();
+               // restart DMA buffer to receive again.
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
+                       upTo = dmaBuf;
+                       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
                }
 
                }
 
+               // https://github.com/Proxmark/proxmark3/issues/103
+               gotFrame =  Handle14443bTagSamplesDemod(ci, cq);
                time_stop = GetCountSspClk() - time_0;
                time_stop = GetCountSspClk() - time_0;
-       
-               if(time_stop > iso14b_timeout || gotFrame)      break;
+
+               finished = (time_stop > iso14b_timeout || gotFrame);
        }
        
        FpgaDisableSscDma();
        }
        
        FpgaDisableSscDma();
-
-       if (!quiet) {
-               Dbprintf("max behindby = %d, samples = %d, gotFrame = %s, Demod.state = %d, Demod.len = %u",
-                       max,
-                       samples, 
-                       (gotFrame) ? "true" : "false", 
+       
+       if ( upTo ) upTo = NULL;
+       
+       if (MF_DBGLEVEL >= 3) {
+               Dbprintf("Demod.state = %d, Demod.len = %u,  PDC_RCR = %u",     
                        Demod.state,
                        Demod.state,
-                       Demod.len
+                       Demod.len,
+                       AT91C_BASE_PDC_SSC->PDC_RCR
                );
        }
                );
        }
-       if ( Demod.len > 0 )
-               LogTrace(Demod.output, Demod.len, Demod.startTime, Demod.endTime, NULL, FALSE);
        
        
-       // free mem refs.
-       // if ( dmaBuf ) dmaBuf = NULL;
-       // if ( upTo )   upTo = NULL;
+       // 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 )
+               LogTrace(Demod.output, Demod.len, time_0, time_stop, NULL, FALSE);
 }
 
 
 }
 
 
@@ -932,29 +1028,47 @@ static void GetTagSamplesFor14443bDemod(bool quiet) {
 //-----------------------------------------------------------------------------
 static void TransmitFor14443b_AsReader(void) {
 
 //-----------------------------------------------------------------------------
 static void TransmitFor14443b_AsReader(void) {
 
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
-       SpinDelay(20);
-       
-       int c;  
        // we could been in following mode:
        // FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ
        // if its second call or more
        // we could been in following mode:
        // FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ
        // if its second call or more
+       
+       // while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+               // AT91C_BASE_SSC->SSC_THR = 0XFF;
+       // }
+       
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
+       SpinDelay(40);
 
 
+       int c;  
+       volatile uint32_t b;
+                                                                                
        // What does this loop do? Is it TR1?
        // What does this loop do? Is it TR1?
-       for(c = 0; c < 10;) {
+       // 0xFF = 8 bits of 1.    1 bit == 1Etu,..  
+       // loop 10 * 8 = 80 ETU of delay, with a non modulated signal.  why?
+       // 80*9 = 720us.
+       for(c = 0; c < 50;) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
                        AT91C_BASE_SSC->SSC_THR = 0xFF;
                        ++c;
                }
                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)) {
+                       b = AT91C_BASE_SSC->SSC_RHR;
+                       (void)b;
+               }
        }
        }
-       
+
        // Send frame loop
        for(c = 0; c < ToSendMax;) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
        // Send frame loop
        for(c = 0; c < ToSendMax;) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
-                       ++c;
+                       AT91C_BASE_SSC->SSC_THR = ToSend[c++];
                }
                }
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
+                       b = AT91C_BASE_SSC->SSC_RHR;
+                       (void)b;
+               }                                       
        }
        }
+       //WaitForFpgaDelayQueueIsEmpty(delay);
+       // We should wait here for the FPGA to send all bits.
        WDT_HIT();
 }
 
        WDT_HIT();
 }
 
@@ -962,8 +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
@@ -974,6 +1087,9 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
        *
        *       1 ETU == 1 BIT!
        *   TR0 - 8 ETUS minimum.
        *
        *       1 ETU == 1 BIT!
        *   TR0 - 8 ETUS minimum.
+       *
+       *   QUESTION:  how long is a 1 or 0 in pulses in the xcorr_848 mode?
+       *              1 "stuffbit" = 1ETU (9us)
        */
        int i;
        uint8_t b;
        */
        int i;
        uint8_t b;
@@ -996,14 +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
@@ -1020,7 +1146,8 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
        // Transition time. TR0 - guard time
        // 8ETUS minum?
        // Per specification, Subcarrier must be stopped no later than 2 ETUs after EOF.        
        // Transition time. TR0 - guard time
        // 8ETUS minum?
        // Per specification, Subcarrier must be stopped no later than 2 ETUs after EOF.        
-       for(i = 0; i < 40 ; ++i) ToSendStuffBit(1);
+       // I'm guessing this is for the FPGA to be able to send all bits before we switch to listening mode
+       for(i = 0; i < 32 ; ++i) ToSendStuffBit(1);
        
        // TR1 - Synchronization time
        // Convert from last character reference to length
        
        // TR1 - Synchronization time
        // Convert from last character reference to length
@@ -1028,20 +1155,20 @@ 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();
-       
-       if (tracing) LogTrace(cmd, len, time_start, GetCountSspClk()-time_start, NULL, TRUE);
+
+       LogTrace(cmd, len, time_start, GetCountSspClk()-time_start, NULL, TRUE);
 }
 
 /* Sends an APDU to the tag
 }
 
 /* Sends an APDU to the tag
@@ -1063,7 +1190,7 @@ uint8_t iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *r
        // send
        CodeAndTransmit14443bAsReader(message_frame, message_length + 4); //no
        // get response
        // send
        CodeAndTransmit14443bAsReader(message_frame, message_length + 4); //no
        // get response
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
        if(Demod.len < 3)
                return 0;
        
        if(Demod.len < 3)
                return 0;
        
@@ -1092,7 +1219,7 @@ uint8_t iso14443b_select_srx_card(iso14b_card_select_t *card )
        uint8_t crc[2] = {0x00, 0x00};
        
        CodeAndTransmit14443bAsReader(init_srx, sizeof(init_srx));
        uint8_t crc[2] = {0x00, 0x00};
        
        CodeAndTransmit14443bAsReader(init_srx, sizeof(init_srx));
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
 
        if (Demod.len == 0) return 2;
 
 
        if (Demod.len == 0) return 2;
 
@@ -1103,7 +1230,7 @@ uint8_t iso14443b_select_srx_card(iso14b_card_select_t *card )
        
        ComputeCrc14443(CRC_14443_B, select_srx, 2, &select_srx[2], &select_srx[3]);
        CodeAndTransmit14443bAsReader(select_srx, sizeof(select_srx));
        
        ComputeCrc14443(CRC_14443_B, select_srx, 2, &select_srx[2], &select_srx[3]);
        CodeAndTransmit14443bAsReader(select_srx, sizeof(select_srx));
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
        
        if (Demod.len != 3)     return 2;
        
        
        if (Demod.len != 3)     return 2;
        
@@ -1119,7 +1246,7 @@ uint8_t iso14443b_select_srx_card(iso14b_card_select_t *card )
 
        ComputeCrc14443(CRC_14443_B, select_srx, 1 , &select_srx[1], &select_srx[2]);
        CodeAndTransmit14443bAsReader(select_srx, 3); // Only first three bytes for this one
 
        ComputeCrc14443(CRC_14443_B, select_srx, 1 , &select_srx[1], &select_srx[2]);
        CodeAndTransmit14443bAsReader(select_srx, 3); // Only first three bytes for this one
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
 
        if (Demod.len != 10) return 2;
        
 
        if (Demod.len != 10) return 2;
        
@@ -1153,7 +1280,7 @@ uint8_t iso14443b_select_card(iso14b_card_select_t *card )
        
        // first, wake up the tag
        CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
        
        // first, wake up the tag
        CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
-       GetTagSamplesFor14443bDemod(TRUE); //select_card
+       GetTagSamplesFor14443bDemod(); //select_card
        
        // ATQB too short?
        if (Demod.len < 14) return 2;
        
        // ATQB too short?
        if (Demod.len < 14) return 2;
@@ -1177,7 +1304,7 @@ uint8_t iso14443b_select_card(iso14b_card_select_t *card )
     ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
 
     CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));
     ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
 
     CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));
-    GetTagSamplesFor14443bDemod(TRUE);//select_card
+    GetTagSamplesFor14443bDemod();//select_card
 
     // Answer to ATTRIB too short?
     if(Demod.len < 3) return 2;
 
     // Answer to ATTRIB too short?
     if(Demod.len < 3) return 2;
@@ -1186,14 +1313,28 @@ 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;
+
+       if (card) { 
        
        
-       // CID
-       if (card) card->cid = Demod.output[0];
-       
-       uint8_t fwt = card->atqb[6]>>4;
-       if ( fwt < 16 ){
-               uint32_t fwt_time = (302 << fwt);
-               iso14b_set_timeout( fwt_time);
+               // CID
+               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);
+                       iso14b_set_timeout( fwt_time);
+               }
        }
        // reset PCB block number
        pcb_blocknum = 0;
        }
        // reset PCB block number
        pcb_blocknum = 0;
@@ -1263,7 +1404,7 @@ void ReadSTMemoryIso14443b(uint8_t numofblocks)
        // First command: wake up the tag using the INITIATE command
        uint8_t cmd1[] = {ISO14443B_INITIATE, 0x00, 0x97, 0x5b};
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
        // First command: wake up the tag using the INITIATE command
        uint8_t cmd1[] = {ISO14443B_INITIATE, 0x00, 0x97, 0x5b};
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
-       GetTagSamplesFor14443bDemod(TRUE); // no
+       GetTagSamplesFor14443bDemod(); // no
 
        if (Demod.len == 0) {
                DbpString("No response from tag");
 
        if (Demod.len == 0) {
                DbpString("No response from tag");
@@ -1280,7 +1421,7 @@ void ReadSTMemoryIso14443b(uint8_t numofblocks)
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
        if (Demod.len != 3) {
                Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
                set_tracing(FALSE);     
        if (Demod.len != 3) {
                Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
                set_tracing(FALSE);     
@@ -1305,7 +1446,7 @@ void ReadSTMemoryIso14443b(uint8_t numofblocks)
        cmd1[0] = ISO14443B_GET_UID;
        ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
        CodeAndTransmit14443bAsReader(cmd1, 3); // no --  Only first three bytes for this one
        cmd1[0] = ISO14443B_GET_UID;
        ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
        CodeAndTransmit14443bAsReader(cmd1, 3); // no --  Only first three bytes for this one
-       GetTagSamplesFor14443bDemod(TRUE); //no
+       GetTagSamplesFor14443bDemod(); //no
        if (Demod.len != 10) {
                Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
                set_tracing(FALSE);     
        if (Demod.len != 10) {
                Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
                set_tracing(FALSE);     
@@ -1336,7 +1477,7 @@ void ReadSTMemoryIso14443b(uint8_t numofblocks)
                cmd1[1] = i;
                ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
                CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
                cmd1[1] = i;
                ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
                CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
-               GetTagSamplesFor14443bDemod(TRUE); //no
+               GetTagSamplesFor14443bDemod(); //no
                
                if (Demod.len != 6) { // Check if we got an answer from the tag
                        DbpString("Expected 6 bytes from tag, got less...");
                
                if (Demod.len != 6) { // Check if we got an answer from the tag
                        DbpString("Expected 6 bytes from tag, got less...");
@@ -1419,16 +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;
 
@@ -1451,40 +1589,25 @@ void RAMFUNC SnoopIso14443b(void) {
        for(;;) {
 
                WDT_HIT();
        for(;;) {
 
                WDT_HIT();
-               
-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1);
 
 
-               if ( behindBy > maxBehindBy )
-                       maxBehindBy = behindBy;
-               
-               if ( behindBy < 2 ) continue;
-               
                ci = upTo[0];
                cq = upTo[1];
                ci = upTo[0];
                cq = upTo[1];
-               upTo += 2;
-               
+               upTo += 2;              
                lastRxCounter -= 2;
                
                if (upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
                        upTo = dmaBuf;
                lastRxCounter -= 2;
                
                if (upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
                        upTo = dmaBuf;
-                       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;
                        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;
                        }
                }
@@ -1496,7 +1619,7 @@ void RAMFUNC SnoopIso14443b(void) {
                        // no need to try decoding reader data if the tag is sending
                        if (Handle14443bReaderUartBit(ci & 0x01)) {
 
                        // no need to try decoding reader data if the tag is sending
                        if (Handle14443bReaderUartBit(ci & 0x01)) {
 
-                               time_stop = (GetCountSspClk()-time_0);
+                               time_stop = GetCountSspClk() - time_0;
                                
                                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);
@@ -1507,34 +1630,35 @@ void RAMFUNC SnoopIso14443b(void) {
                                /* false-triggered by the commands from the reader. */
                                DemodReset();
                        } else {
                                /* false-triggered by the commands from the reader. */
                                DemodReset();
                        } else {
-                               time_start = (GetCountSspClk()-time_0);
+                               time_start = GetCountSspClk() - time_0;
                        }
                        
                        if (Handle14443bReaderUartBit(cq & 0x01)) {
                                
                        }
                        
                        if (Handle14443bReaderUartBit(cq & 0x01)) {
                                
-                               time_stop = (GetCountSspClk()-time_0);
+                               time_stop = GetCountSspClk() - time_0;
                                
                                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 {
                        } else {
-                               time_start = (GetCountSspClk()-time_0);
+                               time_start = GetCountSspClk() - time_0;
                        }
                        ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
                        LED_A_OFF();
                }
                
                        }
                        ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
                        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;
                                
                                LogTrace(Demod.output, Demod.len, time_start, time_stop, NULL, FALSE);
 
                                
                                LogTrace(Demod.output, Demod.len, time_start, time_stop, NULL, FALSE);
 
@@ -1543,7 +1667,7 @@ void RAMFUNC SnoopIso14443b(void) {
                                // And ready to receive another response.
                                DemodReset();
                        } else {
                                // And ready to receive another response.
                                DemodReset();
                        } else {
-                               time_start = (GetCountSspClk()-time_0);
+                               time_start = GetCountSspClk() - time_0;
                        }
                        TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
                }
                        }
                        TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
                }
@@ -1552,13 +1676,12 @@ 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 ( dmaBuf ) dmaBuf = NULL;
-       if ( upTo )   upTo = NULL;
+       if ( upTo ) upTo = NULL;
+       
        // Uart.byteCntMax  should be set with ATQB value..
 }
 
        // Uart.byteCntMax  should be set with ATQB value..
 }
 
@@ -1629,7 +1752,7 @@ void SendRawCommand14443B_Ex(UsbCommand *c)
                }
        
                CodeAndTransmit14443bAsReader(cmd, len); // raw         
                }
        
                CodeAndTransmit14443bAsReader(cmd, len); // raw         
-               GetTagSamplesFor14443bDemod(TRUE); // raw
+               GetTagSamplesFor14443bDemod(); // raw
                
                sendlen = MIN(Demod.len, USB_CMD_DATA_SIZE);
                status =  (Demod.len > 0) ? 0 : 1;
                
                sendlen = MIN(Demod.len, USB_CMD_DATA_SIZE);
                status =  (Demod.len > 0) ? 0 : 1;
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