chg: removed a useless clearing of key_count. From @matrix https://github.com/matrix...

[proxmark3-svn] / armsrc / iso14443b.c
diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c

index 860e96f13bb2972023fd360a0eee5a67a35ed5a2..ed035d3a5e29d780a248da43ea2ca14dbee41e69 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -5,27 +5,52 @@
  // at your option, any later version. See the LICENSE.txt file for the text of
  // the license.
  //-----------------------------------------------------------------------------
  // at your option, any later version. See the LICENSE.txt file for the text of
  // the license.
  //-----------------------------------------------------------------------------
-// Routines to support ISO 14443. This includes both the reader software and
-// the `fake tag' modes. At the moment only the Type B modulation is
-// supported.
+// Routines to support ISO 14443B. This includes both the reader software and
+// the `fake tag' modes.
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
+#include "iso14443b.h"
+
+#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)
+#ifndef TR0
+# define TR0 0
+#endif
+
+// Synchronization time (per 14443-2)
+#ifndef TR1
+# define TR1 0
+#endif
+// Frame Delay Time PICC to PCD  (per 14443-3 Amendment 1)
+#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 uint32_t iso14b_timeout = FWT_TIMEOUT_14B;
  
  
-#include "proxmark3.h"
-#include "apps.h"
-#include "util.h"
-#include "string.h"
-
-#include "iso14443crc.h"
-
-//static void GetSamplesFor14443(int weTx, int n);
-
-/*#define DEMOD_TRACE_SIZE 4096
-#define READER_TAG_BUFFER_SIZE 2048
-#define TAG_READER_BUFFER_SIZE 2048
-#define DEMOD_DMA_BUFFER_SIZE 1024
-*/
-
-#define RECEIVE_SAMPLES_TIMEOUT 2000
  
  //=============================================================================
  // An ISO 14443 Type B tag. We listen for commands from the reader, using
  
  //=============================================================================
  // An ISO 14443 Type B tag. We listen for commands from the reader, using
@@ -35,117 +60,268 @@
  // a response.
  //=============================================================================
  
  // a response.
  //=============================================================================
  
+
+//-----------------------------------------------------------------------------
+// The software UART that receives commands from the reader, and its state variables.
+//-----------------------------------------------------------------------------
+static struct {
+       enum {
+               STATE_UNSYNCD,
+               STATE_GOT_FALLING_EDGE_OF_SOF,
+               STATE_AWAITING_START_BIT,
+               STATE_RECEIVING_DATA
+       }       state;
+       uint16_t shiftReg;
+       int      bitCnt;
+       int      byteCnt;
+       int      byteCntMax;
+       int      posCnt;
+       uint8_t  *output;
+} Uart;
+
+static void UartReset() {
+       Uart.state = STATE_UNSYNCD;
+       Uart.shiftReg = 0;
+       Uart.bitCnt = 0;
+       Uart.byteCnt = 0;
+       Uart.byteCntMax = MAX_FRAME_SIZE;
+       Uart.posCnt = 0;
+}
+
+static void UartInit(uint8_t *data) {
+       Uart.output = data;
+       UartReset();
+//             memset(Uart.output, 0x00, MAX_FRAME_SIZE);
+}
+
+//-----------------------------------------------------------------------------
+// The software Demod that receives commands from the tag, and its state variables.
+//-----------------------------------------------------------------------------
+static struct {
+       enum {
+               DEMOD_UNSYNCD,
+               DEMOD_PHASE_REF_TRAINING,
+               DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
+               DEMOD_GOT_FALLING_EDGE_OF_SOF,
+               DEMOD_AWAITING_START_BIT,
+               DEMOD_RECEIVING_DATA
+       }       state;
+       uint16_t bitCount;
+       int      posCount;
+       int      thisBit;
+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
+       int     metric;
+       int     metricN;
+*/
+       uint16_t shiftReg;
+       uint8_t  *output;
+       uint16_t len;
+       int      sumI;
+       int      sumQ;
+       uint32_t startTime, endTime;
+} Demod;
+
+// Clear out the state of the "UART" that receives from the tag.
+static void DemodReset() {
+       Demod.state = DEMOD_UNSYNCD;
+       Demod.bitCount = 0;
+       Demod.posCount = 0;
+       Demod.thisBit = 0;
+       Demod.shiftReg = 0;
+       Demod.len = 0;
+       Demod.sumI = 0;
+       Demod.sumQ = 0;
+       Demod.startTime = 0;
+       Demod.endTime = 0;      
+}
+
+static void DemodInit(uint8_t *data) {
+       Demod.output = data;
+       DemodReset();
+       //      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);
+}
+
  //-----------------------------------------------------------------------------
  // Code up a string of octets at layer 2 (including CRC, we don't generate
  // that here) so that they can be transmitted to the reader. Doesn't transmit
  // them yet, just leaves them ready to send in ToSend[].
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
  // Code up a string of octets at layer 2 (including CRC, we don't generate
  // that here) so that they can be transmitted to the reader. Doesn't transmit
  // them yet, just leaves them ready to send in ToSend[].
  //-----------------------------------------------------------------------------
-static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
-{
-       int i;
-
+static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
+       /* ISO 14443 B
+       *
+       * Reader to card | ASK  - Amplitude Shift Keying Modulation (PCD to PICC for Type B) (NRZ-L encodig)
+       * Card to reader | BPSK - Binary Phase Shift Keying Modulation, (PICC to PCD for Type B)
+       *
+       * fc - carrier frequency 13.56mHz
+       * TR0 - Guard Time per 14443-2
+       * TR1 - Synchronization Time per 14443-2
+       * TR2 - PICC to PCD Frame Delay Time (per 14443-3 Amendment 1)
+       *
+       * Elementary Time Unit (ETU) is
+       * - 128 Carrier Cycles (9.4395 µS) = 8 Subcarrier Units 
+       * - 1 ETU = 1 bit
+       * - 10 ETU = 1 startbit, 8 databits, 1 stopbit (10bits length)
+       * - startbit is a 0
+       * - stopbit is a 1
+       *
+       * Start of frame (SOF) is
+       * - [10-11] ETU of ZEROS, unmodulated time
+       * - [2-3] ETU of ONES,  
+       *
+       * End of frame (EOF) is
+       * - [10-11] ETU of ZEROS, unmodulated time
+       *
+       *  -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 (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
+       * 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
+       *   - SOF
+       *   - Command, data and CRC_B
+       *   - EOF
+       *   - no modulation ONES
+       *
+       *  Card data transmission
+       *   - TR1
+       *   - SOF
+       *   - data  (each bytes is:  1startbit, 8bits, 1stopbit)
+       *   - CRC_B
+       *   - EOF
+       *
+       * FPGA implementation :
+       * At this point only Type A is implemented. This means that we are using a
+       * bit rate of 106 kbit/s, or fc/128. Oversample by 4, which ought to make
+       * things practical for the ARM (fc/32, 423.8 kbits/s, ~50 kbytes/s)
+       *
+       */
+       
+       int i,j;
+       uint8_t b;
+       
         ToSendReset();
  
         // Transmit a burst of ones, as the initial thing that lets the
         ToSendReset();
  
         // Transmit a burst of ones, as the initial thing that lets the
-       // reader get phase sync. This (TR1) must be > 80/fs, per spec,
-       // but tag that I've tried (a Paypass) exceeds that by a fair bit,
-       // so I will too.
-       for(i = 0; i < 20; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
+       // reader get phase sync. 
+       // This loop is TR1, per specification
+       // TR1 minimum must be > 80/fs
+       // TR1 maximum 200/fs 
+       // 80/fs < TR1 < 200/fs
+       // 10 ETU < TR1 < 24 ETU
  
         // Send SOF.
  
         // Send SOF.
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 2; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-       }
-
-       for(i = 0; i < len; i++) {
-               int j;
-               uint8_t b = cmd[i];
-
+       // 10-11 ETU * 4times samples ZEROS
+       for(i = 0; i < 10; i++) { SEND4STUFFBIT(0); }
+       //for(i = 0; i < 10; i++) { ToSendStuffBit(0); }
+       
+       // 2-3 ETU * 4times samples ONES
+       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
                 // Start bit
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
+               SEND4STUFFBIT(0);
+               //ToSendStuffBit(0);
  
                 // Data bits
  
                 // Data bits
-               for(j = 0; j < 8; j++) {
-                       if(b & 1) {
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                       } else {
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                               ToSendStuffBit(0);
-                       }
+               b = cmd[i];
+               for(j = 0; j < 8; ++j) {
+                       // 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);
-       }
-
-       // Send SOF.
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
-               ToSendStuffBit(1);
+               SEND4STUFFBIT(1);
+               //ToSendStuffBit(1);
+               
+               // Extra Guard bit
+               // For PICC it ranges 0-18us (1etu = 9us)
+               SEND4STUFFBIT(1);
+               //ToSendStuffBit(1);
         }
  
         }
  
+       // Send EOF.
+       // 10-11 ETU * 4 sample rate = ZEROS
+       for(i = 0; i < 10; i++) { SEND4STUFFBIT(0); }
+       //for(i = 0; i < 10; i++) { ToSendStuffBit(0); }
+       
+       // why this?
+       for(i = 0; i < 40; i++) { SEND4STUFFBIT(1); }
+       //for(i = 0; i < 40; i++) { ToSendStuffBit(1); }
+       
         // Convert from last byte pos to length
         // Convert from last byte pos to length
-       ToSendMax++;
-
-       // Add a few more for slop
-       ToSendMax += 2;
+       ++ToSendMax;
  }
  
  }
  
-//-----------------------------------------------------------------------------
-// The software UART that receives commands from the reader, and its state
-// variables.
-//-----------------------------------------------------------------------------
-static struct {
-       enum {
-               STATE_UNSYNCD,
-               STATE_GOT_FALLING_EDGE_OF_SOF,
-               STATE_AWAITING_START_BIT,
-               STATE_RECEIVING_DATA,
-               STATE_ERROR_WAIT
-       }       state;
-       uint16_t    shiftReg;
-       int     bitCnt;
-       int     byteCnt;
-       int     byteCntMax;
-       int     posCnt;
-       uint8_t   *output;
-} Uart;
  
  /* Receive & handle a bit coming from the reader.
  
  /* Receive & handle a bit coming from the reader.
+ *
+ * This function is called 4 times per bit (every 2 subcarrier cycles).
+ * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
   *
   * LED handling:
   * LED A -> ON once we have received the SOF and are expecting the rest.
   *
   * LED handling:
   * LED A -> ON once we have received the SOF and are expecting the rest.
@@ -154,13 +330,11 @@ static struct {
   * Returns: true if we received a EOF
   *          false if we are still waiting for some more
   */
   * Returns: true if we received a EOF
   *          false if we are still waiting for some more
   */
-static int Handle14443UartBit(int bit)
-{
-       switch(Uart.state) {
+static RAMFUNC int Handle14443bReaderUartBit(uint8_t bit) {
+       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;
@@ -169,9 +343,9 @@ static int Handle14443UartBit(int bit)
  
                 case STATE_GOT_FALLING_EDGE_OF_SOF:
                         Uart.posCnt++;
  
                 case STATE_GOT_FALLING_EDGE_OF_SOF:
                         Uart.posCnt++;
-                       if(Uart.posCnt == 2) {
-                               if(bit) {
-                                       if(Uart.bitCnt >= 10) {
+                       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;
@@ -179,30 +353,28 @@ static int Handle14443UartBit(int 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
-                                               Uart.state = STATE_ERROR_WAIT;
+                                               // didn't stay down long enough before going high, error
+                                               Uart.state = STATE_UNSYNCD;
                                         }
                                 } else {
                                         // do nothing, keep waiting
                                 }
                                 Uart.bitCnt++;
                         }
                                         }
                                 } else {
                                         // do nothing, keep waiting
                                 }
                                 Uart.bitCnt++;
                         }
-                       if(Uart.posCnt >= 4) Uart.posCnt = 0;
-                       if(Uart.bitCnt > 14) {
-                               // Give up if we see too many zeros without
-                               // a one, too.
-                               Uart.state = STATE_ERROR_WAIT;
+                       if (Uart.posCnt >= 4) Uart.posCnt = 0;
+                       if (Uart.bitCnt > 12) {
+                               // Give up if we see too many zeros without a one, too.
+                               LED_A_OFF();
+                               Uart.state = STATE_UNSYNCD;
                         }
                         break;
  
                 case STATE_AWAITING_START_BIT:
                         Uart.posCnt++;
                         }
                         break;
  
                 case STATE_AWAITING_START_BIT:
                         Uart.posCnt++;
-                       if(bit) {
-                               if(Uart.posCnt > 25) {
-                                       // stayed high for too long between
-                                       // characters, error
-                                       Uart.state = STATE_ERROR_WAIT;
+                       if (bit) {
+                               if (Uart.posCnt > 50/2) {       // max 57us between characters = 49 1/fs, max 3 etus after low phase of SOF = 24 1/fs
+                                       // stayed high for too long between characters, error
+                                       Uart.state = STATE_UNSYNCD;
                                 }
                         } else {
                                 // falling edge, this starts the data byte
                                 }
                         } else {
                                 // falling edge, this starts the data byte
@@ -215,62 +387,54 @@ static int Handle14443UartBit(int 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
                                                 // Buffer overflowed, give up
-                                               Uart.posCnt = 0;
-                                               Uart.state = STATE_ERROR_WAIT;
+                                               LED_A_OFF();
+                                               Uart.state = STATE_UNSYNCD;
                                         } else {
                                                 // so get the next byte now
                                                 Uart.posCnt = 0;
                                                 Uart.state = STATE_AWAITING_START_BIT;
                                         }
                                         } else {
                                                 // so get the next byte now
                                                 Uart.posCnt = 0;
                                                 Uart.state = STATE_AWAITING_START_BIT;
                                         }
-                               } else if(Uart.shiftReg == 0x000) {
+                               } else if (Uart.shiftReg == 0x000) {
                                         // this is an EOF byte
                                         LED_A_OFF(); // Finished receiving
                                         // this is an EOF byte
                                         LED_A_OFF(); // Finished receiving
-                                       return TRUE;
+                                       Uart.state = STATE_UNSYNCD;
+                                       if (Uart.byteCnt != 0)
+                                               return TRUE;
+                                       
                                 } else {
                                         // this is an error
                                 } else {
                                         // this is an error
-                                       Uart.posCnt = 0;
-                                       Uart.state = STATE_ERROR_WAIT;
+                                       LED_A_OFF();
+                                       Uart.state = STATE_UNSYNCD;
                                 }
                         }
                         break;
  
                                 }
                         }
                         break;
  
-               case STATE_ERROR_WAIT:
-                       // We're all screwed up, so wait a little while
-                       // for whatever went wrong to finish, and then
-                       // start over.
-                       Uart.posCnt++;
-                       if(Uart.posCnt > 10) {
-                               Uart.state = STATE_UNSYNCD;
-                               LED_A_OFF();
-                       }
-                       break;
-
                 default:
                 default:
+                       LED_A_OFF();
                         Uart.state = STATE_UNSYNCD;
                         break;
         }
                         Uart.state = STATE_UNSYNCD;
                         break;
         }
-
         return FALSE;
  }
  
         return FALSE;
  }
  
@@ -283,145 +447,279 @@ static int Handle14443UartBit(int bit)
  // Assume that we're called with the SSC (to the FPGA) and ADC path set
  // correctly.
  //-----------------------------------------------------------------------------
  // Assume that we're called with the SSC (to the FPGA) and ADC path set
  // correctly.
  //-----------------------------------------------------------------------------
-static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
-{
-       uint8_t mask;
-       int i, bit;
-
-       // Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
+static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len) {
+       // Set FPGA mode to "simulated ISO 14443B tag", no modulation (listen
         // only, since we are receiving, not transmitting).
         // Signal field is off with the appropriate LED
         LED_D_OFF();
         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
         // only, since we are receiving, not transmitting).
         // Signal field is off with the appropriate LED
         LED_D_OFF();
         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+               
+       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.
         // Now run a `software UART' on the stream of incoming samples.
-       Uart.output = received;
-       Uart.byteCntMax = maxLen;
-       Uart.state = STATE_UNSYNCD;
+       UartInit(received);
  
  
-       for(;;) {
+       uint8_t mask;
+       while( !BUTTON_PRESS() ) {
                 WDT_HIT();
  
                 WDT_HIT();
  
-               if(BUTTON_PRESS()) return FALSE;
-
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x00;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-
-                       mask = 0x80;
-                       for(i = 0; i < 8; i++, mask >>= 1) {
-                               bit = (b & mask);
-                               if(Handle14443UartBit(bit)) {
+               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;
                                 }
                         }
                 }
-       }
+       }       
+       return FALSE;
  }
  
  }
  
-//-----------------------------------------------------------------------------
-// Main loop of simulated tag: receive commands from reader, decide what
-// response to send, and send it.
-//-----------------------------------------------------------------------------
-void SimulateIso14443Tag(void)
-{
-       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
-       static const uint8_t response1[] = {
-               0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
-               0x00, 0x21, 0x85, 0x5e, 0xd7
-       };
+void ClearFpgaShiftingRegisters(void){
  
  
-       uint8_t *resp;
-       int respLen;
+       volatile uint8_t b;
  
  
-       uint8_t *resp1 = BigBuf_get_addr() + 800;
-       int resp1Len;
+       // clear receiving shift register and holding register
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};
  
  
-       uint8_t *receivedCmd = BigBuf_get_addr();
-       int len;
+       b = AT91C_BASE_SSC->SSC_RHR; (void) b;
  
  
-       int i;
+       while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) {};
  
  
-       int cmdsRecvd = 0;
+       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;
+}
  
  
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       memset(receivedCmd, 0x44, 400);
+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++;
+               }
+       }
+}
  
  
-       CodeIso14443bAsTag(response1, sizeof(response1));
-       memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
+static void TransmitFor14443b_AsTag( uint8_t *response, uint16_t len) {
  
  
-       // We need to listen to the high-frequency, peak-detected path.
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       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();
  
         FpgaSetupSsc();
  
-       cmdsRecvd = 0;
-
-       for(;;) {
-               uint8_t b1, b2;
-
-               if(!GetIso14443CommandFromReader(receivedCmd, &len, 100)) {
-               Dbprintf("button pressed, received %d commands", cmdsRecvd);
-               break;
-               }
-
-               // Good, look at the command now.
-
-               if(len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len)==0) {
-                       resp = resp1; respLen = resp1Len;
-               } else {
-                       Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
-                       // And print whether the CRC fails, just for good measure
-                       ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
-                       if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
-                               // Not so good, try again.
-                               DbpString("+++CRC fail");
-                       } else {
-                               DbpString("CRC passes");
-                       }
-                       break;
+       // 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.
+//-----------------------------------------------------------------------------
+void SimulateIso14443bTag(uint32_t pupi) {
  
  
-               memset(receivedCmd, 0x44, 32);
+       ///////////// setup device.
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
  
  
-               cmdsRecvd++;
+       // allocate command receive buffer
+       BigBuf_free();
+       BigBuf_Clear_ext(false);
+       clear_trace(); //sim
+       set_tracing(TRUE);
+       
+       // connect Demodulated Signal to ADC:
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
  
  
-               if(cmdsRecvd > 0x30) {
-                       DbpString("many commands later...");
-                       break;
-               }
+       // Set up the synchronous serial port
+       FpgaSetupSsc();
+       /////////////
+
+       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
+
+       // ... 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};
+
+       // ...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(respLen <= 0) continue;
+       // prepare "ATQB" tag answer (encoded):
+       CodeIso14443bAsTag(respATQB, sizeof(respATQB));
+       uint8_t *encodedATQB = BigBuf_malloc(ToSendMax);
+       uint16_t encodedATQBLen = ToSendMax;
+       memcpy(encodedATQB, ToSend, ToSendMax); 
  
  
-               // 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();
+       
+       // 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();
  
  
-               // Transmit the response.
-               i = 0;
-               for(;;) {
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                               uint8_t b = resp[i];
+               // 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;
  
  
-                               AT91C_BASE_SSC->SSC_THR = b;
+               // Get reader command
+               if (!GetIso14443bCommandFromReader(receivedCmd, &len)) {
+                       Dbprintf("button pressed, received %d commands", cmdsReceived);
+                       break;
+               }
  
  
-                               i++;
-                               if(i > respLen) {
-                                       break;
-                               }
+               // 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;
+                       }
+               }
+               
+               /*
+               * 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 )
+               */
+               
+               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;
                         }
                         }
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                               (void)b;
+                       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
  }
  
  //=============================================================================
  }
  
  //=============================================================================
@@ -431,31 +729,12 @@ void SimulateIso14443Tag(void)
  // PC side.
  //=============================================================================
  
  // PC side.
  //=============================================================================
  
-static struct {
-       enum {
-               DEMOD_UNSYNCD,
-               DEMOD_PHASE_REF_TRAINING,
-               DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
-               DEMOD_GOT_FALLING_EDGE_OF_SOF,
-               DEMOD_AWAITING_START_BIT,
-               DEMOD_RECEIVING_DATA,
-               DEMOD_ERROR_WAIT
-       }       state;
-       int     bitCount;
-       int     posCount;
-       int     thisBit;
-       int     metric;
-       int     metricN;
-       uint16_t    shiftReg;
-       uint8_t   *output;
-       int     len;
-       int     sumI;
-       int     sumQ;
-} Demod;
-
  /*
   * Handles reception of a bit from the tag
   *
  /*
   * Handles reception of a bit from the tag
   *
+ * This function is called 2 times per bit (every 4 subcarrier cycles).
+ * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 4,72us
+ *
   * LED handling:
   * LED C -> ON once we have received the SOF and are expecting the rest.
   * LED C -> OFF once we have received EOF or are unsynced
   * LED handling:
   * LED C -> ON once we have received the SOF and are expecting the rest.
   * LED C -> OFF once we have received EOF or are unsynced
@@ -464,12 +743,11 @@ static struct {
   *          false if we are still waiting for some more
   *
   */
   *          false if we are still waiting for some more
   *
   */
-static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
-{
-       int v;
+static RAMFUNC int Handle14443bTagSamplesDemod(int ci, int cq) {
+       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.
+// The soft decision on the bit uses an estimate of just the
+// quadrant of the reference angle, not the exact angle.
  #define MAKE_SOFT_DECISION() { \
                 if(Demod.sumI > 0) { \
                         v = ci; \
  #define MAKE_SOFT_DECISION() { \
                 if(Demod.sumI > 0) { \
                         v = ci; \
@@ -483,85 +761,131 @@ static RAMFUNC int Handle14443SamplesDemod(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)))
+#define CHECK_FOR_SUBCARRIER_old() { \
+               if(ci < 0) { \
+                       if(cq < 0) { /* ci < 0, cq < 0 */ \
+                               if (cq < ci) { \
+                                       v = -cq - (ci >> 1); \
+                               } else { \
+                                       v = -ci - (cq >> 1); \
+                               } \
+                       } else {        /* ci < 0, cq >= 0 */ \
+                               if (cq < -ci) { \
+                                       v = -ci + (cq >> 1); \
+                               } else { \
+                                       v = cq - (ci >> 1); \
+                               } \
+                       } \
+               } else { \
+                       if(cq < 0) { /* ci >= 0, cq < 0 */ \
+                               if (-cq < ci) { \
+                                       v = ci - (cq >> 1); \
+                               } else { \
+                                       v = -cq + (ci >> 1); \
+                               } \
+                       } else {        /* ci >= 0, cq >= 0 */ \
+                               if (cq < ci) { \
+                                       v = ci + (cq >> 1); \
+                               } else { \
+                                       v = cq + (ci >> 1); \
+                               } \
+                       } \
+               } \
+       }
+
+//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() { \
+               v = MAX(myI, myQ) + (MIN(myI, myQ) >> 1); \
+       }
+
         switch(Demod.state) {
                 case DEMOD_UNSYNCD:
         switch(Demod.state) {
                 case DEMOD_UNSYNCD:
-                       v = ci;
-                       if(v < 0) v = -v;
-                       if(cq > 0) {
-                               v += cq;
-                       } else {
-                               v -= cq;
-                       }
-                       if(v > 40) {
-                               Demod.posCount = 0;
+
+                       CHECK_FOR_SUBCARRIER();
+               
+                       // subcarrier detected
+                       if (v > SUBCARRIER_DETECT_THRESHOLD) {
                                 Demod.state = DEMOD_PHASE_REF_TRAINING;
                                 Demod.state = DEMOD_PHASE_REF_TRAINING;
-                               Demod.sumI = 0;
-                               Demod.sumQ = 0;
+                               Demod.sumI = ci;
+                               Demod.sumQ = cq;
+                               Demod.posCount = 1;
                         }
                         break;
  
                 case DEMOD_PHASE_REF_TRAINING:
                         }
                         break;
  
                 case DEMOD_PHASE_REF_TRAINING:
-                       if(Demod.posCount < 8) {
-                               Demod.sumI += ci;
-                               Demod.sumQ += cq;
-                       } else if(Demod.posCount > 100) {
-                               // error, waited too long
-                               Demod.state = DEMOD_UNSYNCD;
-                       } else {
-                               MAKE_SOFT_DECISION();
-                               if(v < 0) {
-                                       Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
-                                       Demod.posCount = 0;
+                       if (Demod.posCount < 8) {
+
+                               CHECK_FOR_SUBCARRIER();
+                               
+                               if (v > SUBCARRIER_DETECT_THRESHOLD) {
+                                       // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
+                                       // note: synchronization time > 80 1/fs
+                                       Demod.sumI += ci;
+                                       Demod.sumQ += cq;
+                                       ++Demod.posCount;
+                               } else {        
+                                       // subcarrier lost
+                                       Demod.state = DEMOD_UNSYNCD;
                                 }
                                 }
+                       } else {
+                               Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
                         }
                         }
-                       Demod.posCount++;
                         break;
  
                 case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
                         break;
  
                 case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
+                       
                         MAKE_SOFT_DECISION();
                         MAKE_SOFT_DECISION();
-                       if(v < 0) {
+                       
+                       if (v < 0) {    // logic '0' detected
                                 Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
                                 Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
-                               Demod.posCount = 0;
+                               Demod.posCount = 0;     // start of SOF sequence
                         } else {
                         } else {
-                               if(Demod.posCount > 100) {
-                                       Demod.state = DEMOD_UNSYNCD;
-                               }
+                               // maximum length of TR1 = 200 1/fs
+                               if(Demod.posCount > 26*2) Demod.state = DEMOD_UNSYNCD;
                         }
                         }
-                       Demod.posCount++;
+                       ++Demod.posCount;
                         break;
  
                 case DEMOD_GOT_FALLING_EDGE_OF_SOF:
                         break;
  
                 case DEMOD_GOT_FALLING_EDGE_OF_SOF:
+                       ++Demod.posCount;
+                       
                         MAKE_SOFT_DECISION();
                         MAKE_SOFT_DECISION();
-                       if(v > 0) {
-                               if(Demod.posCount < 12) {
+                       
+                       if (v > 0) {
+                               // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
+                               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.state = DEMOD_AWAITING_START_BIT;
                                         Demod.posCount = 0;
                                         Demod.len = 0;
                                         Demod.state = DEMOD_AWAITING_START_BIT;
                                         Demod.posCount = 0;
                                         Demod.len = 0;
-                                       Demod.metricN = 0;
-                                       Demod.metric = 0;
                                 }
                         } else {
                                 }
                         } else {
-                               if(Demod.posCount > 100) {
+                               // low phase of SOF too long (> 12 etu)
+                               if (Demod.posCount > 14*2) { 
                                         Demod.state = DEMOD_UNSYNCD;
                                         LED_C_OFF();
                                 }
                         }
                                         Demod.state = DEMOD_UNSYNCD;
                                         LED_C_OFF();
                                 }
                         }
-                       Demod.posCount++;
                         break;
  
                 case DEMOD_AWAITING_START_BIT:
                         break;
  
                 case DEMOD_AWAITING_START_BIT:
+                       ++Demod.posCount;
+                       
                         MAKE_SOFT_DECISION();
                         MAKE_SOFT_DECISION();
-                       if(v > 0) {
-                               if(Demod.posCount > 10) {
+                       
+                       if (v > 0) {
+                               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();
                                 }
-                       } else {
+                       } else {                                                        // start bit detected
                                 Demod.bitCount = 0;
                                 Demod.bitCount = 0;
-                               Demod.posCount = 1;
+                               Demod.posCount = 1;                             // this was the first half
                                 Demod.thisBit = v;
                                 Demod.shiftReg = 0;
                                 Demod.state = DEMOD_RECEIVING_DATA;
                                 Demod.thisBit = v;
                                 Demod.shiftReg = 0;
                                 Demod.state = DEMOD_RECEIVING_DATA;
@@ -569,40 +893,42 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                         break;
  
                 case DEMOD_RECEIVING_DATA:
                         break;
  
                 case DEMOD_RECEIVING_DATA:
+                       
                         MAKE_SOFT_DECISION();
                         MAKE_SOFT_DECISION();
-                       if(Demod.posCount == 0) {
+
+                       if (Demod.posCount == 0) { 
+                               // first half of bit
                                 Demod.thisBit = v;
                                 Demod.posCount = 1;
                         } else {
                                 Demod.thisBit = v;
                                 Demod.posCount = 1;
                         } else {
+                               // second half of bit
                                 Demod.thisBit += v;
                                 Demod.thisBit += v;
-
-                               if(Demod.thisBit > 0) {
-                                       Demod.metric += Demod.thisBit;
-                               } else {
-                                       Demod.metric -= Demod.thisBit;
-                               }
-                               (Demod.metricN)++;
-
                                 Demod.shiftReg >>= 1;
                                 Demod.shiftReg >>= 1;
-                               if(Demod.thisBit > 0) {
-                                       Demod.shiftReg |= 0x200;
-                               }
  
  
-                               Demod.bitCount++;
-                               if(Demod.bitCount == 10) {
+                               // OR in a logic '1'
+                               if (Demod.thisBit > 0)  Demod.shiftReg |= 0x200;
+
+                               ++Demod.bitCount;
+                               
+                               // 1 start 8 data 1 stop = 10
+                               if (Demod.bitCount == 10) {
+                                       
                                         uint16_t s = Demod.shiftReg;
                                         uint16_t s = Demod.shiftReg;
-                                       if((s & 0x200) && !(s & 0x001)) {
-                                               uint8_t b = (s >> 1);
-                                               Demod.output[Demod.len] = b;
-                                               Demod.len++;
+                                       
+                                       // stop bit == '1', start bit == '0'
+                                       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.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();
                                                 LED_C_OFF();
                                                 LED_C_OFF();
-                                               if(s == 0x000) {
-                                               // This is EOF
-                                               return TRUE;
-                                               }
+                                               
+                                               // This is EOF (start, stop and all data bits == '0'
+                                               if (s == 0) return TRUE;
                                         }
                                 }
                                 Demod.posCount = 0;
                                         }
                                 }
                                 Demod.posCount = 0;
@@ -614,297 +940,439 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                         LED_C_OFF();
                         break;
         }
                         LED_C_OFF();
                         break;
         }
-
         return FALSE;
  }
  
  
         return FALSE;
  }
  
  
-static void DemodReset()
-{
-       // Clear out the state of the "UART" that receives from the tag.
-       Demod.len = 0;
-       Demod.state = DEMOD_UNSYNCD;
-       memset(Demod.output, 0x00, MAX_FRAME_SIZE);
-}
-
-
-static void DemodInit(uint8_t *data)
-{
-       Demod.output = data;
-       DemodReset();
-}
-
-
-static void UartReset()
-{
-       Uart.byteCntMax = MAX_FRAME_SIZE;
-       Uart.state = STATE_UNSYNCD;
-       Uart.byteCnt = 0;
-       Uart.bitCnt = 0;
-}
-
-
-static void UartInit(uint8_t *data)
-{
-       Uart.output = data;
-       UartReset();
-}
-
-
  /*
   *  Demodulate the samples we received from the tag, also log to tracebuffer
  /*
   *  Demodulate the samples we received from the tag, also log to tracebuffer
- *  weTx: set to 'TRUE' if we behave like a reader
- *        set to 'FALSE' if we behave like a snooper
   *  quiet: set to 'TRUE' to disable debug output
   */
   *  quiet: set to 'TRUE' to disable debug output
   */
-static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
-{
-       int max = 0;
-       int gotFrame = FALSE;
-       int lastRxCounter, ci, cq, samples = 0;
+static void GetTagSamplesFor14443bDemod() {
+       bool gotFrame = FALSE, finished = FALSE;
+       int lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+       int ci = 0, cq = 0;
+       uint32_t time_0 = 0, time_stop = 0;
  
  
-       // Allocate memory from BigBuf for some buffers
-       // free all previous allocations first
         BigBuf_free();
         
         BigBuf_free();
         
-       // The response (tag -> reader) that we're receiving.
-       uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
+       // Set up the demodulator for tag -> reader responses.
+       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
         
         // The DMA buffer, used to stream samples from the FPGA
         
         // The DMA buffer, used to stream samples from the FPGA
-       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(DMA_BUFFER_SIZE);
-
-       // Set up the demodulator for tag -> reader responses.
-       DemodInit(receivedResponse);
-
-       // Setup and start DMA.
-       FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
-
+       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
         int8_t *upTo = dmaBuf;
         int8_t *upTo = dmaBuf;
-       lastRxCounter = DMA_BUFFER_SIZE;
+       
+       // Setup and start DMA.
+       if ( !FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE) ){
+               if (MF_DBGLEVEL > 1) Dbprintf("FpgaSetupSscDma failed. Exiting"); 
+               return;
+       }
  
  
-       // Signal field is ON with the appropriate LED:
-       if (weTx) LED_D_ON(); else LED_D_OFF();
         // And put the FPGA in the appropriate mode
         // And put the FPGA in the appropriate mode
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               (weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
-
-       for(;;) {
-               int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
-               if(behindBy > max) max = behindBy;
-
-               while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (DMA_BUFFER_SIZE-1))
-                                       > 2)
-               {
-                       ci = upTo[0];
-                       cq = upTo[1];
-                       upTo += 2;
-                       if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
-                               upTo = dmaBuf;
-                               AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
-                               AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-                       }
-                       lastRxCounter -= 2;
-                       if(lastRxCounter <= 0) {
-                               lastRxCounter += DMA_BUFFER_SIZE;
-                       }
-
-                       samples += 2;
-
-                       if(Handle14443SamplesDemod(ci, cq)) {
-                               gotFrame = 1;
-                       }
-               }
-
-               if(samples > n) {
-                       break;
-               }
-       }
-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-       if (!quiet) Dbprintf("%x %x %x", max, gotFrame, Demod.len);
-       //Tracing
-       if (tracing && Demod.len > 0) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               GetParity(Demod.output, Demod.len, parity);
-               LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
-       }
-}
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
  
  
+       // get current clock
+       time_0 = GetCountSspClk();
+       
+       // rx counter - dma counter? (how much?) & (mod) mask > 2. (since 2bytes at the time is read)
+       while ( !finished ) {
  
  
-//-----------------------------------------------------------------------------
-// Read the tag's response. We just receive a stream of slightly-processed
-// samples from the FPGA, which we will later do some signal processing on,
-// to get the bits.
-//-----------------------------------------------------------------------------
-/*static void GetSamplesFor14443(int weTx, int n)
-{
-       uint8_t *dest = (uint8_t *)BigBuf;
-       int c;
+               LED_A_INV();
+               WDT_HIT();
  
  
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               (weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
+               // LSB is a fpga signal bit.
+               ci = upTo[0] >> 1;
+               cq = upTo[1] >> 1;
+               upTo += 2;
+               lastRxCounter -= 2;
  
  
-       c = 0;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
+               // 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;
                 }
                 }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
  
  
-                       dest[c++] = (uint8_t)b;
+               // https://github.com/Proxmark/proxmark3/issues/103
+               gotFrame =  Handle14443bTagSamplesDemod(ci, cq);
+               time_stop = GetCountSspClk() - time_0;
  
  
-                       if(c >= n) {
-                               break;
-                       }
-               }
+               finished = (time_stop > iso14b_timeout || gotFrame);
+       }
+       
+       FpgaDisableSscDma();
+       
+       if ( upTo ) upTo = NULL;
+       
+       if (MF_DBGLEVEL >= 3) {
+               Dbprintf("Demod.state = %d, Demod.len = %u,  PDC_RCR = %u",     
+                       Demod.state,
+                       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 )
+               LogTrace(Demod.output, Demod.len, time_0, time_stop, NULL, FALSE);
+}
  
  
  //-----------------------------------------------------------------------------
  // Transmit the command (to the tag) that was placed in ToSend[].
  //-----------------------------------------------------------------------------
  
  
  //-----------------------------------------------------------------------------
  // Transmit the command (to the tag) that was placed in ToSend[].
  //-----------------------------------------------------------------------------
-static void TransmitFor14443(void)
-{
-       int c;
-
-       FpgaSetupSsc();
-
-       while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-               AT91C_BASE_SSC->SSC_THR = 0xff;
-       }
+static void TransmitFor14443b_AsReader(void) {
  
  
-       // Signal field is ON with the appropriate Red LED
-       LED_D_ON();
-       // Signal we are transmitting with the Green LED
-       LED_B_ON();
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
-
-       for(c = 0; c < 10;) {
+       // 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?
+       // 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)) {
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0xff;
-                       c++;
+                       AT91C_BASE_SSC->SSC_THR = 0xFF;
+                       ++c;
                 }
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
                 }
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
+                       b = AT91C_BASE_SSC->SSC_RHR;
+                       (void)b;
                 }
                 }
-               WDT_HIT();
         }
  
         }
  
-       c = 0;
-       for(;;) {
+       // Send frame loop
+       for(c = 0; c < ToSendMax;) {
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
-                       c++;
-                       if(c >= ToSendMax) {
-                               break;
-                       }
+                       AT91C_BASE_SSC->SSC_THR = ToSend[c++];
                 }
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
                 }
                 if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
-               }
-               WDT_HIT();
+                       b = AT91C_BASE_SSC->SSC_RHR;
+                       (void)b;
+               }                                       
         }
         }
-       LED_B_OFF(); // Finished sending
+       //WaitForFpgaDelayQueueIsEmpty(delay);
+       // We should wait here for the FPGA to send all bits.
+       WDT_HIT();
  }
  
  }
  
-
  //-----------------------------------------------------------------------------
  // Code a layer 2 command (string of octets, including CRC) into ToSend[],
  //-----------------------------------------------------------------------------
  // Code a layer 2 command (string of octets, including CRC) into ToSend[],
-// so that it is ready to transmit to the tag using TransmitFor14443().
+// so that it is ready to transmit to the tag using TransmitFor14443b().
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
-static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
-{
-       int i, j;
+static void CodeIso14443bAsReader(const uint8_t *cmd, int len) {
+       /*
+       *  Reader data transmission:
+       *   - no modulation ONES
+       *   - SOF
+       *   - Command, data and CRC_B
+       *   - EOF
+       *   - no modulation ONES
+       *
+       *       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;
         uint8_t b;
-
+       
         ToSendReset();
  
         ToSendReset();
  
-       // Establish initial reference level
-       for(i = 0; i < 40; i++) {
-               ToSendStuffBit(1);
-       }
         // Send SOF
         // Send SOF
-       for(i = 0; i < 10; i++) {
+       // 10-11 ETUs of ZERO 
+       for(i = 0; i < 10; ++i) ToSendStuffBit(0);
+       
+       // 2-3 ETUs of ONE
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       ToSendStuffBit(1);
+       
+       // Sending cmd, LSB
+       // from here we add BITS
+       for(i = 0; i < len; ++i) {
+           // Start bit
                 ToSendStuffBit(0);
                 ToSendStuffBit(0);
-       }
-
-       for(i = 0; i < len; i++) {
-               // Stop bits/EGT
+               // 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);  
+
+               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);
                 ToSendStuffBit(1);
+               // EGT extra guard time
+               // For PCD it ranges 0-57us (1etu = 9us)
                 ToSendStuffBit(1);
                 ToSendStuffBit(1);
-               // Start bit
-               ToSendStuffBit(0);
-               // Data bits
-               b = cmd[i];
-               for(j = 0; j < 8; j++) {
-                       if(b & 1) {
-                               ToSendStuffBit(1);
-                       } else {
-                               ToSendStuffBit(0);
-                       }
-                       b >>= 1;
-               }
-       }
-       // Send EOF
-       ToSendStuffBit(1);
-       for(i = 0; i < 10; i++) {
-               ToSendStuffBit(0);
-       }
-       for(i = 0; i < 8; i++) {
                 ToSendStuffBit(1);
                 ToSendStuffBit(1);
-       }
-
-       // And then a little more, to make sure that the last character makes
-       // it out before we switch to rx mode.
-       for(i = 0; i < 24; i++) {
                 ToSendStuffBit(1);
         }
                 ToSendStuffBit(1);
         }
-
+       
+       // Send EOF
+       // 10-11 ETUs of ZERO
+       for(i = 0; i < 10; ++i) ToSendStuffBit(0);
+
+       // Transition time. TR0 - guard time
+       // 8ETUS minum?
+       // Per specification, Subcarrier must be stopped no later than 2 ETUs after EOF.        
+       // 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
         // Convert from last character reference to length
-       ToSendMax++;
+       ++ToSendMax;
  }
  
  
  }
  
  
-//-----------------------------------------------------------------------------
-// Read an ISO 14443 tag. We send it some set of commands, and record the
-// responses.
-// The command name is misleading, it actually decodes the reponse in HEX
-// into the output buffer (read the result using hexsamples, not hisamples)
-//
-// obsolete function only for test
-//-----------------------------------------------------------------------------
-void AcquireRawAdcSamplesIso14443(uint32_t parameter)
-{
-       uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+/*
+*  Convenience function to encode, transmit and trace iso 14443b comms
+*/
+static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len) {
  
  
-       SendRawCommand14443B(sizeof(cmd1),1,1,cmd1);
+       uint32_t time_start = GetCountSspClk();
+       
+       CodeIso14443bAsReader(cmd, len);
+
+       TransmitFor14443b_AsReader();
+
+       if(trigger) LED_A_ON();
+
+       LogTrace(cmd, len, time_start, GetCountSspClk()-time_start, NULL, TRUE);
  }
  
  }
  
+/* Sends an APDU to the tag
+ * TODO: check CRC and preamble
+ */
+uint8_t iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *response)
+{
+       uint8_t crc[2] = {0x00, 0x00};
+       uint8_t message_frame[message_length + 4];
+       // PCB
+       message_frame[0] = 0x0A | pcb_blocknum;
+       pcb_blocknum ^= 1;
+       // CID
+       message_frame[1] = 0;
+       // INF
+       memcpy(message_frame + 2, message, message_length);
+       // EDC (CRC)
+       ComputeCrc14443(CRC_14443_B, message_frame, message_length + 2, &message_frame[message_length + 2], &message_frame[message_length + 3]);
+       // send
+       CodeAndTransmit14443bAsReader(message_frame, message_length + 4); //no
+       // get response
+       GetTagSamplesFor14443bDemod(); //no
+       if(Demod.len < 3)
+               return 0;
+       
+       // VALIDATE CRC
+    ComputeCrc14443(CRC_14443_B, Demod.output, Demod.len-2, &crc[0], &crc[1]);
+       if ( crc[0] != Demod.output[Demod.len-2] || crc[1] != Demod.output[Demod.len-1] )
+               return 0;
+       
+       // copy response contents
+       if(response != NULL)
+               memcpy(response, Demod.output, Demod.len);
+
+       return Demod.len;
+}
  
  /**
  
  /**
-  Convenience function to encode, transmit and trace iso 14443b comms
-  **/
-static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
+* SRx Initialise.
+*/
+uint8_t iso14443b_select_srx_card(iso14b_card_select_t *card )
  {
  {
-       CodeIso14443bAsReader(cmd, len);
-       TransmitFor14443();
-       if (tracing) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               GetParity(cmd, len, parity);
-               LogTrace(cmd,len, 0, 0, parity, TRUE);
+       // INITIATE command: wake up the tag using the INITIATE
+       static const uint8_t init_srx[] = { ISO14443B_INITIATE, 0x00, 0x97, 0x5b };
+       // SELECT command (with space for CRC)
+       uint8_t select_srx[] = { ISO14443B_SELECT, 0x00, 0x00, 0x00};
+       // temp to calc crc.
+       uint8_t crc[2] = {0x00, 0x00};
+       
+       CodeAndTransmit14443bAsReader(init_srx, sizeof(init_srx));
+       GetTagSamplesFor14443bDemod(); //no
+
+       if (Demod.len == 0) return 2;
+
+       // Randomly generated Chip ID   
+       if (card) card->chipid = Demod.output[0];
+       
+       select_srx[1] = Demod.output[0];
+       
+       ComputeCrc14443(CRC_14443_B, select_srx, 2, &select_srx[2], &select_srx[3]);
+       CodeAndTransmit14443bAsReader(select_srx, sizeof(select_srx));
+       GetTagSamplesFor14443bDemod(); //no
+       
+       if (Demod.len != 3)     return 2;
+       
+       // Check the CRC of the answer:
+       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;
+       
+       // Check response from the tag: should be the same UID as the command we just sent:
+       if (select_srx[1] != Demod.output[0]) return 1;
+
+       // First get the tag's UID:
+       select_srx[0] = ISO14443B_GET_UID;
+
+       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(); //no
+
+       if (Demod.len != 10) return 2;
+       
+       // The check the CRC of the answer
+       ComputeCrc14443(CRC_14443_B, Demod.output, Demod.len-2, &crc[0], &crc[1]);
+       if(crc[0] != Demod.output[8] || crc[1] != Demod.output[9]) return 3;
+
+       if (card) {
+               card->uidlen = 8;
+               memcpy(card->uid, Demod.output, 8);
         }
         }
+
+       return 0;
  }
  }
+/* Perform the ISO 14443 B Card Selection procedure
+ * Currently does NOT do any collision handling.
+ * It expects 0-1 cards in the device's range.
+ * TODO: Support multiple cards (perform anticollision)
+ * TODO: Verify CRC checksums
+ */
+uint8_t iso14443b_select_card(iso14b_card_select_t *card )
+{
+       // WUPB command (including CRC)
+       // Note: WUPB wakes up all tags, REQB doesn't wake up tags in HALT state
+       static const uint8_t wupb[] = { ISO14443B_REQB, 0x00, 0x08, 0x39, 0x73 };
+       // ATTRIB command (with space for CRC)
+       uint8_t attrib[] = { ISO14443B_ATTRIB, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00};
+
+       // temp to calc crc.
+       uint8_t crc[2] = {0x00, 0x00};
+       
+       // first, wake up the tag
+       CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
+       GetTagSamplesFor14443bDemod(); //select_card
+       
+       // ATQB too short?
+       if (Demod.len < 14) return 2;
+       
+       // VALIDATE CRC
+    ComputeCrc14443(CRC_14443_B, Demod.output, Demod.len-2, &crc[0], &crc[1]);
+       if ( crc[0] != Demod.output[12] || crc[1] != Demod.output[13] )
+               return 3;
+       
+       if (card) {
+               card->uidlen = 4;
+               memcpy(card->uid, Demod.output+1, 4);
+               memcpy(card->atqb, Demod.output+5, 7);
+       }
+
+    // copy the PUPI to ATTRIB  ( PUPI == UID )
+    memcpy(attrib + 1, Demod.output + 1, 4);
+       
+    // copy the protocol info from ATQB (Protocol Info -> Protocol_Type) into ATTRIB (Param 3)
+    attrib[7] = Demod.output[10] & 0x0F;
+    ComputeCrc14443(CRC_14443_B, attrib, 9, attrib + 9, attrib + 10);
  
  
+    CodeAndTransmit14443bAsReader(attrib, sizeof(attrib));
+    GetTagSamplesFor14443bDemod();//select_card
+
+    // Answer to ATTRIB too short?
+    if(Demod.len < 3) return 2;
+
+       // VALIDATE CRC
+    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
+               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;
+       return 0;
+}
+
+// Set up ISO 14443 Type B communication (similar to iso14443a_setup)
+// field is setup for "Sending as Reader"
+void iso14443b_setup() {
+       if (MF_DBGLEVEL > 3) Dbprintf("iso1443b_setup Enter");
+       LEDsoff();
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       //BigBuf_free();
+       //BigBuf_Clear_ext(false);
+       
+       // Initialize Demod and Uart structs
+       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
+       UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
+
+       // connect Demodulated Signal to ADC:
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Set up the synchronous serial port
+       FpgaSetupSsc();
+       
+       // Signal field is on with the appropriate LED
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
+       SpinDelay(100);
+
+       // Start the timer
+       StartCountSspClk();
+       
+       LED_D_ON();
+       if (MF_DBGLEVEL > 3) Dbprintf("iso1443b_setup Exit");
+}
  
  //-----------------------------------------------------------------------------
  
  //-----------------------------------------------------------------------------
-// Read a SRI512 ISO 14443 tag.
+// Read a SRI512 ISO 14443B tag.
  //
  // SRI512 tags are just simple memory tags, here we're looking at making a dump
  // of the contents of the memory. No anticollision algorithm is done, we assume
  //
  // SRI512 tags are just simple memory tags, here we're looking at making a dump
  // of the contents of the memory. No anticollision algorithm is done, we assume
@@ -912,19 +1380,17 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
  //
  // I tried to be systematic and check every answer of the tag, every CRC, etc...
  //-----------------------------------------------------------------------------
  //
  // I tried to be systematic and check every answer of the tag, every CRC, etc...
  //-----------------------------------------------------------------------------
-void ReadSTMemoryIso14443(uint32_t dwLast)
+void ReadSTMemoryIso14443b(uint8_t numofblocks)
  {
  {
-       clear_trace();
-       set_tracing(TRUE);
-
-       uint8_t i = 0x00;
-
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+
         // Make sure that we start from off, since the tags are stateful;
         // confusing things will happen if we don't reset them between reads.
         // Make sure that we start from off, since the tags are stateful;
         // confusing things will happen if we don't reset them between reads.
-       LED_D_OFF();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+       switch_off();  // before ReadStMemory
+
+       set_tracing(TRUE);
+
+       uint8_t i = 0x00;
  
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
         FpgaSetupSsc();
  
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
         FpgaSetupSsc();
@@ -932,114 +1398,148 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
         // Now give it time to spin up.
         // Signal field is on with the appropriate LED
         LED_D_ON();
         // Now give it time to spin up.
         // Signal field is on with the appropriate LED
         LED_D_ON();
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
-       SpinDelay(200);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+       SpinDelay(20);
  
         // First command: wake up the tag using the INITIATE command
  
         // First command: wake up the tag using the INITIATE command
-       uint8_t cmd1[] = { 0x06, 0x00, 0x97, 0x5b};
-
-       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       uint8_t cmd1[] = {ISO14443B_INITIATE, 0x00, 0x97, 0x5b};
+       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
+       GetTagSamplesFor14443bDemod(); // no
  
         if (Demod.len == 0) {
  
         if (Demod.len == 0) {
-       DbpString("No response from tag");
-       return;
+               DbpString("No response from tag");
+               set_tracing(FALSE);     
+               return;
         } else {
         } else {
-       Dbprintf("Randomly generated UID from tag (+ 2 byte CRC): %x %x %x",
-               Demod.output[0], Demod.output[1],Demod.output[2]);
+               Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
+                               Demod.output[0], Demod.output[1], Demod.output[2]);
         }
         }
+
         // There is a response, SELECT the uid
         DbpString("Now SELECT tag:");
         // There is a response, SELECT the uid
         DbpString("Now SELECT tag:");
-       cmd1[0] = 0x0E; // 0x0E is SELECT
+       cmd1[0] = ISO14443B_SELECT; // 0x0E is SELECT
         cmd1[1] = Demod.output[0];
         ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
         cmd1[1] = Demod.output[0];
         ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
-       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
+       GetTagSamplesFor14443bDemod(); //no
         if (Demod.len != 3) {
         if (Demod.len != 3) {
-       Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
-       return;
+               Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
+               set_tracing(FALSE);     
+               return;
         }
         // Check the CRC of the answer:
         ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
         if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
         }
         // Check the CRC of the answer:
         ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
         if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
-       DbpString("CRC Error reading select response.");
-       return;
+               DbpString("CRC Error reading select response.");
+               set_tracing(FALSE);     
+               return;
         }
         // Check response from the tag: should be the same UID as the command we just sent:
         if (cmd1[1] != Demod.output[0]) {
         }
         // Check response from the tag: should be the same UID as the command we just sent:
         if (cmd1[1] != Demod.output[0]) {
-       Dbprintf("Bad response to SELECT from Tag, aborting: %x %x", cmd1[1], Demod.output[0]);
-       return;
+               Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
+               set_tracing(FALSE);     
+               return;
         }
         }
+
         // Tag is now selected,
         // First get the tag's UID:
         // Tag is now selected,
         // First get the tag's UID:
-       cmd1[0] = 0x0B;
+       cmd1[0] = ISO14443B_GET_UID;
         ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
         ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
-       CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       CodeAndTransmit14443bAsReader(cmd1, 3); // no --  Only first three bytes for this one
+       GetTagSamplesFor14443bDemod(); //no
         if (Demod.len != 10) {
         if (Demod.len != 10) {
-       Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
-       return;
+               Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
+               set_tracing(FALSE);     
+               return;
         }
         // The check the CRC of the answer (use cmd1 as temporary variable):
         ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
         }
         // The check the CRC of the answer (use cmd1 as temporary variable):
         ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
-                  if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
-       Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
-               (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
+       if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
+               Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
+                               (cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
         // Do not return;, let's go on... (we should retry, maybe ?)
         }
         Dbprintf("Tag UID (64 bits): %08x %08x",
         // Do not return;, let's go on... (we should retry, maybe ?)
         }
         Dbprintf("Tag UID (64 bits): %08x %08x",
-       (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
-       (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
+                       (Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
+                       (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
  
         // Now loop to read all 16 blocks, address from 0 to last block
  
         // Now loop to read all 16 blocks, address from 0 to last block
-       Dbprintf("Tag memory dump, block 0 to %d",dwLast);
+       Dbprintf("Tag memory dump, block 0 to %d", numofblocks);
         cmd1[0] = 0x08;
         i = 0x00;
         cmd1[0] = 0x08;
         i = 0x00;
-       dwLast++;
+       ++numofblocks;
+       
         for (;;) {
         for (;;) {
-                  if (i == dwLast) {
+               if (i == numofblocks) {
                         DbpString("System area block (0xff):");
                         i = 0xff;
                 }
                 cmd1[1] = i;
                 ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
                         DbpString("System area block (0xff):");
                         i = 0xff;
                 }
                 cmd1[1] = i;
                 ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
-               CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
-
-//         LED_A_ON();
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//         LED_A_OFF();
+               CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1)); //no
+               GetTagSamplesFor14443bDemod(); //no
+               
                 if (Demod.len != 6) { // Check if we got an answer from the tag
                 if (Demod.len != 6) { // Check if we got an answer from the tag
-               DbpString("Expected 6 bytes from tag, got less...");
-               return;
+                       DbpString("Expected 6 bytes from tag, got less...");
+                       return;
                 }
                 // The check the CRC of the answer (use cmd1 as temporary variable):
                 ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
                         if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
                 }
                 // The check the CRC of the answer (use cmd1 as temporary variable):
                 ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
                         if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
-               Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
-                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
+                       Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
+                                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
                 // Do not return;, let's go on... (we should retry, maybe ?)
                 }
                 // Now print out the memory location:
                 // Do not return;, let's go on... (we should retry, maybe ?)
                 }
                 // Now print out the memory location:
-               Dbprintf("Address=%x, Contents=%x, CRC=%x", i,
-               (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
-               (Demod.output[4]<<8)+Demod.output[5]);
-               if (i == 0xff) {
-               break;
-               }
-               i++;
+               Dbprintf("Address=%02x, Contents=%08x, CRC=%04x", i,
+                               (Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
+                               (Demod.output[4]<<8)+Demod.output[5]);
+
+               if (i == 0xff) break;
+               ++i;
         }
         }
+       
+       set_tracing(FALSE);
  }
  
  
  }
  
  
+static void iso1444b_setup_snoop(void){
+       if (MF_DBGLEVEL > 3) Dbprintf("iso1443b_setup_snoop Enter");
+       LEDsoff();
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       BigBuf_free();
+       BigBuf_Clear_ext(false); 
+       clear_trace();//setup snoop
+       set_tracing(TRUE);
+
+       // Initialize Demod and Uart structs
+       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
+       UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
+
+       if (MF_DBGLEVEL > 1) {
+               // Print debug information about the buffer sizes
+               Dbprintf("Snooping buffers initialized:");
+               Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
+               Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
+               Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
+               Dbprintf("  DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);
+       }
+
+       // connect Demodulated Signal to ADC:
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Setup for the DMA.
+       FpgaSetupSsc();
+
+       // Set FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
+       SpinDelay(20);  
+
+       // Start the SSP timer
+       StartCountSspClk();
+       if (MF_DBGLEVEL > 3) Dbprintf("iso1443b_setup_snoop Exit");
+}
+
  //=============================================================================
  // Finally, the `sniffer' combines elements from both the reader and
  // simulated tag, to show both sides of the conversation.
  //=============================================================================
  // Finally, the `sniffer' combines elements from both the reader and
  // simulated tag, to show both sides of the conversation.
@@ -1054,220 +1554,222 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
   * Memory usage for this function, (within BigBuf)
   * Last Received command (reader->tag) - MAX_FRAME_SIZE
   * Last Received command (tag->reader) - MAX_FRAME_SIZE
   * Memory usage for this function, (within BigBuf)
   * Last Received command (reader->tag) - MAX_FRAME_SIZE
   * Last Received command (tag->reader) - MAX_FRAME_SIZE
- * DMA Buffer, 1024 bytes (samples) - DMA_BUFFER_SIZE
+ * DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
   * Demodulated samples received - all the rest
   */
   * Demodulated samples received - all the rest
   */
-void RAMFUNC SnoopIso14443(void)
-{
+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
-
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BigBuf_free();
-
-       clear_trace();
-       set_tracing(TRUE);
+       bool triggered = TRUE;                  // TODO: set and evaluate trigger condition             
+       bool TagIsActive = FALSE;
+       bool ReaderIsActive = FALSE;
  
  
+       iso1444b_setup_snoop();
+       
         // The DMA buffer, used to stream samples from the FPGA
         // The DMA buffer, used to stream samples from the FPGA
-       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(DMA_BUFFER_SIZE);
-       int lastRxCounter;
-       int8_t *upTo;
-       int ci, cq;
-       int maxBehindBy = 0;
-
-       // Count of samples received so far, so that we can include timing
-       // information in the trace buffer.
-       int samples = 0;
-
-       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
-       UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
-
-       // Print some debug information about the buffer sizes
-       Dbprintf("Snooping buffers initialized:");
-       Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
-       Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
-       Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
-       Dbprintf("  DMA: %i bytes", DMA_BUFFER_SIZE);
-
-       // Signal field is off with the appropriate LED
-       LED_D_OFF();
-
-       // And put the FPGA in the appropriate mode
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               FPGA_HF_READER_RX_XCORR_SNOOP);
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
+       int8_t *upTo = dmaBuf;
  
  
-       // Setup for the DMA.
-       FpgaSetupSsc();
-       upTo = dmaBuf;
-       lastRxCounter = DMA_BUFFER_SIZE;
-       FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
-       uint8_t parity[MAX_PARITY_SIZE];
-       LED_A_ON();
-               
-       bool TagIsActive = FALSE;
-       bool ReaderIsActive = FALSE;
+       // Setup and start DMA.
+       if ( !FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE) ){
+               if (MF_DBGLEVEL > 1) Dbprintf("FpgaSetupSscDma failed. Exiting"); 
+               BigBuf_free();
+               return;
+       }
         
         
+       time_0 = GetCountSspClk();
+               
         // And now we loop, receiving samples.
         for(;;) {
         // And now we loop, receiving samples.
         for(;;) {
-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
-                                                               (DMA_BUFFER_SIZE-1);
-               if(behindBy > maxBehindBy) {
-                       maxBehindBy = behindBy;
-                       if(behindBy > (9*DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
-                               Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
-                               break;
-                       }
-               }
-               if(behindBy < 2) continue;
+
+               WDT_HIT();
  
                 ci = upTo[0];
                 cq = upTo[1];
  
                 ci = upTo[0];
                 cq = upTo[1];
-               upTo += 2;
+               upTo += 2;              
                 lastRxCounter -= 2;
                 lastRxCounter -= 2;
-               if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
+               
+               if (upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
                         upTo = dmaBuf;
                         upTo = dmaBuf;
-                       lastRxCounter += DMA_BUFFER_SIZE;
+                       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
                         AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
                         AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
-                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-               }
-
-               samples += 2;
-
-               if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
-                       if(Handle14443UartBit(ci & 0x01)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
+               
+                       if (!tracing) {
+                               if (MF_DBGLEVEL >= 2) DbpString("Trace full");
+                               break;
                         }
                         }
-                       if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
-
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
-               }
-                       if(Handle14443UartBit(cq & 0x01)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
+                               
+                       if (BUTTON_PRESS()) {
+                               if (MF_DBGLEVEL >= 2) DbpString("cancelled");
+                               break;
                         }
                         }
-                       if(Uart.byteCnt==0) Dbprintf("[2] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
-
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
                 }
                 }
-                       ReaderIsActive = (Uart.state != STATE_UNSYNCD);
-               }
-
-               if(!ReaderIsActive) {                                           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
-                       if(Handle14443SamplesDemod(ci & 0xFE, cq & 0xFE)) {
-
-                       //Use samples as a time measurement
-                       if(tracing)
-                       {
-                               uint8_t parity[MAX_PARITY_SIZE];
-                               GetParity(Demod.output, Demod.len, parity);
-                               LogTrace(Demod.output, Demod.len,samples, samples, parity, FALSE);
+               
+               if (!TagIsActive) {             
+               
+                       LED_A_ON();
+                       
+                       // no need to try decoding reader data if the tag is sending
+                       if (Handle14443bReaderUartBit(ci & 0x01)) {
+
+                               time_stop = GetCountSspClk() - time_0;
+                               
+                               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();
+                       } else {
+                               time_start = GetCountSspClk() - time_0;
+                       }
+                       
+                       if (Handle14443bReaderUartBit(cq & 0x01)) {
+                               
+                               time_stop = GetCountSspClk() - time_0;
+                               
+                               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();
+                       } else {
+                               time_start = GetCountSspClk() - time_0;
                         }
                         }
-                       triggered = TRUE;
+                       ReaderIsActive = (Uart.state > STATE_GOT_FALLING_EDGE_OF_SOF);
                         LED_A_OFF();
                         LED_A_OFF();
-                       LED_B_ON();
-
-                       // And ready to receive another response.
-                       DemodReset();
-               }
-                       TagIsActive = (Demod.state != DEMOD_UNSYNCD);
-               }
-
-               WDT_HIT();
-
-               if(!tracing) {
-                       DbpString("Reached trace limit");
-                       break;
                 }
                 }
-
-               if(BUTTON_PRESS()) {
-                       DbpString("cancelled");
-                       break;
+               
+               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
+                       // LSB is a fpga signal bit.
+                       if (Handle14443bTagSamplesDemod(ci >> 1, cq >> 1)) {
+                               
+                               time_stop = GetCountSspClk() - time_0;
+                               
+                               LogTrace(Demod.output, Demod.len, time_start, time_stop, NULL, FALSE);
+
+                               triggered = TRUE;
+
+                               // And ready to receive another response.
+                               DemodReset();
+                       } else {
+                               time_start = GetCountSspClk() - time_0;
+                       }
+                       TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
                 }
         }
                 }
         }
-       FpgaDisableSscDma();
-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+
+       switch_off(); // Snoop
+       
         DbpString("Snoop statistics:");
         DbpString("Snoop statistics:");
-       Dbprintf("  Max behind by: %i", maxBehindBy);
-       Dbprintf("  Uart State: %x", Uart.state);
-       Dbprintf("  Uart ByteCnt: %i", Uart.byteCnt);
-       Dbprintf("  Uart ByteCntMax: %i", Uart.byteCntMax);
+       Dbprintf("  Uart State: %x  ByteCount: %i  ByteCountMax: %i", Uart.state,  Uart.byteCnt,  Uart.byteCntMax);
         Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
         Dbprintf("  Trace length: %i", BigBuf_get_traceLen());
+
+       // free mem refs.
+       if ( upTo ) upTo = NULL;
+       
+       // Uart.byteCntMax  should be set with ATQB value..
  }
  
  }
  
+void iso14b_set_trigger(bool enable) {
+       trigger = enable;
+}
  
  /*
   * Send raw command to tag ISO14443B
   * @Input
  
  /*
   * Send raw command to tag ISO14443B
   * @Input
- * datalen     len of buffer data
- * recv        bool when true wait for data from tag and send to client
- * powerfield  bool leave the field on when true
- * data        buffer with byte to send
+ * param   flags enum ISO14B_COMMAND.  (mifare.h)
+ * len     len of buffer data
+ * data    buffer with bytes to send
   *
   * @Output
   * none
   *
   */
   *
   * @Output
   * none
   *
   */
-void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield_trace, uint8_t data[])
+void SendRawCommand14443B_Ex(UsbCommand *c)
  {
  {
-       uint8_t powerfield = powerfield_trace & 1;
-       uint8_t trace = powerfield_trace & 2;
-       if (trace){
-               clear_trace();
-               set_tracing(TRUE);
-       }
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       if(!powerfield)
-       {
+       iso14b_command_t param = c->arg[0];
+       size_t len = c->arg[1] & 0xffff;
+       uint8_t *cmd = c->d.asBytes;
+       uint8_t status = 0;
+       uint32_t sendlen = sizeof(iso14b_card_select_t);
+       uint8_t buf[USB_CMD_DATA_SIZE] = {0x00};
+
+       if (MF_DBGLEVEL > 3) Dbprintf("14b raw: param, %04x", param );
+       
+       // turn on trigger (LED_A)
+       if ((param & ISO14B_REQUEST_TRIGGER) == ISO14B_REQUEST_TRIGGER)
+               iso14b_set_trigger(TRUE);
+       
+       if ((param & ISO14B_CONNECT) == ISO14B_CONNECT) {
                 // Make sure that we start from off, since the tags are stateful;
                 // confusing things will happen if we don't reset them between reads.
                 // Make sure that we start from off, since the tags are stateful;
                 // confusing things will happen if we don't reset them between reads.
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               LED_D_OFF();
-               SpinDelay(200);
+               //switch_off();  // before connect in raw
+               iso14443b_setup();
         }
         }
+       
+       set_tracing(TRUE);
  
  
-       if(!GETBIT(GPIO_LED_D))
-       {
-               SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-               FpgaSetupSsc();
-
-               // Now give it time to spin up.
-               // Signal field is on with the appropriate LED
-               LED_D_ON();
-               FpgaWriteConfWord(
-                       FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
-               SpinDelay(200);
+       if ((param & ISO14B_SELECT_STD) == ISO14B_SELECT_STD) {
+               iso14b_card_select_t *card = (iso14b_card_select_t*)buf;
+               status = iso14443b_select_card(card);   
+               cmd_send(CMD_ACK, status, sendlen, 0, buf, sendlen);
+               // 0: OK 2: attrib fail, 3:crc fail,
+               if ( status > 0 ) return;
+       } 
+       
+       if ((param & ISO14B_SELECT_SR) == ISO14B_SELECT_SR) {
+               iso14b_card_select_t *card = (iso14b_card_select_t*)buf;
+               status = iso14443b_select_srx_card(card);
+               cmd_send(CMD_ACK, status, sendlen, 0, buf, sendlen);
+               // 0: OK 2: attrib fail, 3:crc fail,
+               if ( status > 0 ) return;
+       } 
+       
+       if ((param & ISO14B_APDU) == ISO14B_APDU) {
+               status = iso14443b_apdu(cmd, len, buf);
+               cmd_send(CMD_ACK, status, status, 0, buf, status);
         }
         }
-
-       CodeAndTransmit14443bAsReader(data, datalen);
-
-       if(recv)
-       {
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-               uint16_t iLen = MIN(Demod.len,USB_CMD_DATA_SIZE);
-               cmd_send(CMD_ACK,iLen,0,0,Demod.output,iLen);
+       
+       if ((param & ISO14B_RAW) == ISO14B_RAW) {
+               if((param & ISO14B_APPEND_CRC) == ISO14B_APPEND_CRC) {
+                       AppendCrc14443b(cmd, len);
+                       len += 2;
+               }
+       
+               CodeAndTransmit14443bAsReader(cmd, len); // raw         
+               GetTagSamplesFor14443bDemod(); // raw
+               
+               sendlen = MIN(Demod.len, USB_CMD_DATA_SIZE);
+               status =  (Demod.len > 0) ? 0 : 1;
+               cmd_send(CMD_ACK, status, sendlen, 0, Demod.output, sendlen);
         }
         }
-       if(!powerfield)
-       {
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               LED_D_OFF();
+       
+       // turn off trigger (LED_A)
+       if ((param & ISO14B_REQUEST_TRIGGER) == ISO14B_REQUEST_TRIGGER)
+               iso14b_set_trigger(FALSE);
+
+       // turn off antenna et al
+       // we don't send a HALT command.
+       if ((param & ISO14B_DISCONNECT) == ISO14B_DISCONNECT) {
+               if (MF_DBGLEVEL > 3) Dbprintf("disconnect");
+               switch_off(); // disconnect raw
+       } else {
+               //FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);              
         }
         }
-}
-
+       
+}
+\ No newline at end of file