delete travis. it plaed in folder `CI` (#736)

[proxmark3-svn] / armsrc / iso14443b.c

diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index 8add8f9c3eb27b4a9a5108d55e4280c01407c8fa..cb8567fa570533ae8cee27283ca0e37f22429b78 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -1,13 +1,13 @@
 //-----------------------------------------------------------------------------
 // Jonathan Westhues, split Nov 2006
 //-----------------------------------------------------------------------------
 // Jonathan Westhues, split Nov 2006

+// piwi 2018

 //
 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
 // at your option, any later version. See the LICENSE.txt file for the text of
 // the license.
 //-----------------------------------------------------------------------------
 //
 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
 // at your option, any later version. See the LICENSE.txt file for the text of
 // the license.
 //-----------------------------------------------------------------------------

-// Routines to support ISO 14443. This includes both the reader software and
-// the `fake tag' modes. At the moment only the Type B modulation is
-// supported.
+// Routines to support ISO 14443B. This includes both the reader software and
+// the `fake tag' modes.

 //-----------------------------------------------------------------------------
 
 #include "proxmark3.h"
 //-----------------------------------------------------------------------------
 
 #include "proxmark3.h"


@@ -17,15 +17,11 @@
 
 #include "iso14443crc.h"
 
 
 #include "iso14443crc.h"
 

-//static void GetSamplesFor14443(int weTx, int n);
+#define RECEIVE_SAMPLES_TIMEOUT 1000 // TR0 max is 256/fs = 256/(848kHz) = 302us or 64 samples from FPGA. 1000 seems to be much too high?
+#define ISO14443B_DMA_BUFFER_SIZE 128

 
 

-/*#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
+// PCB Block number for APDUs
+static uint8_t pcb_blocknum = 0;

 
 //=============================================================================
 // 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


@@ -104,14 +100,14 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
                ToSendStuffBit(1);
        }
 
                ToSendStuffBit(1);
        }
 

-       // Send SOF.
+       // Send EOF.

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

-       for(i = 0; i < 10; i++) {
+       for(i = 0; i < 2; i++) {

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


@@ -120,9 +116,6 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
 
        // Convert from last byte pos to length
        ToSendMax++;
 
        // Convert from last byte pos to length
        ToSendMax++;

-
-       // Add a few more for slop
-       ToSendMax += 2;

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


@@ -134,8 +127,7 @@ static struct {
                STATE_UNSYNCD,
                STATE_GOT_FALLING_EDGE_OF_SOF,
                STATE_AWAITING_START_BIT,
                STATE_UNSYNCD,
                STATE_GOT_FALLING_EDGE_OF_SOF,
                STATE_AWAITING_START_BIT,

-               STATE_RECEIVING_DATA,
-               STATE_ERROR_WAIT
+               STATE_RECEIVING_DATA

        }       state;
        uint16_t    shiftReg;
        int     bitCnt;
        }       state;
        uint16_t    shiftReg;
        int     bitCnt;


@@ -146,6 +138,9 @@ static struct {
 } Uart;
 
 /* Receive & handle a bit coming from the reader.
 } Uart;
 
 /* Receive & handle a bit coming from the reader.

+ *
+ * This function is called 4 times per bit (every 2 subcarrier cycles).
+ * Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us

  *
  * LED handling:
  * LED A -> ON once we have received the SOF and are expecting the rest.
  *
  * LED handling:
  * LED A -> ON once we have received the SOF and are expecting the rest.


@@ -154,11 +149,10 @@ 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)
+static RAMFUNC int Handle14443bUartBit(uint8_t bit)

 {
        switch(Uart.state) {
                case STATE_UNSYNCD:
 {
        switch(Uart.state) {
                case STATE_UNSYNCD:

-                       LED_A_OFF();

                        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


@@ -170,9 +164,9 @@ 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(Uart.posCnt == 2) {  // sample every 4 1/fs in the middle of a bit

                                if(bit) {
                                if(bit) {

-                                       if(Uart.bitCnt >= 10) {
+                                       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;


@@ -182,7 +176,7 @@ static int Handle14443UartBit(int bit)
                                        } else {
                                                // didn't stay down long enough
                                                // before going high, error
                                        } else {
                                                // didn't stay down long enough
                                                // before going high, error

-                                               Uart.state = STATE_ERROR_WAIT;
+                                               Uart.state = STATE_UNSYNCD;

                                        }
                                } else {
                                        // do nothing, keep waiting
                                        }
                                } else {
                                        // do nothing, keep waiting


@@ -190,20 +184,21 @@ static int Handle14443UartBit(int bit)
                                Uart.bitCnt++;
                        }
                        if(Uart.posCnt >= 4) Uart.posCnt = 0;
                                Uart.bitCnt++;
                        }
                        if(Uart.posCnt >= 4) Uart.posCnt = 0;

-                       if(Uart.bitCnt > 14) {
+                       if(Uart.bitCnt > 12) {

                                // Give up if we see too many zeros without
                                // a one, too.
                                // Give up if we see too many zeros without
                                // a one, too.

-                               Uart.state = STATE_ERROR_WAIT;
+                               LED_A_OFF();
+                               Uart.state = STATE_UNSYNCD;

                        }
                        break;
 
                case STATE_AWAITING_START_BIT:
                        Uart.posCnt++;
                        if(bit) {
                        }
                        break;
 
                case STATE_AWAITING_START_BIT:
                        Uart.posCnt++;
                        if(bit) {

-                               if(Uart.posCnt > 25) {
+                               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
                                        // stayed high for too long between
                                        // characters, error

-                                       Uart.state = STATE_ERROR_WAIT;
+                                       Uart.state = STATE_UNSYNCD;

                                }
                        } else {
                                // falling edge, this starts the data byte
                                }
                        } else {
                                // falling edge, this starts the data byte


@@ -211,7 +206,6 @@ static int Handle14443UartBit(int bit)
                                Uart.bitCnt = 0;
                                Uart.shiftReg = 0;
                                Uart.state = STATE_RECEIVING_DATA;
                                Uart.bitCnt = 0;
                                Uart.shiftReg = 0;
                                Uart.state = STATE_RECEIVING_DATA;

-                               LED_A_ON(); // Indicate we're receiving

                        }
                        break;
 
                        }
                        break;
 


@@ -238,159 +232,201 @@ static int Handle14443UartBit(int bit)
 
                                        if(Uart.byteCnt >= Uart.byteCntMax) {
                                                // Buffer overflowed, give up
 
                                        if(Uart.byteCnt >= Uart.byteCntMax) {
                                                // 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;
-                       }
-                       break;
-

                default:
                default:

+                       LED_A_OFF();

                        Uart.state = STATE_UNSYNCD;
                        break;
        }
 
                        Uart.state = STATE_UNSYNCD;
                        break;
        }
 

-       // This row make the error blew circular buffer in hf 14b snoop
-       //if (Uart.state == STATE_ERROR_WAIT) LED_A_OFF(); // Error
+       return false;
+}
+

 
 

-       return FALSE;
+static void UartReset()
+{
+       Uart.byteCntMax = MAX_FRAME_SIZE;
+       Uart.state = STATE_UNSYNCD;
+       Uart.byteCnt = 0;
+       Uart.bitCnt = 0;

 }
 
 }
 

+
+static void UartInit(uint8_t *data)
+{
+       Uart.output = data;
+       UartReset();
+}
+
+

 //-----------------------------------------------------------------------------
 // Receive a command (from the reader to us, where we are the simulated tag),
 // and store it in the given buffer, up to the given maximum length. Keeps
 // spinning, waiting for a well-framed command, until either we get one
 //-----------------------------------------------------------------------------
 // Receive a command (from the reader to us, where we are the simulated tag),
 // and store it in the given buffer, up to the given maximum length. Keeps
 // spinning, waiting for a well-framed command, until either we get one

-// (returns TRUE) or someone presses the pushbutton on the board (FALSE).
+// (returns true) or someone presses the pushbutton on the board (false).

 //
 // Assume that we're called with the SSC (to the FPGA) and ADC path set
 // correctly.
 //-----------------------------------------------------------------------------
 //
 // Assume that we're called with the SSC (to the FPGA) and ADC path set
 // correctly.
 //-----------------------------------------------------------------------------

-static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
+static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)

 {
 {

-       uint8_t mask;
-       int i, bit;
-
-       // Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
+       // 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);
 

-

        // 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(;;) {
                WDT_HIT();
 
 
        for(;;) {
                WDT_HIT();
 

-               if(BUTTON_PRESS()) return FALSE;
+               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;
                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)) {
+                       for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
+                               if(Handle14443bUartBit(b & mask)) {

                                        *len = Uart.byteCnt;
                                        *len = Uart.byteCnt;

-                                       return TRUE;
+                                       return true;

                                }
                        }
                }
        }
                                }
                        }
                }
        }

+
+       return false;

 }
 
 //-----------------------------------------------------------------------------
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------

-void SimulateIso14443Tag(void)
+void SimulateIso14443bTag(void)

 {
 {

-       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+       // the only commands we understand is WUPB, AFI=0, Select All, N=1:
+       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // WUPB
+       // ... and REQB, AFI=0, Normal Request, N=1:
+       static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF }; // REQB
+       // ... and HLTB
+       static const uint8_t cmd3[] = { 0x50, 0xff, 0xff, 0xff, 0xff }; // HLTB
+       // ... and ATTRIB
+       static const uint8_t cmd4[] = { 0x1D, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; // ATTRIB
+
+       // ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
+       // supports only 106kBit/s in both directions, max frame size = 32Bytes,
+       // supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:

        static const uint8_t response1[] = {
                0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
                0x00, 0x21, 0x85, 0x5e, 0xd7
        };
        static const uint8_t response1[] = {
                0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
                0x00, 0x21, 0x85, 0x5e, 0xd7
        };

+       // response to HLTB and ATTRIB
+       static const uint8_t response2[] = {0x00, 0x78, 0xF0};

 
 

-       uint8_t *resp;
-       int respLen;

 
 

-       uint8_t *resp1 = BigBuf_get_addr() + 800;
-       int resp1Len;
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

 
 

-       uint8_t *receivedCmd = BigBuf_get_addr();
-       int len;
+       clear_trace();
+       set_tracing(true);

 
 

-       int i;
+       const uint8_t *resp;
+       uint8_t *respCode;
+       uint16_t respLen, respCodeLen;

 
 

-       int cmdsRecvd = 0;
+       // allocate command receive buffer
+       BigBuf_free();
+       uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);

 
 

-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       memset(receivedCmd, 0x44, 400);
+       uint16_t len;
+       uint16_t cmdsRecvd = 0;

 
 

+       // prepare the (only one) tag answer:

        CodeIso14443bAsTag(response1, sizeof(response1));
        CodeIso14443bAsTag(response1, sizeof(response1));

-       memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
+       uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
+       memcpy(resp1Code, ToSend, ToSendMax);
+       uint16_t resp1CodeLen = ToSendMax;
+
+       // prepare the (other) tag answer:
+       CodeIso14443bAsTag(response2, sizeof(response2));
+       uint8_t *resp2Code = BigBuf_malloc(ToSendMax);
+       memcpy(resp2Code, ToSend, ToSendMax);
+       uint16_t resp2CodeLen = ToSendMax;

 
        // We need to listen to the high-frequency, peak-detected path.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        // We need to listen to the high-frequency, peak-detected path.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);

 
        cmdsRecvd = 0;
 
        for(;;) {
 
        cmdsRecvd = 0;
 
        for(;;) {

-               uint8_t b1, b2;

 
 

-               if(!GetIso14443CommandFromReader(receivedCmd, &len, 100)) {
-               Dbprintf("button pressed, received %d commands", cmdsRecvd);
-               break;
+               if(!GetIso14443bCommandFromReader(receivedCmd, &len)) {
+                       Dbprintf("button pressed, received %d commands", cmdsRecvd);
+                       break;
+               }
+
+               if (tracing) {
+                       uint8_t parity[MAX_PARITY_SIZE];
+                       LogTrace(receivedCmd, len, 0, 0, parity, true);

                }
 
                // Good, look at the command now.
                }
 
                // Good, look at the command now.

-
-               if(len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len)==0) {
-                       resp = resp1; respLen = resp1Len;
+               if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
+                       || (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0) ) {
+                       resp = response1;
+                       respLen = sizeof(response1);
+                       respCode = resp1Code;
+                       respCodeLen = resp1CodeLen;
+               } else if ( (len == sizeof(cmd3) && receivedCmd[0] == cmd3[0])
+                       || (len == sizeof(cmd4) && receivedCmd[0] == cmd4[0]) ) {
+                       resp = response2;
+                       respLen = sizeof(response2);
+                       respCode = resp2Code;
+                       respCodeLen = resp2CodeLen;

                } else {
                        Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
                        // And print whether the CRC fails, just for good measure
                } 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");
+                       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]) {
+                                       // Not so good, try again.
+                                       DbpString("+++CRC fail");
+               
+                               } else {
+                                       DbpString("CRC passes");
+                               }

                        }
                        }

-                       break;
+                       //get rid of compiler warning
+                       respCodeLen = 0;
+                       resp = response1;
+                       respLen = 0;
+                       respCode = resp1Code;
+                       //don't crash at new command just wait and see if reader will send other new cmds.
+                       //break;

                }
 
                }
 

-               memset(receivedCmd, 0x44, 32);
-

                cmdsRecvd++;
 
                if(cmdsRecvd > 0x30) {
                cmdsRecvd++;
 
                if(cmdsRecvd > 0x30) {


@@ -398,25 +434,25 @@ void SimulateIso14443Tag(void)
                        break;
                }
 
                        break;
                }
 

-               if(respLen <= 0) continue;
+               if(respCodeLen <= 0) continue;

 
                // Modulate BPSK
                // Signal field is off with the appropriate LED
                LED_D_OFF();
                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
                AT91C_BASE_SSC->SSC_THR = 0xff;
 
                // 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();
+               FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);

 
                // Transmit the response.
 
                // Transmit the response.

-               i = 0;
+               uint16_t i = 0;

                for(;;) {
                        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
                for(;;) {
                        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

-                               uint8_t b = resp[i];
+                               uint8_t b = respCode[i];

 
                                AT91C_BASE_SSC->SSC_THR = b;
 
                                i++;
 
                                AT91C_BASE_SSC->SSC_THR = b;
 
                                i++;

-                               if(i > respLen) {
+                               if(i > respCodeLen) {

                                        break;
                                }
                        }
                                        break;
                                }
                        }


@@ -425,6 +461,13 @@ void SimulateIso14443Tag(void)
                                (void)b;
                        }
                }
                                (void)b;
                        }
                }

+
+               // trace the response:
+               if (tracing) {
+                       uint8_t parity[MAX_PARITY_SIZE];
+                       LogTrace(resp, respLen, 0, 0, parity, false);
+               }
+

        }
 }
 
        }
 }
 


@@ -442,14 +485,15 @@ static struct {
                DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
                DEMOD_GOT_FALLING_EDGE_OF_SOF,
                DEMOD_AWAITING_START_BIT,
                DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
                DEMOD_GOT_FALLING_EDGE_OF_SOF,
                DEMOD_AWAITING_START_BIT,

-               DEMOD_RECEIVING_DATA,
-               DEMOD_ERROR_WAIT
+               DEMOD_RECEIVING_DATA

        }       state;
        int     bitCount;
        int     posCount;
        int     thisBit;
        }       state;
        int     bitCount;
        int     posCount;
        int     thisBit;

+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.

        int     metric;
        int     metricN;
        int     metric;
        int     metricN;

+*/

        uint16_t    shiftReg;
        uint8_t   *output;
        int     len;
        uint16_t    shiftReg;
        uint8_t   *output;
        int     len;


@@ -460,6 +504,9 @@ static struct {
 /*
  * 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


@@ -468,12 +515,12 @@ 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)
+static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)

 {
        int v;
 
 {
        int v;
 

-       // 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; \


@@ -487,47 +534,43 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                } \
        }
 
                } \
        }
 

+#define SUBCARRIER_DETECT_THRESHOLD    8
+
+// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
+#define AMPLITUDE(ci,cq) (MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2))

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

-                       v = ci;
-                       if(v < 0) v = -v;
-                       if(cq > 0) {
-                               v += cq;
-                       } else {
-                               v -= cq;
-                       }
-                       if(v > 40) {
-                               Demod.posCount = 0;
+                       if(AMPLITUDE(ci,cq) > SUBCARRIER_DETECT_THRESHOLD) {    // subcarrier detected

                                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:
                        if(Demod.posCount < 8) {
                        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 (AMPLITUDE(ci,cq) > SUBCARRIER_DETECT_THRESHOLD) {
+                                       // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
+                                       // note: synchronization time > 80 1/fs
+                                       Demod.sumI += ci;
+                                       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:
                        MAKE_SOFT_DECISION();
                        break;
 
                case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
                        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) {
+                               if(Demod.posCount > 200/4) {    // maximum length of TR1 = 200 1/fs

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


@@ -535,35 +578,40 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                        break;
 
                case DEMOD_GOT_FALLING_EDGE_OF_SOF:
                        break;
 
                case DEMOD_GOT_FALLING_EDGE_OF_SOF:

+                       Demod.posCount++;

                        MAKE_SOFT_DECISION();
                        if(v > 0) {
                        MAKE_SOFT_DECISION();
                        if(v > 0) {

-                               if(Demod.posCount < 12) {
+                               if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges

                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF
                                        Demod.state = DEMOD_AWAITING_START_BIT;
                                        Demod.posCount = 0;
                                        Demod.len = 0;
                                        Demod.state = DEMOD_UNSYNCD;
                                } else {
                                        LED_C_ON(); // Got SOF
                                        Demod.state = DEMOD_AWAITING_START_BIT;
                                        Demod.posCount = 0;
                                        Demod.len = 0;

+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.

                                        Demod.metricN = 0;
                                        Demod.metric = 0;
                                        Demod.metricN = 0;
                                        Demod.metric = 0;

+*/

                                }
                        } else {
                                }
                        } else {

-                               if(Demod.posCount > 100) {
+                               if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)

                                        Demod.state = DEMOD_UNSYNCD;
                                        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();
                        if(v > 0) {
                        MAKE_SOFT_DECISION();
                        if(v > 0) {

-                               if(Demod.posCount > 10) {
+                               if(Demod.posCount > 3*2) {              // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs

                                        Demod.state = DEMOD_UNSYNCD;
                                        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;


@@ -572,39 +620,41 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
 
                case DEMOD_RECEIVING_DATA:
                        MAKE_SOFT_DECISION();
 
                case DEMOD_RECEIVING_DATA:
                        MAKE_SOFT_DECISION();

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

                                Demod.thisBit = v;
                                Demod.posCount = 1;
                                Demod.thisBit = v;
                                Demod.posCount = 1;

-                       } else {
+                       } else {                                                        // second half of bit

                                Demod.thisBit += v;
 
                                Demod.thisBit += v;
 

+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.

                                if(Demod.thisBit > 0) {
                                        Demod.metric += Demod.thisBit;
                                } else {
                                        Demod.metric -= Demod.thisBit;
                                }
                                (Demod.metricN)++;
                                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) {
+                               if(Demod.thisBit > 0) { // logic '1'

                                        Demod.shiftReg |= 0x200;
                                }
 
                                Demod.bitCount++;
                                if(Demod.bitCount == 10) {
                                        uint16_t s = Demod.shiftReg;
                                        Demod.shiftReg |= 0x200;
                                }
 
                                Demod.bitCount++;
                                if(Demod.bitCount == 10) {
                                        uint16_t s = Demod.shiftReg;

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

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

-                                       } else if(s == 0x000) {
-                                               // This is EOF
-                                               LED_C_OFF();
-                                               Demod.state = DEMOD_UNSYNCD;
-                                               return TRUE;

                                        } else {
                                                Demod.state = DEMOD_UNSYNCD;
                                        } else {
                                                Demod.state = DEMOD_UNSYNCD;

+                                               LED_C_OFF();
+                                               if(s == 0x000) {
+                                                       // This is EOF (start, stop and all data bits == '0'
+                                                       return true;
+                                               }

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


@@ -613,11 +663,11 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
 
                default:
                        Demod.state = DEMOD_UNSYNCD;
 
                default:
                        Demod.state = DEMOD_UNSYNCD;

+                       LED_C_OFF();

                        break;
        }
 
                        break;
        }
 

-       if (Demod.state == DEMOD_UNSYNCD) LED_C_OFF(); // Not synchronized...
-       return FALSE;
+       return false;

 }
 
 
 }
 
 


@@ -626,6 +676,7 @@ static void DemodReset()
        // Clear out the state of the "UART" that receives from the tag.
        Demod.len = 0;
        Demod.state = DEMOD_UNSYNCD;
        // Clear out the state of the "UART" that receives from the tag.
        Demod.len = 0;
        Demod.state = DEMOD_UNSYNCD;

+       Demod.posCount = 0;

        memset(Demod.output, 0x00, MAX_FRAME_SIZE);
 }
 
        memset(Demod.output, 0x00, MAX_FRAME_SIZE);
 }
 


@@ -637,180 +688,112 @@ static void DemodInit(uint8_t *data)
 }
 
 
 }
 
 

-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)
+static void GetSamplesFor14443bDemod(int n, bool quiet)

 {
 {

-       int max = 0;
-       int gotFrame = FALSE;
-       int lastRxCounter, ci, cq, samples = 0;
-
+       int maxBehindBy = 0;
+       bool gotFrame = false;
+       int lastRxCounter, samples = 0;
+       int8_t ci, cq;
+       

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

-       
+

        // The response (tag -> reader) that we're receiving.
        uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
        // The response (tag -> reader) that we're receiving.
        uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);

-       
+

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

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

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

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

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

-       FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);

 
 

-       int8_t *upTo = dmaBuf;
-       lastRxCounter = DMA_BUFFER_SIZE;
+       uint16_t *upTo = dmaBuf;
+       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;

 
        // Signal field is ON with the appropriate LED:
 
        // Signal field is ON with the appropriate LED:

-       if (weTx) LED_D_ON(); else LED_D_OFF();
+       LED_D_ON();

        // 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));
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);

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

 
 

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

 
 

-                       if(Handle14443SamplesDemod(ci, cq)) {
-                               gotFrame = 1;
-                       }
+               ci = *upTo >> 8;
+               cq = *upTo;
+               upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {               // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning
+                       lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;  // DMA Next Counter registers
+               }
+               samples++;
+
+               if(Handle14443bSamplesDemod(ci, cq)) {
+                       gotFrame = true;
+                       break;

                }
 
                if(samples > n) {
                        break;
                }
        }
                }
 
                if(samples > n) {
                        break;
                }
        }

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

        //Tracing
        if (tracing && Demod.len > 0) {
                uint8_t parity[MAX_PARITY_SIZE];
        //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);
+               LogTrace(Demod.output, Demod.len, 0, 0, parity, false);

        }
 }
 
 
        }
 }
 
 

-//-----------------------------------------------------------------------------
-// Read the tag's response. We just receive a stream of slightly-processed
-// samples from the FPGA, which we will later do some signal processing on,
-// to get the bits.
-//-----------------------------------------------------------------------------
-/*static void GetSamplesFor14443(int weTx, int n)
-{
-       uint8_t *dest = (uint8_t *)BigBuf;
-       int c;
-
-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               (weTx ? 0 : FPGA_HF_READER_RX_XCORR_SNOOP));
-
-       c = 0;
-       for(;;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x43;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       int8_t b;
-                       b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
-
-                       dest[c++] = (uint8_t)b;
-
-                       if(c >= n) {
-                               break;
-                       }
-               }
-       }
-}*/
-
-

 //-----------------------------------------------------------------------------
 // Transmit the command (to the tag) that was placed in ToSend[].
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
 // Transmit the command (to the tag) that was placed in ToSend[].
 //-----------------------------------------------------------------------------

-static void TransmitFor14443(void)
+static void TransmitFor14443b(void)

 {
        int c;
 
 {
        int c;
 

-       FpgaSetupSsc();
-
-       while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-               AT91C_BASE_SSC->SSC_THR = 0xff;
-       }
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);

 
        // Signal field is ON with the appropriate Red LED
        LED_D_ON();
        // Signal we are transmitting with the Green LED
        LED_B_ON();
 
        // Signal field is ON with the appropriate Red LED
        LED_D_ON();
        // Signal we are transmitting with the Green LED
        LED_B_ON();

-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
-
-       for(c = 0; c < 10;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0xff;
-                       c++;
-               }
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
-               }
-               WDT_HIT();
-       }
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);

 
        c = 0;
        for(;;) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
 
        c = 0;
        for(;;) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

-                       AT91C_BASE_SSC->SSC_THR = ToSend[c];
+                       AT91C_BASE_SSC->SSC_THR = ~ToSend[c];

                        c++;
                        if(c >= ToSendMax) {
                                break;
                        }
                }
                        c++;
                        if(c >= ToSendMax) {
                                break;
                        }
                }

-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-                       (void)r;
-               }

                WDT_HIT();
        }
        LED_B_OFF(); // Finished sending
                WDT_HIT();
        }
        LED_B_OFF(); // Finished sending


@@ -819,7 +802,7 @@ static void TransmitFor14443(void)
 
 //-----------------------------------------------------------------------------
 // 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)
 {
 //-----------------------------------------------------------------------------
 static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 {


@@ -828,19 +811,14 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 
        ToSendReset();
 
 
        ToSendReset();
 

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

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

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

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

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

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


@@ -853,19 +831,18 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
                        }
                        b >>= 1;
                }
                        }
                        b >>= 1;
                }

+               // Stop bit
+               ToSendStuffBit(1);

        }
        }

+

        // Send EOF
        // Send EOF

-       ToSendStuffBit(1);

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

-       for(i = 0; i < 8; i++) {
-               ToSendStuffBit(1);
-       }
+       ToSendStuffBit(1);

 
 

-       // And then a little more, to make sure that the last character makes
-       // it out before we switch to rx mode.
-       for(i = 0; i < 24; i++) {
+       // ensure that last byte is filled up
+       for(i = 0; i < 8; i++) {

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


@@ -874,39 +851,111 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 }
 
 
 }
 
 

-//-----------------------------------------------------------------------------
-// Read an ISO 14443 tag. We send it some set of commands, and record the
-// responses.
-// The command name is misleading, it actually decodes the reponse in HEX
-// into the output buffer (read the result using hexsamples, not hisamples)
-//
-// obsolete function only for test
-//-----------------------------------------------------------------------------
-void AcquireRawAdcSamplesIso14443(uint32_t parameter)
-{
-       uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
-
-       SendRawCommand14443B(sizeof(cmd1),1,1,cmd1);
-}
-
-

 /**
   Convenience function to encode, transmit and trace iso 14443b comms
   **/
 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 {
        CodeIso14443bAsReader(cmd, len);
 /**
   Convenience function to encode, transmit and trace iso 14443b comms
   **/
 static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 {
        CodeIso14443bAsReader(cmd, len);

-       TransmitFor14443();
+       TransmitFor14443b();

        if (tracing) {
                uint8_t parity[MAX_PARITY_SIZE];
        if (tracing) {
                uint8_t parity[MAX_PARITY_SIZE];

-               GetParity(cmd, len, parity);
-               LogTrace(cmd,len, 0, 0, parity, TRUE);
+               LogTrace(cmd,len, 0, 0, parity, true);
+       }
+}
+
+/* Sends an APDU to the tag
+ * TODO: check CRC and preamble
+ */
+int iso14443b_apdu(uint8_t const *message, size_t message_length, uint8_t *response)
+{
+       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);
+       // get response
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+       if(Demod.len < 3)
+       {
+               return 0;
+       }
+       // TODO: Check CRC
+       // copy response contents
+       if(response != NULL)
+       {
+               memcpy(response, Demod.output, Demod.len);
+       }
+       return Demod.len;
+}
+
+/* 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
+ */
+int iso14443b_select_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[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+       // ATTRIB command (with space for CRC)
+       uint8_t attrib[] = { 0x1D, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00};
+
+       // first, wake up the tag
+       CodeAndTransmit14443bAsReader(wupb, sizeof(wupb));
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+       // ATQB too short?
+       if (Demod.len < 14)
+       {
+               return 2;

        }
        }

+
+    // select the tag
+    // copy the PUPI to ATTRIB
+    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));
+    GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+    // Answer to ATTRIB too short?
+    if(Demod.len < 3)
+       {
+               return 2;
+       }
+       // reset PCB block number
+       pcb_blocknum = 0;
+       return 1;

 }
 
 }
 

+// Set up ISO 14443 Type B communication (similar to iso14443a_setup)
+void iso14443b_setup() {
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       // Set up the synchronous serial port
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
+       // connect Demodulated Signal to ADC:
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+
+       // Signal field is on with the appropriate LED
+    LED_D_ON();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
+
+       DemodReset();
+       UartReset();
+}

 
 //-----------------------------------------------------------------------------
 
 //-----------------------------------------------------------------------------

-// 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


@@ -914,11 +963,8 @@ 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(uint32_t dwLast)

 {
 {

-       clear_trace();
-       set_tracing(TRUE);
-

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


@@ -929,116 +975,123 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
        SpinDelay(200);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        SpinDelay(200);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

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

-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);

        SpinDelay(200);
 
        SpinDelay(200);
 

-       // First command: wake up the tag using the INITIATE command
-       uint8_t cmd1[] = { 0x06, 0x00, 0x97, 0x5b};
+       clear_trace();
+       set_tracing(true);

 
 

+       // First command: wake up the tag using the INITIATE command
+       uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};

        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));

-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

 
        if (Demod.len == 0) {
 
        if (Demod.len == 0) {

-       DbpString("No response from tag");
-       return;
+               DbpString("No response from tag");
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               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:");
        cmd1[0] = 0x0E; // 0x0E is SELECT
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
        // There is a response, SELECT the uid
        DbpString("Now SELECT tag:");
        cmd1[0] = 0x0E; // 0x0E is SELECT
        cmd1[1] = Demod.output[0];
        ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));

-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

        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);
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               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.");
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               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]);
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               return;

        }
        }

+

        // Tag is now selected,
        // First get the tag's UID:
        cmd1[0] = 0x0B;
        ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
        CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
        // Tag is now selected,
        // First get the tag's UID:
        cmd1[0] = 0x0B;
        ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
        CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one

-
-//    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
-//    LED_A_OFF();
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

        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);
+               LED_D_OFF();
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               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]);
-       // Do not return;, let's go on... (we should retry, maybe ?)
+       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",
        }
        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", dwLast);

        cmd1[0] = 0x08;
        i = 0x00;
        dwLast++;
        for (;;) {
        cmd1[0] = 0x08;
        i = 0x00;
        dwLast++;
        for (;;) {

-                  if (i == dwLast) {
+               if (i == dwLast) {

                        DbpString("System area block (0xff):");
                        i = 0xff;
                }
                cmd1[1] = i;
                ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
                CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
                        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();
+               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);

                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...");
+                       LED_D_OFF();
+                       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+                       return;

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

-                       if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
-               Dbprintf("CRC Error reading block! - Below: expected, got %x %x",
-                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
-               // Do not return;, let's go on... (we should retry, maybe ?)
+               if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
+                       Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
+                                       (cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
+                       // Do not return;, let's go on... (we should retry, maybe ?)

                }
                // Now print out the memory location:
                }
                // 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]);
+               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) {
                if (i == 0xff) {

-               break;
+                       break;

                }
                i++;
        }
                }
                i++;
        }

+       
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);

 }
 
 
 }
 
 


@@ -1054,29 +1107,24 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
 //-----------------------------------------------------------------------------
 /*
  * Memory usage for this function, (within BigBuf)
 //-----------------------------------------------------------------------------
 /*
  * Memory usage for this function, (within BigBuf)

- * 0-4095 : Demodulated samples receive (4096 bytes) - DEMOD_TRACE_SIZE
- * 4096-6143 : Last Received command, 2048 bytes (reader->tag) - READER_TAG_BUFFER_SIZE
- * 6144-8191 : Last Received command, 2048 bytes(tag->reader) - TAG_READER_BUFFER_SIZE
- * 8192-9215 : DMA Buffer, 1024 bytes (samples) - DEMOD_DMA_BUFFER_SIZE
+ * Last Received command (reader->tag) - MAX_FRAME_SIZE
+ * Last Received command (tag->reader) - MAX_FRAME_SIZE
+ * DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
+ * Demodulated samples received - all the rest

  */
  */

-void RAMFUNC SnoopIso14443(void)
+void RAMFUNC SnoopIso14443b(void)

 {
 {

-       // We won't start recording the frames that we acquire until we trigger;
-       // a good trigger condition to get started is probably when we see a
-       // response from the tag.
-       int triggered = TRUE;
-

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

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

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

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

        int lastRxCounter;
        int lastRxCounter;

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

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


@@ -1091,111 +1139,107 @@ void RAMFUNC SnoopIso14443(void)
        Dbprintf("  Trace: %i bytes", BigBuf_max_traceLen());
        Dbprintf("  Reader -> tag: %i bytes", MAX_FRAME_SIZE);
        Dbprintf("  tag -> Reader: %i bytes", MAX_FRAME_SIZE);
        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);
+       Dbprintf("  DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);

 
 

-       // Signal field is off with the appropriate LED
-       LED_D_OFF();
+       // Signal field is off, no reader signal, no tag signal
+       LEDsoff();

 
        // And put the FPGA in the appropriate mode
 
        // And put the FPGA in the appropriate mode

-       FpgaWriteConfWord(
-               FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ |
-               FPGA_HF_READER_RX_XCORR_SNOOP);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);

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

-       FpgaSetupSsc();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

        upTo = dmaBuf;
        upTo = dmaBuf;

-       lastRxCounter = DMA_BUFFER_SIZE;
-       FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
+       lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);

        uint8_t parity[MAX_PARITY_SIZE];
        uint8_t parity[MAX_PARITY_SIZE];

-       LED_A_ON();
-               
+
+       bool TagIsActive = false;
+       bool ReaderIsActive = false;
+       // We won't start recording the frames that we acquire until we trigger.
+       // A good trigger condition to get started is probably when we see a
+       // reader command
+       bool triggered = false;
+

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

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

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

-                       if(behindBy > (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);
+               }
+
+               if(behindBy < 1) continue;
+
+               ci = *upTo>>8;
+               cq = *upTo;
+               upTo++;
+               lastRxCounter--;
+               if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {               // we have read all of the DMA buffer content.
+                       upTo = dmaBuf;                                             // start reading the circular buffer from the beginning again
+                       lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+                       if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { 
+                               Dbprintf("About to blow circular buffer - aborted! behindBy=%d", behindBy);

                                break;
                        }
                }
                                break;
                        }
                }

-               if(behindBy < 2) continue;
-
-               ci = upTo[0];
-               cq = upTo[1];
-               upTo += 2;
-               lastRxCounter -= 2;
-               if(upTo >= dmaBuf + DMA_BUFFER_SIZE) {
-                       upTo = dmaBuf;
-                       lastRxCounter += DMA_BUFFER_SIZE;
-                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
-                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+               if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;  // DMA Next Counter registers
+                       WDT_HIT();
+                       if(BUTTON_PRESS()) {
+                               DbpString("cancelled");
+                               break;
+                       }

                }
 
                }
 

-               samples += 2;
+               samples++;

 
 

-               if(Handle14443UartBit(ci & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
+               if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
+                       if(Handle14443bUartBit(ci & 0x01)) {
+                               triggered = true;
+                               if(tracing) {
+                                       LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, true);
+                               }
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();

                        }
                        }

-                       if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
-
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
-               }
-               if(Handle14443UartBit(cq & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
+                       if(Handle14443bUartBit(cq & 0x01)) {
+                               triggered = true;
+                               if(tracing) {
+                                       LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, true);
+                               }
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();

                        }
                        }

-                       if(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_GOT_FALLING_EDGE_OF_SOF);

                }
 
                }
 

-               if(Handle14443SamplesDemod(ci, cq)) {
+               if(!ReaderIsActive && triggered) {                                              // no need to try decoding tag data if the reader is sending or not yet triggered
+                       if(Handle14443bSamplesDemod(ci/2, cq/2)) {

 
 

-                       //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);
+                               //Use samples as a time measurement
+                               if(tracing)
+                               {
+                                       uint8_t parity[MAX_PARITY_SIZE];
+                                       LogTrace(Demod.output, Demod.len, samples, samples, parity, false);
+                               }
+                               // And ready to receive another response.
+                               DemodReset();

                        }
                        }

-                       triggered = TRUE;
-                       LED_A_OFF();
-                       LED_B_ON();
-
-                       // And ready to receive another response.
-                       DemodReset();
-               }
-               WDT_HIT();
-
-               if(!tracing) {
-                       DbpString("Reached trace limit");
-                       break;
+                       TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);

                }
 
                }
 

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

        }
        }

+

        FpgaDisableSscDma();
        FpgaDisableSscDma();

-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
-       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+       LEDsoff();

        DbpString("Snoop statistics:");
        Dbprintf("  Max behind by: %i", maxBehindBy);
        Dbprintf("  Uart State: %x", Uart.state);
        DbpString("Snoop statistics:");
        Dbprintf("  Max behind by: %i", maxBehindBy);
        Dbprintf("  Uart State: %x", Uart.state);


@@ -1220,38 +1264,26 @@ void RAMFUNC SnoopIso14443(void)
 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

-       if(!powerfield)
-       {
-               // Make sure that we start from off, since the tags are stateful;
-               // confusing things will happen if we don't reset them between reads.
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               LED_D_OFF();
-               SpinDelay(200);
-       }
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

 
 

-       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);
-       }
+       // switch field on and give tag some time to power up
+       LED_D_ON();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
+       SpinDelay(10);

 
 

-       CodeAndTransmit14443bAsReader(data, datalen);
+       if (datalen){
+               set_tracing(true);
+               
+               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(recv) {
+                       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, true);
+                       uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
+                       cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
+               }

        }
        }

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

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