]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/iso14443b.c
FIX: "hf 14a sim" fixes to CRC calc.
[proxmark3-svn] / armsrc / iso14443b.c
index 860e96f13bb2972023fd360a0eee5a67a35ed5a2..53f7e74d0701241778ca4ba1decada624243a51d 100644 (file)
@@ -5,9 +5,8 @@
 // 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 "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
 
 //=============================================================================
@@ -104,14 +95,14 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
                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++) {
+       for(i = 0; i < 2; i++) {
                ToSendStuffBit(1);
                ToSendStuffBit(1);
                ToSendStuffBit(1);
@@ -120,9 +111,6 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
 
        // Convert from last byte pos to length
        ToSendMax++;
-
-       // Add a few more for slop
-       ToSendMax += 2;
 }
 
 //-----------------------------------------------------------------------------
@@ -146,6 +134,9 @@ static struct {
 } 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.
@@ -154,7 +145,7 @@ static struct {
  * Returns: true if we received a EOF
  *          false if we are still waiting for some more
  */
-static int Handle14443UartBit(int bit)
+static int Handle14443bUartBit(int bit)
 {
        switch(Uart.state) {
                case STATE_UNSYNCD:
@@ -169,9 +160,9 @@ static int Handle14443UartBit(int bit)
 
                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(Uart.bitCnt >= 10) {
+                                       if(Uart.bitCnt > 9) {
                                                // we've seen enough consecutive
                                                // zeros that it's a valid SOF
                                                Uart.posCnt = 0;
@@ -189,7 +180,7 @@ static int Handle14443UartBit(int bit)
                                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.
                                Uart.state = STATE_ERROR_WAIT;
@@ -199,7 +190,7 @@ static int Handle14443UartBit(int bit)
                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
                                        Uart.state = STATE_ERROR_WAIT;
@@ -246,7 +237,11 @@ static int Handle14443UartBit(int bit)
                                } else if(Uart.shiftReg == 0x000) {
                                        // this is an EOF byte
                                        LED_A_OFF(); // Finished receiving
+                                       if (Uart.byteCnt != 0) {
                                        return TRUE;
+                                       }
+                                       Uart.posCnt = 0;
+                                       Uart.state = STATE_ERROR_WAIT;
                                } else {
                                        // this is an error
                                        Uart.posCnt = 0;
@@ -283,12 +278,12 @@ static int Handle14443UartBit(int bit)
 // 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, int *len, int maxLen)
 {
        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();
@@ -314,7 +309,7 @@ static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
                        mask = 0x80;
                        for(i = 0; i < 8; i++, mask >>= 1) {
                                bit = (b & mask);
-                               if(Handle14443UartBit(bit)) {
+                               if(Handle14443bUartBit(bit)) {
                                        *len = Uart.byteCnt;
                                        return TRUE;
                                }
@@ -327,9 +322,13 @@ static int GetIso14443CommandFromReader(uint8_t *received, int *len, int maxLen)
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------
-void SimulateIso14443Tag(void)
+void SimulateIso14443bTag(void)
 {
+       // the only command we understand is REQB, AFI=0, Select All, N=0:
        static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
+       // ... and we 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
@@ -338,10 +337,9 @@ void SimulateIso14443Tag(void)
        uint8_t *resp;
        int respLen;
 
-       uint8_t *resp1 = BigBuf_get_addr() + 800;
-       int resp1Len;
-
-       uint8_t *receivedCmd = BigBuf_get_addr();
+       // allocate command receive buffer
+       BigBuf_free();
+       uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
        int len;
 
        int i;
@@ -349,10 +347,12 @@ void SimulateIso14443Tag(void)
        int cmdsRecvd = 0;
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       memset(receivedCmd, 0x44, 400);
 
+       // prepare the (only one) tag answer:
        CodeIso14443bAsTag(response1, sizeof(response1));
-       memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
+       uint8_t *resp1 = BigBuf_malloc(ToSendMax);
+       memcpy(resp1, ToSend, ToSendMax); 
+       uint16_t resp1Len = ToSendMax;
 
        // We need to listen to the high-frequency, peak-detected path.
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
@@ -363,7 +363,7 @@ void SimulateIso14443Tag(void)
        for(;;) {
                uint8_t b1, b2;
 
-               if(!GetIso14443CommandFromReader(receivedCmd, &len, 100)) {
+               if(!GetIso14443bCommandFromReader(receivedCmd, &len, 100)) {
                Dbprintf("button pressed, received %d commands", cmdsRecvd);
                break;
                }
@@ -385,8 +385,6 @@ void SimulateIso14443Tag(void)
                        break;
                }
 
-               memset(receivedCmd, 0x44, 32);
-
                cmdsRecvd++;
 
                if(cmdsRecvd > 0x30) {
@@ -444,8 +442,10 @@ static struct {
        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;
+*/
        uint16_t    shiftReg;
        uint8_t   *output;
        int     len;
@@ -456,6 +456,9 @@ static struct {
 /*
  * 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
@@ -464,7 +467,7 @@ static struct {
  *          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;
 
@@ -483,47 +486,87 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                } \
        }
 
+#define SUBCARRIER_DETECT_THRESHOLD    8
+
+// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by abs(ci) + abs(cq)
+/* #define CHECK_FOR_SUBCARRIER() { \
+               v = ci; \
+               if(v < 0) v = -v; \
+               if(cq > 0) { \
+                       v += cq; \
+               } else { \
+                       v -= cq; \
+               } \
+       }               
+ */
+// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
+#define CHECK_FOR_SUBCARRIER() { \
+               if(ci < 0) { \
+                       if(cq < 0) { /* ci < 0, cq < 0 */ \
+                               if (cq < ci) { \
+                                       v = -cq - (ci >> 1); \
+                               } else { \
+                                       v = -ci - (cq >> 1); \
+                               } \
+                       } else {        /* ci < 0, cq >= 0 */ \
+                               if (cq < -ci) { \
+                                       v = -ci + (cq >> 1); \
+                               } else { \
+                                       v = cq - (ci >> 1); \
+                               } \
+                       } \
+               } else { \
+                       if(cq < 0) { /* ci >= 0, cq < 0 */ \
+                               if (-cq < ci) { \
+                                       v = ci - (cq >> 1); \
+                               } else { \
+                                       v = -cq + (ci >> 1); \
+                               } \
+                       } else {        /* ci >= 0, cq >= 0 */ \
+                               if (cq < ci) { \
+                                       v = ci + (cq >> 1); \
+                               } else { \
+                                       v = cq + (ci >> 1); \
+                               } \
+                       } \
+               } \
+       }
+       
        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();
+                       if(v > SUBCARRIER_DETECT_THRESHOLD) {   // subcarrier detected
                                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) {
+                               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;
-                       } else if(Demod.posCount > 100) {
-                               // error, waited too long
+                                       Demod.posCount++;
+                               } else {                // subcarrier lost
                                Demod.state = DEMOD_UNSYNCD;
+                               }
                        } else {
-                               MAKE_SOFT_DECISION();
-                               if(v < 0) {
                                        Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
-                                       Demod.posCount = 0;
-                               }
                        }
-                       Demod.posCount++;
                        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.posCount = 0;
+                               Demod.posCount = 0;     // start of SOF sequence
                        } else {
-                               if(Demod.posCount > 100) {
+                               if(Demod.posCount > 200/4) {    // maximum length of TR1 = 200 1/fs
                                        Demod.state = DEMOD_UNSYNCD;
                                }
                        }
@@ -531,37 +574,40 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                        break;
 
                case DEMOD_GOT_FALLING_EDGE_OF_SOF:
+                       Demod.posCount++;
                        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;
+/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
                                        Demod.metricN = 0;
                                        Demod.metric = 0;
+*/
                                }
                        } else {
-                               if(Demod.posCount > 100) {
+                               if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
                        }
-                       Demod.posCount++;
                        break;
 
                case DEMOD_AWAITING_START_BIT:
+                       Demod.posCount++;
                        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;
                                        LED_C_OFF();
                                }
-                       } else {
+                       } else {                                                        // start bit detected
                                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;
@@ -570,28 +616,30 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
 
                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;
-                       } else {
+                       } else {                                                        // second half of bit
                                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)++;
+*/                             
 
                                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;
-                                       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++;
@@ -600,7 +648,7 @@ static RAMFUNC int Handle14443SamplesDemod(int ci, int cq)
                                                Demod.state = DEMOD_UNSYNCD;
                                                LED_C_OFF();
                                                if(s == 0x000) {
-                                               // This is EOF
+                                                       // This is EOF (start, stop and all data bits == '0'
                                                return TRUE;
                                                }
                                        }
@@ -624,6 +672,7 @@ static void DemodReset()
        // 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);
 }
 
@@ -653,14 +702,12 @@ static void UartInit(uint8_t *data)
 
 /*
  *  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
  */
-static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
+static void GetSamplesFor14443bDemod(int n, bool quiet)
 {
        int max = 0;
-       int gotFrame = FALSE;
+       bool gotFrame = FALSE;
        int lastRxCounter, ci, cq, samples = 0;
 
        // Allocate memory from BigBuf for some buffers
@@ -683,19 +730,15 @@ static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
        lastRxCounter = DMA_BUFFER_SIZE;
 
        // 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
-       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(;;) {
                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)
-               {
+               while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (DMA_BUFFER_SIZE-1)) > 2) {
                        ci = upTo[0];
                        cq = upTo[1];
                        upTo += 2;
@@ -711,63 +754,33 @@ static void GetSamplesFor14443Demod(int weTx, int n, int quiet)
 
                        samples += 2;
 
-                       if(Handle14443SamplesDemod(ci, cq)) {
-                               gotFrame = 1;
-                       }
+                       if(Handle14443bSamplesDemod(ci, cq)) {
+                               gotFrame = TRUE;
+                       break;
                }
+       }
 
-               if(samples > n) {
+               if(samples > n || gotFrame) {
                        break;
                }
        }
+
        AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-       if (!quiet) Dbprintf("%x %x %x", max, gotFrame, Demod.len);
+
+       if (!quiet) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.len = %d, Demod.sumI = %d, Demod.sumQ = %d", max, samples, gotFrame, Demod.len, Demod.sumI, Demod.sumQ);
        //Tracing
        if (tracing && Demod.len > 0) {
                uint8_t parity[MAX_PARITY_SIZE];
-               GetParity(Demod.output, Demod.len, parity);
+               //GetParity(Demod.output, Demod.len, parity);
                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[].
 //-----------------------------------------------------------------------------
-static void TransmitFor14443(void)
+static void TransmitFor14443b(void)
 {
        int c;
 
@@ -781,8 +794,7 @@ static void TransmitFor14443(void)
        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);
+       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)) {
@@ -817,7 +829,7 @@ static void TransmitFor14443(void)
 
 //-----------------------------------------------------------------------------
 // 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)
 {
@@ -872,29 +884,13 @@ 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);
-       TransmitFor14443();
+       TransmitFor14443b();
        if (tracing) {
                uint8_t parity[MAX_PARITY_SIZE];
                GetParity(cmd, len, parity);
@@ -904,7 +900,7 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 
 
 //-----------------------------------------------------------------------------
-// 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
@@ -912,7 +908,7 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 //
 // 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);
@@ -932,8 +928,7 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
        // 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);
 
        // First command: wake up the tag using the INITIATE command
@@ -941,14 +936,14 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
 
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
 //    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 //    LED_A_OFF();
 
        if (Demod.len == 0) {
-       DbpString("No response from tag");
-       return;
+               DbpString("No response from tag");
+               return;
        } else {
-       Dbprintf("Randomly generated UID from tag (+ 2 byte CRC): %x %x %x",
+               Dbprintf("Randomly generated UID from tag (+ 2 byte CRC): %02x %02x %02x",
                Demod.output[0], Demod.output[1],Demod.output[2]);
        }
        // There is a response, SELECT the uid
@@ -959,22 +954,22 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
        CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
 
 //    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 //    LED_A_OFF();
        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);
+               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]) {
-       DbpString("CRC Error reading select response.");
-       return;
+               DbpString("CRC Error reading select response.");
+               return;
        }
        // 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]);
+               return;
        }
        // Tag is now selected,
        // First get the tag's UID:
@@ -983,22 +978,24 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
        CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
 
 //    LED_A_ON();
-       GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 //    LED_A_OFF();
        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);
+               return;
        }
        // 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",
-       (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
        Dbprintf("Tag memory dump, block 0 to %d",dwLast);
@@ -1015,7 +1012,7 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
                CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
 
 //         LED_A_ON();
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
 //         LED_A_OFF();
                if (Demod.len != 6) { // Check if we got an answer from the tag
                DbpString("Expected 6 bytes from tag, got less...");
@@ -1024,17 +1021,18 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
                // 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:
-               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;
-               }
+               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++;
        }
 }
@@ -1054,10 +1052,10 @@ 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
- * DMA Buffer, 1024 bytes (samples) - DMA_BUFFER_SIZE
+ * DMA Buffer - 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
@@ -1091,13 +1089,11 @@ void RAMFUNC SnoopIso14443(void)
        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();
+       // Signal field is off, no reader signal, no tag signal
+       LEDsoff();
 
        // 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.
@@ -1106,7 +1102,6 @@ void RAMFUNC SnoopIso14443(void)
        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;
@@ -1117,11 +1112,8 @@ void RAMFUNC SnoopIso14443(void)
                                                                (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;
 
                ci = upTo[0];
@@ -1133,31 +1125,40 @@ void RAMFUNC SnoopIso14443(void)
                        lastRxCounter += DMA_BUFFER_SIZE;
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
                        AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+                       WDT_HIT();
+                       if(behindBy > (9*DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
+                               Dbprintf("blew circular buffer! behindBy=%d", behindBy);
+                               break;
+                       }
+                       if(!tracing) {
+                               DbpString("Reached trace limit");
+                               break;
+                       }
+                       if(BUTTON_PRESS()) {
+                               DbpString("cancelled");
+                               break;
+                       }
                }
 
                samples += 2;
 
                if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
-                       if(Handle14443UartBit(ci & 0x01)) {
+                       if(Handle14443bUartBit(ci & 0x01)) {
                        if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
+                                       //GetParity(Uart.output, Uart.byteCnt, parity);
                                LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
                        }
-                       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(Handle14443bUartBit(cq & 0x01)) {
                        if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
+                                       //GetParity(Uart.output, Uart.byteCnt, parity);
                                LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
                        }
-                       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 */
@@ -1168,41 +1169,27 @@ void RAMFUNC SnoopIso14443(void)
                }
 
                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)) {
+                       if(Handle14443bSamplesDemod(ci, cq)) {
 
                        //Use samples as a time measurement
                        if(tracing)
                        {
                                uint8_t parity[MAX_PARITY_SIZE];
-                               GetParity(Demod.output, Demod.len, parity);
+                                       //GetParity(Demod.output, Demod.len, parity);
                                LogTrace(Demod.output, Demod.len,samples, samples, parity, FALSE);
                        }
                        triggered = TRUE;
-                       LED_A_OFF();
-                       LED_B_ON();
 
                        // And ready to receive another response.
                        DemodReset();
                }
-                       TagIsActive = (Demod.state != DEMOD_UNSYNCD);
+                       TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
                }
 
-               WDT_HIT();
-
-               if(!tracing) {
-                       DbpString("Reached trace limit");
-                       break;
-               }
-
-               if(BUTTON_PRESS()) {
-                       DbpString("cancelled");
-                       break;
-               }
        }
+
        FpgaDisableSscDma();
-       LED_A_OFF();
-       LED_B_OFF();
-       LED_C_OFF();
+       LEDsoff();
        AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
        DbpString("Snoop statistics:");
        Dbprintf("  Max behind by: %i", maxBehindBy);
@@ -1225,47 +1212,39 @@ void RAMFUNC SnoopIso14443(void)
  * none
  *
  */
-void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield_trace, uint8_t data[])
+void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {
-       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)
-       {
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc();
+
+               set_tracing(TRUE);
+       
+/*     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);
        }
+ */
 
-       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(!GETBIT(GPIO_LED_D))      {       // if field is off
+               // FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+               // // Signal field is on with the appropriate LED
+               // LED_D_ON();
+               // SpinDelay(200);
+       // }
 
        CodeAndTransmit14443bAsReader(data, datalen);
 
-       if(recv)
-       {
-               GetSamplesFor14443Demod(TRUE, RECEIVE_SAMPLES_TIMEOUT, TRUE);
+       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();
        }
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