]> cvs.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/iso14443b.c
FIX: Coverity, unchecked return value, CID #121292,..
[proxmark3-svn] / armsrc / iso14443b.c
index a8a6460932d32f223bb3076c30b0defbab66a718..0b9962e1e5cf5ffe727051163ede8e9a4c0d6aad 100644 (file)
 #include "apps.h"
 #include "util.h"
 #include "string.h"
-
 #include "iso14443crc.h"
-
-#define RECEIVE_SAMPLES_TIMEOUT 2000
+#include "common.h"
+#define RECEIVE_SAMPLES_TIMEOUT 600000
 #define ISO14443B_DMA_BUFFER_SIZE 256
 
+
+// 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
 // a UART kind of thing that's implemented in software. When we get a
@@ -266,6 +269,8 @@ static void UartReset()
        Uart.state = STATE_UNSYNCD;
        Uart.byteCnt = 0;
        Uart.bitCnt = 0;
+       Uart.posCnt = 0;
+       memset(Uart.output, 0x00, MAX_FRAME_SIZE);
 }
 
 
@@ -321,13 +326,14 @@ static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
 //-----------------------------------------------------------------------------
 void SimulateIso14443bTag(void)
 {
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BigBuf_free();
-       
-       // the only commands we understand is REQB, AFI=0, Select All, N=0:
-       static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
-       // ... and REQB, AFI=0, Normal Request, N=0:
-       static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF };
+       // 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,
@@ -336,6 +342,12 @@ void SimulateIso14443bTag(void)
                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 parity[MAX_PARITY_SIZE];
+                               
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        clear_trace();
        set_tracing(TRUE);
@@ -343,20 +355,26 @@ void SimulateIso14443bTag(void)
        const uint8_t *resp;
        uint8_t *respCode;
        uint16_t respLen, respCodeLen;
-       uint16_t len;
-       uint16_t cmdsRecvd = 0;
-
 
        // allocate command receive buffer
+       BigBuf_free();
        uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
 
+       uint16_t len;
+       uint16_t cmdsRecvd = 0;
+
        // prepare the (only one) tag answer:
        CodeIso14443bAsTag(response1, sizeof(response1));
-
        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);
        FpgaSetupSsc();
@@ -371,7 +389,6 @@ void SimulateIso14443bTag(void)
                }
 
                if (tracing) {
-                       uint8_t parity[MAX_PARITY_SIZE];
                        LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
                }
 
@@ -382,18 +399,33 @@ void SimulateIso14443bTag(void)
                        respLen = sizeof(response1);
                        respCode = resp1Code; 
                        respCodeLen = resp1CodeLen;
+               } else if ( (len == sizeof(cmd3) && receivedCmd[0] == cmd3[0])
+                       || (len == sizeof(cmd4) && receivedCmd[0] == cmd4[0]) ) {
+                       resp = response2; 
+                       respLen = sizeof(response2);
+                       respCode = resp2Code; 
+                       respCodeLen = resp2CodeLen;
                } else {
                        Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
                        // And print whether the CRC fails, just for good measure
                        uint8_t b1, b2;
+                       if (len >= 3){ // if crc exists
                        ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
                        if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
                                // 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;
                }
 
                cmdsRecvd++;
@@ -444,12 +476,10 @@ void SimulateIso14443bTag(void)
                }
                
                // trace the response:
-               if (tracing) {
-                       uint8_t parity[MAX_PARITY_SIZE];
-                       LogTrace(resp, respLen, 0, 0, parity, FALSE);
-               }
-                       
+               if (tracing) LogTrace(resp, respLen, 0, 0, parity, FALSE);                      
        }
+       FpgaDisableSscDma();
+       set_tracing(FALSE);     
 }
 
 //=============================================================================
@@ -496,9 +526,14 @@ static struct {
  *          false if we are still waiting for some more
  *
  */
+ #define abs(x) ( ((x)<0) ? -(x) : (x) )
 static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 {
-       int v;
+       int v = 0;
+       int ai = abs(ci);
+       int aq = abs(cq);
+       int halfci = (ai >> 1);
+       int halfcq = (aq >> 1);
 
 // The soft decision on the bit uses an estimate of just the
 // quadrant of the reference angle, not the exact angle.
@@ -517,50 +552,12 @@ static RAMFUNC int Handle14443bSamplesDemod(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); \
-                               } \
-                       } \
-               } \
-       }
-       
+               v = MAX(ai, aq) + MIN(halfci, halfcq); \
+}
+
+
        switch(Demod.state) {
                case DEMOD_UNSYNCD:
                        CHECK_FOR_SUBCARRIER();
@@ -574,28 +571,30 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 
                case DEMOD_PHASE_REF_TRAINING:
                        if(Demod.posCount < 8) {
+                       //if(Demod.posCount < 10*2) {
                                CHECK_FOR_SUBCARRIER();
                                if (v > SUBCARRIER_DETECT_THRESHOLD) {
                                        // set the reference phase (will code a logic '1') by averaging over 32 1/fs.
                                        // note: synchronization time > 80 1/fs
-                               Demod.sumI += ci;
-                               Demod.sumQ += cq;
+                                       Demod.sumI += ci;
+                                       Demod.sumQ += cq;
                                        Demod.posCount++;
                                } else {                // subcarrier lost
-                               Demod.state = DEMOD_UNSYNCD;
+                                       Demod.state = DEMOD_UNSYNCD;
                                }
                        } else {
-                                       Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
+                               Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
                        }
                        break;
 
                case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
                        MAKE_SOFT_DECISION();
-                       if(v < 0) {     // logic '0' detected
+                       //Dbprintf("ICE: %d %d %d %d %d", v, Demod.sumI, Demod.sumQ, ci, cq );
+                       if(v <= 0) {    // logic '0' detected
                                Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
                                Demod.posCount = 0;     // start of SOF sequence
                        } else {
-                               if(Demod.posCount > 200/4) {    // maximum length of TR1 = 200 1/fs
+                               if(Demod.posCount > 25*2) {     // maximum length of TR1 = 200 1/fs
                                        Demod.state = DEMOD_UNSYNCD;
                                }
                        }
@@ -606,7 +605,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                        Demod.posCount++;
                        MAKE_SOFT_DECISION();
                        if(v > 0) {
-                               if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
+                               if(Demod.posCount < 10*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
@@ -619,7 +618,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 */
                                }
                        } else {
-                               if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
+                               if(Demod.posCount > 13*2) { // low phase of SOF too long (> 12 etu)
                                        Demod.state = DEMOD_UNSYNCD;
                                        LED_C_OFF();
                                }
@@ -678,7 +677,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                                                LED_C_OFF();
                                                if(s == 0x000) {
                                                        // This is EOF (start, stop and all data bits == '0'
-                                               return TRUE;
+                                                       return TRUE;
                                                }
                                        }
                                }
@@ -691,7 +690,6 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
                        LED_C_OFF();
                        break;
        }
-
        return FALSE;
 }
 
@@ -702,6 +700,11 @@ static void DemodReset()
        Demod.len = 0;
        Demod.state = DEMOD_UNSYNCD;
        Demod.posCount = 0;
+       Demod.sumI = 0;
+       Demod.sumQ = 0;
+       Demod.bitCount = 0;
+       Demod.thisBit = 0;
+       Demod.shiftReg = 0;
        memset(Demod.output, 0x00, MAX_FRAME_SIZE);
 }
 
@@ -726,27 +729,25 @@ static void GetSamplesFor14443bDemod(int n, bool quiet)
        // Allocate memory from BigBuf for some buffers
        // free all previous allocations first
        BigBuf_free();
-       
+
+       // And put the FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
+
        // The response (tag -> reader) that we're receiving.
-       uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
+       // Set up the demodulator for tag -> reader responses.
+       DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
        
        // The DMA buffer, used to stream samples from the FPGA
        int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
 
-       // Set up the demodulator for tag -> reader responses.
-       DemodInit(receivedResponse);
-
        // Setup and start DMA.
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
-
+       
        int8_t *upTo = dmaBuf;
        lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
 
        // Signal field is ON with the appropriate LED:
        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);
-
        for(;;) {
                int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
                if(behindBy > max) max = behindBy;
@@ -762,16 +763,16 @@ static void GetSamplesFor14443bDemod(int n, bool quiet)
                        }
                        lastRxCounter -= 2;
                        if(lastRxCounter <= 0) {
-                               lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
+                               lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
                        }
 
                        samples += 2;
 
-                       if(Handle14443bSamplesDemod(ci, cq)) {
-                               gotFrame = TRUE;
+                       //
+                       gotFrame = Handle14443bSamplesDemod(ci , cq );
+                       if ( gotFrame )
                                break;
                }
-       }
 
                if(samples > n || gotFrame) {
                        break;
@@ -780,7 +781,17 @@ static void GetSamplesFor14443bDemod(int n, bool quiet)
 
        AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
 
-       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);
+       if (!quiet && Demod.len == 0) {
+               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];
@@ -797,7 +808,7 @@ static void TransmitFor14443b(void)
        int c;
 
        FpgaSetupSsc();
-
+       
        while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
                AT91C_BASE_SSC->SSC_THR = 0xff;
        }
@@ -807,7 +818,7 @@ static void TransmitFor14443b(void)
        // 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;
@@ -855,7 +866,7 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
                ToSendStuffBit(1);
        }
        // Send SOF
-       for(i = 0; i < 10; i++) {
+       for(i = 0; i < 11; i++) {
                ToSendStuffBit(0);
        }
 
@@ -878,7 +889,7 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
        }
        // Send EOF
        ToSendStuffBit(1);
-       for(i = 0; i < 10; i++) {
+       for(i = 0; i < 11; i++) {
                ToSendStuffBit(0);
        }
        for(i = 0; i < 8; i++) {
@@ -887,7 +898,7 @@ static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
 
        // 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++) {
+       for(i = 0; i < 10; i++) {
                ToSendStuffBit(1);
        }
 
@@ -909,6 +920,103 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
        }
 }
 
+/* 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*100, 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);
+
+       BigBuf_free();
+       // Set up the synchronous serial port
+       FpgaSetupSsc();
+       // 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);
+       
+       //SpinDelay(100);
+
+       // Start the timer
+       //StartCountSspClk();
+
+       DemodReset();
+       UartReset();
+}
 
 //-----------------------------------------------------------------------------
 // Read a SRI512 ISO 14443B tag.
@@ -922,7 +1030,8 @@ static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
 void ReadSTMemoryIso14443b(uint32_t dwLast)
 {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       
+       BigBuf_free();
+
        clear_trace();
        set_tracing(TRUE);
 
@@ -932,6 +1041,8 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        // confusing things will happen if we don't reset them between reads.
        LED_D_OFF();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelay(200);
+
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        FpgaSetupSsc();
 
@@ -948,6 +1059,7 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
 
        if (Demod.len == 0) {
                DbpString("No response from tag");
+               set_tracing(FALSE);     
                return;
        } else {
                Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
@@ -963,17 +1075,20 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
        if (Demod.len != 3) {
                Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
+               set_tracing(FALSE);     
                return;
        }
        // Check the CRC of the answer:
        ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
        if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
                DbpString("CRC Error reading select response.");
+               set_tracing(FALSE);     
                return;
        }
        // Check response from the tag: should be the same UID as the command we just sent:
        if (cmd1[1] != Demod.output[0]) {
                Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
+               set_tracing(FALSE);     
                return;
        }
 
@@ -985,6 +1100,7 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
        GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
        if (Demod.len != 10) {
                Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
+               set_tracing(FALSE);     
                return;
        }
        // The check the CRC of the answer (use cmd1 as temporary variable):
@@ -1032,6 +1148,8 @@ void ReadSTMemoryIso14443b(uint32_t dwLast)
                }
                i++;
        }
+       
+       set_tracing(FALSE);
 }
 
 
@@ -1164,13 +1282,14 @@ void RAMFUNC SnoopIso14443b(void)
                }
 
                if(!ReaderIsActive) {                                           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
-                       if(Handle14443bSamplesDemod(ci | 0x01, cq | 0x01)) {
+                       // is this | 0x01 the error?   & 0xfe  in https://github.com/Proxmark/proxmark3/issues/103
+                       if(Handle14443bSamplesDemod(ci & 0xfe, cq & 0xfe)) {
 
                        //Use samples as a time measurement
                        if(tracing)
                        {
-                               uint8_t parity[MAX_PARITY_SIZE];
-                                       LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
+                               //uint8_t parity[MAX_PARITY_SIZE];
+                               LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
                        }
                        triggered = TRUE;
 
@@ -1179,11 +1298,12 @@ void RAMFUNC SnoopIso14443b(void)
                }
                        TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
                }
-
        }
 
        FpgaDisableSscDma();
        LEDsoff();
+       set_tracing(FALSE);     
+               
        AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
        DbpString("Snoop statistics:");
        Dbprintf("  Max behind by: %i", maxBehindBy);
@@ -1208,23 +1328,25 @@ void RAMFUNC SnoopIso14443b(void)
  */
 void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
 {
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BigBuf_free();
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       FpgaSetupSsc();
-
-       set_tracing(TRUE);
+       iso14443b_setup();
        
-       CodeAndTransmit14443bAsReader(data, datalen);
+       if ( datalen == 0 && recv == 0 && powerfield == 0){
+               
+       } else {                
+               set_tracing(TRUE);
+               CodeAndTransmit14443bAsReader(data, datalen);
+       }
 
        if(recv) {
-               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
+               GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, FALSE);
                uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
                cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
        }
        
        if(!powerfield) {
                FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               FpgaDisableSscDma();
+               set_tracing(FALSE);
                LED_D_OFF();
        }
 }
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