]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/iso15693.c
Bugfix: Output typing on print of HID card formats (#895)
[proxmark3-svn] / armsrc / iso15693.c
index dbc1ca4c4a48101331282c9f504e91e6a4dc1a4a..f10b0206b4a454405f93c82b0ac9a3f8dbab7299 100644 (file)
 
 #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
 
+// Delays in SSP_CLK ticks.
+// SSP_CLK runs at 13,56MHz / 32 = 423.75kHz when simulating a tag
+#define DELAY_READER_TO_ARM               8
+#define DELAY_ARM_TO_READER               0
+//SSP_CLK runs at 13.56MHz / 4 = 3,39MHz when acting as reader. All values should be multiples of 16
+#define DELAY_ARM_TO_TAG                 16
+#define DELAY_TAG_TO_ARM                 32
+//SSP_CLK runs at 13.56MHz / 4 = 3,39MHz when snooping. All values should be multiples of 16
+#define DELAY_TAG_TO_ARM_SNOOP           32
+#define DELAY_READER_TO_ARM_SNOOP        32
+
 static int DEBUG = 0;
 
+
 ///////////////////////////////////////////////////////////////////////
 // ISO 15693 Part 2 - Air Interface
 // This section basically contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 
 // buffers
-#define ISO15693_DMA_BUFFER_SIZE       2048 // must be a power of 2
+#define ISO15693_DMA_BUFFER_SIZE        256 // must be a power of 2
 #define ISO15693_MAX_RESPONSE_LENGTH     36 // allows read single block with the maximum block size of 256bits. Read multiple blocks not supported yet
 #define ISO15693_MAX_COMMAND_LENGTH      45 // allows write single block with the maximum block size of 256bits. Write multiple blocks not supported yet
 
+
+// specific LogTrace function for ISO15693: the duration needs to be scaled because otherwise it won't fit into a uint16_t
+bool LogTrace_ISO15693(const uint8_t *btBytes, uint16_t iLen, uint32_t timestamp_start, uint32_t timestamp_end, uint8_t *parity, bool readerToTag) {
+       uint32_t duration = timestamp_end - timestamp_start;
+       duration /= 32;
+       timestamp_end = timestamp_start + duration;
+       return LogTrace(btBytes, iLen, timestamp_start, timestamp_end, parity, readerToTag);
+}
+
+
 // ---------------------------
 // Signal Processing
 // ---------------------------
@@ -84,83 +106,36 @@ static int DEBUG = 0;
 // resulting data rate is 26.48 kbit/s (fc/512)
 // cmd ... data
 // n ... length of data
-static void CodeIso15693AsReader(uint8_t *cmd, int n)
-{
-       int i, j;
+void CodeIso15693AsReader(uint8_t *cmd, int n) {
 
        ToSendReset();
 
-       // Give it a bit of slack at the beginning
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
-       }
-
        // SOF for 1of4
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       for(i = 0; i < n; i++) {
-               for(j = 0; j < 8; j += 2) {
-                       int these = (cmd[i] >> j) & 3;
+       ToSend[++ToSendMax] = 0x84; //10000100
+
+       // data
+       for (int i = 0; i < n; i++) {
+               for (int j = 0; j < 8; j += 2) {
+                       int these = (cmd[i] >> j) & 0x03;
                        switch(these) {
                                case 0:
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
+                                       ToSend[++ToSendMax] = 0x40; //01000000
                                        break;
                                case 1:
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
+                                       ToSend[++ToSendMax] = 0x10; //00010000
                                        break;
                                case 2:
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
+                                       ToSend[++ToSendMax] = 0x04; //00000100
                                        break;
                                case 3:
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
+                                       ToSend[++ToSendMax] = 0x01; //00000001
                                        break;
                        }
                }
        }
+
        // EOF
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-
-       // Fill remainder of last byte with 1
-       for(i = 0; i < 4; i++) {
-               ToSendStuffBit(1);
-       }
+       ToSend[++ToSendMax] = 0x20; //0010 + 0000 padding
 
        ToSendMax++;
 }
@@ -170,46 +145,26 @@ static void CodeIso15693AsReader(uint8_t *cmd, int n)
 // is designed for more robust communication over longer distances
 static void CodeIso15693AsReader256(uint8_t *cmd, int n)
 {
-       int i, j;
-
        ToSendReset();
 
-       // Give it a bit of slack at the beginning
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
-       }
-
        // SOF for 1of256
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(0);
-
-       for(i = 0; i < n; i++) {
-               for (j = 0; j<=255; j++) {
-                       if (cmd[i]==j) {
-                               ToSendStuffBit(1);
+       ToSend[++ToSendMax] = 0x81; //10000001
+
+       // data
+       for(int i = 0; i < n; i++) {
+               for (int j = 0; j <= 255; j++) {
+                       if (cmd[i] == j) {
                                ToSendStuffBit(0);
-                       } else {
-                               ToSendStuffBit(1);
                                ToSendStuffBit(1);
+                       } else {
+                               ToSendStuffBit(0);
+                               ToSendStuffBit(0);
                        }
                }
        }
+
        // EOF
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-
-       // Fill remainder of last byte with 1
-       for(i = 0; i < 4; i++) {
-               ToSendStuffBit(1);
-       }
+       ToSend[++ToSendMax] = 0x20; //0010 + 0000 padding
 
        ToSendMax++;
 }
@@ -246,6 +201,8 @@ static void CodeIso15693AsReader256(uint8_t *cmd, int n)
        // }
 // }
 
+static const uint8_t encode_4bits[16] = { 0xaa, 0x6a, 0x9a, 0x5a, 0xa6, 0x66, 0x96, 0x56, 0xa9, 0x69, 0x99, 0x59, 0xa5, 0x65, 0x95, 0x55 };
+
 void CodeIso15693AsTag(uint8_t *cmd, size_t len) {
        /*
         * SOF comprises 3 parts;
@@ -280,16 +237,9 @@ void CodeIso15693AsTag(uint8_t *cmd, size_t len) {
        ToSend[++ToSendMax] = 0x1D;  // 00011101
 
        // data
-       for(int i = 0; i < len; i++) {
-               for(int j = 0; j < 8; j++) {
-                       if ((cmd[i] >> j) & 0x01) {
-                                       ToSendStuffBit(0);
-                                       ToSendStuffBit(1);
-                       } else {
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
-                       }
-               }
+       for (int i = 0; i < len; i++) {
+               ToSend[++ToSendMax] = encode_4bits[cmd[i] & 0xF];
+               ToSend[++ToSendMax] = encode_4bits[cmd[i] >> 4];
        }
 
        // EOF
@@ -300,46 +250,73 @@ void CodeIso15693AsTag(uint8_t *cmd, size_t len) {
 
 
 // Transmit the command (to the tag) that was placed in cmd[].
-static void TransmitTo15693Tag(const uint8_t *cmd, int len, uint32_t start_time)
-{
+void TransmitTo15693Tag(const uint8_t *cmd, int len, uint32_t *start_time) {
+
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_FULL_MOD);
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
 
-       while (GetCountSspClk() < start_time) ;
+       if (*start_time < DELAY_ARM_TO_TAG) {
+               *start_time = DELAY_ARM_TO_TAG;
+       }
+
+       *start_time = (*start_time - DELAY_ARM_TO_TAG) & 0xfffffff0;
+
+       if (GetCountSspClk() > *start_time) { // we may miss the intended time
+               *start_time = (GetCountSspClk() + 16) & 0xfffffff0; // next possible time
+       }
+
+       while (GetCountSspClk() < *start_time)
+               /* wait */ ;
 
        LED_B_ON();
-       for(int c = 0; c < len; c++) {
+       for (int c = 0; c < len; c++) {
                uint8_t data = cmd[c];
                for (int i = 0; i < 8; i++) {
-                       uint16_t send_word = (data & 0x80) ? 0x0000 : 0xffff;
+                       uint16_t send_word = (data & 0x80) ? 0xffff : 0x0000;
                        while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
                        AT91C_BASE_SSC->SSC_THR = send_word;
                        while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
                        AT91C_BASE_SSC->SSC_THR = send_word;
+
                        data <<= 1;
                }
                WDT_HIT();
        }
        LED_B_OFF();
+
+       *start_time = *start_time + DELAY_ARM_TO_TAG;
+
 }
 
 
 //-----------------------------------------------------------------------------
 // Transmit the tag response (to the reader) that was placed in cmd[].
 //-----------------------------------------------------------------------------
-void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time, bool slow) {
+void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t *start_time, uint32_t slot_time, bool slow) {
        // don't use the FPGA_HF_SIMULATOR_MODULATE_424K_8BIT minor mode. It would spoil GetCountSspClk()
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K);
 
-       uint8_t shift_delay = start_time & 0x00000007;
+       uint32_t modulation_start_time = *start_time - DELAY_ARM_TO_READER + 3 * 8;  // no need to transfer the unmodulated start of SOF
 
-       while (GetCountSspClk() < (start_time & 0xfffffff8)) ;
+       while (GetCountSspClk() > (modulation_start_time & 0xfffffff8) + 3) { // we will miss the intended time
+               if (slot_time) {
+                       modulation_start_time += slot_time; // use next available slot
+               } else {
+                       modulation_start_time = (modulation_start_time & 0xfffffff8) + 8; // next possible time
+               }
+       }
+
+       while (GetCountSspClk() < (modulation_start_time & 0xfffffff8))
+               /* wait */ ;
+
+       uint8_t shift_delay = modulation_start_time & 0x00000007;
+
+       *start_time = modulation_start_time + DELAY_ARM_TO_READER - 3 * 8;
 
        LED_C_ON();
        uint8_t bits_to_shift = 0x00;
        uint8_t bits_to_send = 0x00;
-       for(size_t c = 0; c < len; c++) {
-               for (int i = 7; i >= 0; i--) {
+       for (size_t c = 0; c < len; c++) {
+               for (int i = (c==0?4:7); i >= 0; i--) {
                        uint8_t cmd_bits = ((cmd[c] >> i) & 0x01) ? 0xff : 0x00;
                        for (int j = 0; j < (slow?4:1); ) {
                                if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
@@ -361,7 +338,6 @@ void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time,
                }
        }
        LED_C_OFF();
-
 }
 
 
@@ -379,15 +355,18 @@ void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start_time,
 //          false if we are still waiting for some more
 //=============================================================================
 
-#define NOISE_THRESHOLD    160      // don't try to correlate noise
+#define NOISE_THRESHOLD          160                   // don't try to correlate noise
+#define MAX_PREVIOUS_AMPLITUDE   (-1 - NOISE_THRESHOLD)
 
 typedef struct DecodeTag {
        enum {
                STATE_TAG_SOF_LOW,
+               STATE_TAG_SOF_RISING_EDGE,
                STATE_TAG_SOF_HIGH,
                STATE_TAG_SOF_HIGH_END,
                STATE_TAG_RECEIVING_DATA,
-               STATE_TAG_EOF
+               STATE_TAG_EOF,
+               STATE_TAG_EOF_TAIL
        }         state;
        int       bitCount;
        int       posCount;
@@ -402,47 +381,67 @@ typedef struct DecodeTag {
        uint8_t   *output;
        int       len;
        int       sum1, sum2;
+       int       threshold_sof;
+       int       threshold_half;
+       uint16_t  previous_amplitude;
 } DecodeTag_t;
 
 
-static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint16_t amplitude, DecodeTag_t *DecodeTag)
-{
-       switch(DecodeTag->state) {
+static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint16_t amplitude, DecodeTag_t *DecodeTag) {
+       switch (DecodeTag->state) {
                case STATE_TAG_SOF_LOW:
-                       // waiting for 12 times low (11 times low is accepted as well)
-                       if (amplitude < NOISE_THRESHOLD) {
-                               DecodeTag->posCount++;
-                       } else {
+                       // waiting for a rising edge
+                       if (amplitude > NOISE_THRESHOLD + DecodeTag->previous_amplitude) {
                                if (DecodeTag->posCount > 10) {
-                                       DecodeTag->posCount = 1;
-                                       DecodeTag->sum1 = 0;
-                                       DecodeTag->state = STATE_TAG_SOF_HIGH;
+                                       DecodeTag->threshold_sof = amplitude - DecodeTag->previous_amplitude; // to be divided by 2
+                                       DecodeTag->threshold_half = 0;
+                                       DecodeTag->state = STATE_TAG_SOF_RISING_EDGE;
                                } else {
                                        DecodeTag->posCount = 0;
                                }
+                       } else {
+                               DecodeTag->posCount++;
+                               DecodeTag->previous_amplitude = amplitude;
+                       }
+                       break;
+
+               case STATE_TAG_SOF_RISING_EDGE:
+                       if (amplitude > DecodeTag->threshold_sof + DecodeTag->previous_amplitude) { // edge still rising
+                               if (amplitude > DecodeTag->threshold_sof + DecodeTag->threshold_sof) { // steeper edge, take this as time reference
+                                       DecodeTag->posCount = 1;
+                               } else {
+                                       DecodeTag->posCount = 2;
+                               }
+                               DecodeTag->threshold_sof = (amplitude - DecodeTag->previous_amplitude) / 2;
+                       } else {
+                               DecodeTag->posCount = 2;
+                               DecodeTag->threshold_sof = DecodeTag->threshold_sof/2;
                        }
+                       // DecodeTag->posCount = 2;
+                       DecodeTag->state = STATE_TAG_SOF_HIGH;
                        break;
 
                case STATE_TAG_SOF_HIGH:
                        // waiting for 10 times high. Take average over the last 8
-                       if (amplitude > NOISE_THRESHOLD) {
+                       if (amplitude > DecodeTag->threshold_sof) {
                                DecodeTag->posCount++;
                                if (DecodeTag->posCount > 2) {
-                                       DecodeTag->sum1 += amplitude; // keep track of average high value
+                                       DecodeTag->threshold_half += amplitude; // keep track of average high value
                                }
                                if (DecodeTag->posCount == 10) {
-                                       DecodeTag->sum1 >>= 4;        // calculate half of average high value (8 samples)
+                                       DecodeTag->threshold_half >>= 2; // (4 times 1/2 average)
                                        DecodeTag->state = STATE_TAG_SOF_HIGH_END;
                                }
                        } else { // high phase was too short
                                DecodeTag->posCount = 1;
+                               DecodeTag->previous_amplitude = amplitude;
                                DecodeTag->state = STATE_TAG_SOF_LOW;
                        }
                        break;
 
                case STATE_TAG_SOF_HIGH_END:
-                       // waiting for a falling edge
-                       if (amplitude < DecodeTag->sum1) {   // signal drops below 50% average high: a falling edge
+                       // check for falling edge
+                       if (DecodeTag->posCount == 13 && amplitude < DecodeTag->threshold_sof) {
                                DecodeTag->lastBit = SOF_PART1;  // detected 1st part of SOF (12 samples low and 12 samples high)
                                DecodeTag->shiftReg = 0;
                                DecodeTag->bitCount = 0;
@@ -451,11 +450,18 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                DecodeTag->sum2 = 0;
                                DecodeTag->posCount = 2;
                                DecodeTag->state = STATE_TAG_RECEIVING_DATA;
+                               // FpgaDisableTracing(); // DEBUGGING
+                               // Dbprintf("amplitude = %d, threshold_sof = %d, threshold_half/4 = %d, previous_amplitude = %d",
+                                       // amplitude,
+                                       // DecodeTag->threshold_sof,
+                                       // DecodeTag->threshold_half/4,
+                                       // DecodeTag->previous_amplitude); // DEBUGGING
                                LED_C_ON();
                        } else {
                                DecodeTag->posCount++;
                                if (DecodeTag->posCount > 13) { // high phase too long
                                        DecodeTag->posCount = 0;
+                                       DecodeTag->previous_amplitude = amplitude;
                                        DecodeTag->state = STATE_TAG_SOF_LOW;
                                        LED_C_OFF();
                                }
@@ -463,6 +469,12 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                        break;
 
                case STATE_TAG_RECEIVING_DATA:
+                               // FpgaDisableTracing(); // DEBUGGING
+                               // Dbprintf("amplitude = %d, threshold_sof = %d, threshold_half/4 = %d, previous_amplitude = %d",
+                                       // amplitude,
+                                       // DecodeTag->threshold_sof,
+                                       // DecodeTag->threshold_half/4,
+                                       // DecodeTag->previous_amplitude); // DEBUGGING
                        if (DecodeTag->posCount == 1) {
                                DecodeTag->sum1 = 0;
                                DecodeTag->sum2 = 0;
@@ -473,18 +485,16 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                DecodeTag->sum2 += amplitude;
                        }
                        if (DecodeTag->posCount == 8) {
-                               int32_t corr_1 = DecodeTag->sum2 - DecodeTag->sum1;
-                               int32_t corr_0 = -corr_1;
-                               int32_t corr_EOF = (DecodeTag->sum1 + DecodeTag->sum2) / 2;
-                               if (corr_EOF > corr_0 && corr_EOF > corr_1) {
+                               if (DecodeTag->sum1 > DecodeTag->threshold_half && DecodeTag->sum2 > DecodeTag->threshold_half) { // modulation in both halves
                                        if (DecodeTag->lastBit == LOGIC0) {  // this was already part of EOF
                                                DecodeTag->state = STATE_TAG_EOF;
                                        } else {
                                                DecodeTag->posCount = 0;
+                                               DecodeTag->previous_amplitude = amplitude;
                                                DecodeTag->state = STATE_TAG_SOF_LOW;
                                                LED_C_OFF();
                                        }
-                               } else if (corr_1 > corr_0) {
+                               } else if (DecodeTag->sum1 < DecodeTag->threshold_half && DecodeTag->sum2 > DecodeTag->threshold_half) { // modulation in second half
                                        // logic 1
                                        if (DecodeTag->lastBit == SOF_PART1) { // still part of SOF
                                                DecodeTag->lastBit = SOF_PART2;    // SOF completed
@@ -496,20 +506,21 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;
+                                                       // if (DecodeTag->shiftReg == 0x12 && DecodeTag->len == 1) FpgaDisableTracing(); // DEBUGGING
                                                        if (DecodeTag->len > DecodeTag->max_len) {
                                                                // buffer overflow, give up
-                                                               DecodeTag->posCount = 0;
-                                                               DecodeTag->state = STATE_TAG_SOF_LOW;
                                                                LED_C_OFF();
+                                                               return true;
                                                        }
                                                        DecodeTag->bitCount = 0;
                                                        DecodeTag->shiftReg = 0;
                                                }
                                        }
-                               } else {
+                               } else if (DecodeTag->sum1 > DecodeTag->threshold_half && DecodeTag->sum2 < DecodeTag->threshold_half) { // modulation in first half
                                        // logic 0
                                        if (DecodeTag->lastBit == SOF_PART1) { // incomplete SOF
                                                DecodeTag->posCount = 0;
+                                               DecodeTag->previous_amplitude = amplitude;
                                                DecodeTag->state = STATE_TAG_SOF_LOW;
                                                LED_C_OFF();
                                        } else {
@@ -519,9 +530,11 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;
+                                                       // if (DecodeTag->shiftReg == 0x12 && DecodeTag->len == 1) FpgaDisableTracing(); // DEBUGGING
                                                        if (DecodeTag->len > DecodeTag->max_len) {
                                                                // buffer overflow, give up
                                                                DecodeTag->posCount = 0;
+                                                               DecodeTag->previous_amplitude = amplitude;
                                                                DecodeTag->state = STATE_TAG_SOF_LOW;
                                                                LED_C_OFF();
                                                        }
@@ -529,6 +542,15 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                                        DecodeTag->shiftReg = 0;
                                                }
                                        }
+                               } else { // no modulation
+                                       if (DecodeTag->lastBit == SOF_PART2) { // only SOF (this is OK for iClass)
+                                               LED_C_OFF();
+                                               return true;
+                                       } else {
+                                               DecodeTag->posCount = 0;
+                                               DecodeTag->state = STATE_TAG_SOF_LOW;
+                                               LED_C_OFF();
+                                       }
                                }
                                DecodeTag->posCount = 0;
                        }
@@ -546,29 +568,50 @@ static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint1
                                DecodeTag->sum2 += amplitude;
                        }
                        if (DecodeTag->posCount == 8) {
-                               int32_t corr_1 = DecodeTag->sum2 - DecodeTag->sum1;
-                               int32_t corr_0 = -corr_1;
-                               int32_t corr_EOF = (DecodeTag->sum1 + DecodeTag->sum2) / 2;
-                               if (corr_EOF > corr_0 || corr_1 > corr_0) {
+                               if (DecodeTag->sum1 > DecodeTag->threshold_half && DecodeTag->sum2 < DecodeTag->threshold_half) { // modulation in first half
+                                       DecodeTag->posCount = 0;
+                                       DecodeTag->state = STATE_TAG_EOF_TAIL;
+                               } else {
                                        DecodeTag->posCount = 0;
+                                       DecodeTag->previous_amplitude = amplitude;
                                        DecodeTag->state = STATE_TAG_SOF_LOW;
                                        LED_C_OFF();
-                               } else {
+                               }
+                       }
+                       DecodeTag->posCount++;
+                       break;
+
+               case STATE_TAG_EOF_TAIL:
+                       if (DecodeTag->posCount == 1) {
+                               DecodeTag->sum1 = 0;
+                               DecodeTag->sum2 = 0;
+                       }
+                       if (DecodeTag->posCount <= 4) {
+                               DecodeTag->sum1 += amplitude;
+                       } else {
+                               DecodeTag->sum2 += amplitude;
+                       }
+                       if (DecodeTag->posCount == 8) {
+                               if (DecodeTag->sum1 < DecodeTag->threshold_half && DecodeTag->sum2 < DecodeTag->threshold_half) { // no modulation in both halves
                                        LED_C_OFF();
                                        return true;
+                               } else {
+                                       DecodeTag->posCount = 0;
+                                       DecodeTag->previous_amplitude = amplitude;
+                                       DecodeTag->state = STATE_TAG_SOF_LOW;
+                                       LED_C_OFF();
                                }
                        }
                        DecodeTag->posCount++;
                        break;
-
        }
 
        return false;
 }
 
 
-static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data, uint16_t max_len)
-{
+static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data, uint16_t max_len) {
+       DecodeTag->previous_amplitude = MAX_PREVIOUS_AMPLITUDE;
        DecodeTag->posCount = 0;
        DecodeTag->state = STATE_TAG_SOF_LOW;
        DecodeTag->output = data;
@@ -576,22 +619,22 @@ static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data, uint16_t max_le
 }
 
 
-static void DecodeTagReset(DecodeTag_t *DecodeTag)
-{
+static void DecodeTagReset(DecodeTag_t *DecodeTag) {
        DecodeTag->posCount = 0;
        DecodeTag->state = STATE_TAG_SOF_LOW;
+       DecodeTag->previous_amplitude = MAX_PREVIOUS_AMPLITUDE;
 }
 
 
 /*
  *  Receive and decode the tag response, also log to tracebuffer
  */
-static int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, int timeout)
-{
+int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, uint16_t timeout, uint32_t *eof_time) {
+
        int samples = 0;
-       bool gotFrame = false;
+       int ret = 0;
 
-       uint16_t *dmaBuf = (uint16_t*)BigBuf_malloc(ISO15693_DMA_BUFFER_SIZE*sizeof(uint16_t));
+       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
 
        // the Decoder data structure
        DecodeTag_t DecodeTag = { 0 };
@@ -606,6 +649,7 @@ static int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, int tim
        // Setup and start DMA.
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+       uint32_t dma_start_time = 0;
        uint16_t *upTo = dmaBuf;
 
        for(;;) {
@@ -613,12 +657,19 @@ static int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, int tim
 
                if (behindBy == 0) continue;
 
+               samples++;
+               if (samples == 1) {
+                       // DMA has transferred the very first data
+                       dma_start_time = GetCountSspClk() & 0xfffffff0;
+               }
+
                uint16_t tagdata = *upTo++;
 
                if(upTo >= dmaBuf + ISO15693_DMA_BUFFER_SIZE) {                // we have read all of the DMA buffer content.
                        upTo = dmaBuf;                                             // start reading the circular buffer from the beginning
-                       if(behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                       if (behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
                                Dbprintf("About to blow circular buffer - aborted! behindBy=%d", behindBy);
+                               ret = -1;
                                break;
                        }
                }
@@ -627,30 +678,42 @@ static int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, int tim
                        AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
                }
 
-               samples++;
-
                if (Handle15693SamplesFromTag(tagdata, &DecodeTag)) {
-                       gotFrame = true;
+                       *eof_time = dma_start_time + samples*16 - DELAY_TAG_TO_ARM; // end of EOF
+                       if (DecodeTag.lastBit == SOF_PART2) {
+                               *eof_time -= 8*16; // needed 8 additional samples to confirm single SOF (iCLASS)
+                       }
+                       if (DecodeTag.len > DecodeTag.max_len) {
+                               ret = -2; // buffer overflow
+                       }
                        break;
                }
 
                if (samples > timeout && DecodeTag.state < STATE_TAG_RECEIVING_DATA) {
-                       DecodeTag.len = 0;
+                       ret = -1;   // timeout
                        break;
                }
 
        }
 
        FpgaDisableSscDma();
-       BigBuf_free();
 
-       if (DEBUG) Dbprintf("samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
-                                               samples, gotFrame, DecodeTag.state, DecodeTag.len, DecodeTag.bitCount, DecodeTag.posCount);
+       if (DEBUG) Dbprintf("samples = %d, ret = %d, Decoder: state = %d, lastBit = %d, len = %d, bitCount = %d, posCount = %d",
+                                               samples, ret, DecodeTag.state, DecodeTag.lastBit, DecodeTag.len, DecodeTag.bitCount, DecodeTag.posCount);
 
-       if (DecodeTag.len > 0) {
-               LogTrace(DecodeTag.output, DecodeTag.len, 0, 0, NULL, false);
+       if (ret < 0) {
+               return ret;
        }
 
+       uint32_t sof_time = *eof_time
+                                               - DecodeTag.len * 8 * 8 * 16 // time for byte transfers
+                                               - 32 * 16  // time for SOF transfer
+                                               - (DecodeTag.lastBit != SOF_PART2?32*16:0); // time for EOF transfer
+
+       if (DEBUG) Dbprintf("timing: sof_time = %d, eof_time = %d", sof_time, *eof_time);
+
+       LogTrace_ISO15693(DecodeTag.output, DecodeTag.len, sof_time*4, *eof_time*4, NULL, false);
+
        return DecodeTag.len;
 }
 
@@ -677,7 +740,8 @@ typedef struct DecodeReader {
                STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF,
                STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4,
                STATE_READER_RECEIVE_DATA_1_OUT_OF_4,
-               STATE_READER_RECEIVE_DATA_1_OUT_OF_256
+               STATE_READER_RECEIVE_DATA_1_OUT_OF_256,
+               STATE_READER_RECEIVE_JAMMING
        }           state;
        enum {
                CODING_1_OUT_OF_4,
@@ -690,11 +754,12 @@ typedef struct DecodeReader {
        int         posCount;
        int         sum1, sum2;
        uint8_t     *output;
+       uint8_t     jam_search_len;
+       uint8_t     *jam_search_string;
 } DecodeReader_t;
 
 
-static void DecodeReaderInit(DecodeReader_t* DecodeReader, uint8_t *data, uint16_t max_len)
-{
+static void DecodeReaderInit(DecodeReader_t* DecodeReader, uint8_t *data, uint16_t max_len, uint8_t jam_search_len, uint8_t *jam_search_string) {
        DecodeReader->output = data;
        DecodeReader->byteCountMax = max_len;
        DecodeReader->state = STATE_READER_UNSYNCD;
@@ -702,17 +767,17 @@ static void DecodeReaderInit(DecodeReader_t* DecodeReader, uint8_t *data, uint16
        DecodeReader->bitCount = 0;
        DecodeReader->posCount = 1;
        DecodeReader->shiftReg = 0;
+       DecodeReader->jam_search_len = jam_search_len;
+       DecodeReader->jam_search_string = jam_search_string;
 }
 
 
-static void DecodeReaderReset(DecodeReader_t* DecodeReader)
-{
+static void DecodeReaderReset(DecodeReader_t* DecodeReader) {
        DecodeReader->state = STATE_READER_UNSYNCD;
 }
 
 
-static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uint8_t bit, DecodeReader_t *restrict DecodeReader)
-{
+static int inline __attribute__((always_inline)) Handle15693SampleFromReader(bool bit, DecodeReader_t *DecodeReader) {
        switch (DecodeReader->state) {
                case STATE_READER_UNSYNCD:
                        // wait for unmodulated carrier
@@ -827,16 +892,15 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                        break;
 
                case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
-                       bit = !!bit;
                        DecodeReader->posCount++;
                        if (DecodeReader->posCount == 1) {
-                               DecodeReader->sum1 = bit;
+                               DecodeReader->sum1 = bit?1:0;
                        } else if (DecodeReader->posCount <= 4) {
-                               DecodeReader->sum1 += bit;
+                               if (bit) DecodeReader->sum1++;
                        } else if (DecodeReader->posCount == 5) {
-                               DecodeReader->sum2 = bit;
+                               DecodeReader->sum2 = bit?1:0;
                        } else {
-                               DecodeReader->sum2 += bit;
+                               if (bit) DecodeReader->sum2++;
                        }
                        if (DecodeReader->posCount == 8) {
                                DecodeReader->posCount = 0;
@@ -846,8 +910,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }
-                               }
-                               if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected a 2bit position
+                               } else if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected a 2bit position
                                        DecodeReader->shiftReg >>= 2;
                                        DecodeReader->shiftReg |= (DecodeReader->bitCount << 6);
                                }
@@ -860,6 +923,13 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                                        }
                                        DecodeReader->bitCount = 0;
                                        DecodeReader->shiftReg = 0;
+                                       if (DecodeReader->byteCount == DecodeReader->jam_search_len) {
+                                               if (!memcmp(DecodeReader->output, DecodeReader->jam_search_string, DecodeReader->jam_search_len)) {
+                                                       LED_D_ON();
+                                                       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_JAM);
+                                                       DecodeReader->state = STATE_READER_RECEIVE_JAMMING;
+                                               }
+                                       }
                                } else {
                                        DecodeReader->bitCount++;
                                }
@@ -867,16 +937,15 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                        break;
 
                case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:
-                       bit = !!bit;
                        DecodeReader->posCount++;
                        if (DecodeReader->posCount == 1) {
-                               DecodeReader->sum1 = bit;
+                               DecodeReader->sum1 = bit?1:0;
                        } else if (DecodeReader->posCount <= 4) {
-                               DecodeReader->sum1 += bit;
+                               if (bit) DecodeReader->sum1++;
                        } else if (DecodeReader->posCount == 5) {
-                               DecodeReader->sum2 = bit;
-                       } else {
-                               DecodeReader->sum2 += bit;
+                               DecodeReader->sum2 = bit?1:0;
+                       } else if (bit) {
+                               DecodeReader->sum2++;
                        }
                        if (DecodeReader->posCount == 8) {
                                DecodeReader->posCount = 0;
@@ -886,8 +955,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }
-                               }
-                               if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected the bit position
+                               } else if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected the bit position
                                        DecodeReader->shiftReg = DecodeReader->bitCount;
                                }
                                if (DecodeReader->bitCount == 255) { // we have a full byte
@@ -897,11 +965,42 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
                                                LED_B_OFF();
                                                DecodeReaderReset(DecodeReader);
                                        }
+                                       if (DecodeReader->byteCount == DecodeReader->jam_search_len) {
+                                               if (!memcmp(DecodeReader->output, DecodeReader->jam_search_string, DecodeReader->jam_search_len)) {
+                                                       LED_D_ON();
+                                                       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_JAM);
+                                                       DecodeReader->state = STATE_READER_RECEIVE_JAMMING;
+                                               }
+                                       }
                                }
                                DecodeReader->bitCount++;
                        }
                        break;
 
+               case STATE_READER_RECEIVE_JAMMING:
+                       DecodeReader->posCount++;
+                       if (DecodeReader->Coding == CODING_1_OUT_OF_4) {
+                               if (DecodeReader->posCount == 7*16) { // 7 bits jammed
+                                       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNOOP_AMPLITUDE); // stop jamming
+                                       // FpgaDisableTracing();
+                                       LED_D_OFF();
+                               } else if (DecodeReader->posCount == 8*16) {
+                                       DecodeReader->posCount = 0;
+                                       DecodeReader->output[DecodeReader->byteCount++] = 0x00;
+                                       DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_4;
+                               }
+                       } else {
+                               if (DecodeReader->posCount == 7*256) { // 7 bits jammend
+                                       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNOOP_AMPLITUDE); // stop jamming
+                                       LED_D_OFF();
+                               } else if (DecodeReader->posCount == 8*256) {
+                                       DecodeReader->posCount = 0;
+                                       DecodeReader->output[DecodeReader->byteCount++] = 0x00;
+                                       DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_256;
+                               }
+                       }
+                       break;
+
                default:
                        LED_B_OFF();
                        DecodeReaderReset(DecodeReader);
@@ -931,7 +1030,7 @@ int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eo
 
        // the decoder data structure
        DecodeReader_t DecodeReader = {0};
-       DecodeReaderInit(&DecodeReader, received, max_len);
+       DecodeReaderInit(&DecodeReader, received, max_len, 0, NULL);
 
        // wait for last transfer to complete
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
@@ -970,7 +1069,7 @@ int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eo
 
                for (int i = 7; i >= 0; i--) {
                        if (Handle15693SampleFromReader((b >> i) & 0x01, &DecodeReader)) {
-                               *eof_time = dma_start_time + samples - DELAY_READER_TO_ARM_SIM; // end of EOF
+                               *eof_time = dma_start_time + samples - DELAY_READER_TO_ARM; // end of EOF
                                gotFrame = true;
                                break;
                        }
@@ -999,7 +1098,7 @@ int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eo
                                                - DecodeReader.byteCount * (DecodeReader.Coding==CODING_1_OUT_OF_4?128:2048) // time for byte transfers
                                                - 32  // time for SOF transfer
                                                - 16; // time for EOF transfer
-               LogTrace(DecodeReader.output, DecodeReader.byteCount, sof_time, *eof_time, NULL, true);
+               LogTrace_ISO15693(DecodeReader.output, DecodeReader.byteCount, sof_time*32, *eof_time*32, NULL, true);
        }
 
        return DecodeReader.byteCount;
@@ -1036,24 +1135,24 @@ static void BuildIdentifyRequest(void)
 //-----------------------------------------------------------------------------
 void AcquireRawAdcSamplesIso15693(void)
 {
-       LEDsoff();
        LED_A_ON();
 
        uint8_t *dest = BigBuf_get_addr();
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER);
+       LED_D_ON();
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        BuildIdentifyRequest();
 
        // Give the tags time to energize
-       LED_D_ON();
        SpinDelay(100);
 
        // Now send the command
-       TransmitTo15693Tag(ToSend, ToSendMax, 0);
+       uint32_t start_time = 0;
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
 
        // wait for last transfer to complete
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY)) ;
@@ -1072,18 +1171,17 @@ void AcquireRawAdcSamplesIso15693(void)
 }
 
 
-void SnoopIso15693(void)
-{
+void SnoopIso15693(uint8_t jam_search_len, uint8_t *jam_search_string) {
+
        LED_A_ON();
+
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BigBuf_free();
 
        clear_trace();
        set_tracing(true);
 
        // The DMA buffer, used to stream samples from the FPGA
-       uint16_t* dmaBuf = (uint16_t*)BigBuf_malloc(ISO15693_DMA_BUFFER_SIZE*sizeof(uint16_t));
-       uint16_t *upTo;
+       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
 
        // Count of samples received so far, so that we can include timing
        // information in the trace buffer.
@@ -1093,9 +1191,9 @@ void SnoopIso15693(void)
        uint8_t response[ISO15693_MAX_RESPONSE_LENGTH];
        DecodeTagInit(&DecodeTag, response, sizeof(response));
 
-       DecodeReader_t DecodeReader = {0};;
+       DecodeReader_t DecodeReader = {0};
        uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH];
-       DecodeReaderInit(&DecodeReader, cmd, sizeof(cmd));
+       DecodeReaderInit(&DecodeReader, cmd, sizeof(cmd), jam_search_len, jam_search_string);
 
        // Print some debug information about the buffer sizes
        if (DEBUG) {
@@ -1108,28 +1206,41 @@ void SnoopIso15693(void)
        Dbprintf("Snoop started. Press PM3 Button to stop.");
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNOOP_AMPLITUDE);
+       LED_D_OFF();
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-
-       // Setup for the DMA.
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
-       upTo = dmaBuf;
+       StartCountSspClk();
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
 
        bool TagIsActive = false;
        bool ReaderIsActive = false;
        bool ExpectTagAnswer = false;
+       uint32_t dma_start_time = 0;
+       uint16_t *upTo = dmaBuf;
 
+       uint16_t max_behindBy = 0;
+       
        // And now we loop, receiving samples.
        for(;;) {
                uint16_t behindBy = ((uint16_t*)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (ISO15693_DMA_BUFFER_SIZE-1);
-
+               if (behindBy > max_behindBy) {
+                       max_behindBy = behindBy;
+               }
+               
                if (behindBy == 0) continue;
 
+               samples++;
+               if (samples == 1) {
+                       // DMA has transferred the very first data
+                       dma_start_time = GetCountSspClk() & 0xfffffff0;
+               }
+
                uint16_t snoopdata = *upTo++;
 
-               if(upTo >= dmaBuf + ISO15693_DMA_BUFFER_SIZE) {                    // we have read all of the DMA buffer content.
+               if (upTo >= dmaBuf + ISO15693_DMA_BUFFER_SIZE) {                   // we have read all of the DMA buffer content.
                        upTo = dmaBuf;                                                 // start reading the circular buffer from the beginning
-                       if(behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                       if (behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                               // FpgaDisableTracing();
                                Dbprintf("About to blow circular buffer - aborted! behindBy=%d, samples=%d", behindBy, samples);
                                break;
                        }
@@ -1137,79 +1248,107 @@ void SnoopIso15693(void)
                                AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
                                AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
                                WDT_HIT();
-                               if(BUTTON_PRESS()) {
+                               if (BUTTON_PRESS()) {
                                        DbpString("Snoop stopped.");
                                        break;
                                }
                        }
                }
-               samples++;
 
-               if (!TagIsActive) {                                            // no need to try decoding reader data if the tag is sending
+               if (!TagIsActive) {                                                // no need to try decoding reader data if the tag is sending
                        if (Handle15693SampleFromReader(snoopdata & 0x02, &DecodeReader)) {
-                               FpgaDisableSscDma();
-                               ExpectTagAnswer = true;
-                               LogTrace(DecodeReader.output, DecodeReader.byteCount, samples, samples, NULL, true);
+                               // FpgaDisableSscDma();
+                               uint32_t eof_time = dma_start_time + samples*16 + 8 - DELAY_READER_TO_ARM_SNOOP; // end of EOF
+                               if (DecodeReader.byteCount > 0) {
+                                       uint32_t sof_time = eof_time
+                                                                       - DecodeReader.byteCount * (DecodeReader.Coding==CODING_1_OUT_OF_4?128*16:2048*16) // time for byte transfers
+                                                                       - 32*16  // time for SOF transfer
+                                                                       - 16*16; // time for EOF transfer
+                                       LogTrace_ISO15693(DecodeReader.output, DecodeReader.byteCount, sof_time*4, eof_time*4, NULL, true);
+                               }
                                /* And ready to receive another command. */
                                DecodeReaderReset(&DecodeReader);
                                /* And also reset the demod code, which might have been */
                                /* false-triggered by the commands from the reader. */
                                DecodeTagReset(&DecodeTag);
-                               upTo = dmaBuf;
-                               FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
-                       }
-                       if (Handle15693SampleFromReader(snoopdata & 0x01, &DecodeReader)) {
-                               FpgaDisableSscDma();
+                               ReaderIsActive = false;
                                ExpectTagAnswer = true;
-                               LogTrace(DecodeReader.output, DecodeReader.byteCount, samples, samples, NULL, true);
+                               // upTo = dmaBuf;
+                               // samples = 0;
+                               // FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               // continue;
+                       } else if (Handle15693SampleFromReader(snoopdata & 0x01, &DecodeReader)) {
+                               // FpgaDisableSscDma();
+                               uint32_t eof_time = dma_start_time + samples*16 + 16 - DELAY_READER_TO_ARM_SNOOP; // end of EOF
+                               if (DecodeReader.byteCount > 0) {
+                                       uint32_t sof_time = eof_time
+                                                                       - DecodeReader.byteCount * (DecodeReader.Coding==CODING_1_OUT_OF_4?128*16:2048*16) // time for byte transfers
+                                                                       - 32*16  // time for SOF transfer
+                                                                       - 16*16; // time for EOF transfer
+                                       LogTrace_ISO15693(DecodeReader.output, DecodeReader.byteCount, sof_time*4, eof_time*4, NULL, true);
+                               }
                                /* And ready to receive another command. */
                                DecodeReaderReset(&DecodeReader);
                                /* And also reset the demod code, which might have been */
                                /* false-triggered by the commands from the reader. */
                                DecodeTagReset(&DecodeTag);
-                               upTo = dmaBuf;
-                               FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               ReaderIsActive = false;
+                               ExpectTagAnswer = true;
+                               // upTo = dmaBuf;
+                               // samples = 0;
+                               // FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               // continue;
+                       } else {
+                               ReaderIsActive = (DecodeReader.state >= STATE_READER_RECEIVE_DATA_1_OUT_OF_4);
                        }
-                       ReaderIsActive = (DecodeReader.state >= STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF);
                }
 
                if (!ReaderIsActive && ExpectTagAnswer) {                       // no need to try decoding tag data if the reader is currently sending or no answer expected yet
                        if (Handle15693SamplesFromTag(snoopdata >> 2, &DecodeTag)) {
-                               FpgaDisableSscDma();
-                               //Use samples as a time measurement
-                               LogTrace(DecodeTag.output, DecodeTag.len, samples, samples, NULL, false);
+                               // FpgaDisableSscDma();
+                               uint32_t eof_time = dma_start_time + samples*16 - DELAY_TAG_TO_ARM_SNOOP; // end of EOF
+                               if (DecodeTag.lastBit == SOF_PART2) {
+                                       eof_time -= 8*16; // needed 8 additional samples to confirm single SOF (iCLASS)
+                               }
+                               uint32_t sof_time = eof_time
+                                                                       - DecodeTag.len * 8 * 8 * 16 // time for byte transfers
+                                                                       - 32 * 16  // time for SOF transfer
+                                                                       - (DecodeTag.lastBit != SOF_PART2?32*16:0); // time for EOF transfer
+                               LogTrace_ISO15693(DecodeTag.output, DecodeTag.len, sof_time*4, eof_time*4, NULL, false);
                                // And ready to receive another response.
                                DecodeTagReset(&DecodeTag);
                                DecodeReaderReset(&DecodeReader);
                                ExpectTagAnswer = false;
-                               upTo = dmaBuf;
-                               FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               TagIsActive = false;
+                               // upTo = dmaBuf;
+                               // samples = 0;
+                               // FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               // continue;
+                       } else {
+                               TagIsActive = (DecodeTag.state >= STATE_TAG_RECEIVING_DATA);
                        }
-                       TagIsActive = (DecodeTag.state >= STATE_TAG_RECEIVING_DATA);
                }
 
        }
 
        FpgaDisableSscDma();
-       BigBuf_free();
-
-       LEDsoff();
 
        DbpString("Snoop statistics:");
-       Dbprintf("  ExpectTagAnswer: %d", ExpectTagAnswer);
+       Dbprintf("  ExpectTagAnswer: %d, TagIsActive: %d, ReaderIsActive: %d", ExpectTagAnswer, TagIsActive, ReaderIsActive);
        Dbprintf("  DecodeTag State: %d", DecodeTag.state);
        Dbprintf("  DecodeTag byteCnt: %d", DecodeTag.len);
+       Dbprintf("  DecodeTag posCount: %d", DecodeTag.posCount);
        Dbprintf("  DecodeReader State: %d", DecodeReader.state);
        Dbprintf("  DecodeReader byteCnt: %d", DecodeReader.byteCount);
+       Dbprintf("  DecodeReader posCount: %d", DecodeReader.posCount);
        Dbprintf("  Trace length: %d", BigBuf_get_traceLen());
+       Dbprintf("  Max behindBy: %d", max_behindBy);
 }
 
 
 // Initialize the proxmark as iso15k reader
-static void Iso15693InitReader() {
+void Iso15693InitReader() {
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       // Setup SSC
-       // FpgaSetupSsc();
 
        // Start from off (no field generated)
        LED_D_OFF();
@@ -1293,16 +1432,15 @@ static void BuildInventoryResponse(uint8_t *uid)
 //  init ... should we initialize the reader?
 //  speed ... 0 low speed, 1 hi speed
 //  *recv will contain the tag's answer
-//  return: lenght of received data
-int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t *recv, uint16_t max_recv_len, uint32_t start_time) {
+//  return: length of received data, or -1 for timeout
+int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t *recv, uint16_t max_recv_len, uint32_t start_time, uint32_t *eof_time) {
 
-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
-
-       if (init) Iso15693InitReader();
+       if (init) {
+               Iso15693InitReader();
+               StartCountSspClk();
+       }
 
-       int answerLen=0;
+       int answerLen = 0;
 
        if (!speed) {
                // low speed (1 out of 256)
@@ -1312,15 +1450,13 @@ int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t *recv,
                CodeIso15693AsReader(send, sendlen);
        }
 
-       TransmitTo15693Tag(ToSend, ToSendMax, start_time);
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
 
        // Now wait for a response
        if (recv != NULL) {
-               answerLen = GetIso15693AnswerFromTag(recv, max_recv_len, DELAY_ISO15693_VCD_TO_VICC_READER * 2);
+               answerLen = GetIso15693AnswerFromTag(recv, max_recv_len, ISO15693_READER_TIMEOUT, eof_time);
        }
 
-       LED_A_OFF();
-
        return answerLen;
 }
 
@@ -1404,9 +1540,8 @@ void SetDebugIso15693(uint32_t debug) {
 // Simulate an ISO15693 reader, perform anti-collision and then attempt to read a sector.
 // all demodulation performed in arm rather than host. - greg
 //---------------------------------------------------------------------------------------
-void ReaderIso15693(uint32_t parameter)
-{
-       LEDsoff();
+void ReaderIso15693(uint32_t parameter) {
+
        LED_A_ON();
 
        set_tracing(true);
@@ -1438,11 +1573,13 @@ void ReaderIso15693(uint32_t parameter)
 
        // Now send the IDENTIFY command
        BuildIdentifyRequest();
-       TransmitTo15693Tag(ToSend, ToSendMax, 0);
+       uint32_t start_time = 0;
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
 
        // Now wait for a response
-       answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC_READER * 2) ;
-       uint32_t start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD_READER;
+       uint32_t eof_time;
+       answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC_READER * 2, &eof_time) ;
+       start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
 
        if (answerLen >=12) // we should do a better check than this
        {
@@ -1480,9 +1617,9 @@ void ReaderIso15693(uint32_t parameter)
        if (answerLen >= 12 && DEBUG) {
                for (int i = 0; i < 32; i++) {  // sanity check, assume max 32 pages
                        BuildReadBlockRequest(TagUID, i);
-                       TransmitTo15693Tag(ToSend, ToSendMax, start_time);
-                       int answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC_READER * 2);
-                       start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD_READER;
+                       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
+                       int answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC_READER * 2, &eof_time);
+                       start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
                        if (answerLen > 0) {
                                Dbprintf("READ SINGLE BLOCK %d returned %d octets:", i, answerLen);
                                DbdecodeIso15693Answer(answerLen, answer);
@@ -1504,9 +1641,8 @@ void ReaderIso15693(uint32_t parameter)
 // Simulate an ISO15693 TAG.
 // For Inventory command: print command and send Inventory Response with given UID
 // TODO: interpret other reader commands and send appropriate response
-void SimTagIso15693(uint32_t parameter, uint8_t *uid)
-{
-       LEDsoff();
+void SimTagIso15693(uint32_t parameter, uint8_t *uid) {
+
        LED_A_ON();
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
@@ -1528,8 +1664,8 @@ void SimTagIso15693(uint32_t parameter, uint8_t *uid)
 
                if ((cmd_len >= 5) && (cmd[0] & ISO15693_REQ_INVENTORY) && (cmd[1] == ISO15693_INVENTORY)) { // TODO: check more flags
                        bool slow = !(cmd[0] & ISO15693_REQ_DATARATE_HIGH);
-                       start_time = eof_time + DELAY_ISO15693_VCD_TO_VICC_SIM - DELAY_ARM_TO_READER_SIM;
-                       TransmitTo15693Reader(ToSend, ToSendMax, start_time, slow);
+                       start_time = eof_time + DELAY_ISO15693_VCD_TO_VICC_SIM;
+                       TransmitTo15693Reader(ToSend, ToSendMax, &start_time, 0, slow);
                }
 
                Dbprintf("%d bytes read from reader:", cmd_len);
@@ -1537,7 +1673,8 @@ void SimTagIso15693(uint32_t parameter, uint8_t *uid)
        }
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LEDsoff();
+       LED_D_OFF();
+       LED_A_OFF();
 }
 
 
@@ -1545,16 +1682,12 @@ void SimTagIso15693(uint32_t parameter, uint8_t *uid)
 // (some manufactures offer a way to read the AFI, though)
 void BruteforceIso15693Afi(uint32_t speed)
 {
-       LEDsoff();
        LED_A_ON();
 
        uint8_t data[6];
        uint8_t recv[ISO15693_MAX_RESPONSE_LENGTH];
-
-       int datalen=0, recvlen=0;
-
-       Iso15693InitReader();
-       StartCountSspClk();
+       int datalen = 0, recvlen = 0;
+       uint32_t eof_time;
 
        // first without AFI
        // Tags should respond without AFI and with AFI=0 even when AFI is active
@@ -1563,8 +1696,9 @@ void BruteforceIso15693Afi(uint32_t speed)
        data[1] = ISO15693_INVENTORY;
        data[2] = 0; // mask length
        datalen = Iso15693AddCrc(data,3);
-       recvlen = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), 0);
-       uint32_t start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD_READER;
+       uint32_t start_time = GetCountSspClk();
+       recvlen = SendDataTag(data, datalen, true, speed, recv, sizeof(recv), 0, &eof_time);
+       start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
        WDT_HIT();
        if (recvlen>=12) {
                Dbprintf("NoAFI UID=%s", Iso15693sprintUID(NULL, &recv[2]));
@@ -1580,8 +1714,8 @@ void BruteforceIso15693Afi(uint32_t speed)
        for (int i = 0; i < 256; i++) {
                data[2] = i & 0xFF;
                datalen = Iso15693AddCrc(data,4);
-               recvlen = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), start_time);
-               start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD_READER;
+               recvlen = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), start_time, &eof_time);
+               start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
                WDT_HIT();
                if (recvlen >= 12) {
                        Dbprintf("AFI=%i UID=%s", i, Iso15693sprintUID(NULL, &recv[2]));
@@ -1590,40 +1724,46 @@ void BruteforceIso15693Afi(uint32_t speed)
        Dbprintf("AFI Bruteforcing done.");
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LEDsoff();
+       LED_D_OFF();
+       LED_A_OFF();
+
 }
 
 // Allows to directly send commands to the tag via the client
 void DirectTag15693Command(uint32_t datalen, uint32_t speed, uint32_t recv, uint8_t data[]) {
 
+       LED_A_ON();
+
        int recvlen = 0;
        uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
-
-       LED_A_ON();
+       uint32_t eof_time;
 
        if (DEBUG) {
                Dbprintf("SEND:");
                Dbhexdump(datalen, data, false);
        }
 
-       recvlen = SendDataTag(data, datalen, true, speed, (recv?recvbuf:NULL), sizeof(recvbuf), 0);
+       recvlen = SendDataTag(data, datalen, true, speed, (recv?recvbuf:NULL), sizeof(recvbuf), 0, &eof_time);
+
+       // for the time being, switch field off to protect rdv4.0
+       // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
 
        if (recv) {
                if (DEBUG) {
                        Dbprintf("RECV:");
-                       Dbhexdump(recvlen, recvbuf, false);
-                       DbdecodeIso15693Answer(recvlen, recvbuf);
+                       if (recvlen > 0) {
+                               Dbhexdump(recvlen, recvbuf, false);
+                               DbdecodeIso15693Answer(recvlen, recvbuf);
+                       }
                }
-
-               cmd_send(CMD_ACK, recvlen>ISO15693_MAX_RESPONSE_LENGTH?ISO15693_MAX_RESPONSE_LENGTH:recvlen, 0, 0, recvbuf, ISO15693_MAX_RESPONSE_LENGTH);
-
+               if (recvlen > ISO15693_MAX_RESPONSE_LENGTH) {
+                       recvlen = ISO15693_MAX_RESPONSE_LENGTH;
+               }
+               cmd_send(CMD_ACK, recvlen, 0, 0, recvbuf, ISO15693_MAX_RESPONSE_LENGTH);
        }
 
-       // for the time being, switch field off to protect rdv4.0
-       // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LED_D_OFF();
-
        LED_A_OFF();
 }
 
@@ -1633,54 +1773,36 @@ void DirectTag15693Command(uint32_t datalen, uint32_t speed, uint32_t recv, uint
 //-----------------------------------------------------------------------------
 
 // Set the UID to the tag (based on Iceman work).
-void SetTag15693Uid(uint8_t *uid)
-{
-       uint8_t cmd[4][9] = {0x00};
+void SetTag15693Uid(uint8_t *uid) {
+
+       LED_A_ON();
+
+       uint8_t cmd[4][9] = {
+               {0x02, 0x21, 0x3e, 0x00, 0x00, 0x00, 0x00},
+               {0x02, 0x21, 0x3f, 0x69, 0x96, 0x00, 0x00},
+               {0x02, 0x21, 0x38},
+               {0x02, 0x21, 0x39}
+       };
 
        uint16_t crc;
 
        int recvlen = 0;
        uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
-
-       LED_A_ON();
-
-       // Command 1 : 02213E00000000
-       cmd[0][0] = 0x02;
-       cmd[0][1] = 0x21;
-       cmd[0][2] = 0x3e;
-       cmd[0][3] = 0x00;
-       cmd[0][4] = 0x00;
-       cmd[0][5] = 0x00;
-       cmd[0][6] = 0x00;
-
-       // Command 2 : 02213F69960000
-       cmd[1][0] = 0x02;
-       cmd[1][1] = 0x21;
-       cmd[1][2] = 0x3f;
-       cmd[1][3] = 0x69;
-       cmd[1][4] = 0x96;
-       cmd[1][5] = 0x00;
-       cmd[1][6] = 0x00;
+       uint32_t eof_time;
 
        // Command 3 : 022138u8u7u6u5 (where uX = uid byte X)
-       cmd[2][0] = 0x02;
-       cmd[2][1] = 0x21;
-       cmd[2][2] = 0x38;
        cmd[2][3] = uid[7];
        cmd[2][4] = uid[6];
        cmd[2][5] = uid[5];
        cmd[2][6] = uid[4];
 
        // Command 4 : 022139u4u3u2u1 (where uX = uid byte X)
-       cmd[3][0] = 0x02;
-       cmd[3][1] = 0x21;
-       cmd[3][2] = 0x39;
        cmd[3][3] = uid[3];
        cmd[3][4] = uid[2];
        cmd[3][5] = uid[1];
        cmd[3][6] = uid[0];
 
-       for (int i=0; i<4; i++) {
+       for (int i = 0; i < 4; i++) {
                // Add the CRC
                crc = Iso15693Crc(cmd[i], 7);
                cmd[i][7] = crc & 0xff;
@@ -1691,19 +1813,19 @@ void SetTag15693Uid(uint8_t *uid)
                        Dbhexdump(sizeof(cmd[i]), cmd[i], false);
                }
 
-               recvlen = SendDataTag(cmd[i], sizeof(cmd[i]), true, 1, recvbuf, sizeof(recvbuf), 0);
+               recvlen = SendDataTag(cmd[i], sizeof(cmd[i]), true, 1, recvbuf, sizeof(recvbuf), 0, &eof_time);
 
                if (DEBUG) {
                        Dbprintf("RECV:");
-                       Dbhexdump(recvlen, recvbuf, false);
-                       DbdecodeIso15693Answer(recvlen, recvbuf);
+                       if (recvlen > 0) {
+                               Dbhexdump(recvlen, recvbuf, false);
+                               DbdecodeIso15693Answer(recvlen, recvbuf);
+                       }
                }
 
                cmd_send(CMD_ACK, recvlen>ISO15693_MAX_RESPONSE_LENGTH?ISO15693_MAX_RESPONSE_LENGTH:recvlen, 0, 0, recvbuf, ISO15693_MAX_RESPONSE_LENGTH);
        }
 
-       LED_D_OFF();
-
        LED_A_OFF();
 }
 
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