Fix for USB uart slowness since PR #720 (#787)

[proxmark3-svn] / armsrc / iso15693.c

diff --git a/armsrc/iso15693.c b/armsrc/iso15693.c
index 9479c3c038c875da8b5bfe98be45bfa9e8cf4de5..9dc4bf187ee60c3c56aa261bcd5672acc866eb43 100644 (file)
--- a/armsrc/iso15693.c
+++ b/armsrc/iso15693.c
@@ -47,9 +47,10 @@
 // *) add anti-collision support for inventory-commands
 // *) read security status of a block
 // *) sniffing and simulation do not support two subcarrier modes.
 // *) add anti-collision support for inventory-commands
 // *) read security status of a block
 // *) sniffing and simulation do not support two subcarrier modes.

-// *) remove or refactor code under "depricated"
+// *) remove or refactor code under "deprecated"

 // *) document all the functions
 
 // *) document all the functions
 

+#include "iso15693.h"

 
 #include "proxmark3.h"
 #include "util.h"
 
 #include "proxmark3.h"
 #include "util.h"


@@ -58,6 +59,7 @@
 #include "iso15693tools.h"
 #include "protocols.h"
 #include "cmd.h"
 #include "iso15693tools.h"
 #include "protocols.h"
 #include "cmd.h"

+#include "BigBuf.h"

 
 #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
 
 
 #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
 


@@ -68,27 +70,20 @@ static int DEBUG = 0;
 // This section basicly contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 
 // This section basicly contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 

-#define FrameSOF              Iso15693FrameSOF
-#define Logic0                Iso15693Logic0
-#define Logic1                Iso15693Logic1
-#define FrameEOF              Iso15693FrameEOF
-

 #define Crc(data,datalen)     Iso15693Crc(data,datalen)
 #define AddCrc(data,datalen)  Iso15693AddCrc(data,datalen)
 #define sprintUID(target,uid)  Iso15693sprintUID(target,uid)
 
 #define Crc(data,datalen)     Iso15693Crc(data,datalen)
 #define AddCrc(data,datalen)  Iso15693AddCrc(data,datalen)
 #define sprintUID(target,uid)  Iso15693sprintUID(target,uid)
 

-// approximate amplitude=sqrt(ci^2+cq^2) by amplitude = max(|ci|,|cq|) + 1/2*min(|ci|,|cq|)
-#define AMPLITUDE(ci, cq) (MAX(ABS(ci), ABS(cq)) + MIN(ABS(ci), ABS(cq))/2)
-

 // buffers
 // buffers

-#define ISO15693_DMA_BUFFER_SIZE     128
-#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
+#define ISO15693_DMA_BUFFER_SIZE        2048 // 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

 
 // timing. Delays in SSP_CLK ticks.
 #define DELAY_READER_TO_ARM            8
 #define DELAY_ARM_TO_READER            1
 #define DELAY_ISO15693_VCD_TO_VICC   132 // 132/423.75kHz = 311.5us from end of EOF to start of tag response
 
 // timing. Delays in SSP_CLK ticks.
 #define DELAY_READER_TO_ARM            8
 #define DELAY_ARM_TO_READER            1
 #define DELAY_ISO15693_VCD_TO_VICC   132 // 132/423.75kHz = 311.5us from end of EOF to start of tag response

+#define DELAY_ISO15693_VICC_TO_VCD  1017 // 1017/3.39MHz = 300us between end of tag response and next reader command

 
 // ---------------------------
 // Signal Processing
 
 // ---------------------------
 // Signal Processing


@@ -175,6 +170,8 @@ static void CodeIso15693AsReader(uint8_t *cmd, int n)
        for(i = 0; i < 4; i++) {
                ToSendStuffBit(1);
        }
        for(i = 0; i < 4; i++) {
                ToSendStuffBit(1);
        }

+       
+       ToSendMax++;

 }
 
 // encode data using "1 out of 256" scheme
 }
 
 // encode data using "1 out of 256" scheme


@@ -269,11 +266,13 @@ static void CodeIso15693AsTag(uint8_t *cmd, int n)
 
 
 // Transmit the command (to the tag) that was placed in cmd[].
 
 
 // Transmit the command (to the tag) that was placed in cmd[].

-static void TransmitTo15693Tag(const uint8_t *cmd, int len)
+static void TransmitTo15693Tag(const uint8_t *cmd, int len, uint32_t start_time)

 {
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
 
 {
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
 

+       while (GetCountSspClk() < start_time);
+

        LED_B_ON();
     for(int c = 0; c < len; ) {
         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
        LED_B_ON();
     for(int c = 0; c < len; ) {
         if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {


@@ -300,6 +299,7 @@ static void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start
        }
 
        while (GetCountSspClk() < (start_time & 0xfffffff8)) ;
        }
 
        while (GetCountSspClk() < (start_time & 0xfffffff8)) ;

+

        AT91C_BASE_SSC->SSC_THR = 0x00; // clear TXRDY
 
        LED_C_ON();
        AT91C_BASE_SSC->SSC_THR = 0x00; // clear TXRDY
 
        LED_C_ON();


@@ -327,7 +327,7 @@ static void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start
 
 //=============================================================================
 // An ISO 15693 decoder for tag responses (one subcarrier only).
 
 //=============================================================================
 // An ISO 15693 decoder for tag responses (one subcarrier only).

-// Uses cross correlation to identify the SOF, each bit, and EOF.
+// Uses cross correlation to identify each bit and EOF.

 // This function is called 8 times per bit (every 2 subcarrier cycles).
 // Subcarrier frequency fs is 424kHz, 1/fs = 2,36us,
 // i.e. function is called every 4,72us
 // This function is called 8 times per bit (every 2 subcarrier cycles).
 // Subcarrier frequency fs is 424kHz, 1/fs = 2,36us,
 // i.e. function is called every 4,72us


@@ -339,16 +339,15 @@ static void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t start
 //          false if we are still waiting for some more
 //=============================================================================
 
 //          false if we are still waiting for some more
 //=============================================================================
 

-#define SUBCARRIER_DETECT_THRESHOLD    2
-#define SOF_CORRELATOR_LEN (1<<5)
+#define NOISE_THRESHOLD    160      // don't try to correlate noise

 
 typedef struct DecodeTag {
        enum {
 
 typedef struct DecodeTag {
        enum {

-               STATE_TAG_UNSYNCD,
-               STATE_TAG_AWAIT_SOF_1,
-               STATE_TAG_AWAIT_SOF_2,
+               STATE_TAG_SOF_LOW,
+               STATE_TAG_SOF_HIGH,
+               STATE_TAG_SOF_HIGH_END,

                STATE_TAG_RECEIVING_DATA,
                STATE_TAG_RECEIVING_DATA,

-               STATE_TAG_AWAIT_EOF
+               STATE_TAG_EOF

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


@@ -359,84 +358,68 @@ typedef struct DecodeTag {
                SOF_PART2
        }         lastBit;
        uint16_t  shiftReg;
                SOF_PART2
        }         lastBit;
        uint16_t  shiftReg;

+       uint16_t  max_len;

        uint8_t   *output;
        int       len;
        int       sum1, sum2;
        uint8_t   *output;
        int       len;
        int       sum1, sum2;

-       uint8_t   SOF_low;
-       uint8_t   SOF_high;
-       uint8_t   SOF_last;
-       int32_t   SOF_corr;
-       int32_t   SOF_corr_prev;
-       uint8_t   SOF_correlator[SOF_CORRELATOR_LEN];

 } DecodeTag_t;
 
 } DecodeTag_t;
 

-static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTag)
+
+static int inline __attribute__((always_inline)) Handle15693SamplesFromTag(uint16_t amplitude, DecodeTag_t *DecodeTag)

 {
        switch(DecodeTag->state) {
 {
        switch(DecodeTag->state) {

-               case STATE_TAG_UNSYNCD:
-                       // initialize SOF correlator. We are looking for 12 samples low and 12 samples high.
-                       DecodeTag->SOF_low = 0;
-                       DecodeTag->SOF_high = 12;
-                       DecodeTag->SOF_last = 23;
-                       memset(DecodeTag->SOF_correlator, 0x00, DecodeTag->SOF_last + 1);
-                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
-                       DecodeTag->SOF_corr = DecodeTag->SOF_correlator[DecodeTag->SOF_last];
-                       DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;
-                       // initialize Decoder
-                       DecodeTag->posCount = 0;
-                       DecodeTag->bitCount = 0;
-                       DecodeTag->len = 0;
-                       DecodeTag->state = STATE_TAG_AWAIT_SOF_1;
-                       break;
-
-               case STATE_TAG_AWAIT_SOF_1:
-                       // calculate the correlation in real time. Look at differences only.
-                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_low++];
-                       DecodeTag->SOF_corr -= 2*DecodeTag->SOF_correlator[DecodeTag->SOF_high++];
-                       DecodeTag->SOF_last++;
-                       DecodeTag->SOF_low &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_high &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_last &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
-                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_last];
-
-                       // if correlation increases for 10 consecutive samples, we are close to maximum correlation
-                       if (DecodeTag->SOF_corr > DecodeTag->SOF_corr_prev + SUBCARRIER_DETECT_THRESHOLD) {
+               case STATE_TAG_SOF_LOW: 
+                       // waiting for 12 times low (11 times low is accepted as well)
+                       if (amplitude < NOISE_THRESHOLD) {

                                DecodeTag->posCount++;
                        } else {
                                DecodeTag->posCount++;
                        } else {

-                               DecodeTag->posCount = 0;
+                               if (DecodeTag->posCount > 10) {
+                                       DecodeTag->posCount = 1;
+                                       DecodeTag->sum1 = 0;
+                                       DecodeTag->state = STATE_TAG_SOF_HIGH;
+                               } else {
+                                       DecodeTag->posCount = 0;
+                               }

                        }
                        }

-
-                       if (DecodeTag->posCount == 10) {        // correlation increased 10 times
-                               DecodeTag->state = STATE_TAG_AWAIT_SOF_2;
+                       break;
+                       
+               case STATE_TAG_SOF_HIGH:
+                       // waiting for 10 times high. Take average over the last 8
+                       if (amplitude > NOISE_THRESHOLD) {
+                               DecodeTag->posCount++;
+                               if (DecodeTag->posCount > 2) {
+                                       DecodeTag->sum1 += amplitude; // keep track of average high value
+                               }
+                               if (DecodeTag->posCount == 10) {
+                                       DecodeTag->sum1 >>= 4;        // calculate half of average high value (8 samples)
+                                       DecodeTag->state = STATE_TAG_SOF_HIGH_END;
+                               }
+                       } else { // high phase was too short
+                               DecodeTag->posCount = 1;
+                               DecodeTag->state = STATE_TAG_SOF_LOW;

                        }
                        }

-
-                       DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;
-

                        break;
 
                        break;
 

-               case STATE_TAG_AWAIT_SOF_2:
-                       // calculate the correlation in real time. Look at differences only.
-                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_low++];
-                       DecodeTag->SOF_corr -= 2*DecodeTag->SOF_correlator[DecodeTag->SOF_high++];
-                       DecodeTag->SOF_last++;
-                       DecodeTag->SOF_low &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_high &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_last &= (SOF_CORRELATOR_LEN-1);
-                       DecodeTag->SOF_correlator[DecodeTag->SOF_last] = AMPLITUDE(ci,cq);
-                       DecodeTag->SOF_corr += DecodeTag->SOF_correlator[DecodeTag->SOF_last];
-
-                       if (DecodeTag->SOF_corr >= DecodeTag->SOF_corr_prev) { // we are looking for the maximum correlation
-                               DecodeTag->SOF_corr_prev = DecodeTag->SOF_corr;
-                       } else {
-                               DecodeTag->lastBit = SOF_PART1;  // detected 1st part of SOF
-                               DecodeTag->sum1 = DecodeTag->SOF_correlator[DecodeTag->SOF_last];
+               case STATE_TAG_SOF_HIGH_END:
+                       // waiting for a falling edge
+                       if (amplitude < DecodeTag->sum1) {   // signal drops below 50% average high: a falling edge
+                               DecodeTag->lastBit = SOF_PART1;  // detected 1st part of SOF (12 samples low and 12 samples high)
+                               DecodeTag->shiftReg = 0;
+                               DecodeTag->bitCount = 0;
+                               DecodeTag->len = 0;
+                               DecodeTag->sum1 = amplitude;

                                DecodeTag->sum2 = 0;
                                DecodeTag->posCount = 2;
                                DecodeTag->state = STATE_TAG_RECEIVING_DATA;
                                LED_C_ON();
                                DecodeTag->sum2 = 0;
                                DecodeTag->posCount = 2;
                                DecodeTag->state = STATE_TAG_RECEIVING_DATA;
                                LED_C_ON();

+                       } else {
+                               DecodeTag->posCount++;
+                               if (DecodeTag->posCount > 13) { // high phase too long
+                                       DecodeTag->posCount = 0;
+                                       DecodeTag->state = STATE_TAG_SOF_LOW;
+                                       LED_C_OFF();
+                               }

                        }
                        }

-

                        break;
 
                case STATE_TAG_RECEIVING_DATA:
                        break;
 
                case STATE_TAG_RECEIVING_DATA:


@@ -444,23 +427,27 @@ static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTa
                                DecodeTag->sum1 = 0;
                                DecodeTag->sum2 = 0;
                        }
                                DecodeTag->sum1 = 0;
                                DecodeTag->sum2 = 0;
                        }

-

                        if (DecodeTag->posCount <= 4) {
                        if (DecodeTag->posCount <= 4) {

-                               DecodeTag->sum1 += AMPLITUDE(ci, cq);
+                               DecodeTag->sum1 += amplitude;

                        } else {
                        } else {

-                               DecodeTag->sum2 += AMPLITUDE(ci, cq);
+                               DecodeTag->sum2 += amplitude;

                        }
                        }

-

                        if (DecodeTag->posCount == 8) {
                        if (DecodeTag->posCount == 8) {

-                               int16_t corr_1 = (DecodeTag->sum2 - DecodeTag->sum1) / 4;
-                               int16_t corr_0 = (DecodeTag->sum1 - DecodeTag->sum2) / 4;
-                               int16_t corr_EOF = (DecodeTag->sum1 + DecodeTag->sum2) / 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 (corr_EOF > corr_0 && corr_EOF > corr_1) {

-                                       DecodeTag->state = STATE_TAG_AWAIT_EOF;
+                                       if (DecodeTag->lastBit == LOGIC0) {  // this was already part of EOF
+                                               DecodeTag->state = STATE_TAG_EOF;
+                                       } else {
+                                               DecodeTag->posCount = 0;
+                                               DecodeTag->state = STATE_TAG_SOF_LOW;
+                                               LED_C_OFF();
+                                       }

                                } else if (corr_1 > corr_0) {
                                        // logic 1
                                        if (DecodeTag->lastBit == SOF_PART1) { // still part of SOF
                                } else if (corr_1 > corr_0) {
                                        // logic 1
                                        if (DecodeTag->lastBit == SOF_PART1) { // still part of SOF

-                                               DecodeTag->lastBit = SOF_PART2;
+                                               DecodeTag->lastBit = SOF_PART2;    // SOF completed

                                        } else {
                                                DecodeTag->lastBit = LOGIC1;
                                                DecodeTag->shiftReg >>= 1;
                                        } else {
                                                DecodeTag->lastBit = LOGIC1;
                                                DecodeTag->shiftReg >>= 1;


@@ -469,6 +456,12 @@ static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTa
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;

+                                                       if (DecodeTag->len > DecodeTag->max_len) {
+                                                               // buffer overflow, give up
+                                                               DecodeTag->posCount = 0;
+                                                               DecodeTag->state = STATE_TAG_SOF_LOW;
+                                                               LED_C_OFF();
+                                                       }

                                                        DecodeTag->bitCount = 0;
                                                        DecodeTag->shiftReg = 0;
                                                }
                                                        DecodeTag->bitCount = 0;
                                                        DecodeTag->shiftReg = 0;
                                                }


@@ -476,7 +469,8 @@ static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTa
                                } else {
                                        // logic 0
                                        if (DecodeTag->lastBit == SOF_PART1) { // incomplete SOF
                                } else {
                                        // logic 0
                                        if (DecodeTag->lastBit == SOF_PART1) { // incomplete SOF

-                                               DecodeTag->state = STATE_TAG_UNSYNCD;
+                                               DecodeTag->posCount = 0;
+                                               DecodeTag->state = STATE_TAG_SOF_LOW;

                                                LED_C_OFF();
                                        } else {
                                                DecodeTag->lastBit = LOGIC0;
                                                LED_C_OFF();
                                        } else {
                                                DecodeTag->lastBit = LOGIC0;


@@ -485,6 +479,12 @@ static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTa
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;
                                                if (DecodeTag->bitCount == 8) {
                                                        DecodeTag->output[DecodeTag->len] = DecodeTag->shiftReg;
                                                        DecodeTag->len++;

+                                                       if (DecodeTag->len > DecodeTag->max_len) {
+                                                               // buffer overflow, give up
+                                                               DecodeTag->posCount = 0;
+                                                               DecodeTag->state = STATE_TAG_SOF_LOW;
+                                                               LED_C_OFF();
+                                                       }

                                                        DecodeTag->bitCount = 0;
                                                        DecodeTag->shiftReg = 0;
                                                }
                                                        DecodeTag->bitCount = 0;
                                                        DecodeTag->shiftReg = 0;
                                                }


@@ -495,89 +495,106 @@ static int Handle15693SamplesFromTag(int8_t ci, int8_t cq, DecodeTag_t *DecodeTa
                        DecodeTag->posCount++;
                        break;
 
                        DecodeTag->posCount++;
                        break;
 

-               case STATE_TAG_AWAIT_EOF:
-                       if (DecodeTag->lastBit == LOGIC0) {  // this was already part of EOF
-                               LED_C_OFF();
-                               return true;
+               case STATE_TAG_EOF:
+                       if (DecodeTag->posCount == 1) {
+                               DecodeTag->sum1 = 0;
+                               DecodeTag->sum2 = 0;
+                       }
+                       if (DecodeTag->posCount <= 4) {
+                               DecodeTag->sum1 += amplitude;

                        } else {
                        } else {

-                               DecodeTag->state = STATE_TAG_UNSYNCD;
-                               LED_C_OFF();
+                               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) {
+                                       DecodeTag->posCount = 0;
+                                       DecodeTag->state = STATE_TAG_SOF_LOW;
+                                       LED_C_OFF();
+                               } else {
+                                       LED_C_OFF();
+                                       return true;
+                               }

                        }
                        }

+                       DecodeTag->posCount++;

                        break;
 
                        break;
 

-               default:
-                       DecodeTag->state = STATE_TAG_UNSYNCD;
-                       LED_C_OFF();
-                       break;

        }
 
        return false;
 }
 
 
        }
 
        return false;
 }
 
 

-static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data)
+static void DecodeTagInit(DecodeTag_t *DecodeTag, uint8_t *data, uint16_t max_len)

 {
 {

+       DecodeTag->posCount = 0;
+       DecodeTag->state = STATE_TAG_SOF_LOW;

        DecodeTag->output = data;
        DecodeTag->output = data;

-       DecodeTag->state = STATE_TAG_UNSYNCD;
+       DecodeTag->max_len = max_len;
+}
+
+
+static void DecodeTagReset(DecodeTag_t *DecodeTag)
+{
+       DecodeTag->posCount = 0;
+       DecodeTag->state = STATE_TAG_SOF_LOW;

 }
 
 }
 

+

 /*
  *  Receive and decode the tag response, also log to tracebuffer
  */
 /*
  *  Receive and decode the tag response, also log to tracebuffer
  */

-static int GetIso15693AnswerFromTag(uint8_t* response, int timeout)
+static int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, int timeout)

 {
 {

-       int maxBehindBy = 0;
-       int lastRxCounter, samples = 0;
-       int8_t ci, cq;
+       int samples = 0;

        bool gotFrame = false;
 
        bool gotFrame = false;
 

-       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
-
+       uint16_t *dmaBuf = (uint16_t*)BigBuf_malloc(ISO15693_DMA_BUFFER_SIZE*sizeof(uint16_t));
+       

        // the Decoder data structure
        // the Decoder data structure

-       DecodeTag_t DecodeTag;
-       DecodeTagInit(&DecodeTag, response);
+       DecodeTag_t DecodeTag = { 0 };
+       DecodeTagInit(&DecodeTag, response, max_len);

 
        // wait for last transfer to complete
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
 
        // And put the FPGA in the appropriate mode
 
        // wait for last transfer to complete
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
 
        // And put the FPGA in the appropriate mode

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

 
        // Setup and start DMA.
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
        uint16_t *upTo = dmaBuf;
 
        // Setup and start DMA.
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
        uint16_t *upTo = dmaBuf;

-       lastRxCounter = ISO15693_DMA_BUFFER_SIZE;

 
        for(;;) {
 
        for(;;) {

-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO15693_DMA_BUFFER_SIZE-1);
-               if(behindBy > maxBehindBy) {
-                       maxBehindBy = behindBy;
-               }
+               uint16_t behindBy = ((uint16_t*)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (ISO15693_DMA_BUFFER_SIZE-1);

 
 

-               if (behindBy < 1) continue;
+               if (behindBy == 0) continue;

 
 

-               ci = (int8_t)(*upTo >> 8);
-               cq = (int8_t)(*upTo & 0xff);
+               uint16_t tagdata = *upTo++;

 
 

-               upTo++;
-               lastRxCounter--;

                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(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

-                       lastRxCounter += ISO15693_DMA_BUFFER_SIZE;
+                       if(behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                               Dbprintf("About to blow circular buffer - aborted! behindBy=%d", behindBy);
+                               break;
+                       }

                }
                if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
                        AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
                }
                }
                if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
                        AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
                }

+

                samples++;
 
                samples++;
 

-               if (Handle15693SamplesFromTag(ci, cq, &DecodeTag)) {
+               if (Handle15693SamplesFromTag(tagdata, &DecodeTag)) {

                        gotFrame = true;
                        break;
                }
 
                        gotFrame = true;
                        break;
                }
 

-               if(samples > timeout && DecodeTag.state < STATE_TAG_RECEIVING_DATA) {
+               if (samples > timeout && DecodeTag.state < STATE_TAG_RECEIVING_DATA) {

                        DecodeTag.len = 0;
                        break;
                }
                        DecodeTag.len = 0;
                        break;
                }


@@ -585,11 +602,12 @@ static int GetIso15693AnswerFromTag(uint8_t* response, int timeout)
        }
 
        FpgaDisableSscDma();
        }
 
        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("max behindby = %d, samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
-                           maxBehindBy, samples, gotFrame, DecodeTag.state, DecodeTag.len, DecodeTag.bitCount, DecodeTag.posCount);
-
-       if (tracing && DecodeTag.len > 0) {
+       if (DecodeTag.len > 0) {

                LogTrace(DecodeTag.output, DecodeTag.len, 0, 0, NULL, false);
        }
 
                LogTrace(DecodeTag.output, DecodeTag.len, 0, 0, NULL, false);
        }
 


@@ -634,14 +652,32 @@ typedef struct DecodeReader {
 } DecodeReader_t;
 
 
 } DecodeReader_t;
 
 

-static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader)
+static void DecodeReaderInit(DecodeReader_t* DecodeReader, uint8_t *data, uint16_t max_len)
+{
+       DecodeReader->output = data;
+       DecodeReader->byteCountMax = max_len;
+       DecodeReader->state = STATE_READER_UNSYNCD;
+       DecodeReader->byteCount = 0;
+       DecodeReader->bitCount = 0;
+       DecodeReader->posCount = 1;
+       DecodeReader->shiftReg = 0;
+}
+
+
+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)

 {
        switch(DecodeReader->state) {
                case STATE_READER_UNSYNCD:
                        if(!bit) {
                                // we went low, so this could be the beginning of a SOF
 {
        switch(DecodeReader->state) {
                case STATE_READER_UNSYNCD:
                        if(!bit) {
                                // we went low, so this could be the beginning of a SOF

-                               DecodeReader->state = STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF;

                                DecodeReader->posCount = 1;
                                DecodeReader->posCount = 1;

+                               DecodeReader->state = STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF;

                        }
                        break;
 
                        }
                        break;
 


@@ -649,13 +685,13 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                        DecodeReader->posCount++;
                        if(bit) { // detected rising edge
                                if(DecodeReader->posCount < 4) { // rising edge too early (nominally expected at 5)
                        DecodeReader->posCount++;
                        if(bit) { // detected rising edge
                                if(DecodeReader->posCount < 4) { // rising edge too early (nominally expected at 5)

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                } else { // SOF
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF;
                                }
                        } else {
                                if(DecodeReader->posCount > 5) { // stayed low for too long
                                } else { // SOF
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF;
                                }
                        } else {
                                if(DecodeReader->posCount > 5) { // stayed low for too long

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

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


@@ -666,19 +702,19 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                        DecodeReader->posCount++;
                        if(!bit) { // detected a falling edge
                                if (DecodeReader->posCount < 20) {         // falling edge too early (nominally expected at 21 earliest)
                        DecodeReader->posCount++;
                        if(!bit) { // detected a falling edge
                                if (DecodeReader->posCount < 20) {         // falling edge too early (nominally expected at 21 earliest)

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                } else if (DecodeReader->posCount < 23) {  // SOF for 1 out of 4 coding
                                        DecodeReader->Coding = CODING_1_OUT_OF_4;
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                                } else if (DecodeReader->posCount < 28) {  // falling edge too early (nominally expected at 29 latest)
                                } else if (DecodeReader->posCount < 23) {  // SOF for 1 out of 4 coding
                                        DecodeReader->Coding = CODING_1_OUT_OF_4;
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                                } else if (DecodeReader->posCount < 28) {  // falling edge too early (nominally expected at 29 latest)

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                } else {                                 // SOF for 1 out of 4 coding
                                        DecodeReader->Coding = CODING_1_OUT_OF_256;
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                                }
                        } else {
                                if(DecodeReader->posCount > 29) { // stayed high for too long
                                } else {                                 // SOF for 1 out of 4 coding
                                        DecodeReader->Coding = CODING_1_OUT_OF_256;
                                        DecodeReader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                                }
                        } else {
                                if(DecodeReader->posCount > 29) { // stayed high for too long

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

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


@@ -690,7 +726,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                        if (bit) { // detected rising edge
                                if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
                                        if (DecodeReader->posCount < 32) { // rising edge too early (nominally expected at 33)
                        if (bit) { // detected rising edge
                                if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
                                        if (DecodeReader->posCount < 32) { // rising edge too early (nominally expected at 33)

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                        } else {
                                                DecodeReader->posCount = 1;
                                                DecodeReader->bitCount = 0;
                                        } else {
                                                DecodeReader->posCount = 1;
                                                DecodeReader->bitCount = 0;


@@ -701,7 +737,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                        }
                                } else { // CODING_1_OUT_OF_4
                                        if (DecodeReader->posCount < 24) { // rising edge too early (nominally expected at 25)
                                        }
                                } else { // CODING_1_OUT_OF_4
                                        if (DecodeReader->posCount < 24) { // rising edge too early (nominally expected at 25)

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                        } else {
                                                DecodeReader->state = STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4;
                                        }
                                        } else {
                                                DecodeReader->state = STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4;
                                        }


@@ -709,13 +745,13 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                        } else {
                                if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
                                        if (DecodeReader->posCount > 34) { // signal stayed low for too long
                        } else {
                                if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
                                        if (DecodeReader->posCount > 34) { // signal stayed low for too long

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                        } else {
                                                // do nothing, keep waiting
                                        }
                                } else { // CODING_1_OUT_OF_4
                                        if (DecodeReader->posCount > 26) { // signal stayed low for too long
                                        } else {
                                                // do nothing, keep waiting
                                        }
                                } else { // CODING_1_OUT_OF_4
                                        if (DecodeReader->posCount > 26) { // signal stayed low for too long

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

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


@@ -737,7 +773,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                        // do nothing, keep waiting
                                }
                        } else { // unexpected falling edge
                                        // do nothing, keep waiting
                                }
                        } else { // unexpected falling edge

-                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                        }
                        break;
 
                        }
                        break;
 


@@ -759,7 +795,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
                                if (corr01 > corr11 && corr01 > corr10) { // EOF
                                        LED_B_OFF(); // Finished receiving
                                int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
                                if (corr01 > corr11 && corr01 > corr10) { // EOF
                                        LED_B_OFF(); // Finished receiving

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }
                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }


@@ -773,9 +809,10 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                        if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
                                                // buffer overflow, give up
                                                LED_B_OFF();
                                        if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
                                                // buffer overflow, give up
                                                LED_B_OFF();

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                               DecodeReaderReset(DecodeReader);

                                        }
                                        DecodeReader->bitCount = 0;
                                        }
                                        DecodeReader->bitCount = 0;

+                                       DecodeReader->shiftReg = 0;

                                } else {
                                        DecodeReader->bitCount++;
                                }
                                } else {
                                        DecodeReader->bitCount++;
                                }


@@ -800,7 +837,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
                                if (corr01 > corr11 && corr01 > corr10) { // EOF
                                        LED_B_OFF(); // Finished receiving
                                int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
                                if (corr01 > corr11 && corr01 > corr10) { // EOF
                                        LED_B_OFF(); // Finished receiving

-                                       DecodeReader->state = STATE_READER_UNSYNCD;
+                                       DecodeReaderReset(DecodeReader);

                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }
                                        if (DecodeReader->byteCount != 0) {
                                                return true;
                                        }


@@ -813,7 +850,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
                                        if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
                                                // buffer overflow, give up
                                                LED_B_OFF();
                                        if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
                                                // buffer overflow, give up
                                                LED_B_OFF();

-                                               DecodeReader->state = STATE_READER_UNSYNCD;
+                                               DecodeReaderReset(DecodeReader);

                                        }
                                }
                                DecodeReader->bitCount++;
                                        }
                                }
                                DecodeReader->bitCount++;


@@ -822,7 +859,7 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
 
                default:
                        LED_B_OFF();
 
                default:
                        LED_B_OFF();

-                       DecodeReader->state = STATE_READER_UNSYNCD;
+                       DecodeReaderReset(DecodeReader);

                        break;
        }
 
                        break;
        }
 


@@ -830,17 +867,6 @@ static int Handle15693SampleFromReader(uint8_t bit, DecodeReader_t* DecodeReader
 }
 
 
 }
 
 

-static void DecodeReaderInit(uint8_t *data, uint16_t max_len, DecodeReader_t* DecodeReader)
-{
-       DecodeReader->output = data;
-       DecodeReader->byteCountMax = max_len;
-       DecodeReader->state = STATE_READER_UNSYNCD;
-       DecodeReader->byteCount = 0;
-       DecodeReader->bitCount = 0;
-       DecodeReader->shiftReg = 0;
-}
-
-

 //-----------------------------------------------------------------------------
 // Receive a command (from the reader to us, where we are the simulated tag),
 // and store it in the given buffer, up to the given maximum length. Keeps
 //-----------------------------------------------------------------------------
 // Receive a command (from the reader to us, where we are the simulated tag),
 // and store it in the given buffer, up to the given maximum length. Keeps


@@ -853,16 +879,15 @@ static void DecodeReaderInit(uint8_t *data, uint16_t max_len, DecodeReader_t* De
 
 static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eof_time)
 {
 
 static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eof_time)
 {

-       int maxBehindBy = 0;
-       int lastRxCounter, samples = 0;
+       int samples = 0;

        bool gotFrame = false;
        uint8_t b;
 
        bool gotFrame = false;
        uint8_t b;
 

-       uint8_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
+       uint8_t *dmaBuf = BigBuf_malloc(ISO15693_DMA_BUFFER_SIZE);

 
        // the decoder data structure
 
        // the decoder data structure

-       DecodeReader_t DecodeReader;
-       DecodeReaderInit(received, max_len, &DecodeReader);
+       DecodeReader_t DecodeReader = {0};
+       DecodeReaderInit(&DecodeReader, received, max_len);

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


@@ -880,21 +905,19 @@ static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint3
        // Setup and start DMA.
        FpgaSetupSscDma(dmaBuf, ISO15693_DMA_BUFFER_SIZE);
        uint8_t *upTo = dmaBuf;
        // Setup and start DMA.
        FpgaSetupSscDma(dmaBuf, ISO15693_DMA_BUFFER_SIZE);
        uint8_t *upTo = dmaBuf;

-       lastRxCounter = ISO15693_DMA_BUFFER_SIZE;

 
        for(;;) {
 
        for(;;) {

-               int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO15693_DMA_BUFFER_SIZE-1);
-               if(behindBy > maxBehindBy) {
-                       maxBehindBy = behindBy;
-               }
+               uint16_t behindBy = ((uint8_t*)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (ISO15693_DMA_BUFFER_SIZE-1);

 
 

-               if (behindBy < 1) continue;
+               if (behindBy == 0) continue;

 
                b = *upTo++;
 
                b = *upTo++;

-               lastRxCounter--;

                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(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

-                       lastRxCounter += ISO15693_DMA_BUFFER_SIZE;
+                       if(behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                               Dbprintf("About to blow circular buffer - aborted! behindBy=%d", behindBy);
+                               break;
+                       }

                }
                if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
                }
                if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
                        AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and


@@ -924,11 +947,12 @@ static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint3
 
 
        FpgaDisableSscDma();
 
 
        FpgaDisableSscDma();

+       BigBuf_free_keep_EM();
+       
+       if (DEBUG) Dbprintf("samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
+                           samples, gotFrame, DecodeReader.state, DecodeReader.byteCount, DecodeReader.bitCount, DecodeReader.posCount);

 
 

-       if (DEBUG) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Decoder: state = %d, len = %d, bitCount = %d, posCount = %d",
-                           maxBehindBy, samples, gotFrame, DecodeReader.state, DecodeReader.byteCount, DecodeReader.bitCount, DecodeReader.posCount);
-
-       if (tracing && DecodeReader.byteCount > 0) {
+       if (DecodeReader.byteCount > 0) {

                LogTrace(DecodeReader.output, DecodeReader.byteCount, 0, 0, NULL, true);
        }
 
                LogTrace(DecodeReader.output, DecodeReader.byteCount, 0, 0, NULL, true);
        }
 


@@ -936,7 +960,29 @@ static int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint3
 }
 
 
 }
 
 

-static void BuildIdentifyRequest(void);
+// Encode (into the ToSend buffers) an identify request, which is the first
+// thing that you must send to a tag to get a response.
+static void BuildIdentifyRequest(void)
+{
+       uint8_t cmd[5];
+
+       uint16_t crc;
+       // one sub-carrier, inventory, 1 slot, fast rate
+       // AFI is at bit 5 (1<<4) when doing an INVENTORY
+       cmd[0] = (1 << 2) | (1 << 5) | (1 << 1);
+       // inventory command code
+       cmd[1] = 0x01;
+       // no mask
+       cmd[2] = 0x00;
+       //Now the CRC
+       crc = Crc(cmd, 3);
+       cmd[3] = crc & 0xff;
+       cmd[4] = crc >> 8;
+
+       CodeIso15693AsReader(cmd, sizeof(cmd));
+}
+
+

 //-----------------------------------------------------------------------------
 // Start to read an ISO 15693 tag. We send an identify request, then wait
 // for the response. The response is not demodulated, just left in the buffer
 //-----------------------------------------------------------------------------
 // Start to read an ISO 15693 tag. We send an identify request, then wait
 // for the response. The response is not demodulated, just left in the buffer


@@ -977,18 +1023,12 @@ void AcquireRawAdcSamplesIso15693(void)
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
 
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
 
        FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

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

 
        for(int c = 0; c < 4000; ) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
 
        for(int c = 0; c < 4000; ) {
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {

-                       uint16_t iq = AT91C_BASE_SSC->SSC_RHR;
-                       // The samples are correlations against I and Q versions of the
-                       // tone that the tag AM-modulates. We just want power,
-                       // so abs(I) + abs(Q) is close to what we want.
-                       int8_t i = (int8_t)(iq >> 8);
-                       int8_t q = (int8_t)(iq & 0xff);
-                       uint8_t r = AMPLITUDE(i, q);
-                       dest[c++] = r;
+                       uint16_t r = AT91C_BASE_SSC->SSC_RHR;
+                       dest[c++] = r >> 5;

                }
        }
 
                }
        }
 


@@ -997,49 +1037,139 @@ void AcquireRawAdcSamplesIso15693(void)
 }
 
 
 }
 
 

-// TODO: there is no trigger condition. The 14000 samples represent a time frame of 66ms.
-// It is unlikely that we get something meaningful.
-// TODO: Currently we only record tag answers. Add tracing of reader commands.
-// TODO: would we get something at all? The carrier is switched on...
-void RecordRawAdcSamplesIso15693(void)
+void SnoopIso15693(void)

 {
 {

-       LEDsoff();
-       LED_A_ON();
+       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
+       BigBuf_free();

 
 

-       uint8_t *dest = BigBuf_get_addr();
+       clear_trace();
+       set_tracing(true);

 
 

-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       // Setup SSC
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);

 
 

-       // Start from off (no field generated)
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+       // 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;
+
+       // Count of samples received so far, so that we can include timing
+       // information in the trace buffer.
+       int samples = 0;
+
+       DecodeTag_t DecodeTag = {0};
+       uint8_t response[ISO15693_MAX_RESPONSE_LENGTH];
+       DecodeTagInit(&DecodeTag, response, sizeof(response));
+
+       DecodeReader_t DecodeReader = {0};;
+       uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH];
+       DecodeReaderInit(&DecodeReader, cmd, sizeof(cmd));

 
 

+       // Print some debug information about the buffer sizes
+       if (DEBUG) {
+               Dbprintf("Snooping buffers initialized:");
+               Dbprintf("  Trace:         %i bytes", BigBuf_max_traceLen());
+               Dbprintf("  Reader -> tag: %i bytes", ISO15693_MAX_COMMAND_LENGTH);
+               Dbprintf("  tag -> Reader: %i bytes", ISO15693_MAX_RESPONSE_LENGTH);
+               Dbprintf("  DMA:           %i bytes", ISO15693_DMA_BUFFER_SIZE * sizeof(uint16_t));
+       }
+       Dbprintf("Snoop started. Press button to stop.");
+       
+       // Signal field is off, no reader signal, no tag signal
+       LEDsoff();
+       // And put the FPGA in the appropriate mode
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_SNOOP | FPGA_HF_READER_RX_XCORR_AMPLITUDE);

        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 

-       SpinDelay(100);
+       // Setup for the DMA.
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       upTo = dmaBuf;
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);

 
 

-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       bool TagIsActive = false;
+       bool ReaderIsActive = false;
+       bool ExpectTagAnswer = false;

 
 

-       for(int c = 0; c < 14000;) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                       uint16_t iq = AT91C_BASE_SSC->SSC_RHR;
-                       // The samples are correlations against I and Q versions of the
-                       // tone that the tag AM-modulates. We just want power,
-                       // so abs(I) + abs(Q) is close to what we want.
-                       int8_t i = (int8_t)(iq >> 8);
-                       int8_t q = (int8_t)(iq & 0xff);
-                       uint8_t r = AMPLITUDE(i, q);
-                       dest[c++] = r;
+       // 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 == 0) continue;
+
+               uint16_t snoopdata = *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)) {
+                               Dbprintf("About to blow circular buffer - aborted! behindBy=%d, samples=%d", behindBy, samples);
+                               break;
+                       }
+                       if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {              // DMA Counter Register had reached 0, already rotated.
+                               AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;          // refresh the DMA Next Buffer and
+                               AT91C_BASE_PDC_SSC->PDC_RNCR = ISO15693_DMA_BUFFER_SIZE;   // DMA Next Counter registers
+                               WDT_HIT();
+                               if(BUTTON_PRESS()) {
+                                       DbpString("Snoop stopped.");
+                                       break;
+                               }
+                       }

                }
                }

+               samples++;
+               
+               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);
+                               /* 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();
+                               ExpectTagAnswer = true;
+                               LogTrace(DecodeReader.output, DecodeReader.byteCount, samples, samples, 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 = (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);
+                               // And ready to receive another response.
+                               DecodeTagReset(&DecodeTag);
+                               DecodeReaderReset(&DecodeReader);
+                               ExpectTagAnswer = false;
+                               upTo = dmaBuf;
+                               FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                       }
+                       TagIsActive = (DecodeTag.state >= STATE_TAG_RECEIVING_DATA);
+               }
+

        }
 
        }
 

-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LED_D_OFF();
-       Dbprintf("finished recording");
-       LED_A_OFF();
+       FpgaDisableSscDma();
+       BigBuf_free();
+       
+       LEDsoff();
+
+       DbpString("Snoop statistics:");
+       Dbprintf("  ExpectTagAnswer: %d", ExpectTagAnswer);
+       Dbprintf("  DecodeTag State: %d", DecodeTag.state);
+       Dbprintf("  DecodeTag byteCnt: %d", DecodeTag.len);
+       Dbprintf("  DecodeReader State: %d", DecodeReader.state);
+       Dbprintf("  DecodeReader byteCnt: %d", DecodeReader.byteCount);
+       Dbprintf("  Trace length: %d", BigBuf_get_traceLen());

 }
 
 
 }
 
 


@@ -1069,27 +1199,6 @@ static void Iso15693InitReader() {
 // This section basically contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 
 // This section basically contains transmission and receiving of bits
 ///////////////////////////////////////////////////////////////////////
 

-// Encode (into the ToSend buffers) an identify request, which is the first
-// thing that you must send to a tag to get a response.
-static void BuildIdentifyRequest(void)
-{
-       uint8_t cmd[5];
-
-       uint16_t crc;
-       // one sub-carrier, inventory, 1 slot, fast rate
-       // AFI is at bit 5 (1<<4) when doing an INVENTORY
-       cmd[0] = (1 << 2) | (1 << 5) | (1 << 1);
-       // inventory command code
-       cmd[1] = 0x01;
-       // no mask
-       cmd[2] = 0x00;
-       //Now the CRC
-       crc = Crc(cmd, 3);
-       cmd[3] = crc & 0xff;
-       cmd[4] = crc >> 8;
-
-       CodeIso15693AsReader(cmd, sizeof(cmd));
-}

 
 // uid is in transmission order (which is reverse of display order)
 static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
 
 // uid is in transmission order (which is reverse of display order)
 static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )


@@ -1097,12 +1206,11 @@ static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
        uint8_t cmd[13];
 
        uint16_t crc;
        uint8_t cmd[13];
 
        uint16_t crc;

-       // If we set the Option_Flag in this request, the VICC will respond with the secuirty status of the block
-       // followed by teh block data
-       // one sub-carrier, inventory, 1 slot, fast rate
-       cmd[0] = (1 << 6)| (1 << 5) | (1 << 1); // no SELECT bit, ADDR bit, OPTION bit
+       // If we set the Option_Flag in this request, the VICC will respond with the security status of the block
+       // followed by the block data
+       cmd[0] = ISO15693_REQ_OPTION | ISO15693_REQ_ADDRESS | ISO15693_REQ_DATARATE_HIGH; 

        // READ BLOCK command code
        // READ BLOCK command code

-       cmd[1] = 0x20;
+       cmd[1] = ISO15693_READBLOCK;

        // UID may be optionally specified here
        // 64-bit UID
        cmd[2] = uid[0];
        // UID may be optionally specified here
        // 64-bit UID
        cmd[2] = uid[0];


@@ -1114,7 +1222,7 @@ static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
        cmd[8] = uid[6];
        cmd[9] = uid[7]; // 0xe0; // always e0 (not exactly unique)
        // Block number to read
        cmd[8] = uid[6];
        cmd[9] = uid[7]; // 0xe0; // always e0 (not exactly unique)
        // Block number to read

-       cmd[10] = blockNumber;//0x00;
+       cmd[10] = blockNumber;

        //Now the CRC
        crc = Crc(cmd, 11); // the crc needs to be calculated over 11 bytes
        cmd[11] = crc & 0xff;
        //Now the CRC
        crc = Crc(cmd, 11); // the crc needs to be calculated over 11 bytes
        cmd[11] = crc & 0xff;


@@ -1153,10 +1261,9 @@ static void BuildInventoryResponse(uint8_t *uid)
 // Universal Method for sending to and recv bytes from a tag
 //     init ... should we initialize the reader?
 //     speed ... 0 low speed, 1 hi speed
 // Universal Method for sending to and recv bytes from a tag
 //     init ... should we initialize the reader?
 //     speed ... 0 low speed, 1 hi speed

-//     **recv will return you a pointer to the received data
-//     If you do not need the answer use NULL for *recv[]
+//     *recv will contain the tag's answer

 //     return: lenght of received data
 //     return: lenght of received data

-int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t **recv) {
+int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t *recv, uint16_t max_recv_len, uint32_t start_time) {

 
        LED_A_ON();
        LED_B_OFF();
 
        LED_A_ON();
        LED_B_OFF();


@@ -1165,8 +1272,6 @@ int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t **recv
        if (init) Iso15693InitReader();
 
        int answerLen=0;
        if (init) Iso15693InitReader();
 
        int answerLen=0;

-       uint8_t *answer = BigBuf_get_addr() + 4000;
-       if (recv != NULL) memset(answer, 0, 100);

 
        if (!speed) {
                // low speed (1 out of 256)
 
        if (!speed) {
                // low speed (1 out of 256)


@@ -1176,11 +1281,11 @@ int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t **recv
                CodeIso15693AsReader(send, sendlen);
        }
 
                CodeIso15693AsReader(send, sendlen);
        }
 

-       TransmitTo15693Tag(ToSend,ToSendMax);
+       TransmitTo15693Tag(ToSend, ToSendMax, start_time);
+

        // Now wait for a response
        // Now wait for a response

-       if (recv!=NULL) {
-               answerLen = GetIso15693AnswerFromTag(answer, 100);
-               *recv=answer;
+       if (recv != NULL) {
+               answerLen = GetIso15693AnswerFromTag(recv, max_recv_len, DELAY_ISO15693_VCD_TO_VICC * 2);

        }
 
        LED_A_OFF();
        }
 
        LED_A_OFF();


@@ -1199,46 +1304,46 @@ void DbdecodeIso15693Answer(int len, uint8_t *d) {
        char status[DBD15STATLEN+1]={0};
        uint16_t crc;
 
        char status[DBD15STATLEN+1]={0};
        uint16_t crc;
 

-       if (len>3) {
-               if (d[0]&(1<<3))
-                       strncat(status,"ProtExt ",DBD15STATLEN);
-               if (d[0]&1) {
+       if (len > 3) {
+               if (d[0] & ISO15693_RES_EXT)
+                       strncat(status,"ProtExt ", DBD15STATLEN);
+               if (d[0] & ISO15693_RES_ERROR) {

                        // error
                        // error

-                       strncat(status,"Error ",DBD15STATLEN);
+                       strncat(status,"Error ", DBD15STATLEN);

                        switch (d[1]) {
                                case 0x01:
                        switch (d[1]) {
                                case 0x01:

-                                       strncat(status,"01:notSupp",DBD15STATLEN);
+                                       strncat(status,"01:notSupp", DBD15STATLEN);

                                        break;
                                case 0x02:
                                        break;
                                case 0x02:

-                                       strncat(status,"02:notRecog",DBD15STATLEN);
+                                       strncat(status,"02:notRecog", DBD15STATLEN);

                                        break;
                                case 0x03:
                                        break;
                                case 0x03:

-                                       strncat(status,"03:optNotSupp",DBD15STATLEN);
+                                       strncat(status,"03:optNotSupp", DBD15STATLEN);

                                        break;
                                case 0x0f:
                                        break;
                                case 0x0f:

-                                       strncat(status,"0f:noInfo",DBD15STATLEN);
+                                       strncat(status,"0f:noInfo", DBD15STATLEN);

                                        break;
                                case 0x10:
                                        break;
                                case 0x10:

-                                       strncat(status,"10:dontExist",DBD15STATLEN);
+                                       strncat(status,"10:doesn'tExist", DBD15STATLEN);

                                        break;
                                case 0x11:
                                        break;
                                case 0x11:

-                                       strncat(status,"11:lockAgain",DBD15STATLEN);
+                                       strncat(status,"11:lockAgain", DBD15STATLEN);

                                        break;
                                case 0x12:
                                        break;
                                case 0x12:

-                                       strncat(status,"12:locked",DBD15STATLEN);
+                                       strncat(status,"12:locked", DBD15STATLEN);

                                        break;
                                case 0x13:
                                        break;
                                case 0x13:

-                                       strncat(status,"13:progErr",DBD15STATLEN);
+                                       strncat(status,"13:progErr", DBD15STATLEN);

                                        break;
                                case 0x14:
                                        break;
                                case 0x14:

-                                       strncat(status,"14:lockErr",DBD15STATLEN);
+                                       strncat(status,"14:lockErr", DBD15STATLEN);

                                        break;
                                default:
                                        break;
                                default:

-                                       strncat(status,"unknownErr",DBD15STATLEN);
+                                       strncat(status,"unknownErr", DBD15STATLEN);

                        }
                        }

-                       strncat(status," ",DBD15STATLEN);
+                       strncat(status," ", DBD15STATLEN);

                } else {
                } else {

-                       strncat(status,"NoErr ",DBD15STATLEN);
+                       strncat(status,"NoErr ", DBD15STATLEN);

                }
 
                crc=Crc(d,len-2);
                }
 
                crc=Crc(d,len-2);


@@ -1263,6 +1368,7 @@ void SetDebugIso15693(uint32_t debug) {
        return;
 }
 
        return;
 }
 

+

 //-----------------------------------------------------------------------------
 // Simulate an ISO15693 reader, perform anti-collision and then attempt to read a sector
 // all demodulation performed in arm rather than host. - greg
 //-----------------------------------------------------------------------------
 // Simulate an ISO15693 reader, perform anti-collision and then attempt to read a sector
 // all demodulation performed in arm rather than host. - greg


@@ -1272,13 +1378,14 @@ void ReaderIso15693(uint32_t parameter)
        LEDsoff();
        LED_A_ON();
 
        LEDsoff();
        LED_A_ON();
 

-       int answerLen1 = 0;
+       set_tracing(true);
+       
+       int answerLen = 0;

        uint8_t TagUID[8] = {0x00};
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 
        uint8_t TagUID[8] = {0x00};
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 

-       uint8_t *answer1 = BigBuf_get_addr() + 4000;
-       memset(answer1, 0x00, 200);
+       uint8_t answer[ISO15693_MAX_RESPONSE_LENGTH];

 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        // Setup SSC
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
        // Setup SSC


@@ -1292,37 +1399,39 @@ void ReaderIso15693(uint32_t parameter)
        LED_D_ON();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(200);
        LED_D_ON();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
        SpinDelay(200);

+       StartCountSspClk();
+

 
        // FIRST WE RUN AN INVENTORY TO GET THE TAG UID
        // THIS MEANS WE CAN PRE-BUILD REQUESTS TO SAVE CPU TIME
 
        // Now send the IDENTIFY command
        BuildIdentifyRequest();
 
        // FIRST WE RUN AN INVENTORY TO GET THE TAG UID
        // THIS MEANS WE CAN PRE-BUILD REQUESTS TO SAVE CPU TIME
 
        // Now send the IDENTIFY command
        BuildIdentifyRequest();

-
-       TransmitTo15693Tag(ToSend,ToSendMax);
+       TransmitTo15693Tag(ToSend, ToSendMax, 0);

 
        // Now wait for a response
 
        // Now wait for a response

-       answerLen1 = GetIso15693AnswerFromTag(answer1, 100) ;
+       answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC * 2) ;
+       uint32_t start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD;

 
 

-       if (answerLen1 >=12) // we should do a better check than this
+       if (answerLen >=12) // we should do a better check than this

        {
        {

-               TagUID[0] = answer1[2];
-               TagUID[1] = answer1[3];
-               TagUID[2] = answer1[4];
-               TagUID[3] = answer1[5];
-               TagUID[4] = answer1[6];
-               TagUID[5] = answer1[7];
-               TagUID[6] = answer1[8]; // IC Manufacturer code
-               TagUID[7] = answer1[9]; // always E0
+               TagUID[0] = answer[2];
+               TagUID[1] = answer[3];
+               TagUID[2] = answer[4];
+               TagUID[3] = answer[5];
+               TagUID[4] = answer[6];
+               TagUID[5] = answer[7];
+               TagUID[6] = answer[8]; // IC Manufacturer code
+               TagUID[7] = answer[9]; // always E0

 
        }
 
 
        }
 

-       Dbprintf("%d octets read from IDENTIFY request:", answerLen1);
-       DbdecodeIso15693Answer(answerLen1, answer1);
-       Dbhexdump(answerLen1, answer1, false);
+       Dbprintf("%d octets read from IDENTIFY request:", answerLen);
+       DbdecodeIso15693Answer(answerLen, answer);
+       Dbhexdump(answerLen, answer, false);

 
        // UID is reverse
 
        // UID is reverse

-       if (answerLen1 >= 12)
+       if (answerLen >= 12)

                Dbprintf("UID = %02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
                        TagUID[7],TagUID[6],TagUID[5],TagUID[4],
                        TagUID[3],TagUID[2],TagUID[1],TagUID[0]);
                Dbprintf("UID = %02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
                        TagUID[7],TagUID[6],TagUID[5],TagUID[4],
                        TagUID[3],TagUID[2],TagUID[1],TagUID[0]);


@@ -1337,18 +1446,21 @@ void ReaderIso15693(uint32_t parameter)
        // Dbhexdump(answerLen3,answer3,true);
 
        // read all pages
        // Dbhexdump(answerLen3,answer3,true);
 
        // read all pages

-       if (answerLen1 >= 12 && DEBUG) {
-               uint8_t *answer2 = BigBuf_get_addr() + 4100;
+       if (answerLen >= 12 && DEBUG) {
+
+               // debugptr = BigBuf_get_addr();
+

                int i = 0;
                while (i < 32) {  // sanity check, assume max 32 pages
                        BuildReadBlockRequest(TagUID, i);
                int i = 0;
                while (i < 32) {  // sanity check, assume max 32 pages
                        BuildReadBlockRequest(TagUID, i);

-                       TransmitTo15693Tag(ToSend, ToSendMax);
-                       int answerLen2 = GetIso15693AnswerFromTag(answer2, 100);
-                       if (answerLen2 > 0) {
-                               Dbprintf("READ SINGLE BLOCK %d returned %d octets:", i, answerLen2);
-                               DbdecodeIso15693Answer(answerLen2, answer2);
-                               Dbhexdump(answerLen2, answer2, false);
-                               if ( *((uint32_t*) answer2) == 0x07160101 ) break; // exit on NoPageErr
+                       TransmitTo15693Tag(ToSend, ToSendMax, start_time);
+                       int answerLen = GetIso15693AnswerFromTag(answer, sizeof(answer), DELAY_ISO15693_VCD_TO_VICC * 2);
+                       start_time = GetCountSspClk() + DELAY_ISO15693_VICC_TO_VCD;
+                       if (answerLen > 0) {
+                               Dbprintf("READ SINGLE BLOCK %d returned %d octets:", i, answerLen);
+                               DbdecodeIso15693Answer(answerLen, answer);
+                               Dbhexdump(answerLen, answer, false);
+                               if ( *((uint32_t*) answer) == 0x07160101 ) break; // exit on NoPageErr

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


@@ -1409,12 +1521,14 @@ void BruteforceIso15693Afi(uint32_t speed)
        LEDsoff();
        LED_A_ON();
 
        LEDsoff();
        LED_A_ON();
 

-       uint8_t data[20];
-       uint8_t *recv=data;
+       uint8_t data[6];
+       uint8_t recv[ISO15693_MAX_RESPONSE_LENGTH];
+       

        int datalen=0, recvlen=0;
 
        Iso15693InitReader();
        int datalen=0, recvlen=0;
 
        Iso15693InitReader();

-
+       StartCountSspClk();
+       

        // first without AFI
        // Tags should respond without AFI and with AFI=0 even when AFI is active
 
        // first without AFI
        // Tags should respond without AFI and with AFI=0 even when AFI is active
 


@@ -1422,10 +1536,11 @@ void BruteforceIso15693Afi(uint32_t speed)
        data[1] = ISO15693_INVENTORY;
        data[2] = 0; // mask length
        datalen = AddCrc(data,3);
        data[1] = ISO15693_INVENTORY;
        data[2] = 0; // mask length
        datalen = AddCrc(data,3);

-       recvlen = SendDataTag(data, datalen, false, speed, &recv);
+       recvlen = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), 0);
+       uint32_t start_time = GetCountSspClk() + DELAY_ISO15693_VCD_TO_VICC;

        WDT_HIT();
        if (recvlen>=12) {
        WDT_HIT();
        if (recvlen>=12) {

-               Dbprintf("NoAFI UID=%s",sprintUID(NULL,&recv[2]));
+               Dbprintf("NoAFI UID=%s", sprintUID(NULL, &recv[2]));

        }
 
        // now with AFI
        }
 
        // now with AFI


@@ -1435,13 +1550,14 @@ void BruteforceIso15693Afi(uint32_t speed)
        data[2] = 0; // AFI
        data[3] = 0; // mask length
 
        data[2] = 0; // AFI
        data[3] = 0; // mask length
 

-       for (int i=0;i<256;i++) {
-               data[2]=i & 0xFF;
-               datalen=AddCrc(data,4);
-               recvlen=SendDataTag(data, datalen, false, speed, &recv);
+       for (int i = 0; i < 256; i++) {
+               data[2] = i & 0xFF;
+               datalen = AddCrc(data,4);
+               recvlen = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), start_time);
+               start_time = GetCountSspClk() + DELAY_ISO15693_VCD_TO_VICC;

                WDT_HIT();
                WDT_HIT();

-               if (recvlen>=12) {
-                       Dbprintf("AFI=%i UID=%s", i, sprintUID(NULL,&recv[2]));
+               if (recvlen >= 12) {
+                       Dbprintf("AFI=%i UID=%s", i, sprintUID(NULL, &recv[2]));

                }
        }
        Dbprintf("AFI Bruteforcing done.");
                }
        }
        Dbprintf("AFI Bruteforcing done.");


@@ -1453,26 +1569,27 @@ void BruteforceIso15693Afi(uint32_t speed)
 // 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[]) {
 
 // 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[]) {
 

-       int recvlen=0;
-       uint8_t *recvbuf = BigBuf_get_addr();
+       int recvlen = 0;
+       uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];

 
        LED_A_ON();
 
        if (DEBUG) {
 
        LED_A_ON();
 
        if (DEBUG) {

-               Dbprintf("SEND");
+               Dbprintf("SEND:");

                Dbhexdump(datalen, data, false);
        }
 
                Dbhexdump(datalen, data, false);
        }
 

-       recvlen = SendDataTag(data, datalen, true, speed, (recv?&recvbuf:NULL));
+       recvlen = SendDataTag(data, datalen, true, speed, (recv?recvbuf:NULL), sizeof(recvbuf), 0);

 
        if (recv) {
 
        if (recv) {

-               cmd_send(CMD_ACK, recvlen>48?48:recvlen, 0, 0, recvbuf, 48);
-

                if (DEBUG) {
                if (DEBUG) {

-                       Dbprintf("RECV");
-                       DbdecodeIso15693Answer(recvlen,recvbuf);
+                       Dbprintf("RECV:");

                        Dbhexdump(recvlen, recvbuf, false);
                        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);
+

        }
 
        // for the time being, switch field off to protect rdv4.0
        }
 
        // for the time being, switch field off to protect rdv4.0