Add string.h

[proxmark3-svn] / armsrc / iso15693.c
diff --git a/armsrc/iso15693.c b/armsrc/iso15693.c

index 9b0ab29ecf4e93a43f9080a83bcc97047e8563f9..f16698bbb901f66120d67a528f6a077fad2118bc 100644 (file)
--- a/armsrc/iso15693.c
+++ b/armsrc/iso15693.c
@@ -2,271 +2,363 @@
  // Jonathan Westhues, split Nov 2006
  // Modified by Greg Jones, Jan 2009
  // Modified by Adrian Dabrowski "atrox", Mar-Sept 2010,Oct 2011
  // Jonathan Westhues, split Nov 2006
  // Modified by Greg Jones, Jan 2009
  // Modified by Adrian Dabrowski "atrox", Mar-Sept 2010,Oct 2011
+// Modified by piwi, Oct 2018
  //
  // This code is licensed to you under the terms of the GNU GPL, version 2 or,
  // at your option, any later version. See the LICENSE.txt file for the text of
  // the license.
  //-----------------------------------------------------------------------------
  // Routines to support ISO 15693. This includes both the reader software and
  //
  // This code is licensed to you under the terms of the GNU GPL, version 2 or,
  // at your option, any later version. See the LICENSE.txt file for the text of
  // the license.
  //-----------------------------------------------------------------------------
  // Routines to support ISO 15693. This includes both the reader software and
-// the `fake tag' modes, but at the moment I've implemented only the reader
-// stuff, and that barely.
-// Modified to perform modulation onboard in arm rather than on PC
-// Also added additional reader commands (SELECT, READ etc.)
+// the `fake tag' modes.
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
-// The ISO 15693 describes two transmission modes from reader to tag, and 4 
-// transmission modes from tag to reader. As of Mar 2010 this code only 
-// supports one of each: "1of4" mode from reader to tag, and the highspeed 
-// variant with one subcarrier from card to reader.
-// As long, as the card fully support ISO 15693 this is no problem, since the 
-// reader chooses both data rates, but some non-standard tags do not. Further for 
-// the simulation to work, we will need to support all data rates.
+
+// The ISO 15693 describes two transmission modes from reader to tag, and four
+// transmission modes from tag to reader. As of Oct 2018 this code supports
+// both reader modes and the high speed variant with one subcarrier from card to reader.
+// As long as the card fully support ISO 15693 this is no problem, since the
+// reader chooses both data rates, but some non-standard tags do not.
+// For card simulation, the code supports both high and low speed modes with one subcarrier.
  //
  // VCD (reader) -> VICC (tag)
  // 1 out of 256:
  //
  // VCD (reader) -> VICC (tag)
  // 1 out of 256:
-//     data rate: 1,66 kbit/s (fc/8192) 
-//     used for long range
+//  data rate: 1,66 kbit/s (fc/8192)
+//  used for long range
  // 1 out of 4:
  // 1 out of 4:
-//     data rate: 26,48 kbit/s (fc/512)
-//     used for short range, high speed
-// 
+//  data rate: 26,48 kbit/s (fc/512)
+//  used for short range, high speed
+//
  // VICC (tag) -> VCD (reader)
  // Modulation:
  // VICC (tag) -> VCD (reader)
  // Modulation:
-//             ASK / one subcarrier (423,75 khz)
-//             FSK / two subcarriers (423,75 khz && 484,28 khz)
+//      ASK / one subcarrier (423,75 khz)
+//      FSK / two subcarriers (423,75 khz && 484,28 khz)
  // Data Rates / Modes:
  // Data Rates / Modes:
-//     low ASK: 6,62 kbit/s
-//     low FSK: 6.67 kbit/s
-//     high ASK: 26,48 kbit/s
-//     high FSK: 26,69 kbit/s
+//  low ASK: 6,62 kbit/s
+//  low FSK: 6.67 kbit/s
+//  high ASK: 26,48 kbit/s
+//  high FSK: 26,69 kbit/s
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
-// added "1 out of 256" mode (for VCD->PICC) - atrox 20100911
  
  
  // Random Remarks:
  // *) UID is always used "transmission order" (LSB), which is reverse to display order
  
  // TODO / BUGS / ISSUES:
  
  
  // Random Remarks:
  // *) UID is always used "transmission order" (LSB), which is reverse to display order
  
  // TODO / BUGS / ISSUES:
-// *) writing to tags takes longer: we miss the answer from the tag in most cases
-//    -> tweak the read-timeout times
-// *) signal decoding from the card is still a bit shaky. 
-// *) signal decoding is unable to detect collissions.
-// *) add anti-collission support for inventory-commands 
+// *) signal decoding is unable to detect collisions.
+// *) add anti-collision support for inventory-commands
  // *) read security status of a block
  // *) read security status of a block
-// *) sniffing and simulation do only support one transmission mode. need to support 
-//             all 8 transmission combinations
-//     *) remove or refactor code under "depricated"
+// *) sniffing and simulation do not support two subcarrier modes.
+// *) remove or refactor code under "deprecated"
  // *) document all the functions
  
  // *) document all the functions
  
+#include "iso15693.h"
  
  #include "proxmark3.h"
  #include "util.h"
  #include "apps.h"
  #include "string.h"
  #include "iso15693tools.h"
  
  #include "proxmark3.h"
  #include "util.h"
  #include "apps.h"
  #include "string.h"
  #include "iso15693tools.h"
-#include "cmd.h"
+#include "protocols.h"
+#include "usb_cdc.h"
+#include "BigBuf.h"
+#include "fpgaloader.h"
  
  #define arraylen(x) (sizeof(x)/sizeof((x)[0]))
  
  
  #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
+
+// times in samples @ 212kHz when acting as reader
+//#define ISO15693_READER_TIMEOUT              80 // 80/212kHz = 378us, nominal t1_max=313,9us
+#define ISO15693_READER_TIMEOUT             330 // 330/212kHz = 1558us, should be even enough for iClass tags responding to ACTALL
+#define ISO15693_READER_TIMEOUT_WRITE      4700 // 4700/212kHz = 22ms, nominal 20ms
+
+
  static int DEBUG = 0;
  
  static int DEBUG = 0;
  
+
  ///////////////////////////////////////////////////////////////////////
  // ISO 15693 Part 2 - Air Interface
  ///////////////////////////////////////////////////////////////////////
  // ISO 15693 Part 2 - Air Interface
-// This section basicly contains transmission and receiving of bits
+// This section basically contains transmission and receiving of bits
  ///////////////////////////////////////////////////////////////////////
  
  ///////////////////////////////////////////////////////////////////////
  
-#define FrameSOF              Iso15693FrameSOF
-#define Logic0                Iso15693Logic0
-#define Logic1                Iso15693Logic1
-#define FrameEOF              Iso15693FrameEOF
+// buffers
+#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
  
  
-#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) 
-#define AMPLITUDE(ci, cq) (MAX(ABS(ci), ABS(cq)) + MIN(ABS(ci), ABS(cq))/2)
+// 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);
+}
  
  
-// DMA buffer
-#define ISO15693_DMA_BUFFER_SIZE 128
  
  // ---------------------------
  
  // ---------------------------
-// Signal Processing 
+// Signal Processing
  // ---------------------------
  
  // prepare data using "1 out of 4" code for later transmission
  // ---------------------------
  
  // prepare data using "1 out of 4" code for later transmission
-// resulting data rate is 26,48 kbit/s (fc/512)
+// resulting data rate is 26.48 kbit/s (fc/512)
  // cmd ... data
  // n ... length of data
  // 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();
  
  
         ToSendReset();
  
-       // Give it a bit of slack at the beginning
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
-       }
-
         // SOF for 1of4
         // 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:
                         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:
                                         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:
                                         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:
                                         break;
                                 case 3:
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(1);
-                                       ToSendStuffBit(0);
+                                       ToSend[++ToSendMax] = 0x01; //00000001
                                         break;
                         }
                 }
         }
                                         break;
                         }
                 }
         }
+
         // EOF
         // 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++;
  }
  
         ToSendMax++;
  }
  
+
+// Encode EOF only
+static void CodeIso15693AsReaderEOF() {
+       ToSendReset();
+       ToSend[++ToSendMax] = 0x20;
+       ToSendMax++;
+}
+
+
  // encode data using "1 out of 256" scheme
  // encode data using "1 out of 256" scheme
-// data rate is 1,66 kbit/s (fc/8192) 
+// data rate is 1,66 kbit/s (fc/8192)
  // is designed for more robust communication over longer distances
  static void CodeIso15693AsReader256(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();
  
         ToSendReset();
  
-       // Give it a bit of slack at the beginning
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
-       }
-
         // SOF for 1of256
         // 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);
                                 ToSendStuffBit(0);
-                       } else {
                                 ToSendStuffBit(1);
                                 ToSendStuffBit(1);
-                               ToSendStuffBit(1);
-                       }                       
-               }       
+                       } else {
+                               ToSendStuffBit(0);
+                               ToSendStuffBit(0);
+                       }
+               }
         }
         }
+
         // EOF
         // EOF
-       ToSendStuffBit(1);
-       ToSendStuffBit(1);
-       ToSendStuffBit(0);
-       ToSendStuffBit(1);
-
-       // And slack at the end, too.
-       for(i = 0; i < 24; i++) {
-               ToSendStuffBit(1);
+       ToSend[++ToSendMax] = 0x20; //0010 + 0000 padding
+
+       ToSendMax++;
+}
+
+
+// static uint8_t encode4Bits(const uint8_t b) {
+       // uint8_t c = b & 0xF;
+       // // OTA, the least significant bits first
+       // //         The columns are
+       // //               1 - Bit value to send
+       // //               2 - Reversed (big-endian)
+       // //               3 - Manchester Encoded
+       // //               4 - Hex values
+
+       // switch(c){
+       // //                          1       2         3         4
+         // case 15: return 0x55; // 1111 -> 1111 -> 01010101 -> 0x55
+         // case 14: return 0x95; // 1110 -> 0111 -> 10010101 -> 0x95
+         // case 13: return 0x65; // 1101 -> 1011 -> 01100101 -> 0x65
+         // case 12: return 0xa5; // 1100 -> 0011 -> 10100101 -> 0xa5
+         // case 11: return 0x59; // 1011 -> 1101 -> 01011001 -> 0x59
+         // case 10: return 0x99; // 1010 -> 0101 -> 10011001 -> 0x99
+         // case 9:  return 0x69; // 1001 -> 1001 -> 01101001 -> 0x69
+         // case 8:  return 0xa9; // 1000 -> 0001 -> 10101001 -> 0xa9
+         // case 7:  return 0x56; // 0111 -> 1110 -> 01010110 -> 0x56
+         // case 6:  return 0x96; // 0110 -> 0110 -> 10010110 -> 0x96
+         // case 5:  return 0x66; // 0101 -> 1010 -> 01100110 -> 0x66
+         // case 4:  return 0xa6; // 0100 -> 0010 -> 10100110 -> 0xa6
+         // case 3:  return 0x5a; // 0011 -> 1100 -> 01011010 -> 0x5a
+         // case 2:  return 0x9a; // 0010 -> 0100 -> 10011010 -> 0x9a
+         // case 1:  return 0x6a; // 0001 -> 1000 -> 01101010 -> 0x6a
+         // default: return 0xaa; // 0000 -> 0000 -> 10101010 -> 0xaa
+
+       // }
+// }
+
+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;
+        * * An unmodulated time of 56.64 us
+        * * 24 pulses of 423.75 kHz (fc/32)
+        * * A logic 1, which starts with an unmodulated time of 18.88us
+        *   followed by 8 pulses of 423.75kHz (fc/32)
+        *
+        * EOF comprises 3 parts:
+        * - A logic 0 (which starts with 8 pulses of fc/32 followed by an unmodulated
+        *   time of 18.88us.
+        * - 24 pulses of fc/32
+        * - An unmodulated time of 56.64 us
+        *
+        * A logic 0 starts with 8 pulses of fc/32
+        * followed by an unmodulated time of 256/fc (~18,88us).
+        *
+        * A logic 0 starts with unmodulated time of 256/fc (~18,88us) followed by
+        * 8 pulses of fc/32 (also 18.88us)
+        *
+        * A bit here becomes 8 pulses of fc/32. Therefore:
+        * The SOF can be written as 00011101 = 0x1D
+        * The EOF can be written as 10111000 = 0xb8
+        * A logic 1 is 01
+        * A logic 0 is 10
+        *
+        * */
+
+       ToSendReset();
+
+       // SOF
+       ToSend[++ToSendMax] = 0x1D;  // 00011101
+
+       // data
+       for (int i = 0; i < len; i++) {
+               ToSend[++ToSendMax] = encode_4bits[cmd[i] & 0xF];
+               ToSend[++ToSendMax] = encode_4bits[cmd[i] >> 4];
         }
         }
+
+       // EOF
+       ToSend[++ToSendMax] = 0xB8; // 10111000
+
+       ToSendMax++;
  }
  
  
  // 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)
-{
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
+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);
+
+       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();
  
         LED_B_ON();
-    for(int c = 0; c < len; ) {
-        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-            AT91C_BASE_SSC->SSC_THR = ~cmd[c];
-            c++;
-        }
-        WDT_HIT();
-    }
+       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) ? 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();
         LED_B_OFF();
+
+       *start_time = *start_time + DELAY_ARM_TO_TAG;
  }
  
  }
  
+
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
-// Transmit the command (to the reader) that was placed in cmd[].
+// Transmit the tag response (to the reader) that was placed in cmd[].
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
-static void TransmitTo15693Reader(const uint8_t *cmd, int len)
-{
+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);
  
         FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K);
  
+       uint32_t modulation_start_time = *start_time - DELAY_ARM_TO_READER + 3 * 8;  // no need to transfer the unmodulated start of SOF
+
+       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();
         LED_C_ON();
-    for(int c = 0; c < len; ) {
-        if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-            AT91C_BASE_SSC->SSC_THR = cmd[c];
-            c++;
-        }
-        WDT_HIT();
-    }
+       uint8_t bits_to_shift = 0x00;
+       uint8_t bits_to_send = 0x00;
+       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) {
+                                       bits_to_send = bits_to_shift << (8 - shift_delay) | cmd_bits >> shift_delay;
+                                       AT91C_BASE_SSC->SSC_THR = bits_to_send;
+                                       bits_to_shift = cmd_bits;
+                                       j++;
+                               }
+                       }
+               }
+               WDT_HIT();
+       }
+       // send the remaining bits, padded with 0:
+       bits_to_send = bits_to_shift << (8 - shift_delay);
+       for ( ; ; ) {
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                       AT91C_BASE_SSC->SSC_THR = bits_to_send;
+                       break;
+               }
+       }
         LED_C_OFF();
  }
  
  
  //=============================================================================
         LED_C_OFF();
  }
  
  
  //=============================================================================
-// An ISO 15693 demodulator (one subcarrier only). Uses cross correlation to 
-// identify the SOF, each bit, and EOF.
+// An ISO 15693 decoder for tag responses (one subcarrier only).
+// Uses cross correlation to identify each bit and EOF.
  // This function is called 8 times per bit (every 2 subcarrier cycles).
  // This function is called 8 times per bit (every 2 subcarrier cycles).
-// Subcarrier frequency fs is 424kHz, 1/fs = 2,36us, 
+// Subcarrier frequency fs is 424kHz, 1/fs = 2,36us,
  // i.e. function is called every 4,72us
  // LED handling:
  //    LED C -> ON once we have received the SOF and are expecting the rest.
  // i.e. function is called every 4,72us
  // LED handling:
  //    LED C -> ON once we have received the SOF and are expecting the rest.
@@ -276,16 +368,18 @@ static void TransmitTo15693Reader(const uint8_t *cmd, int len)
  //          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          80                   // don't try to correlate noise
+#define MAX_PREVIOUS_AMPLITUDE   (-1 - NOISE_THRESHOLD)
  
  
-typedef struct Demod {
+typedef struct DecodeTag {
         enum {
         enum {
-               DEMOD_UNSYNCD,
-               DEMOD_AWAIT_SOF_1,
-               DEMOD_AWAIT_SOF_2,
-               DEMOD_RECEIVING_DATA,
-               DEMOD_AWAIT_EOF
+               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_TAIL
         }         state;
         int       bitCount;
         int       posCount;
         }         state;
         int       bitCount;
         int       posCount;
@@ -296,155 +390,232 @@ typedef struct Demod {
                 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];
-} Demod_t;
-
-static RAMFUNC int Handle15693SamplesDemod(int8_t ci, int8_t cq, Demod_t *Demod)
-{
-       switch(Demod->state) {
-               case DEMOD_UNSYNCD:
-                       // initialize SOF correlator. We are looking for 12 samples low and 12 samples high.
-                       Demod->SOF_low = 0;
-                       Demod->SOF_high = 12;
-                       Demod->SOF_last = 23;
-                       memset(Demod->SOF_correlator, 0x00, Demod->SOF_last + 1);
-                       Demod->SOF_correlator[Demod->SOF_last] = AMPLITUDE(ci,cq);
-                       Demod->SOF_corr = Demod->SOF_correlator[Demod->SOF_last];
-                       Demod->SOF_corr_prev = Demod->SOF_corr;
-                       // initialize Demodulator
-                       Demod->posCount = 0;
-                       Demod->bitCount = 0;
-                       Demod->len = 0;
-                       Demod->state = DEMOD_AWAIT_SOF_1;
+       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) {
+               case STATE_TAG_SOF_LOW:
+                       // waiting for a rising edge
+                       if (amplitude > NOISE_THRESHOLD + DecodeTag->previous_amplitude) {
+                               if (DecodeTag->posCount > 10) {
+                                       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;
                         break;
-                       
-               case DEMOD_AWAIT_SOF_1:
-                       // calculate the correlation in real time. Look at differences only.
-                       Demod->SOF_corr += Demod->SOF_correlator[Demod->SOF_low++];
-                       Demod->SOF_corr -= 2*Demod->SOF_correlator[Demod->SOF_high++];
-                       Demod->SOF_last++;
-                       Demod->SOF_low &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_high &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_last &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_correlator[Demod->SOF_last] = AMPLITUDE(ci,cq);
-                       Demod->SOF_corr += Demod->SOF_correlator[Demod->SOF_last];
-
-                       // if correlation increases for 10 consecutive samples, we are close to maximum correlation
-                       if (Demod->SOF_corr > Demod->SOF_corr_prev + SUBCARRIER_DETECT_THRESHOLD) {
-                               Demod->posCount++;
+
+               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 {
                         } else {
-                               Demod->posCount = 0;
+                               DecodeTag->posCount = 2;
+                               DecodeTag->threshold_sof = DecodeTag->threshold_sof/2;
                         }
                         }
+                       // DecodeTag->posCount = 2;
+                       DecodeTag->state = STATE_TAG_SOF_HIGH;
+                       break;
  
  
-                       if (Demod->posCount == 10) {    // correlation increased 10 times
-                               Demod->state = DEMOD_AWAIT_SOF_2;
+               case STATE_TAG_SOF_HIGH:
+                       // waiting for 10 times high. Take average over the last 8
+                       if (amplitude > DecodeTag->threshold_sof) {
+                               DecodeTag->posCount++;
+                               if (DecodeTag->posCount > 2) {
+                                       DecodeTag->threshold_half += amplitude; // keep track of average high value
+                               }
+                               if (DecodeTag->posCount == 10) {
+                                       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;
                         }
                         }
-                               
-                       Demod->SOF_corr_prev = Demod->SOF_corr;
-                               
                         break;
  
                         break;
  
-               case DEMOD_AWAIT_SOF_2:
-                       // calculate the correlation in real time. Look at differences only.
-                       Demod->SOF_corr += Demod->SOF_correlator[Demod->SOF_low++];
-                       Demod->SOF_corr -= 2*Demod->SOF_correlator[Demod->SOF_high++];
-                       Demod->SOF_last++;
-                       Demod->SOF_low &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_high &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_last &= (SOF_CORRELATOR_LEN-1);
-                       Demod->SOF_correlator[Demod->SOF_last] = AMPLITUDE(ci,cq);
-                       Demod->SOF_corr += Demod->SOF_correlator[Demod->SOF_last];
-
-                       if (Demod->SOF_corr >= Demod->SOF_corr_prev) { // we are looking for the maximum correlation
-                               Demod->SOF_corr_prev = Demod->SOF_corr;
-                       } else {
-                               Demod->lastBit = SOF_PART1;  // detected 1st part of SOF
-                               Demod->sum1 = Demod->SOF_correlator[Demod->SOF_last];
-                               Demod->sum2 = 0;
-                               Demod->posCount = 2;
-                               Demod->state = DEMOD_RECEIVING_DATA;
+               case STATE_TAG_SOF_HIGH_END:
+                       // 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;
+                               DecodeTag->len = 0;
+                               DecodeTag->sum1 = amplitude;
+                               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();
                                 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();
+                               }
                         }
                         }
-                       
                         break;
  
                         break;
  
-               case DEMOD_RECEIVING_DATA:
-                       if (Demod->posCount == 1) {
-                               Demod->sum1 = 0;
-                               Demod->sum2 = 0;
+               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;
                         }
                         }
-
-                       if (Demod->posCount <= 4) {
-                               Demod->sum1 += AMPLITUDE(ci, cq);
+                       if (DecodeTag->posCount <= 4) {
+                               DecodeTag->sum1 += amplitude;
                         } else {
                         } else {
-                               Demod->sum2 += AMPLITUDE(ci, cq);
+                               DecodeTag->sum2 += amplitude;
                         }
                         }
-
-                       if (Demod->posCount == 8) {
-                               int16_t corr_1 = (Demod->sum2 - Demod->sum1) / 4;
-                               int16_t corr_0 = (Demod->sum1 - Demod->sum2) / 4;
-                               int16_t corr_EOF = (Demod->sum1 + Demod->sum2) / 8;
-                               if (corr_EOF > corr_0 && corr_EOF > corr_1) {
-                                       Demod->state = DEMOD_AWAIT_EOF;
-                               } else if (corr_1 > corr_0) {
+                       if (DecodeTag->posCount == 8) {
+                               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 (DecodeTag->sum1 < DecodeTag->threshold_half && DecodeTag->sum2 > DecodeTag->threshold_half) { // modulation in second half
                                         // logic 1
                                         // logic 1
-                                       if (Demod->lastBit == SOF_PART1) { // still part of SOF
-                                               Demod->lastBit = SOF_PART2;
+                                       if (DecodeTag->lastBit == SOF_PART1) { // still part of SOF
+                                               DecodeTag->lastBit = SOF_PART2;    // SOF completed
                                         } else {
                                         } else {
-                                               Demod->lastBit = LOGIC1;
-                                               Demod->shiftReg >>= 1;
-                                               Demod->shiftReg |= 0x80;
-                                               Demod->bitCount++;
-                                               if (Demod->bitCount == 8) {
-                                                       Demod->output[Demod->len] = Demod->shiftReg;
-                                                       Demod->len++;
-                                                       Demod->bitCount = 0;
-                                                       Demod->shiftReg = 0;
+                                               DecodeTag->lastBit = LOGIC1;
+                                               DecodeTag->shiftReg >>= 1;
+                                               DecodeTag->shiftReg |= 0x80;
+                                               DecodeTag->bitCount++;
+                                               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
+                                                               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
                                         // logic 0
-                                       if (Demod->lastBit == SOF_PART1) { // incomplete SOF
-                                               Demod->state = DEMOD_UNSYNCD;
+                                       if (DecodeTag->lastBit == SOF_PART1) { // incomplete SOF
+                                               DecodeTag->posCount = 0;
+                                               DecodeTag->previous_amplitude = amplitude;
+                                               DecodeTag->state = STATE_TAG_SOF_LOW;
                                                 LED_C_OFF();
                                         } else {
                                                 LED_C_OFF();
                                         } else {
-                                               Demod->lastBit = LOGIC0;
-                                               Demod->shiftReg >>= 1;
-                                               Demod->bitCount++;
-                                               if (Demod->bitCount == 8) {
-                                                       Demod->output[Demod->len] = Demod->shiftReg;
-                                                       Demod->len++;
-                                                       Demod->bitCount = 0;
-                                                       Demod->shiftReg = 0;
+                                               DecodeTag->lastBit = LOGIC0;
+                                               DecodeTag->shiftReg >>= 1;
+                                               DecodeTag->bitCount++;
+                                               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();
+                                                       }
+                                                       DecodeTag->bitCount = 0;
+                                                       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();
+                                       }
                                 }
                                 }
-                               Demod->posCount = 0;
+                               DecodeTag->posCount = 0;
                         }
                         }
-                       Demod->posCount++;
+                       DecodeTag->posCount++;
                         break;
                         break;
-               
-               case DEMOD_AWAIT_EOF:
-                       if (Demod->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 {
-                               Demod->state = DEMOD_UNSYNCD;
-                               LED_C_OFF();
+                               DecodeTag->sum2 += amplitude;
                         }
                         }
+                       if (DecodeTag->posCount == 8) {
+                               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();
+                               }
+                       }
+                       DecodeTag->posCount++;
                         break;
  
                         break;
  
-               default:
-                       Demod->state = DEMOD_UNSYNCD;
-                       LED_C_OFF();
+               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;
         }
  
                         break;
         }
  
@@ -452,278 +623,554 @@ static RAMFUNC int Handle15693SamplesDemod(int8_t ci, int8_t cq, Demod_t *Demod)
  }
  
  
  }
  
  
-static void DemodInit(Demod_t* Demod, uint8_t* data)
-{
-       Demod->output = data;
-       Demod->state = DEMOD_UNSYNCD;
+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;
+       DecodeTag->max_len = max_len;
+}
+
+
+static void DecodeTagReset(DecodeTag_t *DecodeTag) {
+       DecodeTag->posCount = 0;
+       DecodeTag->state = STATE_TAG_SOF_LOW;
+       DecodeTag->previous_amplitude = MAX_PREVIOUS_AMPLITUDE;
  }
  
  
  /*
  }
  
  
  /*
- *  Demodulate the samples we received from the tag, also log to tracebuffer
+ *  Receive and decode the tag response, also log to tracebuffer
   */
   */
-static int GetIso15693AnswerFromTag(uint8_t* response, int timeout)
-{
-       int maxBehindBy = 0;
-       int lastRxCounter, samples = 0;
-       int8_t ci, cq;
-       bool gotFrame = false;
-       
-       // Allocate memory from BigBuf for some buffers
-       // free all previous allocations first
-       BigBuf_free();
+int GetIso15693AnswerFromTag(uint8_t* response, uint16_t max_len, uint16_t timeout, uint32_t *eof_time) {
  
  
-       // The DMA buffer, used to stream samples from the FPGA
-       uint16_t* dmaBuf = (uint16_t*) BigBuf_malloc(ISO15693_DMA_BUFFER_SIZE * sizeof(uint16_t));
+       int samples = 0;
+       int ret = 0;
  
  
-       // the Demodulatur data structure
-       Demod_t* Demod = (Demod_t*) BigBuf_malloc(sizeof(Demod_t));
-       
-       // Set up the demodulator for tag -> reader responses.
-       DemodInit(Demod, response);
+       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
+
+       // the Decoder data structure
+       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 | FPGA_HF_READER_SUBCARRIER_424_KHZ | FPGA_HF_READER_MODE_RECEIVE_AMPLITUDE);
  
         // Setup and start DMA.
  
         // Setup and start DMA.
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
         FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
         FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
-
+       uint32_t dma_start_time = 0;
         uint16_t *upTo = dmaBuf;
         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 == 0) continue;
+
+               samples++;
+               if (samples == 1) {
+                       // DMA has transferred the very first data
+                       dma_start_time = GetCountSspClk() & 0xfffffff0;
                 }
  
                 }
  
-               if (behindBy < 1) 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);
+                               ret = -1;
+                               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++;
  
  
-               if (Handle15693SamplesDemod(ci, cq, Demod)) {
-                       gotFrame = true;
+               if (Handle15693SamplesFromTag(tagdata, &DecodeTag)) {
+                       *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;
                 }
  
                         break;
                 }
  
-               if(samples > timeout && Demod->state < DEMOD_RECEIVING_DATA) {
-                       Demod->len = 0;
+               if (samples > timeout && DecodeTag.state < STATE_TAG_RECEIVING_DATA) {
+                       ret = -1;   // timeout
                         break;
                 }
                         break;
                 }
+
         }
  
         FpgaDisableSscDma();
  
         }
  
         FpgaDisableSscDma();
  
-       if (DEBUG) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.state = %d, Demod.len = %d, Demod.bitCount = %d, Demod.posCount = %d", 
-                           maxBehindBy, samples, gotFrame, Demod->state, Demod->len, Demod->bitCount, Demod->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 (tracing && Demod->len > 0) {
-               uint8_t parity[MAX_PARITY_SIZE];
-               LogTrace(Demod->output, Demod->len, 0, 0, parity, false);
+       if (ret < 0) {
+               return ret;
         }
  
         }
  
-       return Demod->len;
+       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;
  }
  
  
  }
  
  
-// Now the GetISO15693 message from sniffing command
-// TODO: fix it. This cannot work for several reasons: 
-//   1. Carrier is switched on during sniffing?
-//   2. We most probable miss the next reader command when demodulating
-static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed)
-{
-       uint8_t *dest = BigBuf_get_addr();
+//=============================================================================
+// An ISO15693 decoder for reader commands.
+//
+// This function is called 4 times per bit (every 2 subcarrier cycles).
+// Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
+// LED handling:
+//    LED B -> ON once we have received the SOF and are expecting the rest.
+//    LED B -> OFF once we have received EOF or are in error state or unsynced
+//
+// Returns: true  if we received a EOF
+//          false if we are still waiting for some more
+//=============================================================================
  
  
-// NOW READ RESPONSE
-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
-       //spindelay(60);        // greg - experiment to get rid of some of the 0 byte/failed reads
-       for(int c = 0; c < BIGBUF_SIZE; ) {
-               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;
-               }
-       }
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LED_D_OFF();
+typedef struct DecodeReader {
+       enum {
+               STATE_READER_UNSYNCD,
+               STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF,
+               STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF,
+               STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF,
+               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_JAMMING
+       }           state;
+       enum {
+               CODING_1_OUT_OF_4,
+               CODING_1_OUT_OF_256
+       }           Coding;
+       uint8_t     shiftReg;
+       uint8_t     bitCount;
+       int         byteCount;
+       int         byteCountMax;
+       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, uint8_t jam_search_len, uint8_t *jam_search_string) {
+       DecodeReader->output = data;
+       DecodeReader->byteCountMax = max_len;
+       DecodeReader->state = STATE_READER_UNSYNCD;
+       DecodeReader->byteCount = 0;
+       DecodeReader->bitCount = 0;
+       DecodeReader->posCount = 1;
+       DecodeReader->shiftReg = 0;
+       DecodeReader->jam_search_len = jam_search_len;
+       DecodeReader->jam_search_string = jam_search_string;
+}
  
  
-       //////////////////////////////////////////
-       /////////// DEMODULATE ///////////////////
-       //////////////////////////////////////////
  
  
-       int i, j;
-       int max = 0, maxPos=0;
+static void DecodeReaderReset(DecodeReader_t* DecodeReader) {
+       DecodeReader->state = STATE_READER_UNSYNCD;
+}
  
  
-       int skip = 2;
  
  
-       // First, correlate for SOF
-       for(i = 0; i < 38000; i++) {
-               int corr = 0;
-               for(j = 0; j < arraylen(FrameSOF); j += skip) {
-                       corr += FrameSOF[j]*dest[i+(j/skip)];
-               }
-               if(corr > max) {
-                       max = corr;
-                       maxPos = i;
-               }
-       }
+static int inline __attribute__((always_inline)) Handle15693SampleFromReader(bool bit, DecodeReader_t *DecodeReader) {
+       switch (DecodeReader->state) {
+               case STATE_READER_UNSYNCD:
+                       // wait for unmodulated carrier
+                       if (bit) {
+                               DecodeReader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
+                       }
+                       break;
  
  
-       if (DEBUG) Dbprintf("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));
+               case STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF:
+                       if (!bit) {
+                               // we went low, so this could be the beginning of a SOF
+                               DecodeReader->posCount = 1;
+                               DecodeReader->state = STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF;
+                       }
+                       break;
  
  
-       int k = 0; // this will be our return value
+               case STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       if (bit) { // detected rising edge
+                               if (DecodeReader->posCount < 4) { // rising edge too early (nominally expected at 5)
+                                       DecodeReader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
+                               } else { // SOF
+                                       DecodeReader->state = STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF;
+                               }
+                       } else {
+                               if (DecodeReader->posCount > 5) { // stayed low for too long
+                                       DecodeReaderReset(DecodeReader);
+                               } else {
+                                       // do nothing, keep waiting
+                               }
+                       }
+                       break;
  
  
-       // greg - If correlation is less than 1 then there's little point in continuing
-       if ((max/(arraylen(FrameSOF)/skip)) >= 1)       // THIS SHOULD BE 1
-       {
-       
-               i = maxPos + arraylen(FrameSOF)/skip;
-       
-               uint8_t outBuf[20];
-               memset(outBuf, 0, sizeof(outBuf));
-               uint8_t mask = 0x01;
-               for(;;) {
-                       int corr0 = 0, corr00 = 0, corr01 = 0, corr1 = 0, corrEOF = 0;
-                       for(j = 0; j < arraylen(Logic0); j += skip) {
-                               corr0 += Logic0[j]*dest[i+(j/skip)];
+               case STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       if (!bit) { // detected a falling edge
+                               if (DecodeReader->posCount < 20) {         // falling edge too early (nominally expected at 21 earliest)
+                                       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)
+                                       DecodeReaderReset(DecodeReader);
+                               } else {                                   // SOF for 1 out of 256 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_AWAIT_1ST_FALLING_EDGE_OF_SOF;
+                               } else {
+                                       // do nothing, keep waiting
+                               }
                         }
                         }
-                       corr01 = corr00 = corr0;
-                       for(j = 0; j < arraylen(Logic0); j += skip) {
-                               corr00 += Logic0[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
-                               corr01 += Logic1[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
+                       break;
+
+               case STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF:
+                       DecodeReader->posCount++;
+                       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_AWAIT_1ST_FALLING_EDGE_OF_SOF;
+                                       } else {
+                                               DecodeReader->posCount = 1;
+                                               DecodeReader->bitCount = 0;
+                                               DecodeReader->byteCount = 0;
+                                               DecodeReader->sum1 = 1;
+                                               DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_256;
+                                               LED_B_ON();
+                                       }
+                               } else { // CODING_1_OUT_OF_4
+                                       if (DecodeReader->posCount < 24) { // rising edge too early (nominally expected at 25)
+                                               DecodeReader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
+                                       } else {
+                                               DecodeReader->posCount = 1;
+                                               DecodeReader->state = STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4;
+                                       }
+                               }
+                       } else {
+                               if (DecodeReader->Coding == CODING_1_OUT_OF_256) {
+                                       if (DecodeReader->posCount > 34) { // signal stayed low for too long
+                                               DecodeReaderReset(DecodeReader);
+                                       } else {
+                                               // do nothing, keep waiting
+                                       }
+                               } else { // CODING_1_OUT_OF_4
+                                       if (DecodeReader->posCount > 26) { // signal stayed low for too long
+                                               DecodeReaderReset(DecodeReader);
+                                       } else {
+                                               // do nothing, keep waiting
+                                       }
+                               }
                         }
                         }
-                       for(j = 0; j < arraylen(Logic1); j += skip) {
-                               corr1 += Logic1[j]*dest[i+(j/skip)];
+                       break;
+
+               case STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4:
+                       DecodeReader->posCount++;
+                       if (bit) {
+                               if (DecodeReader->posCount == 9) {
+                                       DecodeReader->posCount = 1;
+                                       DecodeReader->bitCount = 0;
+                                       DecodeReader->byteCount = 0;
+                                       DecodeReader->sum1 = 1;
+                                       DecodeReader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_4;
+                                       LED_B_ON();
+                               } else {
+                                       // do nothing, keep waiting
+                               }
+                       } else { // unexpected falling edge
+                                       DecodeReaderReset(DecodeReader);
                         }
                         }
-                       for(j = 0; j < arraylen(FrameEOF); j += skip) {
-                               corrEOF += FrameEOF[j]*dest[i+(j/skip)];
+                       break;
+
+               case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
+                       DecodeReader->posCount++;
+                       if (DecodeReader->posCount == 1) {
+                               DecodeReader->sum1 = bit?1:0;
+                       } else if (DecodeReader->posCount <= 4) {
+                               if (bit) DecodeReader->sum1++;
+                       } else if (DecodeReader->posCount == 5) {
+                               DecodeReader->sum2 = bit?1:0;
+                       } else {
+                               if (bit) DecodeReader->sum2++;
                         }
                         }
-                       // Even things out by the length of the target waveform.
-                       corr00 *= 2;
-                       corr01 *= 2;
-                       corr0 *= 4;
-                       corr1 *= 4;
-       
-                       if(corrEOF > corr1 && corrEOF > corr00 && corrEOF > corr01) {
-                               if (DEBUG) Dbprintf("EOF at %d, correlation %d (corr01: %d, corr00: %d, corr1: %d, corr0: %d)", 
-                                        i, corrEOF, corr01, corr00, corr1, corr0);
-                               break;
-                       } else if(corr1 > corr0) {
-                               i += arraylen(Logic1)/skip;
-                               outBuf[k] |= mask;
+                       if (DecodeReader->posCount == 8) {
+                               DecodeReader->posCount = 0;
+                               if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
+                                       LED_B_OFF(); // Finished receiving
+                                       DecodeReaderReset(DecodeReader);
+                                       if (DecodeReader->byteCount != 0) {
+                                               return true;
+                                       }
+                               } else if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected a 2bit position
+                                       DecodeReader->shiftReg >>= 2;
+                                       DecodeReader->shiftReg |= (DecodeReader->bitCount << 6);
+                               }
+                               if (DecodeReader->bitCount == 15) { // we have a full byte
+                                       DecodeReader->output[DecodeReader->byteCount++] = DecodeReader->shiftReg;
+                                       if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
+                                               // buffer overflow, give up
+                                               LED_B_OFF();
+                                               DecodeReaderReset(DecodeReader);
+                                       }
+                                       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++;
+                               }
+                       }
+                       break;
+
+               case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:
+                       DecodeReader->posCount++;
+                       if (DecodeReader->posCount == 1) {
+                               DecodeReader->sum1 = bit?1:0;
+                       } else if (DecodeReader->posCount <= 4) {
+                               if (bit) DecodeReader->sum1++;
+                       } else if (DecodeReader->posCount == 5) {
+                               DecodeReader->sum2 = bit?1:0;
+                       } else if (bit) {
+                               DecodeReader->sum2++;
+                       }
+                       if (DecodeReader->posCount == 8) {
+                               DecodeReader->posCount = 0;
+                               if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
+                                       LED_B_OFF(); // Finished receiving
+                                       DecodeReaderReset(DecodeReader);
+                                       if (DecodeReader->byteCount != 0) {
+                                               return true;
+                                       }
+                               } 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
+                                       DecodeReader->output[DecodeReader->byteCount++] = DecodeReader->shiftReg;
+                                       if (DecodeReader->byteCount > DecodeReader->byteCountMax) {
+                                               // buffer overflow, give up
+                                               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 {
                         } else {
-                               i += arraylen(Logic0)/skip;
+                               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;
+                               }
                         }
                         }
-                       mask <<= 1;
-                       if(mask == 0) {
-                               k++;
-                               mask = 0x01;
+                       break;
+
+               default:
+                       LED_B_OFF();
+                       DecodeReaderReset(DecodeReader);
+                       break;
+       }
+
+       return false;
+}
+
+
+//-----------------------------------------------------------------------------
+// Receive a command (from the reader to us, where we are the simulated tag),
+// and store it in the given buffer, up to the given maximum length. Keeps
+// spinning, waiting for a well-framed command, until either we get one
+// (returns len) or someone presses the pushbutton on the board (returns -1).
+//
+// Assume that we're called with the SSC (to the FPGA) and ADC path set
+// correctly.
+//-----------------------------------------------------------------------------
+
+int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eof_time) {
+       int samples = 0;
+       bool gotFrame = false;
+       uint8_t b;
+
+       uint8_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
+
+       // the decoder data structure
+       DecodeReader_t DecodeReader = {0};
+       DecodeReaderInit(&DecodeReader, received, max_len, 0, NULL);
+
+       // wait for last transfer to complete
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
+
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+
+       // clear receive register and wait for next transfer
+       uint32_t temp = AT91C_BASE_SSC->SSC_RHR;
+       (void) temp;
+       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) ;
+
+       uint32_t dma_start_time = GetCountSspClk() & 0xfffffff8;
+
+       // Setup and start DMA.
+       FpgaSetupSscDma(dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+       uint8_t *upTo = dmaBuf;
+
+       for (;;) {
+               uint16_t behindBy = ((uint8_t*)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (ISO15693_DMA_BUFFER_SIZE-1);
+
+               if (behindBy == 0) continue;
+
+               b = *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", behindBy);
+                               break;
                         }
                         }
-                       if((i+(int)arraylen(FrameEOF)/skip) >= BIGBUF_SIZE) {
-                               DbpString("ran off end!");
+               }
+               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
+               }
+
+               for (int i = 7; i >= 0; i--) {
+                       if (Handle15693SampleFromReader((b >> i) & 0x01, &DecodeReader)) {
+                               *eof_time = dma_start_time + samples - DELAY_READER_TO_ARM; // end of EOF
+                               gotFrame = true;
                                 break;
                         }
                                 break;
                         }
+                       samples++;
                 }
                 }
-               if(mask != 0x01) {
-                       DbpString("sniff: error, uneven octet! (discard extra bits!)");
-       ///             DbpString("   mask=%02x", mask);
+
+               if (gotFrame) {
+                       break;
                 }
                 }
-       //      uint8_t str1 [8];
-       //      itoa(k,str1);
-       //      strncat(str1," octets read",8);
-       
-       //      DbpString(  str1);    // DbpString("%d octets", k);
-       
-       //      for(i = 0; i < k; i+=3) {
-       //              //DbpString("# %2d: %02x ", i, outBuf[i]);
-       //              DbpIntegers(outBuf[i],outBuf[i+1],outBuf[i+2]);
-       //      }
-       
-               for(i = 0; i < k; i++) {
-                       receivedResponse[i] = outBuf[i];
+
+               if (BUTTON_PRESS()) {
+                       DecodeReader.byteCount = -1;
+                       break;
                 }
                 }
-       } // "end if correlation > 0"   (max/(arraylen(FrameSOF)/skip))
-       return k; // return the number of bytes demodulated
  
  
-///    DbpString("CRC=%04x", Iso15693Crc(outBuf, k-2));
+               WDT_HIT();
+       }
+
+       FpgaDisableSscDma();
+
+       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 (DecodeReader.byteCount > 0) {
+               uint32_t sof_time = *eof_time
+                                               - 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_ISO15693(DecodeReader.output, DecodeReader.byteCount, sof_time*32, *eof_time*32, NULL, true);
+       }
+
+       return DecodeReader.byteCount;
+}
+
+
+// Construct an identify (Inventory) request, which is the first
+// thing that you must send to a tag to get a response.
+static void BuildIdentifyRequest(uint8_t *cmd) {
+       uint16_t crc;
+       // one sub-carrier, inventory, 1 slot, fast rate
+       cmd[0] = ISO15693_REQ_INVENTORY | ISO15693_REQINV_SLOT1 | ISO15693_REQ_DATARATE_HIGH;
+       // inventory command code
+       cmd[1] = 0x01;
+       // no mask
+       cmd[2] = 0x00;
+       //Now the CRC
+       crc = Iso15693Crc(cmd, 3);
+       cmd[3] = crc & 0xff;
+       cmd[4] = crc >> 8;
  }
  
  
  }
  
  
-static void BuildIdentifyRequest(void);
  //-----------------------------------------------------------------------------
  // 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
  // so that it can be downloaded to a PC and processed there.
  //-----------------------------------------------------------------------------
  //-----------------------------------------------------------------------------
  // 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
  // so that it can be downloaded to a PC and processed there.
  //-----------------------------------------------------------------------------
-void AcquireRawAdcSamplesIso15693(void)
-{
-       LEDsoff();
+void AcquireRawAdcSamplesIso15693(void) {
         LED_A_ON();
         LED_A_ON();
-       
+
         uint8_t *dest = BigBuf_get_addr();
  
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
         uint8_t *dest = BigBuf_get_addr();
  
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       BuildIdentifyRequest();
-
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER);
+       LED_D_ON();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
  
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
  
+       uint8_t cmd[5];
+       BuildIdentifyRequest(cmd);
+       CodeIso15693AsReader(cmd, sizeof(cmd));
+
         // Give the tags time to energize
         // Give the tags time to energize
-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
         SpinDelay(100);
  
         // Now send the command
         SpinDelay(100);
  
         // Now send the command
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_TX);
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
-
-       LED_B_ON();
-       for(int c = 0; c < ToSendMax; ) {
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = ~ToSend[c];
-                       c++;
-               }
-               WDT_HIT();
-       }
-       LED_B_OFF();
+       uint32_t start_time = 0;
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
  
         // wait for last transfer to complete
  
         // wait for last transfer to complete
-       while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));
+       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 | FPGA_HF_READER_SUBCARRIER_424_KHZ | FPGA_HF_READER_MODE_RECEIVE_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;
                 }
         }
  
                 }
         }
  
@@ -732,70 +1179,199 @@ 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)
-{
-       LEDsoff();
+void SnoopIso15693(uint8_t jam_search_len, uint8_t *jam_search_string) {
+
         LED_A_ON();
         LED_A_ON();
-       
-       uint8_t *dest = BigBuf_get_addr();
  
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
  
         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);
+       clear_trace();
+       set_tracing(true);
+
+       // The DMA buffer, used to stream samples from the FPGA
+       uint16_t dmaBuf[ISO15693_DMA_BUFFER_SIZE];
+
+       // 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), jam_search_len, jam_search_string);
+
+       // 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 PM3 Button to stop.");
  
  
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNOOP_AMPLITUDE);
+       LED_D_OFF();
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
+       StartCountSspClk();
+       FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
  
  
-       SpinDelay(100);
+       bool TagIsActive = false;
+       bool ReaderIsActive = false;
+       bool ExpectTagAnswer = false;
+       uint32_t dma_start_time = 0;
+       uint16_t *upTo = dmaBuf;
  
  
-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       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;
  
  
-       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;
+               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.
+                       upTo = dmaBuf;                                                 // start reading the circular buffer from the beginning
+                       if (behindBy > (9*ISO15693_DMA_BUFFER_SIZE/10)) {
+                               // FpgaDisableTracing();
+                               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;
+                               }
+                       }
                 }
                 }
+
+               if (!TagIsActive) {                                                // no need to try decoding reader data if the tag is sending
+                       if (Handle15693SampleFromReader(snoopdata & 0x02, &DecodeReader)) {
+                               // 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);
+                               ReaderIsActive = false;
+                               ExpectTagAnswer = 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);
+                               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);
+                       }
+               }
+
+               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();
+                               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;
+                               TagIsActive = false;
+                               // upTo = dmaBuf;
+                               // samples = 0;
+                               // FpgaSetupSscDma((uint8_t*) dmaBuf, ISO15693_DMA_BUFFER_SIZE);
+                               // continue;
+                       } else {
+                               TagIsActive = (DecodeTag.state >= STATE_TAG_RECEIVING_DATA);
+                       }
+               }
+
         }
  
         }
  
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LED_D_OFF();
-       Dbprintf("finished recording");
-       LED_A_OFF();
+       FpgaDisableSscDma();
+
+       DbpString("Snoop statistics:");
+       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 
-// (this might produces glitches that confuse some tags
-static void Iso15693InitReader() {
+// Initialize the proxmark as iso15k reader
+void Iso15693InitReader(void) {
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-       // Setup SSC
-       // FpgaSetupSsc();
  
  
-       // Start from off (no field generated)
-       LED_D_OFF();
+       // switch field off and wait until tag resets
         FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
         FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
         SpinDelay(10);
  
         SpinDelay(10);
  
+       // switch field on
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER);
+       LED_D_ON();
+       
+       // initialize SSC and select proper AD input
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
  
  
-       // Give the tags time to energize
-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       // give tags some time to energize
         SpinDelay(250);
  }
  
         SpinDelay(250);
  }
  
@@ -804,40 +1380,15 @@ 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)
  
  // uid is in transmission order (which is reverse of display order)
-static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber )
-{
-       uint8_t cmd[13];
-
+static void BuildReadBlockRequest(uint8_t *uid, uint8_t blockNumber, uint8_t *cmd) {
         uint16_t crc;
         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];
@@ -849,26 +1400,22 @@ 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
         //Now the CRC
-       crc = Crc(cmd, 11); // the crc needs to be calculated over 12 bytes
+       crc = Iso15693Crc(cmd, 11); // the crc needs to be calculated over 11 bytes
         cmd[11] = crc & 0xff;
         cmd[12] = crc >> 8;
  
         cmd[11] = crc & 0xff;
         cmd[12] = crc >> 8;
  
-       CodeIso15693AsReader(cmd, sizeof(cmd));
  }
  
  
  // Now the VICC>VCD responses when we are simulating a tag
  }
  
  
  // Now the VICC>VCD responses when we are simulating a tag
-static void BuildInventoryResponse( uint8_t *uid)
-{
+static void BuildInventoryResponse(uint8_t *uid) {
         uint8_t cmd[12];
  
         uint16_t crc;
         uint8_t cmd[12];
  
         uint16_t crc;
-       // one sub-carrier, inventory, 1 slot, fast rate
-       // AFI is at bit 5 (1<<4) when doing an INVENTORY
-    //(1 << 2) | (1 << 5) | (1 << 1);
-       cmd[0] = 0; // 
+
+       cmd[0] = 0; // No error, no protocol format extension
         cmd[1] = 0; // DSFID (data storage format identifier).  0x00 = not supported
         // 64-bit UID
         cmd[2] = uid[7]; //0x32;
         cmd[1] = 0; // DSFID (data storage format identifier).  0x00 = not supported
         // 64-bit UID
         cmd[2] = uid[7]; //0x32;
@@ -880,54 +1427,69 @@ static void BuildInventoryResponse( uint8_t *uid)
         cmd[8] = uid[1]; //0x05;
         cmd[9] = uid[0]; //0xe0;
         //Now the CRC
         cmd[8] = uid[1]; //0x05;
         cmd[9] = uid[0]; //0xe0;
         //Now the CRC
-       crc = Crc(cmd, 10);
+       crc = Iso15693Crc(cmd, 10);
         cmd[10] = crc & 0xff;
         cmd[11] = crc >> 8;
  
         cmd[10] = crc & 0xff;
         cmd[11] = crc >> 8;
  
-       CodeIso15693AsReader(cmd, sizeof(cmd));
+       CodeIso15693AsTag(cmd, sizeof(cmd));
  }
  
  // Universal Method for sending to and recv bytes from a tag
  }
  
  // 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[] 
-//     return: lenght of received data
-int SendDataTag(uint8_t *send, int sendlen, bool init, int speed, uint8_t **recv) {
-
-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
-       
-       if (init) Iso15693InitReader();
+//  init ... should we initialize the reader?
+//  speed ... 0 low speed, 1 hi speed
+//  *recv will contain the tag's answer
+//  return: length of received data, or -1 for timeout
+int SendDataTag(uint8_t *send, int sendlen, bool init, bool speed_fast, uint8_t *recv, uint16_t max_recv_len, uint32_t start_time, uint16_t timeout, uint32_t *eof_time) {
+
+       if (init) {
+               Iso15693InitReader();
+               StartCountSspClk();
+       }
  
  
-       int answerLen=0;
-       uint8_t *answer = BigBuf_get_addr() + 4000;
-       if (recv != NULL) memset(answer, 0, 100);
+       int answerLen = 0;
  
  
-       if (!speed) {
-               // low speed (1 out of 256)
-               CodeIso15693AsReader256(send, sendlen);
-       } else {
+       if (speed_fast) {
                 // high speed (1 out of 4)
                 CodeIso15693AsReader(send, sendlen);
                 // high speed (1 out of 4)
                 CodeIso15693AsReader(send, sendlen);
+       } else {
+               // low speed (1 out of 256)
+               CodeIso15693AsReader256(send, sendlen);
         }
         }
-       
-       TransmitTo15693Tag(ToSend,ToSendMax);   
+
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
+       uint32_t end_time = start_time + 32*(8*ToSendMax-4); // substract the 4 padding bits after EOF
+       LogTrace_ISO15693(send, sendlen, start_time*4, end_time*4, NULL, true);
+
         // 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, timeout, eof_time);
+       }
+
+       return answerLen;
+}
+
+
+int SendDataTagEOF(uint8_t *recv, uint16_t max_recv_len, uint32_t start_time, uint16_t timeout, uint32_t *eof_time) {
+
+       int answerLen = 0;
+
+       CodeIso15693AsReaderEOF();
+
+       TransmitTo15693Tag(ToSend, ToSendMax, &start_time);
+       uint32_t end_time = start_time + 32*(8*ToSendMax-4); // substract the 4 padding bits after EOF
+       LogTrace_ISO15693(NULL, 0, start_time*4, end_time*4, NULL, true);
+
+       // Now wait for a response
+       if (recv != NULL) {
+               answerLen = GetIso15693AnswerFromTag(recv, max_recv_len, timeout, eof_time);
         }
  
         }
  
-       LED_A_OFF();
-       
         return answerLen;
  }
  
  
  // --------------------------------------------------------------------
         return answerLen;
  }
  
  
  // --------------------------------------------------------------------
-// Debug Functions 
+// Debug Functions
  // --------------------------------------------------------------------
  
  // Decodes a message from a tag and displays its metadata and content
  // --------------------------------------------------------------------
  
  // Decodes a message from a tag and displays its metadata and content
@@ -936,53 +1498,53 @@ 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]) {
                         switch (d[1]) {
-                               case 0x01: 
-                                       strncat(status,"01:notSupp",DBD15STATLEN);
+                               case 0x01:
+                                       strncat(status,"01:notSupp", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x02: 
-                                       strncat(status,"02:notRecog",DBD15STATLEN);
+                               case 0x02:
+                                       strncat(status,"02:notRecog", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x03: 
-                                       strncat(status,"03:optNotSupp",DBD15STATLEN);
+                               case 0x03:
+                                       strncat(status,"03:optNotSupp", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x0f: 
-                                       strncat(status,"0f:noInfo",DBD15STATLEN);
+                               case 0x0f:
+                                       strncat(status,"0f:noInfo", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x10: 
-                                       strncat(status,"10:dontExist",DBD15STATLEN);
+                               case 0x10:
+                                       strncat(status,"10:doesn'tExist", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x11: 
-                                       strncat(status,"11:lockAgain",DBD15STATLEN);
+                               case 0x11:
+                                       strncat(status,"11:lockAgain", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x12: 
-                                       strncat(status,"12:locked",DBD15STATLEN);
+                               case 0x12:
+                                       strncat(status,"12:locked", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x13: 
-                                       strncat(status,"13:progErr",DBD15STATLEN);
+                               case 0x13:
+                                       strncat(status,"13:progErr", DBD15STATLEN);
                                         break;
                                         break;
-                               case 0x14: 
-                                       strncat(status,"14:lockErr",DBD15STATLEN);
+                               case 0x14:
+                                       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);
-               if ( (( crc & 0xff ) == d[len-2]) && (( crc >> 8 ) == d[len-1]) ) 
+
+               crc=Iso15693Crc(d,len-2);
+               if ( (( crc & 0xff ) == d[len-2]) && (( crc >> 8 ) == d[len-1]) )
                         strncat(status,"CrcOK",DBD15STATLEN);
                 else
                         strncat(status,"CrcOK",DBD15STATLEN);
                 else
-                       strncat(status,"CrcFail!",DBD15STATLEN); 
+                       strncat(status,"CrcFail!",DBD15STATLEN);
  
                 Dbprintf("%s",status);
         }
  
                 Dbprintf("%s",status);
         }
@@ -1000,236 +1562,298 @@ 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
-//-----------------------------------------------------------------------------
-void ReaderIso15693(uint32_t parameter)
-{
-       LEDsoff();
-       LED_A_ON();
-
-       int answerLen1 = 0;
-       uint8_t TagUID[8] = {0x00};
-
-       FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
  
  
-       uint8_t *answer1 = BigBuf_get_addr() + 4000;
-       memset(answer1, 0x00, 200);
+//---------------------------------------------------------------------------------------
+// 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) {
  
  
-       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       // Setup SSC
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       LED_A_ON();
  
  
-       // Start from off (no field generated)
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+       set_tracing(true);
  
  
-       // Give the tags time to energize
-       LED_D_ON();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
-       SpinDelay(200);
+       uint8_t TagUID[8] = {0x00};
+       uint8_t answer[ISO15693_MAX_RESPONSE_LENGTH];
  
         // 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
  
         // 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);
-       
-       // Now wait for a response
-       answerLen1 = GetIso15693AnswerFromTag(answer1, 100) ;
-
-       if (answerLen1 >=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
-
+       uint8_t cmd[5];
+       BuildIdentifyRequest(cmd);
+       uint32_t start_time = 0;
+       uint32_t eof_time;
+       int answerLen = SendDataTag(cmd, sizeof(cmd), true, true, answer, sizeof(answer), start_time, ISO15693_READER_TIMEOUT, &eof_time);
+       start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
+
+       if (answerLen >= 12) { // we should do a better check than this
+               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,true);
+       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]);
  
-
-       // Dbprintf("%d octets read from SELECT request:", answerLen2);
-       // DbdecodeIso15693Answer(answerLen2,answer2);
-       // Dbhexdump(answerLen2,answer2,true);
-
-       // Dbprintf("%d octets read from XXX request:", answerLen3);
-       // DbdecodeIso15693Answer(answerLen3,answer3);
-       // Dbhexdump(answerLen3,answer3,true);
-
         // read all pages
         // read all pages
-       if (answerLen1 >= 12 && DEBUG) {
-               uint8_t *answer2 = BigBuf_get_addr() + 4100;
-               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,true);
-                               if ( *((uint32_t*) answer2) == 0x07160101 ) break; // exit on NoPageErr 
-                       } 
-                       i++;
-               } 
+       if (answerLen >= 12 && DEBUG) {
+               for (int i = 0; i < 32; i++) {  // sanity check, assume max 32 pages
+                       uint8_t cmd[13];
+                       BuildReadBlockRequest(TagUID, i, cmd);
+                       answerLen = SendDataTag(cmd, sizeof(cmd), false, true, answer, sizeof(answer), start_time, ISO15693_READER_TIMEOUT, &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);
+                               Dbhexdump(answerLen, answer, false);
+                               if ( *((uint32_t*) answer) == 0x07160101 ) break; // exit on NoPageErr
+                       }
+               }
         }
  
         }
  
-       // for the time being, switch field off to protect rdv4.0 
+       // for the time being, switch field off to protect RDV4
         // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
         // note: this prevents using hf 15 cmd with s option - which isn't implemented yet anyway
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
         LED_D_OFF();
         LED_D_OFF();
-       
+
         LED_A_OFF();
  }
  
         LED_A_OFF();
  }
  
-// Simulate an ISO15693 TAG, perform anti-collision and then print any reader commands
-// all demodulation performed in arm rather than host. - greg
-void SimTagIso15693(uint32_t parameter, uint8_t *uid)
-{
-       LEDsoff();
-       LED_A_ON();
-
-       int answerLen1 = 0;
-       int samples = 0;
-       int elapsed = 0;
  
  
+// Initialize the proxmark as iso15k tag
+void Iso15693InitTag(void) {
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
         FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
-
-       uint8_t *buf = BigBuf_get_addr() + 4000;
-       memset(buf, 0x00, 100);
-       
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
         SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
+       LED_D_OFF();
+       FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);
+       StartCountSspClk();
+}
  
  
-       // Start from off (no field generated)
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
  
  
-       // Listen to reader
-       answerLen1 = GetIso15693AnswerFromSniff(buf, 100, &samples, &elapsed) ;
+// 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) {
  
  
-       if (answerLen1 >=1) // we should do a better check than this
-       {
-               // Build a suitable reponse to the reader INVENTORY cocmmand
-               // not so obsvious, but in the call to BuildInventoryResponse,  the command is copied to the global ToSend buffer used below.
-               
-               BuildInventoryResponse(uid);
-       
-               TransmitTo15693Reader(ToSend,ToSendMax);
-       }
+       LED_A_ON();
  
  
-       Dbprintf("%d octets read from reader command: %x %x %x %x %x %x %x %x %x", answerLen1,
-               buf[0], buf[1], buf[2], buf[3],
-               buf[4], buf[5], buf[6], buf[7], buf[8]);
+       Iso15693InitTag();
  
  
-       Dbprintf("Simulationg uid: %x %x %x %x %x %x %x %x",
-               uid[0], uid[1], uid[2], uid[3],
-               uid[4], uid[5], uid[6], uid[7]);
+       // Build a suitable response to the reader INVENTORY command
+       BuildInventoryResponse(uid);
  
  
-       LEDsoff();
+       // Listen to reader
+       while (!BUTTON_PRESS()) {
+               uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH];
+               uint32_t eof_time = 0, start_time = 0;
+               int cmd_len = GetIso15693CommandFromReader(cmd, sizeof(cmd), &eof_time);
+
+               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;
+                       TransmitTo15693Reader(ToSend, ToSendMax, &start_time, 0, slow);
+               }
+
+               Dbprintf("%d bytes read from reader:", cmd_len);
+               Dbhexdump(cmd_len, cmd, false);
+       }
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
+       LED_A_OFF();
  }
  
  
  // Since there is no standardized way of reading the AFI out of a tag, we will brute force it
  // (some manufactures offer a way to read the AFI, though)
  }
  
  
  // Since there is no standardized way of reading the AFI out of a tag, we will brute force it
  // (some manufactures offer a way to read the AFI, though)
-void BruteforceIso15693Afi(uint32_t speed) 
-{      
-       LEDsoff();
+void BruteforceIso15693Afi(uint32_t speed) {
         LED_A_ON();
         LED_A_ON();
-       
-       uint8_t data[20];
-       uint8_t *recv=data;
-       int datalen=0, recvlen=0;
-               
-       Iso15693InitReader();
-       
+
+       uint8_t data[6];
+       uint8_t recv[ISO15693_MAX_RESPONSE_LENGTH];
+       int datalen = 0, recvlen = 0;
+       uint32_t eof_time;
+
         // first without AFI
         // first without AFI
-       // Tags should respond wihtout AFI and with AFI=0 even when AFI is active
-       
-       data[0]=ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | 
-               ISO15_REQ_INVENTORY | ISO15_REQINV_SLOT1;
-       data[1]=ISO15_CMD_INVENTORY;
-       data[2]=0; // mask length
-       datalen=AddCrc(data,3);
-       recvlen=SendDataTag(data, datalen, false, speed, &recv);
+       // Tags should respond without AFI and with AFI=0 even when AFI is active
+
+       data[0] = ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_INVENTORY | ISO15693_REQINV_SLOT1;
+       data[1] = ISO15693_INVENTORY;
+       data[2] = 0; // mask length
+       datalen = Iso15693AddCrc(data,3);
+       uint32_t start_time = GetCountSspClk();
+       recvlen = SendDataTag(data, datalen, true, speed, recv, sizeof(recv), 0, ISO15693_READER_TIMEOUT, &eof_time);
+       start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
         WDT_HIT();
         if (recvlen>=12) {
         WDT_HIT();
         if (recvlen>=12) {
-               Dbprintf("NoAFI UID=%s",sprintUID(NULL,&recv[2]));
+               Dbprintf("NoAFI UID=%s", Iso15693sprintUID(NULL, &recv[2]));
         }
         }
-       
+
         // now with AFI
         // now with AFI
-       
-       data[0]=ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | 
-               ISO15_REQ_INVENTORY | ISO15_REQINV_AFI | ISO15_REQINV_SLOT1;
-       data[1]=ISO15_CMD_INVENTORY;
-       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);
+
+       data[0] = ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_INVENTORY | ISO15693_REQINV_AFI | ISO15693_REQINV_SLOT1;
+       data[1] = ISO15693_INVENTORY;
+       data[2] = 0; // AFI
+       data[3] = 0; // mask length
+
+       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, ISO15693_READER_TIMEOUT, &eof_time);
+               start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
                 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, Iso15693sprintUID(NULL, &recv[2]));
                 }
                 }
-       }       
+       }
         Dbprintf("AFI Bruteforcing done.");
         Dbprintf("AFI Bruteforcing done.");
-       
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       LEDsoff();
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       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[]) {
  
  }
  
  // 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();
-       
         LED_A_ON();
         LED_A_ON();
+
+       int recvlen = 0;
+       uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
+       uint32_t eof_time;
+
+       uint16_t timeout;
+    bool request_answer = false;
         
         
+       switch (data[1]) {
+               case ISO15693_WRITEBLOCK:
+               case ISO15693_LOCKBLOCK:
+               case ISO15693_WRITE_MULTI_BLOCK:
+               case ISO15693_WRITE_AFI:
+               case ISO15693_LOCK_AFI:
+               case ISO15693_WRITE_DSFID:
+               case ISO15693_LOCK_DSFID:
+                       timeout = ISO15693_READER_TIMEOUT_WRITE;
+                       request_answer = data[0] & ISO15693_REQ_OPTION;
+                       break;
+               default:
+                       timeout = ISO15693_READER_TIMEOUT;
+       }               
+
         if (DEBUG) {
         if (DEBUG) {
-               Dbprintf("SEND");
-               Dbhexdump(datalen,data,true);
+               Dbprintf("SEND:");
+               Dbhexdump(datalen, data, false);
+       }
+
+       recvlen = SendDataTag(data, datalen, true, speed, (recv?recvbuf:NULL), sizeof(recvbuf), 0, timeout, &eof_time);
+
+       if (request_answer) { // send a single EOF to get the tag response
+               recvlen = SendDataTagEOF((recv?recvbuf:NULL), sizeof(recvbuf), 0, ISO15693_READER_TIMEOUT, &eof_time);
         }
         
         }
         
-       recvlen = SendDataTag(data, datalen, true, speed, (recv?&recvbuf:NULL));
+       // 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) { 
-               cmd_send(CMD_ACK, recvlen>48?48:recvlen, 0, 0, recvbuf, 48);
-               
+       if (recv) {
                 if (DEBUG) {
                 if (DEBUG) {
-                       Dbprintf("RECV");
-                       DbdecodeIso15693Answer(recvlen,recvbuf); 
-                       Dbhexdump(recvlen,recvbuf,true);
+                       Dbprintf("RECV:");
+                       if (recvlen > 0) {
+                               Dbhexdump(recvlen, recvbuf, false);
+                               DbdecodeIso15693Answer(recvlen, recvbuf);
+                       }
                 }
                 }
+               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();
  }
  
         LED_A_OFF();
  }
  
+//-----------------------------------------------------------------------------
+// Work with "magic Chinese" card.
+//
+//-----------------------------------------------------------------------------
+
+// Set the UID on Magic ISO15693 tag (based on Iceman's LUA-script).
+void SetTag15693Uid(uint8_t *uid) {
+
+       LED_A_ON();
+
+       uint8_t cmd[4][9] = {
+               {ISO15693_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x3e, 0x00, 0x00, 0x00, 0x00},
+               {ISO15693_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x3f, 0x69, 0x96, 0x00, 0x00},
+               {ISO15693_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x38},
+               {ISO15693_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x39}
+       };
+
+       uint16_t crc;
+
+       int recvlen = 0;
+       uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
+       uint32_t eof_time;
+
+       // Command 3 : 022138u8u7u6u5 (where uX = uid byte X)
+       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][3] = uid[3];
+       cmd[3][4] = uid[2];
+       cmd[3][5] = uid[1];
+       cmd[3][6] = uid[0];
+
+       uint32_t start_time = 0;
+       
+       for (int i = 0; i < 4; i++) {
+               // Add the CRC
+               crc = Iso15693Crc(cmd[i], 7);
+               cmd[i][7] = crc & 0xff;
+               cmd[i][8] = crc >> 8;
+
+               recvlen = SendDataTag(cmd[i], sizeof(cmd[i]), i==0?true:false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, &eof_time);
+               start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
+               if (DEBUG) {
+                       Dbprintf("SEND:");
+                       Dbhexdump(sizeof(cmd[i]), cmd[i], false);
+                       Dbprintf("RECV:");
+                       if (recvlen > 0) {
+                               Dbhexdump(recvlen, recvbuf, false);
+                               DbdecodeIso15693Answer(recvlen, recvbuf);
+                       }
+               }
+               // Note: need to know if we expect an answer from one of the magic commands
+               // if (recvlen < 0) {
+                       // break;
+               // }
+       }
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
+
+       cmd_send(CMD_ACK, recvlen, 0, 0, recvbuf, recvlen);
+       LED_A_OFF();
+}
  
  
  
  
  
  
@@ -1245,8 +1869,8 @@ static void __attribute__((unused)) BuildSysInfoRequest(uint8_t *uid)
         uint8_t cmd[12];
  
         uint16_t crc;
         uint8_t cmd[12];
  
         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
+       // 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
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =  (1 << 5) | (1 << 1); // no SELECT bit
         // System Information command code
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =  (1 << 5) | (1 << 1); // no SELECT bit
         // System Information command code
@@ -1262,7 +1886,7 @@ static void __attribute__((unused)) BuildSysInfoRequest(uint8_t *uid)
         cmd[8] = 0x05;
         cmd[9]= 0xe0; // always e0 (not exactly unique)
         //Now the CRC
         cmd[8] = 0x05;
         cmd[9]= 0xe0; // always e0 (not exactly unique)
         //Now the CRC
-       crc = Crc(cmd, 10); // the crc needs to be calculated over 2 bytes
+       crc = Iso15693Crc(cmd, 10); // the crc needs to be calculated over 2 bytes
         cmd[10] = crc & 0xff;
         cmd[11] = crc >> 8;
  
         cmd[10] = crc & 0xff;
         cmd[11] = crc >> 8;
  
@@ -1276,8 +1900,8 @@ static void __attribute__((unused)) BuildReadMultiBlockRequest(uint8_t *uid)
         uint8_t cmd[14];
  
         uint16_t crc;
         uint8_t cmd[14];
  
         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
+       // 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
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =  (1 << 5) | (1 << 1); // no SELECT bit
         // READ Multi BLOCK command code
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =  (1 << 5) | (1 << 1); // no SELECT bit
         // READ Multi BLOCK command code
@@ -1297,7 +1921,7 @@ static void __attribute__((unused)) BuildReadMultiBlockRequest(uint8_t *uid)
         // Number of Blocks to read
         cmd[11] = 0x2f; // read quite a few
         //Now the CRC
         // Number of Blocks to read
         cmd[11] = 0x2f; // read quite a few
         //Now the CRC
-       crc = Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
+       crc = Iso15693Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;
  
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;
  
@@ -1310,8 +1934,8 @@ static void __attribute__((unused)) BuildArbitraryRequest(uint8_t *uid,uint8_t C
         uint8_t cmd[14];
  
         uint16_t crc;
         uint8_t cmd[14];
  
         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
+       // 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
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =   (1 << 5) | (1 << 1); // no SELECT bit
         // READ BLOCK command code
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =   (1 << 5) | (1 << 1); // no SELECT bit
         // READ BLOCK command code
@@ -1330,9 +1954,9 @@ static void __attribute__((unused)) BuildArbitraryRequest(uint8_t *uid,uint8_t C
         cmd[10] = 0x00;
         cmd[11] = 0x0a;
  
         cmd[10] = 0x00;
         cmd[11] = 0x0a;
  
-//     cmd[12] = 0x00;
-//     cmd[13] = 0x00; //Now the CRC
-       crc = Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
+//  cmd[12] = 0x00;
+//  cmd[13] = 0x00; //Now the CRC
+       crc = Iso15693Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;
  
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;
  
@@ -1345,8 +1969,8 @@ static void __attribute__((unused)) BuildArbitraryCustomRequest(uint8_t uid[], u
         uint8_t cmd[14];
  
         uint16_t crc;
         uint8_t cmd[14];
  
         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
+       // 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
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =   (1 << 5) | (1 << 1); // no SELECT bit
         // READ BLOCK command code
         // one sub-carrier, inventory, 1 slot, fast rate
         cmd[0] =   (1 << 5) | (1 << 1); // no SELECT bit
         // READ BLOCK command code
@@ -1362,12 +1986,12 @@ static void __attribute__((unused)) BuildArbitraryCustomRequest(uint8_t uid[], u
         cmd[8] = 0x05;
         cmd[9]= 0xe0; // always e0 (not exactly unique)
         // Parameter
         cmd[8] = 0x05;
         cmd[9]= 0xe0; // always e0 (not exactly unique)
         // Parameter
-       cmd[10] = 0x05; // for custom codes this must be manufcturer code
+       cmd[10] = 0x05; // for custom codes this must be manufacturer code
         cmd[11] = 0x00;
  
         cmd[11] = 0x00;
  
-//     cmd[12] = 0x00;
-//     cmd[13] = 0x00; //Now the CRC
-       crc = Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
+//  cmd[12] = 0x00;
+//  cmd[13] = 0x00; //Now the CRC
+       crc = Iso15693Crc(cmd, 12); // the crc needs to be calculated over 2 bytes
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;
  
         cmd[12] = crc & 0xff;
         cmd[13] = crc >> 8;