]> cvs.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/lfops.c
Refactoring low frequency operations, now 'lf hid fskdemod' is more stable. Also...
[proxmark3-svn] / armsrc / lfops.c
index b53f370e4ed6a3bb03c6523023d5ce78bd60bac4..397ea8475e8af050eab2670bece8f59b1555c0ac 100644 (file)
 #include "crc16.h"
 #include "string.h"
 
-void AcquireRawAdcSamples125k(int at134khz)
-{
-       if (at134khz)
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
-       else
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
-
-       // Connect the A/D to the peak-detected low-frequency path.
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
-
-       // Give it a bit of time for the resonant antenna to settle.
-       SpinDelay(50);
-
-       // Now set up the SSC to get the ADC samples that are now streaming at us.
-       FpgaSetupSsc();
-
-       // Now call the acquisition routine
-       DoAcquisition125k();
-}
-
 // split into two routines so we can avoid timing issues after sending commands //
-void DoAcquisition125k(void)
+void DoAcquisition125k_internal(bool silent)
 {
        uint8_t *dest = (uint8_t *)BigBuf;
        int n = sizeof(BigBuf);
@@ -58,8 +36,44 @@ void DoAcquisition125k(void)
                        if (i >= n) break;
                }
        }
-       Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
-                       dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
+       if( ! silent)
+       {
+               Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
+                               dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
+       }
+}
+
+void DoAcquisition125k(void)
+{
+       DoAcquisition125k_internal(false);
+}
+
+void SetupToAcquireRawAdcSamples(int divisor)
+{
+       if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+       else if (divisor == 0)
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       else
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+
+       // Connect the A/D to the peak-detected low-frequency path.
+       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+
+       // Give it a bit of time for the resonant antenna to settle.
+       SpinDelay(50);
+
+       // Now set up the SSC to get the ADC samples that are now streaming at us.
+       FpgaSetupSsc();
+}
+
+void AcquireRawAdcSamples125k(int divisor)
+{
+       SetupToAcquireRawAdcSamples(divisor);
+       // Now call the acquisition routine
+       DoAcquisition125k_internal(false);
 }
 
 void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int period_1, uint8_t *command)
@@ -433,17 +447,17 @@ void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
 {
        int i;
        uint8_t *tab = (uint8_t *)BigBuf;
-
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);
-
+    
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
+    
        AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT | GPIO_SSC_CLK;
-
+    
        AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
        AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_CLK;
-
+    
 #define SHORT_COIL()   LOW(GPIO_SSC_DOUT)
 #define OPEN_COIL()            HIGH(GPIO_SSC_DOUT)
-
+    
        i = 0;
        for(;;) {
                while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {
@@ -453,18 +467,18 @@ void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
                        }
                        WDT_HIT();
                }
-
+        
                if (ledcontrol)
                        LED_D_ON();
-
+        
                if(tab[i])
                        OPEN_COIL();
                else
                        SHORT_COIL();
-
+        
                if (ledcontrol)
                        LED_D_OFF();
-
+        
                while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK) {
                        if(BUTTON_PRESS()) {
                                DbpString("Stopped");
@@ -472,7 +486,7 @@ void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
                        }
                        WDT_HIT();
                }
-
+        
                i++;
                if(i == period) {
                        i = 0;
@@ -484,197 +498,9 @@ void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
        }
 }
 
-/* Provides a framework for bidirectional LF tag communication
- * Encoding is currently Hitag2, but the general idea can probably
- * be transferred to other encodings.
- *
- * The new FPGA code will, for the LF simulator mode, give on SSC_FRAME
- * (PA15) a thresholded version of the signal from the ADC. Setting the
- * ADC path to the low frequency peak detection signal, will enable a
- * somewhat reasonable receiver for modulation on the carrier signal
- * that is generated by the reader. The signal is low when the reader
- * field is switched off, and high when the reader field is active. Due
- * to the way that the signal looks like, mostly only the rising edge is
- * useful, your mileage may vary.
- *
- * Neat perk: PA15 can not only be used as a bit-banging GPIO, but is also
- * TIOA1, which can be used as the capture input for timer 1. This should
- * make it possible to measure the exact edge-to-edge time, without processor
- * intervention.
- *
- * Arguments: divisor is the divisor to be sent to the FPGA (e.g. 95 for 125kHz)
- * t0 is the carrier frequency cycle duration in terms of MCK (384 for 125kHz)
- *
- * The following defines are in carrier periods:
- */
-#define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
-#define HITAG_T_1_MIN 24 /* T[1] should be 26..30 */
-#define HITAG_T_EOF   40 /* T_EOF should be > 36 */
-#define HITAG_T_WRESP 208 /* T_wresp should be 204..212 */
-
-static void hitag_handle_frame(int t0, int frame_len, char *frame);
-//#define DEBUG_RA_VALUES 1
 #define DEBUG_FRAME_CONTENTS 1
 void SimulateTagLowFrequencyBidir(int divisor, int t0)
 {
-#if DEBUG_RA_VALUES || DEBUG_FRAME_CONTENTS
-       int i = 0;
-#endif
-       char frame[10];
-       int frame_pos=0;
-
-       DbpString("Starting Hitag2 emulator, press button to end");
-       hitag2_init();
-
-       /* Set up simulator mode, frequency divisor which will drive the FPGA
-        * and analog mux selection.
-        */
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
-       RELAY_OFF();
-
-       /* Set up Timer 1:
-        * Capture mode, timer source MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
-        * external trigger rising edge, load RA on rising edge of TIOA, load RB on rising
-        * edge of TIOA. Assign PA15 to TIOA1 (peripheral B)
-        */
-
-       AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
-       AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
-       AT91C_BASE_TC1->TC_CMR =        AT91C_TC_CLKS_TIMER_DIV1_CLOCK |
-                                                               AT91C_TC_ETRGEDG_RISING |
-                                                               AT91C_TC_ABETRG |
-                                                               AT91C_TC_LDRA_RISING |
-                                                               AT91C_TC_LDRB_RISING;
-       AT91C_BASE_TC1->TC_CCR =        AT91C_TC_CLKEN |
-                                                               AT91C_TC_SWTRG;
-
-       /* calculate the new value for the carrier period in terms of TC1 values */
-       t0 = t0/2;
-
-       int overflow = 0;
-       while(!BUTTON_PRESS()) {
-               WDT_HIT();
-               if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
-                       int ra = AT91C_BASE_TC1->TC_RA;
-                       if((ra > t0*HITAG_T_EOF) | overflow) ra = t0*HITAG_T_EOF+1;
-#if DEBUG_RA_VALUES
-                       if(ra > 255 || overflow) ra = 255;
-                       ((char*)BigBuf)[i] = ra;
-                       i = (i+1) % 8000;
-#endif
-
-                       if(overflow || (ra > t0*HITAG_T_EOF) || (ra < t0*HITAG_T_0_MIN)) {
-                               /* Ignore */
-                       } else if(ra >= t0*HITAG_T_1_MIN ) {
-                               /* '1' bit */
-                               if(frame_pos < 8*sizeof(frame)) {
-                                       frame[frame_pos / 8] |= 1<<( 7-(frame_pos%8) );
-                                       frame_pos++;
-                               }
-                       } else if(ra >= t0*HITAG_T_0_MIN) {
-                               /* '0' bit */
-                               if(frame_pos < 8*sizeof(frame)) {
-                                       frame[frame_pos / 8] |= 0<<( 7-(frame_pos%8) );
-                                       frame_pos++;
-                               }
-                       }
-
-                       overflow = 0;
-                       LED_D_ON();
-               } else {
-                       if(AT91C_BASE_TC1->TC_CV > t0*HITAG_T_EOF) {
-                               /* Minor nuisance: In Capture mode, the timer can not be
-                                * stopped by a Compare C. There's no way to stop the clock
-                                * in software, so we'll just have to note the fact that an
-                                * overflow happened and the next loaded timer value might
-                                * have wrapped. Also, this marks the end of frame, and the
-                                * still running counter can be used to determine the correct
-                                * time for the start of the reply.
-                                */
-                               overflow = 1;
-
-                               if(frame_pos > 0) {
-                                       /* Have a frame, do something with it */
-#if DEBUG_FRAME_CONTENTS
-                                       ((char*)BigBuf)[i++] = frame_pos;
-                                       memcpy( ((char*)BigBuf)+i, frame, 7);
-                                       i+=7;
-                                       i = i % sizeof(BigBuf);
-#endif
-                                       hitag_handle_frame(t0, frame_pos, frame);
-                                       memset(frame, 0, sizeof(frame));
-                               }
-                               frame_pos = 0;
-
-                       }
-                       LED_D_OFF();
-               }
-       }
-       DbpString("All done");
-}
-
-static void hitag_send_bit(int t0, int bit) {
-       if(bit == 1) {
-               /* Manchester: Loaded, then unloaded */
-               LED_A_ON();
-               SHORT_COIL();
-               while(AT91C_BASE_TC1->TC_CV < t0*15);
-               OPEN_COIL();
-               while(AT91C_BASE_TC1->TC_CV < t0*31);
-               LED_A_OFF();
-       } else if(bit == 0) {
-               /* Manchester: Unloaded, then loaded */
-               LED_B_ON();
-               OPEN_COIL();
-               while(AT91C_BASE_TC1->TC_CV < t0*15);
-               SHORT_COIL();
-               while(AT91C_BASE_TC1->TC_CV < t0*31);
-               LED_B_OFF();
-       }
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset clock for the next bit */
-
-}
-static void hitag_send_frame(int t0, int frame_len, const char const * frame, int fdt)
-{
-       OPEN_COIL();
-       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
-
-       /* Wait for HITAG_T_WRESP carrier periods after the last reader bit,
-        * not that since the clock counts since the rising edge, but T_wresp is
-        * with respect to the falling edge, we need to wait actually (T_wresp - T_g)
-        * periods. The gap time T_g varies (4..10).
-        */
-       while(AT91C_BASE_TC1->TC_CV < t0*(fdt-8));
-
-       int saved_cmr = AT91C_BASE_TC1->TC_CMR;
-       AT91C_BASE_TC1->TC_CMR &= ~AT91C_TC_ETRGEDG; /* Disable external trigger for the clock */
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset the clock and use it for response timing */
-
-       int i;
-       for(i=0; i<5; i++)
-               hitag_send_bit(t0, 1); /* Start of frame */
-
-       for(i=0; i<frame_len; i++) {
-               hitag_send_bit(t0, !!(frame[i/ 8] & (1<<( 7-(i%8) ))) );
-       }
-
-       OPEN_COIL();
-       AT91C_BASE_TC1->TC_CMR = saved_cmr;
-}
-
-/* Callback structure to cleanly separate tag emulation code from the radio layer. */
-static int hitag_cb(const char* response_data, const int response_length, const int fdt, void *cb_cookie)
-{
-       hitag_send_frame(*(int*)cb_cookie, response_length, response_data, fdt);
-       return 0;
-}
-/* Frame length in bits, frame contents in MSBit first format */
-static void hitag_handle_frame(int t0, int frame_len, char *frame)
-{
-       hitag2_handle_command(frame, frame_len, hitag_cb, &t0);
 }
 
 // compose fc/8 fc/10 waveform
@@ -780,200 +606,242 @@ void CmdHIDsimTAG(int hi, int lo, int ledcontrol)
                LED_A_OFF();
 }
 
-
-// loop to capture raw HID waveform then FSK demodulate the TAG ID from it
-void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
+size_t fsk_demod(uint8_t * dest, size_t size)
 {
-       uint8_t *dest = (uint8_t *)BigBuf;
-       int m=0, n=0, i=0, idx=0, found=0, lastval=0;
-       uint32_t hi=0, lo=0;
+       uint32_t last_transition = 0;
+       uint32_t idx = 1;
 
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+       // we don't care about actual value, only if it's more or less than a
+       // threshold essentially we capture zero crossings for later analysis
+       uint8_t threshold_value = 127;
 
-       // Connect the A/D to the peak-detected low-frequency path.
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
 
-       // Give it a bit of time for the resonant antenna to settle.
-       SpinDelay(50);
+       // sync to first lo-hi transition, and threshold
 
-       // Now set up the SSC to get the ADC samples that are now streaming at us.
-       FpgaSetupSsc();
+       //Need to threshold first sample
+       if(dest[0] < threshold_value) dest[0] = 0;
+       else dest[0] = 1;
 
-       for(;;) {
-               WDT_HIT();
-               if (ledcontrol)
-                       LED_A_ON();
-               if(BUTTON_PRESS()) {
-                       DbpString("Stopped");
-                       if (ledcontrol)
-                               LED_A_OFF();
-                       return;
-               }
+       size_t numBits = 0;
+       // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
+       // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
+       // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
+       for(idx = 1; idx < size; idx++) {
+               // threshold current value
+               if (dest[idx] < threshold_value) dest[idx] = 0;
+               else dest[idx] = 1;
 
-               i = 0;
-               m = sizeof(BigBuf);
-               memset(dest,128,m);
-               for(;;) {
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                               AT91C_BASE_SSC->SSC_THR = 0x43;
-                               if (ledcontrol)
-                                       LED_D_ON();
-                       }
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                               // we don't care about actual value, only if it's more or less than a
-                               // threshold essentially we capture zero crossings for later analysis
-                               if(dest[i] < 127) dest[i] = 0; else dest[i] = 1;
-                               i++;
-                               if (ledcontrol)
-                                       LED_D_OFF();
-                               if(i >= m) {
-                                       break;
-                               }
+               // Check for 0->1 transition
+               if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
+
+                       if (idx-last_transition <  9) {
+                                       dest[numBits]=1;
+                       } else {
+                                       dest[numBits]=0;
                        }
+                       last_transition = idx;
+                       numBits++;
                }
+       }
+       return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
+}
 
-               // FSK demodulator
 
-               // sync to first lo-hi transition
-               for( idx=1; idx<m; idx++) {
-                       if (dest[idx-1]<dest[idx])
-                               lastval=idx;
-                               break;
+size_t aggregate_bits(uint8_t *dest,size_t size, uint8_t h2l_crossing_value,uint8_t l2h_crossing_value, uint8_t maxConsequtiveBits )
+{
+       uint8_t lastval=dest[0];
+       uint32_t idx=0;
+       size_t numBits=0;
+       uint32_t n=1;
+
+       for( idx=1; idx < size; idx++) {
+
+               if (dest[idx]==lastval) {
+                       n++;
+                       continue;
+               }
+               //if lastval was 1, we have a 1->0 crossing
+               if ( dest[idx-1] ) {
+                       n=(n+1) / h2l_crossing_value;
+               } else {// 0->1 crossing
+                       n=(n+1) / l2h_crossing_value;
                }
+               if (n == 0) n = 1;
+
+               if(n < maxConsequtiveBits)
+               {
+                       memset(dest+numBits, dest[idx-1] , n);
+                       numBits += n;
+               }
+               n=0;
+               lastval=dest[idx];
+       }//end for
+
+       return numBits;
+
+}
+// loop to capture raw HID waveform then FSK demodulate the TAG ID from it
+void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
+{
+       uint8_t *dest = (uint8_t *)BigBuf;
+
+       size_t size=0,idx=0; //, found=0;
+       uint32_t hi2=0, hi=0, lo=0;
+
+
+       while(!BUTTON_PRESS()) {
+
+               // Configure to go in 125Khz listen mode
+               SetupToAcquireRawAdcSamples(0);
+
                WDT_HIT();
+               if (ledcontrol) LED_A_ON();
 
-               // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
-               // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
-               // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
-               for( i=0; idx<m; idx++) {
-                       if (dest[idx-1]<dest[idx]) {
-                               dest[i]=idx-lastval;
-                               if (dest[i] <= 8) {
-                                               dest[i]=1;
-                               } else {
-                                               dest[i]=0;
-                               }
+               DoAcquisition125k_internal(true);
+               size  = sizeof(BigBuf);
 
-                               lastval=idx;
-                               i++;
-                       }
-               }
-               m=i;
+               // FSK demodulator
+               size = fsk_demod(dest, size);
                WDT_HIT();
 
                // we now have a set of cycle counts, loop over previous results and aggregate data into bit patterns
-               lastval=dest[0];
-               idx=0;
-               i=0;
-               n=0;
-               for( idx=0; idx<m; idx++) {
-                       if (dest[idx]==lastval) {
-                               n++;
-                       } else {
-                               // a bit time is five fc/10 or six fc/8 cycles so figure out how many bits a pattern width represents,
-                               // an extra fc/8 pattern preceeds every 4 bits (about 200 cycles) just to complicate things but it gets
-                               // swallowed up by rounding
-                               // expected results are 1 or 2 bits, any more and it's an invalid manchester encoding
-                               // special start of frame markers use invalid manchester states (no transitions) by using sequences
-                               // like 111000
-                               if (dest[idx-1]) {
-                                       n=(n+1)/6;                      // fc/8 in sets of 6
-                               } else {
-                                       n=(n+1)/5;                      // fc/10 in sets of 5
-                               }
-                               switch (n) {                    // stuff appropriate bits in buffer
-                                       case 0:
-                                       case 1: // one bit
-                                               dest[i++]=dest[idx-1];
-                                               break;
-                                       case 2: // two bits
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               break;
-                                       case 3: // 3 bit start of frame markers
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               break;
-                                       // When a logic 0 is immediately followed by the start of the next transmisson
-                                       // (special pattern) a pattern of 4 bit duration lengths is created.
-                                       case 4:
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               dest[i++]=dest[idx-1];
-                                               break;
-                                       default:        // this shouldn't happen, don't stuff any bits
-                                               break;
-                               }
-                               n=0;
-                               lastval=dest[idx];
-                       }
-               }
-               m=i;
+               // 1->0 : fc/8 in sets of 6
+               // 0->1 : fc/10 in sets of 5
+               size = aggregate_bits(dest,size, 6,5,5);
+
                WDT_HIT();
 
                // final loop, go over previously decoded manchester data and decode into usable tag ID
                // 111000 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0
-               for( idx=0; idx<m-6; idx++) {
+               uint8_t frame_marker_mask[] = {1,1,1,0,0,0};
+               int numshifts = 0;
+               idx = 0;
+               while( idx + sizeof(frame_marker_mask) < size) {
                        // search for a start of frame marker
-                       if ( dest[idx] && dest[idx+1] && dest[idx+2] && (!dest[idx+3]) && (!dest[idx+4]) && (!dest[idx+5]) )
-                       {
-                               found=1;
-                               idx+=6;
-                               if (found && (hi|lo)) {
-                                       Dbprintf("TAG ID: %x%08x (%d)",
-                                               (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
-                                       /* if we're only looking for one tag */
-                                       if (findone)
-                                       {
-                                               *high = hi;
-                                               *low = lo;
-                                               return;
-                                       }
-                                       hi=0;
-                                       lo=0;
-                                       found=0;
-                               }
-                       }
-                       if (found) {
-                               if (dest[idx] && (!dest[idx+1]) ) {
-                                       hi=(hi<<1)|(lo>>31);
-                                       lo=(lo<<1)|0;
-                               } else if ( (!dest[idx]) && dest[idx+1]) {
-                                       hi=(hi<<1)|(lo>>31);
-                                       lo=(lo<<1)|1;
-                               } else {
-                                       found=0;
-                                       hi=0;
-                                       lo=0;
+                       if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
+                       { // frame marker found
+                               idx+=sizeof(frame_marker_mask);
+
+                               while(dest[idx] != dest[idx+1] && idx < size-2)
+                               {       // Keep going until next frame marker (or error)
+                                       // Shift in a bit. Start by shifting high registers
+                                       hi2 = (hi2<<1)|(hi>>31);
+                                       hi = (hi<<1)|(lo>>31);
+                                       //Then, shift in a 0 or one into low
+                                       if (dest[idx] && !dest[idx+1])  // 1 0
+                                               lo=(lo<<1)|0;
+                                       else // 0 1
+                                               lo=(lo<<1)|
+                                                               1;
+                                       numshifts ++;
+                                       idx += 2;
                                }
-                               idx++;
-                       }
-                       if ( dest[idx] && dest[idx+1] && dest[idx+2] && (!dest[idx+3]) && (!dest[idx+4]) && (!dest[idx+5]) )
-                       {
-                               found=1;
-                               idx+=6;
-                               if (found && (hi|lo)) {
-                                       Dbprintf("TAG ID: %x%08x (%d)",
-                                               (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
-                                       /* if we're only looking for one tag */
-                                       if (findone)
-                                       {
-                                               *high = hi;
-                                               *low = lo;
-                                               return;
+                               //Dbprintf("Num shifts: %d ", numshifts);
+                               // Hopefully, we read a tag and  hit upon the next frame marker
+                               if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
+                               {
+                                       if (hi2 != 0){
+                                               Dbprintf("TAG ID: %x%08x%08x (%d)",
+                                                        (unsigned int) hi2, (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
+                                       }
+                                       else {
+                                               Dbprintf("TAG ID: %x%08x (%d)",
+                                                (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
                                        }
-                                       hi=0;
-                                       lo=0;
-                                       found=0;
                                }
+
+                               // reset
+                               hi2 = hi = lo = 0;
+                               numshifts = 0;
+                       }else
+                       {
+                               idx++;
                        }
                }
                WDT_HIT();
+
        }
+       DbpString("Stopped");
+       if (ledcontrol) LED_A_OFF();
+}
+
+uint32_t bytebits_to_byte(uint8_t* src, int numbits)
+{
+       uint32_t num = 0;
+       for(int i = 0 ; i < numbits ; i++)
+       {
+               num = (num << 1) | (*src);
+               src++;
+       }
+       return num;
+}
+
+
+void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
+{
+       uint8_t *dest = (uint8_t *)BigBuf;
+
+       size_t size=0, idx=0;
+       uint32_t code=0, code2=0;
+
+
+       while(!BUTTON_PRESS()) {
+
+               // Configure to go in 125Khz listen mode
+               SetupToAcquireRawAdcSamples(0);
+
+               WDT_HIT();
+               if (ledcontrol) LED_A_ON();
+
+               DoAcquisition125k_internal(true);
+               size  = sizeof(BigBuf);
+
+               // FSK demodulator
+               size = fsk_demod(dest, size);
+               WDT_HIT();
+
+               // we now have a set of cycle counts, loop over previous results and aggregate data into bit patterns
+               // 1->0 : fc/8 in sets of 7
+               // 0->1 : fc/10 in sets of 6
+               size = aggregate_bits(dest, size, 7,6,13);
+
+               WDT_HIT();
+               
+               //Handle the data
+           uint8_t mask[] = {0,0,0,0,0,0,0,0,0,1};
+               for( idx=0; idx < size - 64; idx++) {
+
+               if ( memcmp(dest + idx, mask, sizeof(mask)) ) continue;
+
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx],   dest[idx+1],   dest[idx+2],dest[idx+3],dest[idx+4],dest[idx+5],dest[idx+6],dest[idx+7]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+8], dest[idx+9], dest[idx+10],dest[idx+11],dest[idx+12],dest[idx+13],dest[idx+14],dest[idx+15]);                         
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+16],dest[idx+17],dest[idx+18],dest[idx+19],dest[idx+20],dest[idx+21],dest[idx+22],dest[idx+23]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+24],dest[idx+25],dest[idx+26],dest[idx+27],dest[idx+28],dest[idx+29],dest[idx+30],dest[idx+31]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+32],dest[idx+33],dest[idx+34],dest[idx+35],dest[idx+36],dest[idx+37],dest[idx+38],dest[idx+39]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+40],dest[idx+41],dest[idx+42],dest[idx+43],dest[idx+44],dest[idx+45],dest[idx+46],dest[idx+47]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+48],dest[idx+49],dest[idx+50],dest[idx+51],dest[idx+52],dest[idx+53],dest[idx+54],dest[idx+55]);
+                   Dbprintf("%d%d%d%d%d%d%d%d",dest[idx+56],dest[idx+57],dest[idx+58],dest[idx+59],dest[idx+60],dest[idx+61],dest[idx+62],dest[idx+63]);
+                       
+                   code = bytebits_to_byte(dest+idx,32);
+                   code2 = bytebits_to_byte(dest+idx+32,32); 
+
+                   short version = bytebits_to_byte(dest+idx+14,4); 
+                   char unknown = bytebits_to_byte(dest+idx+19,8) ;
+                   uint16_t number = bytebits_to_byte(dest+idx+36,9); 
+                   
+                   Dbprintf("XSF(%02d)%02x:%d (%08x%08x)",version,unknown,number,code,code2);
+                   if (ledcontrol)     LED_D_OFF();
+               
+                       // if we're only looking for one tag 
+                       if (findone){
+                               LED_A_OFF();
+                               return;
+                       }               
+               }
+               WDT_HIT();
+       }
+       DbpString("Stopped");
+       if (ledcontrol) LED_A_OFF();
 }
 
 /*------------------------------
@@ -1054,7 +922,7 @@ void T55xxWriteBit(int bit)
 }
 
 // Write one card block in page 0, no lock
-void T55xxWriteBlock(int Data, int Block)
+void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
 {
        unsigned int i;
 
@@ -1072,6 +940,11 @@ void T55xxWriteBlock(int Data, int Block)
        // Opcode
        T55xxWriteBit(1);
        T55xxWriteBit(0); //Page 0
+  if (PwdMode == 1){
+    // Pwd
+    for (i = 0x80000000; i != 0; i >>= 1)
+      T55xxWriteBit(Pwd & i);
+  }
        // Lock bit
        T55xxWriteBit(0);
 
@@ -1079,7 +952,7 @@ void T55xxWriteBlock(int Data, int Block)
        for (i = 0x80000000; i != 0; i >>= 1)
                T55xxWriteBit(Data & i);
 
-       // Page
+       // Block
        for (i = 0x04; i != 0; i >>= 1)
                T55xxWriteBit(Block & i);
 
@@ -1091,58 +964,265 @@ void T55xxWriteBlock(int Data, int Block)
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
 }
 
-// Copy HID id to card and setup block 0 config
-void CopyHIDtoT5567(int hi, int lo)
+// Read one card block in page 0
+void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
 {
-       int data1, data2, data3;
-
-       // Ensure no more than 44 bits supplied
-       if (hi>0xFFF) {
-               DbpString("Tags can only have 44 bits.");
-               return;
-       }
-
-       // Build the 3 data blocks for supplied 44bit ID
-       data1 = 0x1D000000; // load preamble
-
-       for (int i=0;i<12;i++) {
-               if (hi & (1<<(11-i)))
-                       data1 |= (1<<(((11-i)*2)+1)); // 1 -> 10
-               else
-                       data1 |= (1<<((11-i)*2)); // 0 -> 01
+       uint8_t *dest = (uint8_t *)BigBuf;
+       int m=0, i=0;
+  
+       m = sizeof(BigBuf);
+  // Clear destination buffer before sending the command
+       memset(dest, 128, m);
+       // Connect the A/D to the peak-detected low-frequency path.
+       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+       // Now set up the SSC to get the ADC samples that are now streaming at us.
+       FpgaSetupSsc();
+  
+       LED_D_ON();
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  
+       // Give it a bit of time for the resonant antenna to settle.
+       // And for the tag to fully power up
+       SpinDelay(150);
+  
+       // Now start writting
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelayUs(START_GAP);
+  
+       // Opcode
+       T55xxWriteBit(1);
+       T55xxWriteBit(0); //Page 0
+       if (PwdMode == 1){
+               // Pwd
+               for (i = 0x80000000; i != 0; i >>= 1)
+                       T55xxWriteBit(Pwd & i);
        }
-
-       data2 = 0;
-       for (int i=0;i<16;i++) {
-               if (lo & (1<<(31-i)))
-                       data2 |= (1<<(((15-i)*2)+1)); // 1 -> 10
-               else
-                       data2 |= (1<<((15-i)*2)); // 0 -> 01
+       // Lock bit
+       T55xxWriteBit(0);
+       // Block
+       for (i = 0x04; i != 0; i >>= 1)
+               T55xxWriteBit(Block & i);
+  
+  // Turn field on to read the response
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  
+       // Now do the acquisition
+       i = 0;
+       for(;;) {
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                       AT91C_BASE_SSC->SSC_THR = 0x43;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
+                       dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       // we don't care about actual value, only if it's more or less than a
+                       // threshold essentially we capture zero crossings for later analysis
+      //                       if(dest[i] < 127) dest[i] = 0; else dest[i] = 1;
+                       i++;
+                       if (i >= m) break;
+               }
        }
+  
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+       LED_D_OFF();
+       DbpString("DONE!");
+}
 
-       data3 = 0;
-       for (int i=0;i<16;i++) {
-               if (lo & (1<<(15-i)))
-                       data3 |= (1<<(((15-i)*2)+1)); // 1 -> 10
-               else
-                       data3 |= (1<<((15-i)*2)); // 0 -> 01
+// Read card traceability data (page 1)
+void T55xxReadTrace(void){
+       uint8_t *dest = (uint8_t *)BigBuf;
+       int m=0, i=0;
+  
+       m = sizeof(BigBuf);
+  // Clear destination buffer before sending the command
+       memset(dest, 128, m);
+       // Connect the A/D to the peak-detected low-frequency path.
+       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+       // Now set up the SSC to get the ADC samples that are now streaming at us.
+       FpgaSetupSsc();
+  
+       LED_D_ON();
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  
+       // Give it a bit of time for the resonant antenna to settle.
+       // And for the tag to fully power up
+       SpinDelay(150);
+  
+       // Now start writting
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelayUs(START_GAP);
+  
+       // Opcode
+       T55xxWriteBit(1);
+       T55xxWriteBit(1); //Page 1
+  
+  // Turn field on to read the response
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  
+       // Now do the acquisition
+       i = 0;
+       for(;;) {
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                       AT91C_BASE_SSC->SSC_THR = 0x43;
+               }
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
+                       dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       i++;
+                       if (i >= m) break;
+               }
        }
+  
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+       LED_D_OFF();
+       DbpString("DONE!");
+}
 
-       // Program the 3 data blocks for supplied 44bit ID
+/*-------------- Cloning routines -----------*/
+// Copy HID id to card and setup block 0 config
+void CopyHIDtoT55x7(uint32_t hi2, uint32_t hi, uint32_t lo, uint8_t longFMT)
+{
+       int data1=0, data2=0, data3=0, data4=0, data5=0, data6=0; //up to six blocks for long format
+       int last_block = 0;
+  
+  if (longFMT){
+         // Ensure no more than 84 bits supplied
+         if (hi2>0xFFFFF) {
+                 DbpString("Tags can only have 84 bits.");
+                 return;
+         }
+    // Build the 6 data blocks for supplied 84bit ID
+    last_block = 6;
+    data1 = 0x1D96A900; // load preamble (1D) & long format identifier (9E manchester encoded)
+         for (int i=0;i<4;i++) {
+                 if (hi2 & (1<<(19-i)))
+                         data1 |= (1<<(((3-i)*2)+1)); // 1 -> 10
+                 else
+                         data1 |= (1<<((3-i)*2)); // 0 -> 01
+         }
+    
+       data2 = 0;
+       for (int i=0;i<16;i++) {
+               if (hi2 & (1<<(15-i)))
+                       data2 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data2 |= (1<<((15-i)*2)); // 0 -> 01
+    }
+    
+       data3 = 0;
+       for (int i=0;i<16;i++) {
+               if (hi & (1<<(31-i)))
+                       data3 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data3 |= (1<<((15-i)*2)); // 0 -> 01
+       }
+    
+       data4 = 0;
+       for (int i=0;i<16;i++) {
+               if (hi & (1<<(15-i)))
+                       data4 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data4 |= (1<<((15-i)*2)); // 0 -> 01
+    }
+    
+       data5 = 0;
+       for (int i=0;i<16;i++) {
+               if (lo & (1<<(31-i)))
+                       data5 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data5 |= (1<<((15-i)*2)); // 0 -> 01
+       }
+    
+       data6 = 0;
+       for (int i=0;i<16;i++) {
+               if (lo & (1<<(15-i)))
+                       data6 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data6 |= (1<<((15-i)*2)); // 0 -> 01
+    }
+  }
+  else {
+         // Ensure no more than 44 bits supplied
+         if (hi>0xFFF) {
+                 DbpString("Tags can only have 44 bits.");
+                 return;
+         }
+    
+       // Build the 3 data blocks for supplied 44bit ID
+       last_block = 3;
+       
+       data1 = 0x1D000000; // load preamble
+    
+    for (int i=0;i<12;i++) {
+      if (hi & (1<<(11-i)))
+        data1 |= (1<<(((11-i)*2)+1)); // 1 -> 10
+      else
+        data1 |= (1<<((11-i)*2)); // 0 -> 01
+    }
+    
+       data2 = 0;
+       for (int i=0;i<16;i++) {
+               if (lo & (1<<(31-i)))
+                       data2 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data2 |= (1<<((15-i)*2)); // 0 -> 01
+       }
+    
+       data3 = 0;
+       for (int i=0;i<16;i++) {
+               if (lo & (1<<(15-i)))
+                       data3 |= (1<<(((15-i)*2)+1)); // 1 -> 10
+               else
+                       data3 |= (1<<((15-i)*2)); // 0 -> 01
+       }
+  }
+  
+       LED_D_ON();
+       // Program the data blocks for supplied ID
        // and the block 0 for HID format
-       T55xxWriteBlock(data1,1);
-       T55xxWriteBlock(data2,2);
-       T55xxWriteBlock(data3,3);
-
-       // Config for HID (RF/50, FSK2a, Maxblock=3)
-       T55xxWriteBlock(T55x7_BITRATE_RF_50         |
-                       T55x7_MODULATION_MANCHESTER |
-                       3 << T55x7_MAXBLOCK_SHIFT,
-                       0);
-
+       T55xxWriteBlock(data1,1,0,0);
+       T55xxWriteBlock(data2,2,0,0);
+       T55xxWriteBlock(data3,3,0,0);
+       
+       if (longFMT) { // if long format there are 6 blocks
+         T55xxWriteBlock(data4,4,0,0);
+         T55xxWriteBlock(data5,5,0,0);
+         T55xxWriteBlock(data6,6,0,0);
+  }
+  
+       // Config for HID (RF/50, FSK2a, Maxblock=3 for short/6 for long)
+       T55xxWriteBlock(T55x7_BITRATE_RF_50    |
+                  T55x7_MODULATION_FSK2a |
+                  last_block << T55x7_MAXBLOCK_SHIFT,
+                  0,0,0);
+  
+       LED_D_OFF();
+       
        DbpString("DONE!");
 }
 
+void CopyIOtoT55x7(uint32_t hi, uint32_t lo, uint8_t longFMT)
+{
+   int data1=0, data2=0; //up to six blocks for long format
+       
+    data1 = hi;  // load preamble
+    data2 = lo;
+    
+    LED_D_ON();
+    // Program the data blocks for supplied ID
+    // and the block 0 for HID format
+    T55xxWriteBlock(data1,1,0,0);
+    T55xxWriteBlock(data2,2,0,0);
+       
+    //Config Block
+    T55xxWriteBlock(0x00147040,0,0,0);
+    LED_D_OFF();
+       
+    DbpString("DONE!");
+}
+
 // Define 9bit header for EM410x tags
 #define EM410X_HEADER          0x1FF
 #define EM410X_ID_LENGTH       40
@@ -1154,6 +1234,7 @@ void WriteEM410x(uint32_t card, uint32_t id_hi, uint32_t id_lo)
        uint64_t rev_id = 0;    // reversed ID
        int c_parity[4];        // column parity
        int r_parity = 0;       // row parity
+       uint32_t clock = 0;
 
        // Reverse ID bits given as parameter (for simpler operations)
        for (i = 0; i < EM410X_ID_LENGTH; ++i) {
@@ -1207,24 +1288,568 @@ void WriteEM410x(uint32_t card, uint32_t id_hi, uint32_t id_lo)
        LED_D_ON();
 
        // Write EM410x ID
-       T55xxWriteBlock((uint32_t)(id >> 32), 1);
-       T55xxWriteBlock((uint32_t)id, 2);
+       T55xxWriteBlock((uint32_t)(id >> 32), 1, 0, 0);
+       T55xxWriteBlock((uint32_t)id, 2, 0, 0);
 
        // Config for EM410x (RF/64, Manchester, Maxblock=2)
-       if (card)
+       if (card) {
+               // Clock rate is stored in bits 8-15 of the card value
+               clock = (card & 0xFF00) >> 8;
+               Dbprintf("Clock rate: %d", clock);
+               switch (clock)
+               {
+                       case 32:
+                               clock = T55x7_BITRATE_RF_32;
+                               break;
+                       case 16:
+                               clock = T55x7_BITRATE_RF_16;
+                               break;
+                       case 0:
+                               // A value of 0 is assumed to be 64 for backwards-compatibility
+                               // Fall through...
+                       case 64:
+                               clock = T55x7_BITRATE_RF_64;
+                               break;      
+                       default:
+                               Dbprintf("Invalid clock rate: %d", clock);
+                               return;
+               }
+
                // Writing configuration for T55x7 tag
-               T55xxWriteBlock(T55x7_BITRATE_RF_64         |
+               T55xxWriteBlock(clock       |
                                T55x7_MODULATION_MANCHESTER |
                                2 << T55x7_MAXBLOCK_SHIFT,
-                               0);
+                               0, 0, 0);
+  }
        else
                // Writing configuration for T5555(Q5) tag
                T55xxWriteBlock(0x1F << T5555_BITRATE_SHIFT |
                                T5555_MODULATION_MANCHESTER   |
                                2 << T5555_MAXBLOCK_SHIFT,
-                               0);
+                               0, 0, 0);
 
        LED_D_OFF();
        Dbprintf("Tag %s written with 0x%08x%08x\n", card ? "T55x7":"T5555",
                                        (uint32_t)(id >> 32), (uint32_t)id);
 }
+
+// Clone Indala 64-bit tag by UID to T55x7
+void CopyIndala64toT55x7(int hi, int lo)
+{
+
+       //Program the 2 data blocks for supplied 64bit UID
+       // and the block 0 for Indala64 format
+       T55xxWriteBlock(hi,1,0,0);
+       T55xxWriteBlock(lo,2,0,0);
+       //Config for Indala (RF/32;PSK1 with RF/2;Maxblock=2)
+       T55xxWriteBlock(T55x7_BITRATE_RF_32    |
+                       T55x7_MODULATION_PSK1 |
+                       2 << T55x7_MAXBLOCK_SHIFT,
+                       0, 0, 0);
+       //Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=2;Inverse data)
+//     T5567WriteBlock(0x603E1042,0);
+
+       DbpString("DONE!");
+
+}      
+
+void CopyIndala224toT55x7(int uid1, int uid2, int uid3, int uid4, int uid5, int uid6, int uid7)
+{
+
+       //Program the 7 data blocks for supplied 224bit UID
+       // and the block 0 for Indala224 format
+       T55xxWriteBlock(uid1,1,0,0);
+       T55xxWriteBlock(uid2,2,0,0);
+       T55xxWriteBlock(uid3,3,0,0);
+       T55xxWriteBlock(uid4,4,0,0);
+       T55xxWriteBlock(uid5,5,0,0);
+       T55xxWriteBlock(uid6,6,0,0);
+       T55xxWriteBlock(uid7,7,0,0);
+       //Config for Indala (RF/32;PSK1 with RF/2;Maxblock=7)
+       T55xxWriteBlock(T55x7_BITRATE_RF_32    |
+                       T55x7_MODULATION_PSK1 |
+                       7 << T55x7_MAXBLOCK_SHIFT,
+                       0,0,0);
+       //Alternative config for Indala (Extended mode;RF/32;PSK1 with RF/2;Maxblock=7;Inverse data)
+//     T5567WriteBlock(0x603E10E2,0);
+
+       DbpString("DONE!");
+
+}
+
+
+#define abs(x) ( ((x)<0) ? -(x) : (x) )
+#define max(x,y) ( x<y ? y:x)
+
+int DemodPCF7931(uint8_t **outBlocks) {
+       uint8_t BitStream[256];
+       uint8_t Blocks[8][16];
+       uint8_t *GraphBuffer = (uint8_t *)BigBuf;
+       int GraphTraceLen = sizeof(BigBuf);
+       int i, j, lastval, bitidx, half_switch;
+       int clock = 64;
+       int tolerance = clock / 8;
+       int pmc, block_done;
+       int lc, warnings = 0;
+       int num_blocks = 0;
+       int lmin=128, lmax=128;
+       uint8_t dir;
+       
+       AcquireRawAdcSamples125k(0);
+       
+       lmin = 64;
+       lmax = 192;
+       
+       i = 2;
+       
+       /* Find first local max/min */
+       if(GraphBuffer[1] > GraphBuffer[0]) {
+    while(i < GraphTraceLen) {
+      if( !(GraphBuffer[i] > GraphBuffer[i-1]) && GraphBuffer[i] > lmax)
+        break;
+      i++;
+    }
+    dir = 0;
+       }
+       else {
+    while(i < GraphTraceLen) {
+      if( !(GraphBuffer[i] < GraphBuffer[i-1]) && GraphBuffer[i] < lmin)
+        break;
+      i++;
+    }
+    dir = 1;
+       }
+       
+       lastval = i++;
+       half_switch = 0;
+       pmc = 0;
+       block_done = 0;
+       
+       for (bitidx = 0; i < GraphTraceLen; i++)
+       {
+    if ( (GraphBuffer[i-1] > GraphBuffer[i] && dir == 1 && GraphBuffer[i] > lmax) || (GraphBuffer[i-1] < GraphBuffer[i] && dir == 0 && GraphBuffer[i] < lmin))
+    {
+      lc = i - lastval;
+      lastval = i;
+      
+      // Switch depending on lc length:
+      // Tolerance is 1/8 of clock rate (arbitrary)
+      if (abs(lc-clock/4) < tolerance) {
+        // 16T0
+        if((i - pmc) == lc) { /* 16T0 was previous one */
+          /* It's a PMC ! */
+          i += (128+127+16+32+33+16)-1;
+          lastval = i;
+          pmc = 0;
+          block_done = 1;
+        }
+        else {
+          pmc = i;
+        }
+      } else if (abs(lc-clock/2) < tolerance) {
+        // 32TO
+        if((i - pmc) == lc) { /* 16T0 was previous one */
+          /* It's a PMC ! */
+          i += (128+127+16+32+33)-1;
+          lastval = i;
+          pmc = 0;
+          block_done = 1;
+        }
+        else if(half_switch == 1) {
+          BitStream[bitidx++] = 0;
+          half_switch = 0;
+        }
+        else
+          half_switch++;
+      } else if (abs(lc-clock) < tolerance) {
+        // 64TO
+        BitStream[bitidx++] = 1;
+      } else {
+        // Error
+        warnings++;
+        if (warnings > 10)
+        {
+          Dbprintf("Error: too many detection errors, aborting.");
+          return 0;
+        }
+      }
+      
+      if(block_done == 1) {
+        if(bitidx == 128) {
+          for(j=0; j<16; j++) {
+            Blocks[num_blocks][j] = 128*BitStream[j*8+7]+
+            64*BitStream[j*8+6]+
+            32*BitStream[j*8+5]+
+            16*BitStream[j*8+4]+
+            8*BitStream[j*8+3]+
+            4*BitStream[j*8+2]+
+            2*BitStream[j*8+1]+
+            BitStream[j*8];
+          }
+          num_blocks++;
+        }
+        bitidx = 0;
+        block_done = 0;
+        half_switch = 0;
+      }
+      if (GraphBuffer[i-1] > GraphBuffer[i]) dir=0;
+      else dir = 1;
+    }
+    if(bitidx==255)
+      bitidx=0;
+    warnings = 0;
+    if(num_blocks == 4) break;
+       }
+       memcpy(outBlocks, Blocks, 16*num_blocks);
+       return num_blocks;
+}
+
+int IsBlock0PCF7931(uint8_t *Block) {
+       // Assume RFU means 0 :)
+       if((memcmp(Block, "\x00\x00\x00\x00\x00\x00\x00\x01", 8) == 0) && memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) // PAC enabled
+    return 1;
+       if((memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) && Block[7] == 0) // PAC disabled, can it *really* happen ?
+    return 1;
+       return 0;
+}
+
+int IsBlock1PCF7931(uint8_t *Block) {
+       // Assume RFU means 0 :)
+       if(Block[10] == 0 && Block[11] == 0 && Block[12] == 0 && Block[13] == 0)
+    if((Block[14] & 0x7f) <= 9 && Block[15] <= 9)
+      return 1;
+       
+       return 0;
+}
+
+#define ALLOC 16
+
+void ReadPCF7931() {
+       uint8_t Blocks[8][17];
+       uint8_t tmpBlocks[4][16];
+       int i, j, ind, ind2, n;
+       int num_blocks = 0;
+       int max_blocks = 8;
+       int ident = 0;
+       int error = 0;
+       int tries = 0;
+       
+       memset(Blocks, 0, 8*17*sizeof(uint8_t));
+       
+       do {
+    memset(tmpBlocks, 0, 4*16*sizeof(uint8_t));
+    n = DemodPCF7931((uint8_t**)tmpBlocks);
+    if(!n)
+      error++;
+    if(error==10 && num_blocks == 0) {
+      Dbprintf("Error, no tag or bad tag");
+      return;
+    }
+    else if (tries==20 || error==10) {
+      Dbprintf("Error reading the tag");
+      Dbprintf("Here is the partial content");
+      goto end;
+    }
+    
+    for(i=0; i<n; i++)
+      Dbprintf("(dbg) %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
+               tmpBlocks[i][0], tmpBlocks[i][1], tmpBlocks[i][2], tmpBlocks[i][3], tmpBlocks[i][4], tmpBlocks[i][5], tmpBlocks[i][6], tmpBlocks[i][7],
+               tmpBlocks[i][8], tmpBlocks[i][9], tmpBlocks[i][10], tmpBlocks[i][11], tmpBlocks[i][12], tmpBlocks[i][13], tmpBlocks[i][14], tmpBlocks[i][15]);
+    if(!ident) {
+      for(i=0; i<n; i++) {
+        if(IsBlock0PCF7931(tmpBlocks[i])) {
+          // Found block 0 ?
+          if(i < n-1 && IsBlock1PCF7931(tmpBlocks[i+1])) {
+            // Found block 1!
+            // \o/
+            ident = 1;
+            memcpy(Blocks[0], tmpBlocks[i], 16);
+            Blocks[0][ALLOC] = 1;
+            memcpy(Blocks[1], tmpBlocks[i+1], 16);
+            Blocks[1][ALLOC] = 1;
+            max_blocks = max((Blocks[1][14] & 0x7f), Blocks[1][15]) + 1;
+            // Debug print
+            Dbprintf("(dbg) Max blocks: %d", max_blocks);
+            num_blocks = 2;
+            // Handle following blocks
+            for(j=i+2, ind2=2; j!=i; j++, ind2++, num_blocks++) {
+              if(j==n) j=0;
+              if(j==i) break;
+              memcpy(Blocks[ind2], tmpBlocks[j], 16);
+              Blocks[ind2][ALLOC] = 1;
+            }
+            break;
+          }
+        }
+      }
+    }
+    else {
+      for(i=0; i<n; i++) { // Look for identical block in known blocks
+        if(memcmp(tmpBlocks[i], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16)) { // Block is not full of 00
+          for(j=0; j<max_blocks; j++) {
+            if(Blocks[j][ALLOC] == 1 && !memcmp(tmpBlocks[i], Blocks[j], 16)) {
+              // Found an identical block
+              for(ind=i-1,ind2=j-1; ind >= 0; ind--,ind2--) {
+                if(ind2 < 0)
+                  ind2 = max_blocks;
+                if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
+                  // Dbprintf("Tmp %d -> Block %d", ind, ind2);
+                  memcpy(Blocks[ind2], tmpBlocks[ind], 16);
+                  Blocks[ind2][ALLOC] = 1;
+                  num_blocks++;
+                  if(num_blocks == max_blocks) goto end;
+                }
+              }
+              for(ind=i+1,ind2=j+1; ind < n; ind++,ind2++) {
+                if(ind2 > max_blocks)
+                  ind2 = 0;
+                if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
+                  // Dbprintf("Tmp %d -> Block %d", ind, ind2);
+                  memcpy(Blocks[ind2], tmpBlocks[ind], 16);
+                  Blocks[ind2][ALLOC] = 1;
+                  num_blocks++;
+                  if(num_blocks == max_blocks) goto end;
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+    tries++;
+    if (BUTTON_PRESS()) return;
+       } while (num_blocks != max_blocks);
+end:
+       Dbprintf("-----------------------------------------");
+       Dbprintf("Memory content:");
+       Dbprintf("-----------------------------------------");
+       for(i=0; i<max_blocks; i++) {
+    if(Blocks[i][ALLOC]==1)
+      Dbprintf("%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
+               Blocks[i][0], Blocks[i][1], Blocks[i][2], Blocks[i][3], Blocks[i][4], Blocks[i][5], Blocks[i][6], Blocks[i][7],
+               Blocks[i][8], Blocks[i][9], Blocks[i][10], Blocks[i][11], Blocks[i][12], Blocks[i][13], Blocks[i][14], Blocks[i][15]);
+    else
+      Dbprintf("<missing block %d>", i);
+       }
+       Dbprintf("-----------------------------------------");
+       
+       return ;
+}
+
+
+//-----------------------------------
+// EM4469 / EM4305 routines
+//-----------------------------------
+#define FWD_CMD_LOGIN 0xC //including the even parity, binary mirrored
+#define FWD_CMD_WRITE 0xA
+#define FWD_CMD_READ 0x9
+#define FWD_CMD_DISABLE 0x5
+
+
+uint8_t forwardLink_data[64]; //array of forwarded bits
+uint8_t * forward_ptr; //ptr for forward message preparation
+uint8_t fwd_bit_sz; //forwardlink bit counter
+uint8_t * fwd_write_ptr; //forwardlink bit pointer
+
+//====================================================================
+// prepares command bits
+// see EM4469 spec
+//====================================================================
+//--------------------------------------------------------------------
+uint8_t Prepare_Cmd( uint8_t cmd ) {
+  //--------------------------------------------------------------------
+  
+  *forward_ptr++ = 0; //start bit
+  *forward_ptr++ = 0; //second pause for 4050 code
+  
+  *forward_ptr++ = cmd;
+  cmd >>= 1;
+  *forward_ptr++ = cmd;
+  cmd >>= 1;
+  *forward_ptr++ = cmd;
+  cmd >>= 1;
+  *forward_ptr++ = cmd;
+  
+  return 6; //return number of emited bits
+}
+
+//====================================================================
+// prepares address bits
+// see EM4469 spec
+//====================================================================
+
+//--------------------------------------------------------------------
+uint8_t Prepare_Addr( uint8_t addr ) {
+  //--------------------------------------------------------------------
+  
+  register uint8_t line_parity;
+  
+  uint8_t i;
+  line_parity = 0;
+  for(i=0;i<6;i++) {
+    *forward_ptr++ = addr;
+    line_parity ^= addr;
+    addr >>= 1;
+  }
+  
+  *forward_ptr++ = (line_parity & 1);
+  
+  return 7; //return number of emited bits
+}
+
+//====================================================================
+// prepares data bits intreleaved with parity bits
+// see EM4469 spec
+//====================================================================
+
+//--------------------------------------------------------------------
+uint8_t Prepare_Data( uint16_t data_low, uint16_t data_hi) {
+  //--------------------------------------------------------------------
+  
+  register uint8_t line_parity;
+  register uint8_t column_parity;
+  register uint8_t i, j;
+  register uint16_t data;
+  
+  data = data_low;
+  column_parity = 0;
+  
+  for(i=0; i<4; i++) {
+    line_parity = 0;
+    for(j=0; j<8; j++) {
+      line_parity ^= data;
+      column_parity ^= (data & 1) << j;
+      *forward_ptr++ = data;
+      data >>= 1;
+    }
+    *forward_ptr++ = line_parity;
+    if(i == 1)
+      data = data_hi;
+  }
+  
+  for(j=0; j<8; j++) {
+    *forward_ptr++ = column_parity;
+    column_parity >>= 1;
+  }
+  *forward_ptr = 0;
+  
+  return 45; //return number of emited bits
+}
+
+//====================================================================
+// Forward Link send function
+// Requires: forwarLink_data filled with valid bits (1 bit per byte)
+// fwd_bit_count set with number of bits to be sent
+//====================================================================
+void SendForward(uint8_t fwd_bit_count) {
+  
+  fwd_write_ptr = forwardLink_data;
+  fwd_bit_sz = fwd_bit_count;
+  
+  LED_D_ON();
+  
+  //Field on
+  FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  
+  // Give it a bit of time for the resonant antenna to settle.
+  // And for the tag to fully power up
+  SpinDelay(150);
+  
+  // force 1st mod pulse (start gap must be longer for 4305)
+  fwd_bit_sz--; //prepare next bit modulation
+  fwd_write_ptr++;
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+  SpinDelayUs(55*8); //55 cycles off (8us each)for 4305
+  FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);//field on
+  SpinDelayUs(16*8); //16 cycles on (8us each)
+  
+  // now start writting
+  while(fwd_bit_sz-- > 0) { //prepare next bit modulation
+    if(((*fwd_write_ptr++) & 1) == 1)
+      SpinDelayUs(32*8); //32 cycles at 125Khz (8us each)
+    else {
+      //These timings work for 4469/4269/4305 (with the 55*8 above)
+      FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+      SpinDelayUs(23*8); //16-4 cycles off (8us each)
+      FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+      FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);//field on
+      SpinDelayUs(9*8); //16 cycles on (8us each)
+    }
+  }
+}
+
+void EM4xLogin(uint32_t Password) {
+  
+  uint8_t fwd_bit_count;
+  
+  forward_ptr = forwardLink_data;
+  fwd_bit_count = Prepare_Cmd( FWD_CMD_LOGIN );
+  fwd_bit_count += Prepare_Data( Password&0xFFFF, Password>>16 );
+  
+  SendForward(fwd_bit_count);
+  
+  //Wait for command to complete
+  SpinDelay(20);
+  
+}
+
+void EM4xReadWord(uint8_t Address, uint32_t Pwd, uint8_t PwdMode) {
+  
+  uint8_t fwd_bit_count;
+  uint8_t *dest = (uint8_t *)BigBuf;
+  int m=0, i=0;
+  
+  //If password mode do login
+  if (PwdMode == 1) EM4xLogin(Pwd);
+  
+  forward_ptr = forwardLink_data;
+  fwd_bit_count = Prepare_Cmd( FWD_CMD_READ );
+  fwd_bit_count += Prepare_Addr( Address );
+  
+  m = sizeof(BigBuf);
+  // Clear destination buffer before sending the command
+  memset(dest, 128, m);
+  // Connect the A/D to the peak-detected low-frequency path.
+  SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+  // Now set up the SSC to get the ADC samples that are now streaming at us.
+  FpgaSetupSsc();
+  
+  SendForward(fwd_bit_count);
+  
+  // Now do the acquisition
+  i = 0;
+  for(;;) {
+    if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+      AT91C_BASE_SSC->SSC_THR = 0x43;
+    }
+    if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
+      dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+      i++;
+      if (i >= m) break;
+    }
+  }
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+  LED_D_OFF();
+}
+
+void EM4xWriteWord(uint32_t Data, uint8_t Address, uint32_t Pwd, uint8_t PwdMode) {
+  
+  uint8_t fwd_bit_count;
+  
+  //If password mode do login
+  if (PwdMode == 1) EM4xLogin(Pwd);
+  
+  forward_ptr = forwardLink_data;
+  fwd_bit_count = Prepare_Cmd( FWD_CMD_WRITE );
+  fwd_bit_count += Prepare_Addr( Address );
+  fwd_bit_count += Prepare_Data( Data&0xFFFF, Data>>16 );
+  
+  SendForward(fwd_bit_count);
+  
+  //Wait for write to complete
+  SpinDelay(20);
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+  LED_D_OFF();
+}
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