]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/lfops.c
Merge pull request #1 from midnitesnake/master
[proxmark3-svn] / armsrc / lfops.c
index 7ba0ad130918333fd314391e6206884cb92d9199..fbd07e65f8705e6fb76d610db9bdc27b40758361 100644 (file)
-//-----------------------------------------------------------------------------\r
-// Miscellaneous routines for low frequency tag operations.\r
-// Tags supported here so far are Texas Instruments (TI), HID\r
-// Also routines for raw mode reading/simulating of LF waveform\r
-//\r
-//-----------------------------------------------------------------------------\r
-#include <proxmark3.h>\r
-#include "apps.h"\r
-#include "hitag2.h"\r
-#include "../common/crc16.c"\r
-\r
-int sprintf(char *dest, const char *fmt, ...);\r
-\r
-void AcquireRawAdcSamples125k(BOOL at134khz)\r
-{\r
-       if (at134khz)\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-       else\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);\r
-\r
-       // Connect the A/D to the peak-detected low-frequency path.\r
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);\r
-\r
-       // Give it a bit of time for the resonant antenna to settle.\r
-       SpinDelay(50);\r
-\r
-       // Now set up the SSC to get the ADC samples that are now streaming at us.\r
-       FpgaSetupSsc();\r
-\r
-       // Now call the acquisition routine\r
-       DoAcquisition125k();\r
-}\r
-\r
-// split into two routines so we can avoid timing issues after sending commands //\r
-void DoAcquisition125k(void)\r
-{\r
-       BYTE *dest = (BYTE *)BigBuf;\r
-       int n = sizeof(BigBuf);\r
-       int i;\r
-       \r
-       memset(dest, 0, n);\r
-       i = 0;\r
-       for(;;) {\r
-               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {\r
-                       AT91C_BASE_SSC->SSC_THR = 0x43;\r
-                       LED_D_ON();\r
-               }\r
-               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {\r
-                       dest[i] = (BYTE)AT91C_BASE_SSC->SSC_RHR;\r
-                       i++;\r
-                       LED_D_OFF();\r
-                       if (i >= n) break;\r
-               }\r
-       }\r
-       Dbprintf("read samples, dest[0]=%x dest[1]=%x", dest[0], dest[1]);\r
-}\r
-\r
-void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int period_1, BYTE *command)\r
-{\r
-       BOOL at134khz;\r
-\r
-       /* Make sure the tag is reset */\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);\r
-       SpinDelay(2500);\r
-       \r
-       // see if 'h' was specified\r
-       if (command[strlen((char *) command) - 1] == 'h')\r
-               at134khz = TRUE;\r
-       else\r
-               at134khz = FALSE;\r
-\r
-       if (at134khz)\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-       else\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);\r
-\r
-       // Give it a bit of time for the resonant antenna to settle.\r
-       SpinDelay(50);\r
-       // And a little more time for the tag to fully power up\r
-       SpinDelay(2000);\r
-\r
-       // Now set up the SSC to get the ADC samples that are now streaming at us.\r
-       FpgaSetupSsc();\r
-\r
-       // now modulate the reader field\r
-       while(*command != '\0' && *command != ' ') {\r
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);\r
-               LED_D_OFF();\r
-               SpinDelayUs(delay_off);\r
-               if (at134khz)\r
-                       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-               else\r
-                       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz\r
-\r
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);\r
-               LED_D_ON();\r
-               if(*(command++) == '0')\r
-                       SpinDelayUs(period_0);\r
-               else\r
-                       SpinDelayUs(period_1);\r
-       }\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);\r
-       LED_D_OFF();\r
-       SpinDelayUs(delay_off);\r
-       if (at134khz)\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-       else\r
-               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);\r
-\r
-       // now do the read\r
-       DoAcquisition125k();\r
-}\r
-\r
-/* blank r/w tag data stream\r
-...0000000000000000 01111111\r
-1010101010101010101010101010101010101010101010101010101010101010\r
-0011010010100001\r
-01111111\r
-101010101010101[0]000...\r
-\r
-[5555fe852c5555555555555555fe0000]\r
-*/\r
-void ReadTItag(void)\r
-{\r
-       // some hardcoded initial params\r
-       // when we read a TI tag we sample the zerocross line at 2Mhz\r
-       // TI tags modulate a 1 as 16 cycles of 123.2Khz\r
-       // TI tags modulate a 0 as 16 cycles of 134.2Khz\r
-       #define FSAMPLE 2000000\r
-       #define FREQLO 123200\r
-       #define FREQHI 134200\r
-\r
-       signed char *dest = (signed char *)BigBuf;\r
-       int n = sizeof(BigBuf);\r
-//     int *dest = GraphBuffer;\r
-//     int n = GraphTraceLen;\r
-\r
-       // 128 bit shift register [shift3:shift2:shift1:shift0]\r
-       DWORD shift3 = 0, shift2 = 0, shift1 = 0, shift0 = 0;\r
-\r
-       int i, cycles=0, samples=0;\r
-       // how many sample points fit in 16 cycles of each frequency\r
-       DWORD sampleslo = (FSAMPLE<<4)/FREQLO, sampleshi = (FSAMPLE<<4)/FREQHI;\r
-       // when to tell if we're close enough to one freq or another\r
-       DWORD threshold = (sampleslo - sampleshi + 1)>>1;\r
-\r
-       // TI tags charge at 134.2Khz\r
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-\r
-       // Place FPGA in passthrough mode, in this mode the CROSS_LO line\r
-       // connects to SSP_DIN and the SSP_DOUT logic level controls\r
-       // whether we're modulating the antenna (high)\r
-       // or listening to the antenna (low)\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);\r
-\r
-       // get TI tag data into the buffer\r
-       AcquireTiType();\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);\r
-\r
-       for (i=0; i<n-1; i++) {\r
-               // count cycles by looking for lo to hi zero crossings\r
-               if ( (dest[i]<0) && (dest[i+1]>0) ) {\r
-                       cycles++;\r
-                       // after 16 cycles, measure the frequency\r
-                       if (cycles>15) {\r
-                               cycles=0;\r
-                               samples=i-samples; // number of samples in these 16 cycles\r
-\r
-                               // TI bits are coming to us lsb first so shift them\r
-                               // right through our 128 bit right shift register\r
-                         shift0 = (shift0>>1) | (shift1 << 31);\r
-                         shift1 = (shift1>>1) | (shift2 << 31);\r
-                         shift2 = (shift2>>1) | (shift3 << 31);\r
-                         shift3 >>= 1;\r
-\r
-                               // check if the cycles fall close to the number\r
-                               // expected for either the low or high frequency\r
-                               if ( (samples>(sampleslo-threshold)) && (samples<(sampleslo+threshold)) ) {\r
-                                       // low frequency represents a 1\r
-                                       shift3 |= (1<<31);\r
-                               } else if ( (samples>(sampleshi-threshold)) && (samples<(sampleshi+threshold)) ) {\r
-                                       // high frequency represents a 0\r
-                               } else {\r
-                                       // probably detected a gay waveform or noise\r
-                                       // use this as gaydar or discard shift register and start again\r
-                                       shift3 = shift2 = shift1 = shift0 = 0;\r
-                               }\r
-                               samples = i;\r
-\r
-                               // for each bit we receive, test if we've detected a valid tag\r
-\r
-                               // if we see 17 zeroes followed by 6 ones, we might have a tag\r
-                               // remember the bits are backwards\r
-                               if ( ((shift0 & 0x7fffff) == 0x7e0000) ) {\r
-                                       // if start and end bytes match, we have a tag so break out of the loop\r
-                                       if ( ((shift0>>16)&0xff) == ((shift3>>8)&0xff) ) {\r
-                                               cycles = 0xF0B; //use this as a flag (ugly but whatever)\r
-                                               break;\r
-                                       }\r
-                               }\r
-                       }\r
-               }\r
-       }\r
-\r
-       // if flag is set we have a tag\r
-       if (cycles!=0xF0B) {\r
-               DbpString("Info: No valid tag detected.");\r
-       } else {\r
-         // put 64 bit data into shift1 and shift0\r
-         shift0 = (shift0>>24) | (shift1 << 8);\r
-         shift1 = (shift1>>24) | (shift2 << 8);\r
-\r
-               // align 16 bit crc into lower half of shift2\r
-         shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;\r
-\r
-               // if r/w tag, check ident match\r
-               if ( shift3&(1<<15) ) {\r
-                       DbpString("Info: TI tag is rewriteable");\r
-                       // only 15 bits compare, last bit of ident is not valid\r
-                       if ( ((shift3>>16)^shift0)&0x7fff ) {\r
-                               DbpString("Error: Ident mismatch!");\r
-                       } else {\r
-                               DbpString("Info: TI tag ident is valid");\r
-                       }\r
-               } else {\r
-                       DbpString("Info: TI tag is readonly");\r
-               }\r
-\r
-               // WARNING the order of the bytes in which we calc crc below needs checking\r
-               // i'm 99% sure the crc algorithm is correct, but it may need to eat the\r
-               // bytes in reverse or something\r
-               // calculate CRC\r
-               DWORD crc=0;\r
-\r
-               crc = update_crc16(crc, (shift0)&0xff);\r
-               crc = update_crc16(crc, (shift0>>8)&0xff);\r
-               crc = update_crc16(crc, (shift0>>16)&0xff);\r
-               crc = update_crc16(crc, (shift0>>24)&0xff);\r
-               crc = update_crc16(crc, (shift1)&0xff);\r
-               crc = update_crc16(crc, (shift1>>8)&0xff);\r
-               crc = update_crc16(crc, (shift1>>16)&0xff);\r
-               crc = update_crc16(crc, (shift1>>24)&0xff);\r
-\r
-               Dbprintf("Info: Tag data_hi=%x, data_lo=%x, crc=%x",\r
-                       (unsigned int)shift1, (unsigned int)shift0, (unsigned int)shift2 & 0xFFFF);\r
-               if (crc != (shift2&0xffff)) {\r
-                       Dbprintf("Error: CRC mismatch, expected %x", (unsigned int)crc);\r
-               } else {\r
-                       DbpString("Info: CRC is good");\r
-               }\r
-       }\r
-}\r
-\r
-void WriteTIbyte(BYTE b)\r
-{\r
-       int i = 0;\r
-\r
-       // modulate 8 bits out to the antenna\r
-       for (i=0; i<8; i++)\r
-       {\r
-               if (b&(1<<i)) {\r
-                       // stop modulating antenna\r
-                       LOW(GPIO_SSC_DOUT);\r
-                       SpinDelayUs(1000);\r
-                       // modulate antenna\r
-                       HIGH(GPIO_SSC_DOUT);\r
-                       SpinDelayUs(1000);\r
-               } else {\r
-                       // stop modulating antenna\r
-                       LOW(GPIO_SSC_DOUT);\r
-                       SpinDelayUs(300);\r
-                       // modulate antenna\r
-                       HIGH(GPIO_SSC_DOUT);\r
-                       SpinDelayUs(1700);\r
-               }\r
-       }\r
-}\r
-\r
-void AcquireTiType(void)\r
-{\r
-       int i, j, n;\r
-       // tag transmission is <20ms, sampling at 2M gives us 40K samples max\r
-       // each sample is 1 bit stuffed into a DWORD so we need 1250 DWORDS\r
-       #define TIBUFLEN 1250\r
-\r
-       // clear buffer\r
-       memset(BigBuf,0,sizeof(BigBuf));\r
-\r
-       // Set up the synchronous serial port\r
-       AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DIN;\r
-       AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN;\r
-\r
-       // steal this pin from the SSP and use it to control the modulation\r
-       AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;\r
-       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;\r
-\r
-       AT91C_BASE_SSC->SSC_CR = AT91C_SSC_SWRST;\r
-       AT91C_BASE_SSC->SSC_CR = AT91C_SSC_RXEN | AT91C_SSC_TXEN;\r
-\r
-       // Sample at 2 Mbit/s, so TI tags are 16.2 vs. 14.9 clocks long\r
-       // 48/2 = 24 MHz clock must be divided by 12\r
-       AT91C_BASE_SSC->SSC_CMR = 12;\r
-\r
-       AT91C_BASE_SSC->SSC_RCMR = SSC_CLOCK_MODE_SELECT(0);\r
-       AT91C_BASE_SSC->SSC_RFMR = SSC_FRAME_MODE_BITS_IN_WORD(32) | AT91C_SSC_MSBF;\r
-       AT91C_BASE_SSC->SSC_TCMR = 0;\r
-       AT91C_BASE_SSC->SSC_TFMR = 0;\r
-\r
-       LED_D_ON();\r
-\r
-       // modulate antenna\r
-       HIGH(GPIO_SSC_DOUT);\r
-\r
-       // Charge TI tag for 50ms.\r
-       SpinDelay(50);\r
-\r
-       // stop modulating antenna and listen\r
-       LOW(GPIO_SSC_DOUT);\r
-\r
-       LED_D_OFF();\r
-\r
-       i = 0;\r
-       for(;;) {\r
-               if(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {\r
-                       BigBuf[i] = AT91C_BASE_SSC->SSC_RHR;    // store 32 bit values in buffer\r
-                       i++; if(i >= TIBUFLEN) break;\r
-               }\r
-               WDT_HIT();\r
-       }\r
-\r
-       // return stolen pin to SSP\r
-       AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DOUT;\r
-       AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN | GPIO_SSC_DOUT;\r
-\r
-       char *dest = (char *)BigBuf;\r
-       n = TIBUFLEN*32;\r
-       // unpack buffer\r
-       for (i=TIBUFLEN-1; i>=0; i--) {\r
-//             DbpIntegers(0, 0, BigBuf[i]);\r
-               for (j=0; j<32; j++) {\r
-                       if(BigBuf[i] & (1 << j)) {\r
-                               dest[--n] = 1;\r
-                       } else {\r
-                               dest[--n] = -1;\r
-                       }\r
-               }\r
-       }\r
-}\r
-\r
-// arguments: 64bit data split into 32bit idhi:idlo and optional 16bit crc\r
-// if crc provided, it will be written with the data verbatim (even if bogus)\r
-// if not provided a valid crc will be computed from the data and written.\r
-void WriteTItag(DWORD idhi, DWORD idlo, WORD crc)\r
-{\r
-\r
-       // WARNING the order of the bytes in which we calc crc below needs checking\r
-       // i'm 99% sure the crc algorithm is correct, but it may need to eat the\r
-       // bytes in reverse or something\r
-\r
-       if(crc == 0) {\r
-               crc = update_crc16(crc, (idlo)&0xff);\r
-               crc = update_crc16(crc, (idlo>>8)&0xff);\r
-               crc = update_crc16(crc, (idlo>>16)&0xff);\r
-               crc = update_crc16(crc, (idlo>>24)&0xff);\r
-               crc = update_crc16(crc, (idhi)&0xff);\r
-               crc = update_crc16(crc, (idhi>>8)&0xff);\r
-               crc = update_crc16(crc, (idhi>>16)&0xff);\r
-               crc = update_crc16(crc, (idhi>>24)&0xff);\r
-       }\r
-       Dbprintf("Writing the following data to tag: %x, %x, %x",\r
-               (unsigned int) idhi, (unsigned int) idlo, crc);\r
-\r
-       // TI tags charge at 134.2Khz\r
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz\r
-       // Place FPGA in passthrough mode, in this mode the CROSS_LO line\r
-       // connects to SSP_DIN and the SSP_DOUT logic level controls\r
-       // whether we're modulating the antenna (high)\r
-       // or listening to the antenna (low)\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);\r
-       LED_A_ON();\r
-\r
-       // steal this pin from the SSP and use it to control the modulation\r
-       AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;\r
-       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;\r
-\r
-       // writing algorithm:\r
-       // a high bit consists of a field off for 1ms and field on for 1ms\r
-       // a low bit consists of a field off for 0.3ms and field on for 1.7ms\r
-       // initiate a charge time of 50ms (field on) then immediately start writing bits\r
-       // start by writing 0xBB (keyword) and 0xEB (password)\r
-       // then write 80 bits of data (or 64 bit data + 16 bit crc if you prefer)\r
-       // finally end with 0x0300 (write frame)\r
-       // all data is sent lsb firts\r
-       // finish with 15ms programming time\r
-\r
-       // modulate antenna\r
-       HIGH(GPIO_SSC_DOUT);\r
-       SpinDelay(50);  // charge time\r
-\r
-       WriteTIbyte(0xbb); // keyword\r
-       WriteTIbyte(0xeb); // password\r
-       WriteTIbyte( (idlo    )&0xff );\r
-       WriteTIbyte( (idlo>>8 )&0xff );\r
-       WriteTIbyte( (idlo>>16)&0xff );\r
-       WriteTIbyte( (idlo>>24)&0xff );\r
-       WriteTIbyte( (idhi    )&0xff );\r
-       WriteTIbyte( (idhi>>8 )&0xff );\r
-       WriteTIbyte( (idhi>>16)&0xff );\r
-       WriteTIbyte( (idhi>>24)&0xff ); // data hi to lo\r
-       WriteTIbyte( (crc     )&0xff ); // crc lo\r
-       WriteTIbyte( (crc>>8  )&0xff ); // crc hi\r
-       WriteTIbyte(0x00); // write frame lo\r
-       WriteTIbyte(0x03); // write frame hi\r
-       HIGH(GPIO_SSC_DOUT);\r
-       SpinDelay(50);  // programming time\r
-\r
-       LED_A_OFF();\r
-\r
-       // get TI tag data into the buffer\r
-       AcquireTiType();\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);\r
-       DbpString("Now use tiread to check");\r
-}\r
-\r
-void SimulateTagLowFrequency(int period, int ledcontrol)\r
-{\r
-       int i;\r
-       BYTE *tab = (BYTE *)BigBuf;\r
-\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);\r
-\r
-       AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT | GPIO_SSC_CLK;\r
-\r
-       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;\r
-       AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_CLK;\r
-\r
-#define SHORT_COIL()   LOW(GPIO_SSC_DOUT)\r
-#define OPEN_COIL()            HIGH(GPIO_SSC_DOUT)\r
-\r
-       i = 0;\r
-       for(;;) {\r
-               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {\r
-                       if(BUTTON_PRESS()) {\r
-                               DbpString("Stopped");\r
-                               return;\r
-                       }\r
-                       WDT_HIT();\r
-               }\r
-\r
-               if (ledcontrol)\r
-                       LED_D_ON();\r
-\r
-               if(tab[i])\r
-                       OPEN_COIL();\r
-               else\r
-                       SHORT_COIL();\r
-\r
-               if (ledcontrol)\r
-                       LED_D_OFF();\r
-\r
-               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK) {\r
-                       if(BUTTON_PRESS()) {\r
-                               DbpString("Stopped");\r
-                               return;\r
-                       }\r
-                       WDT_HIT();\r
-               }\r
-\r
-               i++;\r
-               if(i == period) i = 0;\r
-       }\r
-}\r
-\r
-/* Provides a framework for bidirectional LF tag communication\r
- * Encoding is currently Hitag2, but the general idea can probably\r
- * be transferred to other encodings.\r
- * \r
- * The new FPGA code will, for the LF simulator mode, give on SSC_FRAME\r
- * (PA15) a thresholded version of the signal from the ADC. Setting the\r
- * ADC path to the low frequency peak detection signal, will enable a\r
- * somewhat reasonable receiver for modulation on the carrier signal\r
- * that is generated by the reader. The signal is low when the reader\r
- * field is switched off, and high when the reader field is active. Due\r
- * to the way that the signal looks like, mostly only the rising edge is\r
- * useful, your mileage may vary.\r
- * \r
- * Neat perk: PA15 can not only be used as a bit-banging GPIO, but is also\r
- * TIOA1, which can be used as the capture input for timer 1. This should\r
- * make it possible to measure the exact edge-to-edge time, without processor\r
- * intervention.\r
- * \r
- * Arguments: divisor is the divisor to be sent to the FPGA (e.g. 95 for 125kHz)\r
- * t0 is the carrier frequency cycle duration in terms of MCK (384 for 125kHz)\r
- * \r
- * The following defines are in carrier periods: \r
- */\r
-#define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */ \r
-#define HITAG_T_1_MIN 24 /* T[1] should be 26..30 */\r
-#define HITAG_T_EOF   40 /* T_EOF should be > 36 */\r
-#define HITAG_T_WRESP 208 /* T_wresp should be 204..212 */\r
-\r
-static void hitag_handle_frame(int t0, int frame_len, char *frame);\r
-//#define DEBUG_RA_VALUES 1\r
-#define DEBUG_FRAME_CONTENTS 1\r
-void SimulateTagLowFrequencyBidir(int divisor, int t0)\r
-{\r
-#if DEBUG_RA_VALUES || DEBUG_FRAME_CONTENTS\r
-       int i = 0;\r
-#endif\r
-       char frame[10];\r
-       int frame_pos=0;\r
-       \r
-       DbpString("Starting Hitag2 emulator, press button to end");\r
-       hitag2_init();\r
-       \r
-       /* Set up simulator mode, frequency divisor which will drive the FPGA\r
-        * and analog mux selection.\r
-        */\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);\r
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);\r
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);\r
-       RELAY_OFF();\r
-       \r
-       /* Set up Timer 1:\r
-        * Capture mode, timer source MCK/2 (TIMER_CLOCK1), TIOA is external trigger,\r
-        * external trigger rising edge, load RA on rising edge of TIOA, load RB on rising\r
-        * edge of TIOA. Assign PA15 to TIOA1 (peripheral B)\r
-        */\r
-       \r
-       AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);\r
-       AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;\r
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;\r
-       AT91C_BASE_TC1->TC_CMR =        TC_CMR_TCCLKS_TIMER_CLOCK1 |\r
-                                                               AT91C_TC_ETRGEDG_RISING |\r
-                                                               AT91C_TC_ABETRG |\r
-                                                               AT91C_TC_LDRA_RISING |\r
-                                                               AT91C_TC_LDRB_RISING;\r
-       AT91C_BASE_TC1->TC_CCR =        AT91C_TC_CLKEN |\r
-                                                               AT91C_TC_SWTRG;\r
-       \r
-       /* calculate the new value for the carrier period in terms of TC1 values */\r
-       t0 = t0/2;\r
-       \r
-       int overflow = 0;\r
-       while(!BUTTON_PRESS()) {\r
-               WDT_HIT();\r
-               if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {\r
-                       int ra = AT91C_BASE_TC1->TC_RA;\r
-                       if((ra > t0*HITAG_T_EOF) | overflow) ra = t0*HITAG_T_EOF+1;\r
-#if DEBUG_RA_VALUES\r
-                       if(ra > 255 || overflow) ra = 255;\r
-                       ((char*)BigBuf)[i] = ra;\r
-                       i = (i+1) % 8000;\r
-#endif\r
-                       \r
-                       if(overflow || (ra > t0*HITAG_T_EOF) || (ra < t0*HITAG_T_0_MIN)) {\r
-                               /* Ignore */\r
-                       } else if(ra >= t0*HITAG_T_1_MIN ) {\r
-                               /* '1' bit */\r
-                               if(frame_pos < 8*sizeof(frame)) {\r
-                                       frame[frame_pos / 8] |= 1<<( 7-(frame_pos%8) );\r
-                                       frame_pos++;\r
-                               }\r
-                       } else if(ra >= t0*HITAG_T_0_MIN) {\r
-                               /* '0' bit */\r
-                               if(frame_pos < 8*sizeof(frame)) {\r
-                                       frame[frame_pos / 8] |= 0<<( 7-(frame_pos%8) );\r
-                                       frame_pos++;\r
-                               }\r
-                       }\r
-                       \r
-                       overflow = 0;\r
-                       LED_D_ON();\r
-               } else {\r
-                       if(AT91C_BASE_TC1->TC_CV > t0*HITAG_T_EOF) {\r
-                               /* Minor nuisance: In Capture mode, the timer can not be\r
-                                * stopped by a Compare C. There's no way to stop the clock\r
-                                * in software, so we'll just have to note the fact that an\r
-                                * overflow happened and the next loaded timer value might\r
-                                * have wrapped. Also, this marks the end of frame, and the\r
-                                * still running counter can be used to determine the correct\r
-                                * time for the start of the reply.\r
-                                */ \r
-                               overflow = 1;\r
-                               \r
-                               if(frame_pos > 0) {\r
-                                       /* Have a frame, do something with it */\r
-#if DEBUG_FRAME_CONTENTS\r
-                                       ((char*)BigBuf)[i++] = frame_pos;\r
-                                       memcpy( ((char*)BigBuf)+i, frame, 7);\r
-                                       i+=7;\r
-                                       i = i % sizeof(BigBuf);\r
-#endif\r
-                                       hitag_handle_frame(t0, frame_pos, frame);\r
-                                       memset(frame, 0, sizeof(frame));\r
-                               }\r
-                               frame_pos = 0;\r
-\r
-                       }\r
-                       LED_D_OFF();\r
-               }\r
-       }\r
-       DbpString("All done");\r
-}\r
-\r
-static void hitag_send_bit(int t0, int bit) {\r
-       if(bit == 1) {\r
-               /* Manchester: Loaded, then unloaded */\r
-               LED_A_ON();\r
-               SHORT_COIL();\r
-               while(AT91C_BASE_TC1->TC_CV < t0*15);\r
-               OPEN_COIL();\r
-               while(AT91C_BASE_TC1->TC_CV < t0*31);\r
-               LED_A_OFF();\r
-       } else if(bit == 0) {\r
-               /* Manchester: Unloaded, then loaded */\r
-               LED_B_ON();\r
-               OPEN_COIL();\r
-               while(AT91C_BASE_TC1->TC_CV < t0*15);\r
-               SHORT_COIL();\r
-               while(AT91C_BASE_TC1->TC_CV < t0*31);\r
-               LED_B_OFF();\r
-       }\r
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset clock for the next bit */\r
-       \r
-}\r
-static void hitag_send_frame(int t0, int frame_len, const char const * frame, int fdt)\r
-{\r
-       OPEN_COIL();\r
-       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;\r
-       \r
-       /* Wait for HITAG_T_WRESP carrier periods after the last reader bit,\r
-        * not that since the clock counts since the rising edge, but T_wresp is\r
-        * with respect to the falling edge, we need to wait actually (T_wresp - T_g)\r
-        * periods. The gap time T_g varies (4..10).\r
-        */\r
-       while(AT91C_BASE_TC1->TC_CV < t0*(fdt-8));\r
-\r
-       int saved_cmr = AT91C_BASE_TC1->TC_CMR;\r
-       AT91C_BASE_TC1->TC_CMR &= ~AT91C_TC_ETRGEDG; /* Disable external trigger for the clock */\r
-       AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset the clock and use it for response timing */\r
-       \r
-       int i;\r
-       for(i=0; i<5; i++)\r
-               hitag_send_bit(t0, 1); /* Start of frame */\r
-       \r
-       for(i=0; i<frame_len; i++) {\r
-               hitag_send_bit(t0, !!(frame[i/ 8] & (1<<( 7-(i%8) ))) );\r
-       }\r
-       \r
-       OPEN_COIL();\r
-       AT91C_BASE_TC1->TC_CMR = saved_cmr;\r
-}\r
-\r
-/* Callback structure to cleanly separate tag emulation code from the radio layer. */\r
-static int hitag_cb(const char* response_data, const int response_length, const int fdt, void *cb_cookie)\r
-{\r
-       hitag_send_frame(*(int*)cb_cookie, response_length, response_data, fdt);\r
-       return 0;\r
-}\r
-/* Frame length in bits, frame contents in MSBit first format */\r
-static void hitag_handle_frame(int t0, int frame_len, char *frame)\r
-{\r
-       hitag2_handle_command(frame, frame_len, hitag_cb, &t0);\r
-}\r
-\r
-// compose fc/8 fc/10 waveform\r
-static void fc(int c, int *n) {\r
-       BYTE *dest = (BYTE *)BigBuf;\r
-       int idx;\r
-\r
-       // for when we want an fc8 pattern every 4 logical bits\r
-       if(c==0) {\r
-               dest[((*n)++)]=1;\r
-               dest[((*n)++)]=1;\r
-               dest[((*n)++)]=0;\r
-               dest[((*n)++)]=0;\r
-               dest[((*n)++)]=0;\r
-               dest[((*n)++)]=0;\r
-               dest[((*n)++)]=0;\r
-               dest[((*n)++)]=0;\r
-       }\r
-       //      an fc/8  encoded bit is a bit pattern of  11000000  x6 = 48 samples\r
-       if(c==8) {\r
-               for (idx=0; idx<6; idx++) {\r
-                       dest[((*n)++)]=1;\r
-                       dest[((*n)++)]=1;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-               }\r
-       }\r
-\r
-       //      an fc/10 encoded bit is a bit pattern of 1110000000 x5 = 50 samples\r
-       if(c==10) {\r
-               for (idx=0; idx<5; idx++) {\r
-                       dest[((*n)++)]=1;\r
-                       dest[((*n)++)]=1;\r
-                       dest[((*n)++)]=1;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-                       dest[((*n)++)]=0;\r
-               }\r
-       }\r
-}\r
-\r
-// prepare a waveform pattern in the buffer based on the ID given then\r
-// simulate a HID tag until the button is pressed\r
-void CmdHIDsimTAG(int hi, int lo, int ledcontrol)\r
-{\r
-       int n=0, i=0;\r
-       /*\r
-        HID tag bitstream format\r
-        The tag contains a 44bit unique code. This is sent out MSB first in sets of 4 bits\r
-        A 1 bit is represented as 6 fc8 and 5 fc10 patterns\r
-        A 0 bit is represented as 5 fc10 and 6 fc8 patterns\r
-        A fc8 is inserted before every 4 bits\r
-        A special start of frame pattern is used consisting a0b0 where a and b are neither 0\r
-        nor 1 bits, they are special patterns (a = set of 12 fc8 and b = set of 10 fc10)\r
-       */\r
-\r
-       if (hi>0xFFF) {\r
-               DbpString("Tags can only have 44 bits.");\r
-               return;\r
-       }\r
-       fc(0,&n);\r
-       // special start of frame marker containing invalid bit sequences\r
-       fc(8,  &n);     fc(8,  &n);     // invalid\r
-       fc(8,  &n);     fc(10, &n); // logical 0\r
-       fc(10, &n);     fc(10, &n); // invalid\r
-       fc(8,  &n);     fc(10, &n); // logical 0\r
-\r
-       WDT_HIT();\r
-       // manchester encode bits 43 to 32\r
-       for (i=11; i>=0; i--) {\r
-               if ((i%4)==3) fc(0,&n);\r
-               if ((hi>>i)&1) {\r
-                       fc(10, &n);     fc(8,  &n);             // low-high transition\r
-               } else {\r
-                       fc(8,  &n);     fc(10, &n);             // high-low transition\r
-               }\r
-       }\r
-\r
-       WDT_HIT();\r
-       // manchester encode bits 31 to 0\r
-       for (i=31; i>=0; i--) {\r
-               if ((i%4)==3) fc(0,&n);\r
-               if ((lo>>i)&1) {\r
-                       fc(10, &n);     fc(8,  &n);             // low-high transition\r
-               } else {\r
-                       fc(8,  &n);     fc(10, &n);             // high-low transition\r
-               }\r
-       }\r
-\r
-       if (ledcontrol)\r
-               LED_A_ON();\r
-       SimulateTagLowFrequency(n, ledcontrol);\r
-\r
-       if (ledcontrol)\r
-               LED_A_OFF();\r
-}\r
-\r
-\r
-// loop to capture raw HID waveform then FSK demodulate the TAG ID from it\r
-void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)\r
-{\r
-       BYTE *dest = (BYTE *)BigBuf;\r
-       int m=0, n=0, i=0, idx=0, found=0, lastval=0;\r
-       DWORD hi=0, lo=0;\r
-\r
-       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz\r
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);\r
-\r
-       // Connect the A/D to the peak-detected low-frequency path.\r
-       SetAdcMuxFor(GPIO_MUXSEL_LOPKD);\r
-\r
-       // Give it a bit of time for the resonant antenna to settle.\r
-       SpinDelay(50);\r
-\r
-       // Now set up the SSC to get the ADC samples that are now streaming at us.\r
-       FpgaSetupSsc();\r
-\r
-       for(;;) {\r
-               WDT_HIT();\r
-               if (ledcontrol)\r
-                       LED_A_ON();\r
-               if(BUTTON_PRESS()) {\r
-                       DbpString("Stopped");\r
-                       if (ledcontrol)\r
-                               LED_A_OFF();\r
-                       return;\r
-               }\r
-\r
-               i = 0;\r
-               m = sizeof(BigBuf);\r
-               memset(dest,128,m);\r
-               for(;;) {\r
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {\r
-                               AT91C_BASE_SSC->SSC_THR = 0x43;\r
-                               if (ledcontrol)\r
-                                       LED_D_ON();\r
-                       }\r
-                       if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {\r
-                               dest[i] = (BYTE)AT91C_BASE_SSC->SSC_RHR;\r
-                               // we don't care about actual value, only if it's more or less than a\r
-                               // threshold essentially we capture zero crossings for later analysis\r
-                               if(dest[i] < 127) dest[i] = 0; else dest[i] = 1;\r
-                               i++;\r
-                               if (ledcontrol)\r
-                                       LED_D_OFF();\r
-                               if(i >= m) {\r
-                                       break;\r
-                               }\r
-                       }\r
-               }\r
-\r
-               // FSK demodulator\r
-\r
-               // sync to first lo-hi transition\r
-               for( idx=1; idx<m; idx++) {\r
-                       if (dest[idx-1]<dest[idx])\r
-                               lastval=idx;\r
-                               break;\r
-               }\r
-               WDT_HIT();\r
-\r
-               // count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)\r
-               // or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere\r
-               // between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10\r
-               for( i=0; idx<m; idx++) {\r
-                       if (dest[idx-1]<dest[idx]) {\r
-                               dest[i]=idx-lastval;\r
-                               if (dest[i] <= 8) {\r
-                                               dest[i]=1;\r
-                               } else {\r
-                                               dest[i]=0;\r
-                               }\r
-\r
-                               lastval=idx;\r
-                               i++;\r
-                       }\r
-               }\r
-               m=i;\r
-               WDT_HIT();\r
-\r
-               // we now have a set of cycle counts, loop over previous results and aggregate data into bit patterns\r
-               lastval=dest[0];\r
-               idx=0;\r
-               i=0;\r
-               n=0;\r
-               for( idx=0; idx<m; idx++) {\r
-                       if (dest[idx]==lastval) {\r
-                               n++;\r
-                       } else {\r
-                               // a bit time is five fc/10 or six fc/8 cycles so figure out how many bits a pattern width represents,\r
-                               // an extra fc/8 pattern preceeds every 4 bits (about 200 cycles) just to complicate things but it gets\r
-                               // swallowed up by rounding\r
-                               // expected results are 1 or 2 bits, any more and it's an invalid manchester encoding\r
-                               // special start of frame markers use invalid manchester states (no transitions) by using sequences\r
-                               // like 111000\r
-                               if (dest[idx-1]) {\r
-                                       n=(n+1)/6;                      // fc/8 in sets of 6\r
-                               } else {\r
-                                       n=(n+1)/5;                      // fc/10 in sets of 5\r
-                               }\r
-                               switch (n) {                    // stuff appropriate bits in buffer\r
-                                       case 0:\r
-                                       case 1: // one bit\r
-                                               dest[i++]=dest[idx-1];\r
-                                               break;\r
-                                       case 2: // two bits\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               break;\r
-                                       case 3: // 3 bit start of frame markers\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               break;\r
-                                       // When a logic 0 is immediately followed by the start of the next transmisson\r
-                                       // (special pattern) a pattern of 4 bit duration lengths is created.\r
-                                       case 4:\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               dest[i++]=dest[idx-1];\r
-                                               break;\r
-                                       default:        // this shouldn't happen, don't stuff any bits\r
-                                               break;\r
-                               }\r
-                               n=0;\r
-                               lastval=dest[idx];\r
-                       }\r
-               }\r
-               m=i;\r
-               WDT_HIT();\r
-\r
-               // final loop, go over previously decoded manchester data and decode into usable tag ID\r
-               // 111000 bit pattern represent start of frame, 01 pattern represents a 1 and 10 represents a 0\r
-               for( idx=0; idx<m-6; idx++) {\r
-                       // search for a start of frame marker\r
-                       if ( dest[idx] && dest[idx+1] && dest[idx+2] && (!dest[idx+3]) && (!dest[idx+4]) && (!dest[idx+5]) )\r
-                       {\r
-                               found=1;\r
-                               idx+=6;\r
-                               if (found && (hi|lo)) {\r
-                                       Dbprintf("TAG ID: %x %x %x", \r
-                                               (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);\r
-                                       /* if we're only looking for one tag */\r
-                                       if (findone)\r
-                                       {\r
-                                               *high = hi;\r
-                                               *low = lo;\r
-                                               return;\r
-                                       }\r
-                                       hi=0;\r
-                                       lo=0;\r
-                                       found=0;\r
-                               }\r
-                       }\r
-                       if (found) {\r
-                               if (dest[idx] && (!dest[idx+1]) ) {\r
-                                       hi=(hi<<1)|(lo>>31);\r
-                                       lo=(lo<<1)|0;\r
-                               } else if ( (!dest[idx]) && dest[idx+1]) {\r
-                                       hi=(hi<<1)|(lo>>31);\r
-                                       lo=(lo<<1)|1;\r
-                               } else {\r
-                                       found=0;\r
-                                       hi=0;\r
-                                       lo=0;\r
-                               }\r
-                               idx++;\r
-                       }\r
-                       if ( dest[idx] && dest[idx+1] && dest[idx+2] && (!dest[idx+3]) && (!dest[idx+4]) && (!dest[idx+5]) )\r
-                       {\r
-                               found=1;\r
-                               idx+=6;\r
-                               if (found && (hi|lo)) {\r
-                                       Dbprintf("TAG ID: %x %x %x", \r
-                                               (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);\r
-                                       /* if we're only looking for one tag */\r
-                                       if (findone)\r
-                                       {\r
-                                               *high = hi;\r
-                                               *low = lo;\r
-                                               return;\r
-                                       }\r
-                                       hi=0;\r
-                                       lo=0;\r
-                                       found=0;\r
-                               }\r
-                       }\r
-               }\r
-               WDT_HIT();\r
-       }\r
-}\r
+//-----------------------------------------------------------------------------
+// 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.
+//-----------------------------------------------------------------------------
+// Miscellaneous routines for low frequency tag operations.
+// Tags supported here so far are Texas Instruments (TI), HID
+// Also routines for raw mode reading/simulating of LF waveform
+//-----------------------------------------------------------------------------
+
+#include "proxmark3.h"
+#include "apps.h"
+#include "util.h"
+#include "hitag2.h"
+#include "crc16.h"
+#include "string.h"
+
+void AcquireRawAdcSamples125k(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();
+
+       // Now call the acquisition routine
+       DoAcquisition125k();
+}
+
+// split into two routines so we can avoid timing issues after sending commands //
+void DoAcquisition125k(void)
+{
+       uint8_t *dest = (uint8_t *)BigBuf;
+       int n = sizeof(BigBuf);
+       int i;
+
+       memset(dest, 0, n);
+       i = 0;
+       for(;;) {
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
+                       AT91C_BASE_SSC->SSC_THR = 0x43;
+                       LED_D_ON();
+               }
+               if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
+                       dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+                       i++;
+                       LED_D_OFF();
+                       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]);
+}
+
+void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int period_1, uint8_t *command)
+{
+       int at134khz;
+
+       /* Make sure the tag is reset */
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelay(2500);
+
+       // see if 'h' was specified
+       if (command[strlen((char *) command) - 1] == 'h')
+               at134khz = TRUE;
+       else
+               at134khz = FALSE;
+
+       if (at134khz)
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+       else
+               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.
+       SpinDelay(50);
+       // And a little more time for the tag to fully power up
+       SpinDelay(2000);
+
+       // Now set up the SSC to get the ADC samples that are now streaming at us.
+       FpgaSetupSsc();
+
+       // now modulate the reader field
+       while(*command != '\0' && *command != ' ') {
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+               LED_D_OFF();
+               SpinDelayUs(delay_off);
+               if (at134khz)
+                       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+               else
+                       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+               LED_D_ON();
+               if(*(command++) == '0')
+                       SpinDelayUs(period_0);
+               else
+                       SpinDelayUs(period_1);
+       }
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       LED_D_OFF();
+       SpinDelayUs(delay_off);
+       if (at134khz)
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+       else
+               FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+
+       // now do the read
+       DoAcquisition125k();
+}
+
+/* blank r/w tag data stream
+...0000000000000000 01111111
+1010101010101010101010101010101010101010101010101010101010101010
+0011010010100001
+01111111
+101010101010101[0]000...
+
+[5555fe852c5555555555555555fe0000]
+*/
+void ReadTItag(void)
+{
+       // some hardcoded initial params
+       // when we read a TI tag we sample the zerocross line at 2Mhz
+       // TI tags modulate a 1 as 16 cycles of 123.2Khz
+       // TI tags modulate a 0 as 16 cycles of 134.2Khz
+       #define FSAMPLE 2000000
+       #define FREQLO 123200
+       #define FREQHI 134200
+
+       signed char *dest = (signed char *)BigBuf;
+       int n = sizeof(BigBuf);
+//     int *dest = GraphBuffer;
+//     int n = GraphTraceLen;
+
+       // 128 bit shift register [shift3:shift2:shift1:shift0]
+       uint32_t shift3 = 0, shift2 = 0, shift1 = 0, shift0 = 0;
+
+       int i, cycles=0, samples=0;
+       // how many sample points fit in 16 cycles of each frequency
+       uint32_t sampleslo = (FSAMPLE<<4)/FREQLO, sampleshi = (FSAMPLE<<4)/FREQHI;
+       // when to tell if we're close enough to one freq or another
+       uint32_t threshold = (sampleslo - sampleshi + 1)>>1;
+
+       // TI tags charge at 134.2Khz
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+
+       // Place FPGA in passthrough mode, in this mode the CROSS_LO line
+       // connects to SSP_DIN and the SSP_DOUT logic level controls
+       // whether we're modulating the antenna (high)
+       // or listening to the antenna (low)
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);
+
+       // get TI tag data into the buffer
+       AcquireTiType();
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+
+       for (i=0; i<n-1; i++) {
+               // count cycles by looking for lo to hi zero crossings
+               if ( (dest[i]<0) && (dest[i+1]>0) ) {
+                       cycles++;
+                       // after 16 cycles, measure the frequency
+                       if (cycles>15) {
+                               cycles=0;
+                               samples=i-samples; // number of samples in these 16 cycles
+
+                               // TI bits are coming to us lsb first so shift them
+                               // right through our 128 bit right shift register
+                         shift0 = (shift0>>1) | (shift1 << 31);
+                         shift1 = (shift1>>1) | (shift2 << 31);
+                         shift2 = (shift2>>1) | (shift3 << 31);
+                         shift3 >>= 1;
+
+                               // check if the cycles fall close to the number
+                               // expected for either the low or high frequency
+                               if ( (samples>(sampleslo-threshold)) && (samples<(sampleslo+threshold)) ) {
+                                       // low frequency represents a 1
+                                       shift3 |= (1<<31);
+                               } else if ( (samples>(sampleshi-threshold)) && (samples<(sampleshi+threshold)) ) {
+                                       // high frequency represents a 0
+                               } else {
+                                       // probably detected a gay waveform or noise
+                                       // use this as gaydar or discard shift register and start again
+                                       shift3 = shift2 = shift1 = shift0 = 0;
+                               }
+                               samples = i;
+
+                               // for each bit we receive, test if we've detected a valid tag
+
+                               // if we see 17 zeroes followed by 6 ones, we might have a tag
+                               // remember the bits are backwards
+                               if ( ((shift0 & 0x7fffff) == 0x7e0000) ) {
+                                       // if start and end bytes match, we have a tag so break out of the loop
+                                       if ( ((shift0>>16)&0xff) == ((shift3>>8)&0xff) ) {
+                                               cycles = 0xF0B; //use this as a flag (ugly but whatever)
+                                               break;
+                                       }
+                               }
+                       }
+               }
+       }
+
+       // if flag is set we have a tag
+       if (cycles!=0xF0B) {
+               DbpString("Info: No valid tag detected.");
+       } else {
+         // put 64 bit data into shift1 and shift0
+         shift0 = (shift0>>24) | (shift1 << 8);
+         shift1 = (shift1>>24) | (shift2 << 8);
+
+               // align 16 bit crc into lower half of shift2
+         shift2 = ((shift2>>24) | (shift3 << 8)) & 0x0ffff;
+
+               // if r/w tag, check ident match
+               if ( shift3&(1<<15) ) {
+                       DbpString("Info: TI tag is rewriteable");
+                       // only 15 bits compare, last bit of ident is not valid
+                       if ( ((shift3>>16)^shift0)&0x7fff ) {
+                               DbpString("Error: Ident mismatch!");
+                       } else {
+                               DbpString("Info: TI tag ident is valid");
+                       }
+               } else {
+                       DbpString("Info: TI tag is readonly");
+               }
+
+               // WARNING the order of the bytes in which we calc crc below needs checking
+               // i'm 99% sure the crc algorithm is correct, but it may need to eat the
+               // bytes in reverse or something
+               // calculate CRC
+               uint32_t crc=0;
+
+               crc = update_crc16(crc, (shift0)&0xff);
+               crc = update_crc16(crc, (shift0>>8)&0xff);
+               crc = update_crc16(crc, (shift0>>16)&0xff);
+               crc = update_crc16(crc, (shift0>>24)&0xff);
+               crc = update_crc16(crc, (shift1)&0xff);
+               crc = update_crc16(crc, (shift1>>8)&0xff);
+               crc = update_crc16(crc, (shift1>>16)&0xff);
+               crc = update_crc16(crc, (shift1>>24)&0xff);
+
+               Dbprintf("Info: Tag data: %x%08x, crc=%x",
+                       (unsigned int)shift1, (unsigned int)shift0, (unsigned int)shift2 & 0xFFFF);
+               if (crc != (shift2&0xffff)) {
+                       Dbprintf("Error: CRC mismatch, expected %x", (unsigned int)crc);
+               } else {
+                       DbpString("Info: CRC is good");
+               }
+       }
+}
+
+void WriteTIbyte(uint8_t b)
+{
+       int i = 0;
+
+       // modulate 8 bits out to the antenna
+       for (i=0; i<8; i++)
+       {
+               if (b&(1<<i)) {
+                       // stop modulating antenna
+                       LOW(GPIO_SSC_DOUT);
+                       SpinDelayUs(1000);
+                       // modulate antenna
+                       HIGH(GPIO_SSC_DOUT);
+                       SpinDelayUs(1000);
+               } else {
+                       // stop modulating antenna
+                       LOW(GPIO_SSC_DOUT);
+                       SpinDelayUs(300);
+                       // modulate antenna
+                       HIGH(GPIO_SSC_DOUT);
+                       SpinDelayUs(1700);
+               }
+       }
+}
+
+void AcquireTiType(void)
+{
+       int i, j, n;
+       // tag transmission is <20ms, sampling at 2M gives us 40K samples max
+       // each sample is 1 bit stuffed into a uint32_t so we need 1250 uint32_t
+       #define TIBUFLEN 1250
+
+       // clear buffer
+       memset(BigBuf,0,sizeof(BigBuf));
+
+       // Set up the synchronous serial port
+       AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DIN;
+       AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN;
+
+       // steal this pin from the SSP and use it to control the modulation
+       AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
+       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
+
+       AT91C_BASE_SSC->SSC_CR = AT91C_SSC_SWRST;
+       AT91C_BASE_SSC->SSC_CR = AT91C_SSC_RXEN | AT91C_SSC_TXEN;
+
+       // Sample at 2 Mbit/s, so TI tags are 16.2 vs. 14.9 clocks long
+       // 48/2 = 24 MHz clock must be divided by 12
+       AT91C_BASE_SSC->SSC_CMR = 12;
+
+       AT91C_BASE_SSC->SSC_RCMR = SSC_CLOCK_MODE_SELECT(0);
+       AT91C_BASE_SSC->SSC_RFMR = SSC_FRAME_MODE_BITS_IN_WORD(32) | AT91C_SSC_MSBF;
+       AT91C_BASE_SSC->SSC_TCMR = 0;
+       AT91C_BASE_SSC->SSC_TFMR = 0;
+
+       LED_D_ON();
+
+       // modulate antenna
+       HIGH(GPIO_SSC_DOUT);
+
+       // Charge TI tag for 50ms.
+       SpinDelay(50);
+
+       // stop modulating antenna and listen
+       LOW(GPIO_SSC_DOUT);
+
+       LED_D_OFF();
+
+       i = 0;
+       for(;;) {
+               if(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
+                       BigBuf[i] = AT91C_BASE_SSC->SSC_RHR;    // store 32 bit values in buffer
+                       i++; if(i >= TIBUFLEN) break;
+               }
+               WDT_HIT();
+       }
+
+       // return stolen pin to SSP
+       AT91C_BASE_PIOA->PIO_PDR = GPIO_SSC_DOUT;
+       AT91C_BASE_PIOA->PIO_ASR = GPIO_SSC_DIN | GPIO_SSC_DOUT;
+
+       char *dest = (char *)BigBuf;
+       n = TIBUFLEN*32;
+       // unpack buffer
+       for (i=TIBUFLEN-1; i>=0; i--) {
+               for (j=0; j<32; j++) {
+                       if(BigBuf[i] & (1 << j)) {
+                               dest[--n] = 1;
+                       } else {
+                               dest[--n] = -1;
+                       }
+               }
+       }
+}
+
+// arguments: 64bit data split into 32bit idhi:idlo and optional 16bit crc
+// if crc provided, it will be written with the data verbatim (even if bogus)
+// if not provided a valid crc will be computed from the data and written.
+void WriteTItag(uint32_t idhi, uint32_t idlo, uint16_t crc)
+{
+       if(crc == 0) {
+               crc = update_crc16(crc, (idlo)&0xff);
+               crc = update_crc16(crc, (idlo>>8)&0xff);
+               crc = update_crc16(crc, (idlo>>16)&0xff);
+               crc = update_crc16(crc, (idlo>>24)&0xff);
+               crc = update_crc16(crc, (idhi)&0xff);
+               crc = update_crc16(crc, (idhi>>8)&0xff);
+               crc = update_crc16(crc, (idhi>>16)&0xff);
+               crc = update_crc16(crc, (idhi>>24)&0xff);
+       }
+       Dbprintf("Writing to tag: %x%08x, crc=%x",
+               (unsigned int) idhi, (unsigned int) idlo, crc);
+
+       // TI tags charge at 134.2Khz
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+       // Place FPGA in passthrough mode, in this mode the CROSS_LO line
+       // connects to SSP_DIN and the SSP_DOUT logic level controls
+       // whether we're modulating the antenna (high)
+       // or listening to the antenna (low)
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);
+       LED_A_ON();
+
+       // steal this pin from the SSP and use it to control the modulation
+       AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
+       AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
+
+       // writing algorithm:
+       // a high bit consists of a field off for 1ms and field on for 1ms
+       // a low bit consists of a field off for 0.3ms and field on for 1.7ms
+       // initiate a charge time of 50ms (field on) then immediately start writing bits
+       // start by writing 0xBB (keyword) and 0xEB (password)
+       // then write 80 bits of data (or 64 bit data + 16 bit crc if you prefer)
+       // finally end with 0x0300 (write frame)
+       // all data is sent lsb firts
+       // finish with 15ms programming time
+
+       // modulate antenna
+       HIGH(GPIO_SSC_DOUT);
+       SpinDelay(50);  // charge time
+
+       WriteTIbyte(0xbb); // keyword
+       WriteTIbyte(0xeb); // password
+       WriteTIbyte( (idlo    )&0xff );
+       WriteTIbyte( (idlo>>8 )&0xff );
+       WriteTIbyte( (idlo>>16)&0xff );
+       WriteTIbyte( (idlo>>24)&0xff );
+       WriteTIbyte( (idhi    )&0xff );
+       WriteTIbyte( (idhi>>8 )&0xff );
+       WriteTIbyte( (idhi>>16)&0xff );
+       WriteTIbyte( (idhi>>24)&0xff ); // data hi to lo
+       WriteTIbyte( (crc     )&0xff ); // crc lo
+       WriteTIbyte( (crc>>8  )&0xff ); // crc hi
+       WriteTIbyte(0x00); // write frame lo
+       WriteTIbyte(0x03); // write frame hi
+       HIGH(GPIO_SSC_DOUT);
+       SpinDelay(50);  // programming time
+
+       LED_A_OFF();
+
+       // get TI tag data into the buffer
+       AcquireTiType();
+
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       DbpString("Now use tiread to check");
+}
+
+void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
+{
+       int i;
+       uint8_t *tab = (uint8_t *)BigBuf;
+    
+       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)) {
+                       if(BUTTON_PRESS()) {
+                               DbpString("Stopped");
+                               return;
+                       }
+                       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");
+                               return;
+                       }
+                       WDT_HIT();
+               }
+        
+               i++;
+               if(i == period) {
+                       i = 0;
+                       if (gap) {
+                               SHORT_COIL();
+                               SpinDelayUs(gap);
+                       }
+               }
+       }
+}
+
+#define DEBUG_FRAME_CONTENTS 1
+void SimulateTagLowFrequencyBidir(int divisor, int t0)
+{
+}
+
+// compose fc/8 fc/10 waveform
+static void fc(int c, int *n) {
+       uint8_t *dest = (uint8_t *)BigBuf;
+       int idx;
+
+       // for when we want an fc8 pattern every 4 logical bits
+       if(c==0) {
+               dest[((*n)++)]=1;
+               dest[((*n)++)]=1;
+               dest[((*n)++)]=0;
+               dest[((*n)++)]=0;
+               dest[((*n)++)]=0;
+               dest[((*n)++)]=0;
+               dest[((*n)++)]=0;
+               dest[((*n)++)]=0;
+       }
+       //      an fc/8  encoded bit is a bit pattern of  11000000  x6 = 48 samples
+       if(c==8) {
+               for (idx=0; idx<6; idx++) {
+                       dest[((*n)++)]=1;
+                       dest[((*n)++)]=1;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+               }
+       }
+
+       //      an fc/10 encoded bit is a bit pattern of 1110000000 x5 = 50 samples
+       if(c==10) {
+               for (idx=0; idx<5; idx++) {
+                       dest[((*n)++)]=1;
+                       dest[((*n)++)]=1;
+                       dest[((*n)++)]=1;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+                       dest[((*n)++)]=0;
+               }
+       }
+}
+
+// prepare a waveform pattern in the buffer based on the ID given then
+// simulate a HID tag until the button is pressed
+void CmdHIDsimTAG(int hi, int lo, int ledcontrol)
+{
+       int n=0, i=0;
+       /*
+        HID tag bitstream format
+        The tag contains a 44bit unique code. This is sent out MSB first in sets of 4 bits
+        A 1 bit is represented as 6 fc8 and 5 fc10 patterns
+        A 0 bit is represented as 5 fc10 and 6 fc8 patterns
+        A fc8 is inserted before every 4 bits
+        A special start of frame pattern is used consisting a0b0 where a and b are neither 0
+        nor 1 bits, they are special patterns (a = set of 12 fc8 and b = set of 10 fc10)
+       */
+
+       if (hi>0xFFF) {
+               DbpString("Tags can only have 44 bits.");
+               return;
+       }
+       fc(0,&n);
+       // special start of frame marker containing invalid bit sequences
+       fc(8,  &n);     fc(8,  &n);     // invalid
+       fc(8,  &n);     fc(10, &n); // logical 0
+       fc(10, &n);     fc(10, &n); // invalid
+       fc(8,  &n);     fc(10, &n); // logical 0
+
+       WDT_HIT();
+       // manchester encode bits 43 to 32
+       for (i=11; i>=0; i--) {
+               if ((i%4)==3) fc(0,&n);
+               if ((hi>>i)&1) {
+                       fc(10, &n);     fc(8,  &n);             // low-high transition
+               } else {
+                       fc(8,  &n);     fc(10, &n);             // high-low transition
+               }
+       }
+
+       WDT_HIT();
+       // manchester encode bits 31 to 0
+       for (i=31; i>=0; i--) {
+               if ((i%4)==3) fc(0,&n);
+               if ((lo>>i)&1) {
+                       fc(10, &n);     fc(8,  &n);             // low-high transition
+               } else {
+                       fc(8,  &n);     fc(10, &n);             // high-low transition
+               }
+       }
+
+       if (ledcontrol)
+               LED_A_ON();
+       SimulateTagLowFrequency(n, 0, ledcontrol);
+
+       if (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)
+{
+       uint8_t *dest = (uint8_t *)BigBuf;
+       int m=0, n=0, i=0, idx=0, found=0, lastval=0;
+  uint32_t hi2=0, hi=0, lo=0;
+
+       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();
+
+       for(;;) {
+               WDT_HIT();
+               if (ledcontrol)
+                       LED_A_ON();
+               if(BUTTON_PRESS()) {
+                       DbpString("Stopped");
+                       if (ledcontrol)
+                               LED_A_OFF();
+                       return;
+               }
+
+               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;
+                               }
+                       }
+               }
+
+               // FSK demodulator
+
+               // sync to first lo-hi transition
+               for( idx=1; idx<m; idx++) {
+                       if (dest[idx-1]<dest[idx])
+                               lastval=idx;
+                               break;
+               }
+               WDT_HIT();
+
+               // 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;
+                               }
+
+                               lastval=idx;
+                               i++;
+                       }
+               }
+               m=i;
+               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;
+               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++) {
+                       // 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 && (hi2|hi|lo)) {
+          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);
+          }
+                                       /* if we're only looking for one tag */
+                                       if (findone)
+                                       {
+                                               *high = hi;
+                                               *low = lo;
+                                               return;
+                                       }
+          hi2=0;
+                                       hi=0;
+                                       lo=0;
+                                       found=0;
+                               }
+                       }
+                       if (found) {
+                               if (dest[idx] && (!dest[idx+1]) ) {
+          hi2=(hi2<<1)|(hi>>31);
+                                       hi=(hi<<1)|(lo>>31);
+                                       lo=(lo<<1)|0;
+                               } else if ( (!dest[idx]) && dest[idx+1]) {
+          hi2=(hi2<<1)|(hi>>31);
+                                       hi=(hi<<1)|(lo>>31);
+                                       lo=(lo<<1)|1;
+                               } else {
+                                       found=0;
+          hi2=0;
+                                       hi=0;
+                                       lo=0;
+                               }
+                               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)) {
+          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);
+          }
+                                       /* if we're only looking for one tag */
+                                       if (findone)
+                                       {
+                                               *high = hi;
+                                               *low = lo;
+                                               return;
+                                       }
+          hi2=0;
+                                       hi=0;
+                                       lo=0;
+                                       found=0;
+                               }
+                       }
+               }
+               WDT_HIT();
+       }
+}
+
+/*------------------------------
+ * T5555/T5557/T5567 routines
+ *------------------------------
+ */
+
+/* T55x7 configuration register definitions */
+#define T55x7_POR_DELAY                        0x00000001
+#define T55x7_ST_TERMINATOR            0x00000008
+#define T55x7_PWD                      0x00000010
+#define T55x7_MAXBLOCK_SHIFT           5
+#define T55x7_AOR                      0x00000200
+#define T55x7_PSKCF_RF_2               0
+#define T55x7_PSKCF_RF_4               0x00000400
+#define T55x7_PSKCF_RF_8               0x00000800
+#define T55x7_MODULATION_DIRECT                0
+#define T55x7_MODULATION_PSK1          0x00001000
+#define T55x7_MODULATION_PSK2          0x00002000
+#define T55x7_MODULATION_PSK3          0x00003000
+#define T55x7_MODULATION_FSK1          0x00004000
+#define T55x7_MODULATION_FSK2          0x00005000
+#define T55x7_MODULATION_FSK1a         0x00006000
+#define T55x7_MODULATION_FSK2a         0x00007000
+#define T55x7_MODULATION_MANCHESTER    0x00008000
+#define T55x7_MODULATION_BIPHASE       0x00010000
+#define T55x7_BITRATE_RF_8             0
+#define T55x7_BITRATE_RF_16            0x00040000
+#define T55x7_BITRATE_RF_32            0x00080000
+#define T55x7_BITRATE_RF_40            0x000C0000
+#define T55x7_BITRATE_RF_50            0x00100000
+#define T55x7_BITRATE_RF_64            0x00140000
+#define T55x7_BITRATE_RF_100           0x00180000
+#define T55x7_BITRATE_RF_128           0x001C0000
+
+/* T5555 (Q5) configuration register definitions */
+#define T5555_ST_TERMINATOR            0x00000001
+#define T5555_MAXBLOCK_SHIFT           0x00000001
+#define T5555_MODULATION_MANCHESTER    0
+#define T5555_MODULATION_PSK1          0x00000010
+#define T5555_MODULATION_PSK2          0x00000020
+#define T5555_MODULATION_PSK3          0x00000030
+#define T5555_MODULATION_FSK1          0x00000040
+#define T5555_MODULATION_FSK2          0x00000050
+#define T5555_MODULATION_BIPHASE       0x00000060
+#define T5555_MODULATION_DIRECT                0x00000070
+#define T5555_INVERT_OUTPUT            0x00000080
+#define T5555_PSK_RF_2                 0
+#define T5555_PSK_RF_4                 0x00000100
+#define T5555_PSK_RF_8                 0x00000200
+#define T5555_USE_PWD                  0x00000400
+#define T5555_USE_AOR                  0x00000800
+#define T5555_BITRATE_SHIFT            12
+#define T5555_FAST_WRITE               0x00004000
+#define T5555_PAGE_SELECT              0x00008000
+
+/*
+ * Relevant times in microsecond
+ * To compensate antenna falling times shorten the write times
+ * and enlarge the gap ones.
+ */
+#define START_GAP 250
+#define WRITE_GAP 160
+#define WRITE_0   144 // 192
+#define WRITE_1   400 // 432 for T55x7; 448 for E5550
+
+// Write one bit to card
+void T55xxWriteBit(int bit)
+{
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+       if (bit == 0)
+               SpinDelayUs(WRITE_0);
+       else
+               SpinDelayUs(WRITE_1);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       SpinDelayUs(WRITE_GAP);
+}
+
+// Write one card block in page 0, no lock
+void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
+{
+       unsigned int i;
+
+       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);
+  }
+       // Lock bit
+       T55xxWriteBit(0);
+
+       // Data
+       for (i = 0x80000000; i != 0; i >>= 1)
+               T55xxWriteBit(Data & i);
+
+       // Block
+       for (i = 0x04; i != 0; i >>= 1)
+               T55xxWriteBit(Block & i);
+
+       // Now perform write (nominal is 5.6 ms for T55x7 and 18ms for E5550,
+       // so wait a little more)
+       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+       SpinDelay(20);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+}
+
+// Read one card block in page 0
+void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
+{
+       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);
+       }
+       // 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!");
+}
+
+// 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!");
+}
+
+/*-------------- 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(data1,1,0,0);
+       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!");
+}
+
+// Define 9bit header for EM410x tags
+#define EM410X_HEADER          0x1FF
+#define EM410X_ID_LENGTH       40
+
+void WriteEM410x(uint32_t card, uint32_t id_hi, uint32_t id_lo)
+{
+       int i, id_bit;
+       uint64_t id = EM410X_HEADER;
+       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) {
+               if (i < 32) {
+                       rev_id = (rev_id << 1) | (id_lo & 1);
+                       id_lo >>= 1;
+               } else {
+                       rev_id = (rev_id << 1) | (id_hi & 1);
+                       id_hi >>= 1;
+               }
+       }
+
+       for (i = 0; i < EM410X_ID_LENGTH; ++i) {
+               id_bit = rev_id & 1;
+
+               if (i % 4 == 0) {
+                       // Don't write row parity bit at start of parsing
+                       if (i)
+                               id = (id << 1) | r_parity;
+                       // Start counting parity for new row
+                       r_parity = id_bit;
+               } else {
+                       // Count row parity
+                       r_parity ^= id_bit;
+               }
+
+               // First elements in column?
+               if (i < 4)
+                       // Fill out first elements
+                       c_parity[i] = id_bit;
+               else
+                       // Count column parity
+                       c_parity[i % 4] ^= id_bit;
+
+               // Insert ID bit
+               id = (id << 1) | id_bit;
+               rev_id >>= 1;
+       }
+
+       // Insert parity bit of last row
+       id = (id << 1) | r_parity;
+
+       // Fill out column parity at the end of tag
+       for (i = 0; i < 4; ++i)
+               id = (id << 1) | c_parity[i];
+
+       // Add stop bit
+       id <<= 1;
+
+       Dbprintf("Started writing %s tag ...", card ? "T55x7":"T5555");
+       LED_D_ON();
+
+       // Write EM410x ID
+       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) {
+               // 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(clock       |
+                               T55x7_MODULATION_MANCHESTER |
+                               2 << T55x7_MAXBLOCK_SHIFT,
+                               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);
+
+       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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