-//-----------------------------------------------------------------------------\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 "crc16.h"\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("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",\r
- dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);\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: %x%08x, 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
- 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
- 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 to tag: %x%08x, crc=%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 gap, 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) {\r
- i = 0;\r
- if (gap) { \r
- SHORT_COIL();\r
- SpinDelayUs(gap);\r
- }\r
- }\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, 0, 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%08x (%d)",\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%08x (%d)",\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
+//-----------------------------------------------------------------------------
+// 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 "hitag2.h"
+#include "crc16.h"
+
+void AcquireRawAdcSamples125k(BOOL at134khz)
+{
+ if (at134khz)
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+ else
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
+
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+
+ // Connect the A/D to the peak-detected low-frequency path.
+ SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+
+ // Give it a bit of time for the resonant antenna to settle.
+ SpinDelay(50);
+
+ // Now set up the SSC to get the ADC samples that are now streaming at us.
+ FpgaSetupSsc();
+
+ // Now call the acquisition routine
+ DoAcquisition125k();
+}
+
+// split into two routines so we can avoid timing issues after sending commands //
+void DoAcquisition125k(void)
+{
+ BYTE *dest = (BYTE *)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] = (BYTE)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, BYTE *command)
+{
+ BOOL 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]
+ DWORD 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
+ DWORD sampleslo = (FSAMPLE<<4)/FREQLO, sampleshi = (FSAMPLE<<4)/FREQHI;
+ // when to tell if we're close enough to one freq or another
+ DWORD 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
+ DWORD 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(BYTE 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 DWORD so we need 1250 DWORDS
+ #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(DWORD idhi, DWORD idlo, WORD 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;
+ BYTE *tab = (BYTE *)BigBuf;
+
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);
+
+ 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);
+ }
+ }
+ }
+}
+
+/* Provides a framework for bidirectional LF tag communication
+ * Encoding is currently Hitag2, but the general idea can probably
+ * be transferred to other encodings.
+ *
+ * The new FPGA code will, for the LF simulator mode, give on SSC_FRAME
+ * (PA15) a thresholded version of the signal from the ADC. Setting the
+ * ADC path to the low frequency peak detection signal, will enable a
+ * somewhat reasonable receiver for modulation on the carrier signal
+ * that is generated by the reader. The signal is low when the reader
+ * field is switched off, and high when the reader field is active. Due
+ * to the way that the signal looks like, mostly only the rising edge is
+ * useful, your mileage may vary.
+ *
+ * Neat perk: PA15 can not only be used as a bit-banging GPIO, but is also
+ * TIOA1, which can be used as the capture input for timer 1. This should
+ * make it possible to measure the exact edge-to-edge time, without processor
+ * intervention.
+ *
+ * Arguments: divisor is the divisor to be sent to the FPGA (e.g. 95 for 125kHz)
+ * t0 is the carrier frequency cycle duration in terms of MCK (384 for 125kHz)
+ *
+ * The following defines are in carrier periods:
+ */
+#define HITAG_T_0_MIN 15 /* T[0] should be 18..22 */
+#define HITAG_T_1_MIN 24 /* T[1] should be 26..30 */
+#define HITAG_T_EOF 40 /* T_EOF should be > 36 */
+#define HITAG_T_WRESP 208 /* T_wresp should be 204..212 */
+
+static void hitag_handle_frame(int t0, int frame_len, char *frame);
+//#define DEBUG_RA_VALUES 1
+#define DEBUG_FRAME_CONTENTS 1
+void SimulateTagLowFrequencyBidir(int divisor, int t0)
+{
+#if DEBUG_RA_VALUES || DEBUG_FRAME_CONTENTS
+ int i = 0;
+#endif
+ char frame[10];
+ int frame_pos=0;
+
+ DbpString("Starting Hitag2 emulator, press button to end");
+ hitag2_init();
+
+ /* Set up simulator mode, frequency divisor which will drive the FPGA
+ * and analog mux selection.
+ */
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_SIMULATOR);
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
+ SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
+ RELAY_OFF();
+
+ /* Set up Timer 1:
+ * Capture mode, timer source MCK/2 (TIMER_CLOCK1), TIOA is external trigger,
+ * external trigger rising edge, load RA on rising edge of TIOA, load RB on rising
+ * edge of TIOA. Assign PA15 to TIOA1 (peripheral B)
+ */
+
+ AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
+ AT91C_BASE_PIOA->PIO_BSR = GPIO_SSC_FRAME;
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+ AT91C_BASE_TC1->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK1 |
+ AT91C_TC_ETRGEDG_RISING |
+ AT91C_TC_ABETRG |
+ AT91C_TC_LDRA_RISING |
+ AT91C_TC_LDRB_RISING;
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN |
+ AT91C_TC_SWTRG;
+
+ /* calculate the new value for the carrier period in terms of TC1 values */
+ t0 = t0/2;
+
+ int overflow = 0;
+ while(!BUTTON_PRESS()) {
+ WDT_HIT();
+ if(AT91C_BASE_TC1->TC_SR & AT91C_TC_LDRAS) {
+ int ra = AT91C_BASE_TC1->TC_RA;
+ if((ra > t0*HITAG_T_EOF) | overflow) ra = t0*HITAG_T_EOF+1;
+#if DEBUG_RA_VALUES
+ if(ra > 255 || overflow) ra = 255;
+ ((char*)BigBuf)[i] = ra;
+ i = (i+1) % 8000;
+#endif
+
+ if(overflow || (ra > t0*HITAG_T_EOF) || (ra < t0*HITAG_T_0_MIN)) {
+ /* Ignore */
+ } else if(ra >= t0*HITAG_T_1_MIN ) {
+ /* '1' bit */
+ if(frame_pos < 8*sizeof(frame)) {
+ frame[frame_pos / 8] |= 1<<( 7-(frame_pos%8) );
+ frame_pos++;
+ }
+ } else if(ra >= t0*HITAG_T_0_MIN) {
+ /* '0' bit */
+ if(frame_pos < 8*sizeof(frame)) {
+ frame[frame_pos / 8] |= 0<<( 7-(frame_pos%8) );
+ frame_pos++;
+ }
+ }
+
+ overflow = 0;
+ LED_D_ON();
+ } else {
+ if(AT91C_BASE_TC1->TC_CV > t0*HITAG_T_EOF) {
+ /* Minor nuisance: In Capture mode, the timer can not be
+ * stopped by a Compare C. There's no way to stop the clock
+ * in software, so we'll just have to note the fact that an
+ * overflow happened and the next loaded timer value might
+ * have wrapped. Also, this marks the end of frame, and the
+ * still running counter can be used to determine the correct
+ * time for the start of the reply.
+ */
+ overflow = 1;
+
+ if(frame_pos > 0) {
+ /* Have a frame, do something with it */
+#if DEBUG_FRAME_CONTENTS
+ ((char*)BigBuf)[i++] = frame_pos;
+ memcpy( ((char*)BigBuf)+i, frame, 7);
+ i+=7;
+ i = i % sizeof(BigBuf);
+#endif
+ hitag_handle_frame(t0, frame_pos, frame);
+ memset(frame, 0, sizeof(frame));
+ }
+ frame_pos = 0;
+
+ }
+ LED_D_OFF();
+ }
+ }
+ DbpString("All done");
+}
+
+static void hitag_send_bit(int t0, int bit) {
+ if(bit == 1) {
+ /* Manchester: Loaded, then unloaded */
+ LED_A_ON();
+ SHORT_COIL();
+ while(AT91C_BASE_TC1->TC_CV < t0*15);
+ OPEN_COIL();
+ while(AT91C_BASE_TC1->TC_CV < t0*31);
+ LED_A_OFF();
+ } else if(bit == 0) {
+ /* Manchester: Unloaded, then loaded */
+ LED_B_ON();
+ OPEN_COIL();
+ while(AT91C_BASE_TC1->TC_CV < t0*15);
+ SHORT_COIL();
+ while(AT91C_BASE_TC1->TC_CV < t0*31);
+ LED_B_OFF();
+ }
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset clock for the next bit */
+
+}
+static void hitag_send_frame(int t0, int frame_len, const char const * frame, int fdt)
+{
+ OPEN_COIL();
+ AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
+
+ /* Wait for HITAG_T_WRESP carrier periods after the last reader bit,
+ * not that since the clock counts since the rising edge, but T_wresp is
+ * with respect to the falling edge, we need to wait actually (T_wresp - T_g)
+ * periods. The gap time T_g varies (4..10).
+ */
+ while(AT91C_BASE_TC1->TC_CV < t0*(fdt-8));
+
+ int saved_cmr = AT91C_BASE_TC1->TC_CMR;
+ AT91C_BASE_TC1->TC_CMR &= ~AT91C_TC_ETRGEDG; /* Disable external trigger for the clock */
+ AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG; /* Reset the clock and use it for response timing */
+
+ int i;
+ for(i=0; i<5; i++)
+ hitag_send_bit(t0, 1); /* Start of frame */
+
+ for(i=0; i<frame_len; i++) {
+ hitag_send_bit(t0, !!(frame[i/ 8] & (1<<( 7-(i%8) ))) );
+ }
+
+ OPEN_COIL();
+ AT91C_BASE_TC1->TC_CMR = saved_cmr;
+}
+
+/* Callback structure to cleanly separate tag emulation code from the radio layer. */
+static int hitag_cb(const char* response_data, const int response_length, const int fdt, void *cb_cookie)
+{
+ hitag_send_frame(*(int*)cb_cookie, response_length, response_data, fdt);
+ return 0;
+}
+/* Frame length in bits, frame contents in MSBit first format */
+static void hitag_handle_frame(int t0, int frame_len, char *frame)
+{
+ hitag2_handle_command(frame, frame_len, hitag_cb, &t0);
+}
+
+// compose fc/8 fc/10 waveform
+static void fc(int c, int *n) {
+ BYTE *dest = (BYTE *)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)
+{
+ BYTE *dest = (BYTE *)BigBuf;
+ int m=0, n=0, i=0, idx=0, found=0, lastval=0;
+ DWORD 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] = (BYTE)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 && (hi|lo)) {
+ Dbprintf("TAG ID: %x%08x (%d)",
+ (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
+ /* if we're only looking for one tag */
+ if (findone)
+ {
+ *high = hi;
+ *low = lo;
+ return;
+ }
+ hi=0;
+ lo=0;
+ found=0;
+ }
+ }
+ if (found) {
+ if (dest[idx] && (!dest[idx+1]) ) {
+ hi=(hi<<1)|(lo>>31);
+ lo=(lo<<1)|0;
+ } else if ( (!dest[idx]) && dest[idx+1]) {
+ hi=(hi<<1)|(lo>>31);
+ lo=(lo<<1)|1;
+ } else {
+ found=0;
+ hi=0;
+ lo=0;
+ }
+ idx++;
+ }
+ if ( dest[idx] && dest[idx+1] && dest[idx+2] && (!dest[idx+3]) && (!dest[idx+4]) && (!dest[idx+5]) )
+ {
+ found=1;
+ idx+=6;
+ if (found && (hi|lo)) {
+ Dbprintf("TAG ID: %x%08x (%d)",
+ (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
+ /* if we're only looking for one tag */
+ if (findone)
+ {
+ *high = hi;
+ *low = lo;
+ return;
+ }
+ hi=0;
+ lo=0;
+ found=0;
+ }
+ }
+ }
+ WDT_HIT();
+ }
+}
projects / proxmark3-svn / blobdiff