+ (uint32_t)(id >> 32), (uint32_t)id);
+}
+
+//-----------------------------------
+// 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
+//====================================================================
+//--------------------------------------------------------------------
+// VALUES TAKEN FROM EM4x function: SendForward
+// START_GAP = 440; (55*8) cycles at 125Khz (8us = 1cycle)
+// WRITE_GAP = 128; (16*8)
+// WRITE_1 = 256 32*8; (32*8)
+
+// These timings work for 4469/4269/4305 (with the 55*8 above)
+// WRITE_0 = 23*8 , 9*8 SpinDelayUs(23*8);
+
+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;
+
+ // Set up FPGA, 125kHz or 95 divisor
+ LFSetupFPGAForADC(95, true);
+
+ // 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
+ WaitUS(55*8); //55 cycles off (8us each)for 4305 //another reader has 37 here...
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
+ WaitUS(18*8); //18 cycles on (8us each)
+
+ // now start writting
+ while(fwd_bit_sz-- > 0) { //prepare next bit modulation
+ if(((*fwd_write_ptr++) & 1) == 1)
+ WaitUS(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
+ WaitUS(23*8); //23 cycles off (8us each)
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
+ WaitUS(18*8); //18 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;
+
+ // Clear destination buffer before sending the command
+ BigBuf_Clear_ext(false);
+
+ LED_A_ON();
+ StartTicks();
+ //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 );
+
+ SendForward(fwd_bit_count);
+ WaitUS(400);
+ // Now do the acquisition
+ DoPartialAcquisition(20, true, 6000, 1000);
+
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+ LED_A_OFF();
+ cmd_send(CMD_ACK,0,0,0,0,0);
+}
+
+void EM4xWriteWord(uint32_t flag, uint32_t Data, uint32_t Pwd) {
+
+ bool PwdMode = (flag & 0xF);
+ uint8_t Address = (flag >> 8) & 0xFF;
+ uint8_t fwd_bit_count;
+
+ //clear buffer now so it does not interfere with timing later
+ BigBuf_Clear_ext(false);
+
+ LED_A_ON();
+ StartTicks();
+ //If password mode do login
+ if (PwdMode) 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(10);
+
+ WaitUS(6500);
+ //Capture response if one exists
+ DoPartialAcquisition(20, true, 6000, 1000);
+
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+ LED_A_OFF();
+ cmd_send(CMD_ACK,0,0,0,0,0);
+}
+/*
+Reading a COTAG.
+
+COTAG needs the reader to send a startsequence and the card has an extreme slow datarate.
+because of this, we can "sample" the data signal but we interpreate it to Manchester direct.
+
+READER START SEQUENCE:
+burst 800 us, gap 2.2 msecs
+burst 3.6 msecs gap 2.2 msecs
+burst 800 us gap 2.2 msecs
+pulse 3.6 msecs
+
+This triggers a COTAG tag to response
+*/
+void Cotag(uint32_t arg0) {
+
+#define OFF { FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); WaitUS(2035); }
+#define ON(x) { FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD); WaitUS((x)); }
+
+ uint8_t rawsignal = arg0 & 0xF;
+
+ LED_A_ON();
+
+ // Switching to LF image on FPGA. This might empty BigBuff
+ FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
+
+ //clear buffer now so it does not interfere with timing later
+ BigBuf_Clear_ext(false);
+
+ // Set up FPGA, 132kHz to power up the tag
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 89);
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
+
+ // 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();
+
+ // start clock - 1.5ticks is 1us
+ StartTicks();
+
+ //send COTAG start pulse
+ ON(740) OFF
+ ON(3330) OFF
+ ON(740) OFF
+ ON(1000)
+
+ switch(rawsignal) {
+ case 0: doCotagAcquisition(50000); break;
+ case 1: doCotagAcquisitionManchester(); break;
+ case 2: DoAcquisition_config(true, 0); break;
+ }
+
+ // Turn the field off
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
+ cmd_send(CMD_ACK,0,0,0,0,0);
+ LED_A_OFF();