Merge branch 'master' of https://github.com/Proxmark/proxmark3

[proxmark3-svn] / armsrc / lfops.c

//-----------------------------------------------------------------------------
// 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"
#include "lfdemod.h"
#include "lfsampling.h"
#include "usb_cdc.h"


/**
 * Function to do a modulation and then get samples.
 * @param delay_off
 * @param period_0
 * @param period_1
 * @param command
 */
void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int period_1, uint8_t *command)
{

    int divisor_used = 95; // 125 KHz
    // see if 'h' was specified

    if (command[strlen((char *) command) - 1] == 'h')
        divisor_used = 88; // 134.8 KHz

	sample_config sc = { 0,0,1, divisor_used, 0};
	setSamplingConfig(&sc);

    /* Make sure the tag is reset */
    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    SpinDelay(2500);

	LFSetupFPGAForADC(sc.divisor, 1);

    // And a little more time for the tag to fully power up
    SpinDelay(2000);

    // now modulate the reader field
    while(*command != '\0' && *command != ' ') {
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LED_D_OFF();
        SpinDelayUs(delay_off);
		FpgaSendCommand(FPGA_CMD_SET_DIVISOR, sc.divisor);

        FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
        LED_D_ON();
        if(*(command++) == '0')
            SpinDelayUs(period_0);
        else
            SpinDelayUs(period_1);
    }
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    LED_D_OFF();
    SpinDelayUs(delay_off);
	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, sc.divisor);

    FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);

    // now do the read
	DoAcquisition_config(false);
}

/* 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_get_addr();
    uint16_t n = BigBuf_max_traceLen();
    // 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
    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    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
	uint32_t *BigBuf = (uint32_t *)BigBuf_get_addr();
    memset(BigBuf,0,BigBuf_max_traceLen()/sizeof(uint32_t));

    // 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_get_addr();
    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)
{
    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    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(uint16_t period, uint32_t gap, uint8_t ledcontrol)
{
    int i;
    uint8_t *tab = BigBuf_get_addr();

    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    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(;;) {
        //wait until SSC_CLK goes HIGH
        while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)) {
			if(BUTTON_PRESS() || usb_poll()) {
                DbpString("Stopped");
                return;
            }
            WDT_HIT();
        }
        if (ledcontrol)
            LED_D_ON();

        if(tab[i])
            OPEN_COIL();
        else
            SHORT_COIL();

        if (ledcontrol)
            LED_D_OFF();
        //wait until SSC_CLK goes LOW
        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 (FSK2)
static void fc(int c, int *n)
{
    uint8_t *dest = BigBuf_get_addr();
    int idx;

    // for when we want an fc8 pattern every 4 logical bits
    if(c==0) {
        dest[((*n)++)]=1;
        dest[((*n)++)]=1;
        dest[((*n)++)]=1;
        dest[((*n)++)]=1;
        dest[((*n)++)]=0;
        dest[((*n)++)]=0;
        dest[((*n)++)]=0;
        dest[((*n)++)]=0;
    }
  
    //	an fc/8  encoded bit is a bit pattern of  11110000  x6 = 48 samples
    if(c==8) {
        for (idx=0; idx<6; idx++) {
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
        }
    }

    //	an fc/10 encoded bit is a bit pattern of 1111100000 x5 = 50 samples
    if(c==10) {
        for (idx=0; idx<5; idx++) {
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=1;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
            dest[((*n)++)]=0;
        }
    }
}
// compose fc/X fc/Y waveform (FSKx)
static void fcAll(uint8_t fc, int *n, uint8_t clock, uint16_t *modCnt) 
{
    uint8_t *dest = BigBuf_get_addr();
    uint8_t halfFC = fc/2;
    uint8_t wavesPerClock = clock/fc;
    uint8_t mod = clock % fc;    //modifier
    uint8_t modAdj = fc/mod;     //how often to apply modifier
    bool modAdjOk = !(fc % mod); //if (fc % mod==0) modAdjOk=TRUE;
    // loop through clock - step field clock
    for (uint8_t idx=0; idx < wavesPerClock; idx++){
        // put 1/2 FC length 1's and 1/2 0's per field clock wave (to create the wave)
        memset(dest+(*n), 0, fc-halfFC);  //in case of odd number use extra here
        memset(dest+(*n)+(fc-halfFC), 1, halfFC);
        *n += fc;
    }
    if (mod>0) (*modCnt)++;
    if ((mod>0) && modAdjOk){  //fsk2 
        if ((*modCnt % modAdj) == 0){ //if 4th 8 length wave in a rf/50 add extra 8 length wave
            memset(dest+(*n), 0, fc-halfFC);
            memset(dest+(*n)+(fc-halfFC), 1, halfFC);
            *n += fc;
        }
    }
    if (mod>0 && !modAdjOk){  //fsk1
        memset(dest+(*n), 0, mod-(mod/2));
        memset(dest+(*n)+(mod-(mod/2)), 1, mod/2);
        *n += mod;
    }
}

// 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. - USE lf simfsk for larger tags");
        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();
}

// prepare a waveform pattern in the buffer based on the ID given then
// simulate a FSK tag until the button is pressed
// arg1 contains fcHigh and fcLow, arg2 contains invert and clock
void CmdFSKsimTAG(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
    int ledcontrol=1;
    int n=0, i=0;
    uint8_t fcHigh = arg1 >> 8;
    uint8_t fcLow = arg1 & 0xFF;
    uint16_t modCnt = 0;
    uint8_t clk = arg2 & 0xFF;
    uint8_t invert = (arg2 >> 8) & 1;

    for (i=0; i<size; i++){
        if (BitStream[i] == invert){
            fcAll(fcLow, &n, clk, &modCnt);
        } else {
            fcAll(fcHigh, &n, clk, &modCnt);
        }
    }
    Dbprintf("Simulating with fcHigh: %d, fcLow: %d, clk: %d, invert: %d, n: %d",fcHigh, fcLow, clk, invert, n);
    /*Dbprintf("DEBUG: First 32:");
    uint8_t *dest = BigBuf_get_addr();
    i=0;
    Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
    i+=16;
    Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
    */     
    if (ledcontrol)
        LED_A_ON();

    SimulateTagLowFrequency(n, 0, ledcontrol);

    if (ledcontrol)
        LED_A_OFF();
}

// compose ask waveform for one bit(ASK)
static void askSimBit(uint8_t c, int *n, uint8_t clock, uint8_t manchester) 
{
    uint8_t *dest = BigBuf_get_addr();
    uint8_t halfClk = clock/2;
    // c = current bit 1 or 0
    if (manchester==1){
        memset(dest+(*n), c, halfClk);
        memset(dest+(*n) + halfClk, c^1, halfClk);
    } else {
        memset(dest+(*n), c, clock);
    }
    *n += clock;        
}

static void biphaseSimBit(uint8_t c, int *n, uint8_t clock, uint8_t *phase)
{
    uint8_t *dest = BigBuf_get_addr();
    uint8_t halfClk = clock/2;
    if (c){
        memset(dest+(*n), c ^ 1 ^ *phase, halfClk);
        memset(dest+(*n) + halfClk, c ^ *phase, halfClk);        
    } else {
        memset(dest+(*n), c ^ *phase, clock);
        *phase ^= 1;
    }

}

// args clock, ask/man or askraw, invert, transmission separator
void CmdASKsimTag(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
    int ledcontrol = 1;
    int n=0, i=0;
    uint8_t clk = (arg1 >> 8) & 0xFF;
    uint8_t encoding = arg1 & 1;
    uint8_t separator = arg2 & 1;
    uint8_t invert = (arg2 >> 8) & 1;

    if (encoding==2){  //biphase
        uint8_t phase=0;
    for (i=0; i<size; i++){
            biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
    }
        if (BitStream[0]==BitStream[size-1]){ //run a second set inverted to keep phase in check
        for (i=0; i<size; i++){
                biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
            }
        }
    } else {  // ask/manchester || ask/raw
        for (i=0; i<size; i++){
            askSimBit(BitStream[i]^invert, &n, clk, encoding);
        }
        if (encoding==0 && BitStream[0]==BitStream[size-1]){ //run a second set inverted (for biphase phase)
            for (i=0; i<size; i++){
                askSimBit(BitStream[i]^invert^1, &n, clk, encoding);
        }    
        }    
    }
    
    if (separator==1) Dbprintf("sorry but separator option not yet available"); 

    Dbprintf("Simulating with clk: %d, invert: %d, encoding: %d, separator: %d, n: %d",clk, invert, encoding, separator, n);
    //DEBUG
    //Dbprintf("First 32:");
    //uint8_t *dest = BigBuf_get_addr();
    //i=0;
    //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
    //i+=16;
    //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);

    if (ledcontrol)
        LED_A_ON();
    
    SimulateTagLowFrequency(n, 0, ledcontrol);

    if (ledcontrol)
        LED_A_OFF();
}

//carrier can be 2,4 or 8
static void pskSimBit(uint8_t waveLen, int *n, uint8_t clk, uint8_t *curPhase, bool phaseChg)
{
    uint8_t *dest = BigBuf_get_addr();
    uint8_t halfWave = waveLen/2;
    //uint8_t idx;
    int i = 0;
    if (phaseChg){
        // write phase change
        memset(dest+(*n), *curPhase^1, halfWave);
        memset(dest+(*n) + halfWave, *curPhase, halfWave);
        *n += waveLen;
        *curPhase ^= 1;
        i += waveLen;
    }
    //write each normal clock wave for the clock duration
    for (; i < clk; i+=waveLen){
        memset(dest+(*n), *curPhase, halfWave);
        memset(dest+(*n) + halfWave, *curPhase^1, halfWave);
        *n += waveLen;
    }
}

// args clock, carrier, invert,
void CmdPSKsimTag(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
{
    int ledcontrol=1;
    int n=0, i=0;
    uint8_t clk = arg1 >> 8;
    uint8_t carrier = arg1 & 0xFF;
    uint8_t invert = arg2 & 0xFF;
    uint8_t curPhase = 0;
    for (i=0; i<size; i++){
        if (BitStream[i] == curPhase){
            pskSimBit(carrier, &n, clk, &curPhase, FALSE);
        } else {
            pskSimBit(carrier, &n, clk, &curPhase, TRUE);
        }            
    }
    Dbprintf("Simulating with Carrier: %d, clk: %d, invert: %d, n: %d",carrier, clk, invert, n);
    //Dbprintf("DEBUG: First 32:");
    //uint8_t *dest = BigBuf_get_addr();
    //i=0;
    //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
    //i+=16;
    //Dbprintf("%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d", dest[i],dest[i+1],dest[i+2],dest[i+3],dest[i+4],dest[i+5],dest[i+6],dest[i+7],dest[i+8],dest[i+9],dest[i+10],dest[i+11],dest[i+12],dest[i+13],dest[i+14],dest[i+15]);
           
    if (ledcontrol)
        LED_A_ON();
    SimulateTagLowFrequency(n, 0, ledcontrol);

    if (ledcontrol)
        LED_A_OFF();
}

// loop to get raw HID waveform then FSK demodulate the TAG ID from it
void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
{
    uint8_t *dest = BigBuf_get_addr();
    const size_t sizeOfBigBuff = BigBuf_max_traceLen();
    size_t size = 0; 
    uint32_t hi2=0, hi=0, lo=0;
    int idx=0;
    // Configure to go in 125Khz listen mode
    LFSetupFPGAForADC(95, true);

    while(!BUTTON_PRESS()) {

        WDT_HIT();
        if (ledcontrol) LED_A_ON();

		DoAcquisition_default(-1,true);
        // FSK demodulator
        size = sizeOfBigBuff;  //variable size will change after demod so re initialize it before use
		idx = HIDdemodFSK(dest, &size, &hi2, &hi, &lo);
        
		if (idx>0 && lo>0){
            // 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
            if (hi2 != 0){ //extra large HID tags
                Dbprintf("TAG ID: %x%08x%08x (%d)",
                         (unsigned int) hi2, (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
            }else {  //standard HID tags <38 bits
                //Dbprintf("TAG ID: %x%08x (%d)",(unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF); //old print cmd
                uint8_t bitlen = 0;
                uint32_t fc = 0;
                uint32_t cardnum = 0;
				if (((hi>>5)&1) == 1){//if bit 38 is set then < 37 bit format is used
                    uint32_t lo2=0;
                    lo2=(((hi & 31) << 12) | (lo>>20)); //get bits 21-37 to check for format len bit
                    uint8_t idx3 = 1;
					while(lo2 > 1){ //find last bit set to 1 (format len bit)
						lo2=lo2 >> 1;
                        idx3++;
                    }
					bitlen = idx3+19;
                    fc =0;
                    cardnum=0;
					if(bitlen == 26){
                        cardnum = (lo>>1)&0xFFFF;
                        fc = (lo>>17)&0xFF;
                    }
					if(bitlen == 37){
                        cardnum = (lo>>1)&0x7FFFF;
                        fc = ((hi&0xF)<<12)|(lo>>20);
                    }
					if(bitlen == 34){
                        cardnum = (lo>>1)&0xFFFF;
                        fc= ((hi&1)<<15)|(lo>>17);
                    }
					if(bitlen == 35){
                        cardnum = (lo>>1)&0xFFFFF;
                        fc = ((hi&1)<<11)|(lo>>21);
                    }
                }
                else { //if bit 38 is not set then 37 bit format is used
                    bitlen= 37;
                    fc =0;
                    cardnum=0;
                    if(bitlen==37){
                        cardnum = (lo>>1)&0x7FFFF;
                        fc = ((hi&0xF)<<12)|(lo>>20);
                    }
                }
                //Dbprintf("TAG ID: %x%08x (%d)",
                // (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
                Dbprintf("TAG ID: %x%08x (%d) - Format Len: %dbit - FC: %d - Card: %d",
                         (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF,
                         (unsigned int) bitlen, (unsigned int) fc, (unsigned int) cardnum);
            }
            if (findone){
                if (ledcontrol)	LED_A_OFF();
                *high = hi;
                *low = lo;
                return;
            }
            // reset
            hi2 = hi = lo = 0;
        }
        WDT_HIT();
    }
    DbpString("Stopped");
    if (ledcontrol) LED_A_OFF();
}

void CmdEM410xdemod(int findone, int *high, int *low, int ledcontrol)
{
    uint8_t *dest = BigBuf_get_addr();

	size_t size=0, idx=0;
    int clk=0, invert=0, errCnt=0, maxErr=20;
    uint32_t hi=0;
    uint64_t lo=0;
    // Configure to go in 125Khz listen mode
    LFSetupFPGAForADC(95, true);

    while(!BUTTON_PRESS()) {

        WDT_HIT();
        if (ledcontrol) LED_A_ON();

		DoAcquisition_default(-1,true);
        size  = BigBuf_max_traceLen();
        //Dbprintf("DEBUG: Buffer got");
		//askdemod and manchester decode
		errCnt = askmandemod(dest, &size, &clk, &invert, maxErr);
        //Dbprintf("DEBUG: ASK Got");
        WDT_HIT();

        if (errCnt>=0){
            errCnt = Em410xDecode(dest, &size, &idx, &hi, &lo);
            //Dbprintf("DEBUG: EM GOT");
            if (errCnt){
                if (size>64){
                    Dbprintf("EM XL TAG ID: %06x%08x%08x - (%05d_%03d_%08d)",
                        hi,
                        (uint32_t)(lo>>32),
                        (uint32_t)lo,
                        (uint32_t)(lo&0xFFFF),
                        (uint32_t)((lo>>16LL) & 0xFF),
                        (uint32_t)(lo & 0xFFFFFF));
                } else {
				Dbprintf("EM TAG ID: %02x%08x - (%05d_%03d_%08d)",
				    (uint32_t)(lo>>32),
				    (uint32_t)lo,
				    (uint32_t)(lo&0xFFFF),
				    (uint32_t)((lo>>16LL) & 0xFF),
				    (uint32_t)(lo & 0xFFFFFF));
            }
            }
            if (findone){
                if (ledcontrol)	LED_A_OFF();
                *high=lo>>32;
                *low=lo & 0xFFFFFFFF;
                return;
            }
        } else{
            //Dbprintf("DEBUG: No Tag");
        }
        WDT_HIT();
        lo = 0;
        clk=0;
        invert=0;
        errCnt=0;
        size=0;
    }
    DbpString("Stopped");
    if (ledcontrol) LED_A_OFF();
}

void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
{
    uint8_t *dest = BigBuf_get_addr();
    int idx=0;
    uint32_t code=0, code2=0;
    uint8_t version=0;
    uint8_t facilitycode=0;
    uint16_t number=0;
	uint8_t crc = 0;
	uint16_t calccrc = 0;
    // Configure to go in 125Khz listen mode
    LFSetupFPGAForADC(95, true);

    while(!BUTTON_PRESS()) {
        WDT_HIT();
        if (ledcontrol) LED_A_ON();
		DoAcquisition_default(-1,true);
        //fskdemod and get start index
        WDT_HIT();
        idx = IOdemodFSK(dest, BigBuf_max_traceLen());
        if (idx>0){
            //valid tag found

            //Index map
            //0           10          20          30          40          50          60
            //|           |           |           |           |           |           |
            //01234567 8 90123456 7 89012345 6 78901234 5 67890123 4 56789012 3 45678901 23
            //-----------------------------------------------------------------------------
            //00000000 0 11110000 1 facility 1 version* 1 code*one 1 code*two 1 checksum 11
            //
			//Checksum:  
			//00000000 0 11110000 1 11100000 1 00000001 1 00000011 1 10110110 1 01110101 11
			//preamble      F0         E0         01         03         B6         75
			// How to calc checksum,
			// http://www.proxmark.org/forum/viewtopic.php?id=364&p=6
			//   F0 + E0 + 01 + 03 + B6 = 28A
			//   28A & FF = 8A
			//   FF - 8A = 75
			// Checksum: 0x75
            //XSF(version)facility:codeone+codetwo
            //Handle the data
            if(findone){ //only print binary if we are doing one
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx],   dest[idx+1],   dest[idx+2],dest[idx+3],dest[idx+4],dest[idx+5],dest[idx+6],dest[idx+7],dest[idx+8]);
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+9], dest[idx+10],dest[idx+11],dest[idx+12],dest[idx+13],dest[idx+14],dest[idx+15],dest[idx+16],dest[idx+17]);
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+18],dest[idx+19],dest[idx+20],dest[idx+21],dest[idx+22],dest[idx+23],dest[idx+24],dest[idx+25],dest[idx+26]);
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+27],dest[idx+28],dest[idx+29],dest[idx+30],dest[idx+31],dest[idx+32],dest[idx+33],dest[idx+34],dest[idx+35]);
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+36],dest[idx+37],dest[idx+38],dest[idx+39],dest[idx+40],dest[idx+41],dest[idx+42],dest[idx+43],dest[idx+44]);
                Dbprintf("%d%d%d%d%d%d%d%d %d",dest[idx+45],dest[idx+46],dest[idx+47],dest[idx+48],dest[idx+49],dest[idx+50],dest[idx+51],dest[idx+52],dest[idx+53]);
                Dbprintf("%d%d%d%d%d%d%d%d %d%d",dest[idx+54],dest[idx+55],dest[idx+56],dest[idx+57],dest[idx+58],dest[idx+59],dest[idx+60],dest[idx+61],dest[idx+62],dest[idx+63]);
            }
            code = bytebits_to_byte(dest+idx,32);
            code2 = bytebits_to_byte(dest+idx+32,32);
            version = bytebits_to_byte(dest+idx+27,8); //14,4
            facilitycode = bytebits_to_byte(dest+idx+18,8) ;
            number = (bytebits_to_byte(dest+idx+36,8)<<8)|(bytebits_to_byte(dest+idx+45,8)); //36,9

			crc = bytebits_to_byte(dest+idx+54,8);
			for (uint8_t i=1; i<6; ++i)
				calccrc += bytebits_to_byte(dest+idx+9*i,8);
			calccrc &= 0xff;
			calccrc = 0xff - calccrc;
			
			char *crcStr = (crc == calccrc) ? "ok":"!crc";

            Dbprintf("IO Prox XSF(%02d)%02x:%05d (%08x%08x)  [%02x %s]",version,facilitycode,number,code,code2, crc, crcStr);
            // if we're only looking for one tag
            if (findone){
                if (ledcontrol)	LED_A_OFF();
                //LED_A_OFF();
                *high=code;
                *low=code2;
                return;
            }
            code=code2=0;
            version=facilitycode=0;
            number=0;
            idx=0;
        }
        WDT_HIT();
    }
    DbpString("Stopped");
    if (ledcontrol) LED_A_OFF();
}

/*------------------------------
 * 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 50*8 // 10 - 50fc 250
#define WRITE_GAP 20*8 //  8 - 30fc
#define WRITE_0   24*8 // 16 - 31fc 24fc 192
#define WRITE_1   54*8 // 48 - 63fc 54fc 432 for T55x7; 448 for E5550

//  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); 

// Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
// TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
// Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
// T0 = TIMER_CLOCK1 / 125000 = 192
// 1 Cycle = 8 microseconds(us)

#define T55xx_SAMPLES_SIZE		12000 // 32 x 32 x 10  (32 bit times numofblock (7), times clock skip..)

// Write one bit to card
void T55xxWriteBit(int bit)
{
    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
    FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
	if (!bit)
        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)
{
    uint32_t i = 0;

    // Set up FPGA, 125kHz
    // Wait for config.. (192+8190xPOW)x8 == 67ms
    LFSetupFPGAForADC(0, true);

    // 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_ADC | FPGA_LF_ADC_READER_FIELD);
    SpinDelay(20);
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
}

void TurnReadLFOn(){
    FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
    // Give it a bit of time for the resonant antenna to settle.
    SpinDelayUs(8*150);
}


// Read one card block in page 0
void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
{
    uint32_t i = 0;
    uint8_t *dest = BigBuf_get_addr();
    uint16_t bufferlength = BigBuf_max_traceLen();
    if ( bufferlength > T55xx_SAMPLES_SIZE )
        bufferlength = T55xx_SAMPLES_SIZE;

    // Clear destination buffer before sending the command
    memset(dest, 0x80, bufferlength);

    // Set up FPGA, 125kHz
    // Wait for config.. (192+8190xPOW)x8 == 67ms
    LFSetupFPGAForADC(0, true);
    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
    TurnReadLFOn();
    // Now do the acquisition
    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 >= bufferlength) break;
        }
    }

    cmd_send(CMD_ACK,0,0,0,0,0);    
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
    LED_D_OFF();
}

// Read card traceability data (page 1)
void T55xxReadTrace(void){
    
    uint32_t i = 0;
    uint8_t *dest = BigBuf_get_addr();
    uint16_t bufferlength = BigBuf_max_traceLen();
    if ( bufferlength > T55xx_SAMPLES_SIZE )
        bufferlength= T55xx_SAMPLES_SIZE;

    // Clear destination buffer before sending the command
    memset(dest, 0x80, bufferlength);

    LFSetupFPGAForADC(0, true);
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    SpinDelayUs(START_GAP);

    // Opcode
    T55xxWriteBit(1);
    T55xxWriteBit(1); //Page 1

    // Turn field on to read the response
    TurnReadLFOn();

    // Now do the acquisition
    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 >= bufferlength) break;
		}
	}
  
	cmd_send(CMD_ACK,0,0,0,0,0);
    cmd_send(CMD_ACK,0,0,0,0,0);
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
    LED_D_OFF();
}

void TurnReadLFOn(){
	//FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
	// Give it a bit of time for the resonant antenna to settle.
	//SpinDelay(30);
	SpinDelayUs(8*150);
}

/*-------------- 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!");
}

void CopyIOtoT55x7(uint32_t hi, uint32_t lo, uint8_t longFMT)
{
    int data1=0, data2=0; //up to six blocks for long format

    data1 = hi;  // load preamble
    data2 = lo;

    LED_D_ON();
    // Program the data blocks for supplied ID
    // and the block 0 for HID format
    T55xxWriteBlock(data1,1,0,0);
    T55xxWriteBlock(data2,2,0,0);

    //Config Block
    T55xxWriteBlock(0x00147040,0,0,0);
    LED_D_OFF();

    DbpString("DONE!");
}

// Define 9bit header for EM410x tags
#define EM410X_HEADER		0x1FF
#define EM410X_ID_LENGTH	40

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 bits[256] = {0x00};
	uint8_t blocks[8][16];
    uint8_t *dest = BigBuf_get_addr();
    
	int GraphTraceLen = BigBuf_max_traceLen();
	if (  GraphTraceLen > 18000 )
		GraphTraceLen = 18000;
	
	
    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;

	LFSetupFPGAForADC(95, true);
	DoAcquisition_default(0, true);

    lmin = 64;
    lmax = 192;

    i = 2;

    /* Find first local max/min */
    if(dest[1] > dest[0]) {
        while(i < GraphTraceLen) {
            if( !(dest[i] > dest[i-1]) && dest[i] > lmax)
                break;
            i++;
        }
        dir = 0;
    }
    else {
        while(i < GraphTraceLen) {
            if( !(dest[i] < dest[i-1]) && dest[i] < lmin)
                break;
            i++;
        }
        dir = 1;
    }

    lastval = i++;
    half_switch = 0;
    pmc = 0;
    block_done = 0;

    for (bitidx = 0; i < GraphTraceLen; i++)
    {
        if ( (dest[i-1] > dest[i] && dir == 1 && dest[i] > lmax) || (dest[i-1] < dest[i] && dir == 0 && dest[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) {
                    bits[bitidx++] = 0;
                    half_switch = 0;
                }
                else
                    half_switch++;
            } else if (abs(lc-clock) < tolerance) {
                // 64TO
                bits[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*bits[j*8+7]+
                                64*bits[j*8+6]+
                                32*bits[j*8+5]+
                                16*bits[j*8+4]+
                                8*bits[j*8+3]+
                                4*bits[j*8+2]+
                                2*bits[j*8+1]+
                                bits[j*8];
						
                    }
                    num_blocks++;
                }
                bitidx = 0;
                block_done = 0;
                half_switch = 0;
            }
            if(i < GraphTraceLen)
                dir =(dest[i-1] > dest[i]) ? 0 : 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
    FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
    FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
    FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);

    // 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_ADC | FPGA_LF_ADC_READER_FIELD);//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_ADC | FPGA_LF_ADC_READER_FIELD);//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 *dest =  BigBuf_get_addr();
	uint16_t bufferlength = BigBuf_max_traceLen();
	uint32_t i = 0;

	// Clear destination buffer before sending the command  0x80 = average.
	memset(dest, 0x80, bufferlength);
	
    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_READ );
    fwd_bit_count += Prepare_Addr( Address );

    // 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 >= bufferlength) break;
		}
	}
  
	cmd_send(CMD_ACK,0,0,0,0,0);
    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();
}