X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/69d88ec4639d7bec0d3b226c2f4d2186703e9055..90e278d3daf11b501043d7ae628a25aeb0227420:/armsrc/lfops.c

diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index 072961a2..74f04913 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -15,8 +15,14 @@
 #include "crc16.h"
 #include "string.h"
 
-// split into two routines so we can avoid timing issues after sending commands //
-void DoAcquisition125k_internal(bool silent)
+
+/**
+* Does the sample acquisition. If threshold is specified, the actual sampling 
+* is not commenced until the threshold has been reached. 
+* @param trigger_threshold - the threshold
+* @param silent - is true, now outputs are made. If false, dbprints the status
+*/
+void DoAcquisition125k_internal(int trigger_threshold,bool silent)
 {
 	uint8_t *dest = (uint8_t *)BigBuf;
 	int n = sizeof(BigBuf);
@@ -31,25 +37,39 @@ void DoAcquisition125k_internal(bool silent)
 		}
 		if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
 			dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-			i++;
 			LED_D_OFF();
-			if (i >= n) break;
+			if (trigger_threshold != -1 && dest[i] < trigger_threshold)
+				continue;
+			else
+				trigger_threshold = -1;
+			if (++i >= n) break;
 		}
 	}
-	if( ! silent)
+	if(!silent)
 	{
 		Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
 				dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
+		
 	}
 }
-
-void DoAcquisition125k(void)
+/**
+* Perform sample aquisition. 
+*/
+void DoAcquisition125k(int trigger_threshold)
 {
-	DoAcquisition125k_internal(false);
+	DoAcquisition125k_internal(trigger_threshold, false);
 }
 
-void SetupToAcquireRawAdcSamples(int divisor)
+/**
+* Setup the FPGA to listen for samples. This method downloads the FPGA bitstream 
+* if not already loaded, sets divisor and starts up the antenna. 
+* @param divisor : 1, 88> 255 or negative ==> 134.8 KHz
+* 				   0 or 95 ==> 125 KHz
+* 				   
+**/
+void LFSetupFPGAForADC(int divisor, bool lf_field)
 {
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
 		FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
 	else if (divisor == 0)
@@ -57,48 +77,55 @@ void SetupToAcquireRawAdcSamples(int divisor)
 	else
 		FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
 
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | (lf_field ? FPGA_LF_ADC_READER_FIELD : 0));
 
 	// 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();
 }
-
+/**
+* Initializes the FPGA, and acquires the samples. 
+**/
 void AcquireRawAdcSamples125k(int divisor)
 {
-	SetupToAcquireRawAdcSamples(divisor);
+	LFSetupFPGAForADC(divisor, true);
 	// Now call the acquisition routine
-	DoAcquisition125k_internal(false);
+	DoAcquisition125k_internal(-1,false);
+}
+/**
+* Initializes the FPGA for snoop-mode, and acquires the samples. 
+**/
+
+void SnoopLFRawAdcSamples(int divisor, int trigger_threshold)
+{
+	LFSetupFPGAForADC(divisor, false);
+	DoAcquisition125k(trigger_threshold);
 }
 
 void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int period_1, uint8_t *command)
 {
-	int at134khz;
 
 	/* Make sure the tag is reset */
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
 	SpinDelay(2500);
 
+
+	int divisor_used = 95; // 125 KHz
 	// 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
+	if (command[strlen((char *) command) - 1] == 'h')
+		divisor_used = 88; // 134.8 KHz
 
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
 
+	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor_used); 
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
 	// 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);
 
@@ -110,12 +137,9 @@ void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int 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
+		FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor_used); 
 
-		FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+		FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
 		LED_D_ON();
 		if(*(command++) == '0')
 			SpinDelayUs(period_0);
@@ -125,15 +149,12 @@ void ModThenAcquireRawAdcSamples125k(int delay_off, int period_0, int 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
+	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor_used); 
 
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
 
 	// now do the read
-	DoAcquisition125k();
+	DoAcquisition125k(-1);
 }
 
 /* blank r/w tag data stream
@@ -170,6 +191,7 @@ void ReadTItag(void)
 	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
@@ -377,6 +399,7 @@ void AcquireTiType(void)
 // 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);
@@ -448,6 +471,7 @@ void SimulateTagLowFrequency(int period, int gap, int ledcontrol)
 	int i;
 	uint8_t *tab = (uint8_t *)BigBuf;
     
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
     
 	AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT | GPIO_SSC_CLK;
@@ -605,68 +629,27 @@ void CmdHIDsimTAG(int hi, int lo, int ledcontrol)
 	if (ledcontrol)
 		LED_A_OFF();
 }
-void setup_for_125khz()
-{
-	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();
-
-}
-void get_samples(int ledcontrol, uint8_t* dest, int size)
-{
-	int i = 0;
-
-	memset(dest,128,size);
-	for(;;) {
-		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-			AT91C_BASE_SSC->SSC_THR = 0x43;
-			if (ledcontrol) LED_D_ON();
-		}
-		if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-			dest[i] = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-			// we don't care about actual value, only if it's more or less than a
-			// threshold essentially we capture zero crossings for later analysis
-			if(dest[i] < 127) dest[i] = 0; else dest[i] = 1;
-			i++;
-			if (ledcontrol) LED_D_OFF();
-			if(i >= size) {
-				break;
-			}
-		}
-	}
-}
 
-uint8_t fsk_demod(uint8_t * dest, int size)
+size_t fsk_demod(uint8_t * dest, size_t size)
 {
-	uint8_t last_transition = 0;
-	uint8_t idx = 1;
+	uint32_t last_transition = 0;
+	uint32_t idx = 1;
 
 	// we don't care about actual value, only if it's more or less than a
 	// threshold essentially we capture zero crossings for later analysis
 	uint8_t threshold_value = 127;
 
-	WDT_HIT();
-
 	// sync to first lo-hi transition, and threshold
 
 	//Need to threshold first sample
 	if(dest[0] < threshold_value) dest[0] = 0;
 	else dest[0] = 1;
 
-	uint8_t numBits = 0;
+	size_t numBits = 0;
 	// count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
 	// or 10 (fc/10) cycles but in practice due to noise etc we may end up with with anywhere
 	// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
 	for(idx = 1; idx < size; idx++) {
-
 		// threshold current value
 		if (dest[idx] < threshold_value) dest[idx] = 0;
 		else dest[idx] = 1;
@@ -686,12 +669,13 @@ uint8_t fsk_demod(uint8_t * dest, int size)
 	return numBits; //Actually, it returns the number of bytes, but each byte represents a bit: 1 or 0
 }
 
-uint8_t aggregate_bits(uint8_t *dest,uint8_t size, uint8_t h2l_crossing_value,uint8_t l2h_crossing_value, uint8_t maxConsequtiveBits )
+
+size_t aggregate_bits(uint8_t *dest,size_t size, uint8_t h2l_crossing_value,uint8_t l2h_crossing_value, uint8_t maxConsequtiveBits )
 {
 	uint8_t lastval=dest[0];
-	uint8_t idx=0;
-	uint8_t numBits=0;
-	uint8_t n=1, i=0;
+	uint32_t idx=0;
+	size_t numBits=0;
+	uint32_t n=1;
 
 	for( idx=1; idx < size; idx++) {
 
@@ -700,14 +684,16 @@ uint8_t aggregate_bits(uint8_t *dest,uint8_t size, uint8_t h2l_crossing_value,ui
 			continue;
 		}
 		//if lastval was 1, we have a 1->0 crossing
-		if ( lastval ) {
-			n=(n+1)/7;
+		if ( dest[idx-1] ) {
+			n=(n+1) / h2l_crossing_value;
 		} else {// 0->1 crossing
-			n=(n+1)/6;
+			n=(n+1) / l2h_crossing_value;
 		}
-		if(n < 13)
+		if (n == 0) n = 1;
+
+		if(n < maxConsequtiveBits)
 		{
-			memset(dest+i, lastval ^ 1, n);
+			memset(dest+numBits, dest[idx-1] , n);
 			numBits += n;
 		}
 		n=0;
@@ -722,34 +708,24 @@ void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
 {
 	uint8_t *dest = (uint8_t *)BigBuf;
 
-	int size=0, idx=0, found=0;
+	size_t size=0,idx=0; //, found=0;
 	uint32_t hi2=0, hi=0, lo=0;
 
 	// Configure to go in 125Khz listen mode
-	SetupToAcquireRawAdcSamples(0);
+	LFSetupFPGAForADC(95, true);
 
-	for(;;) {
-		WDT_HIT();
-		if (ledcontrol)
-			LED_A_ON();
-		if(BUTTON_PRESS()) {
-			DbpString("Stopped");
-			if (ledcontrol)
-				LED_A_OFF();
-			return;
-		}
+	while(!BUTTON_PRESS()) {
 
+		WDT_HIT();
+		if (ledcontrol) LED_A_ON();
 
-		DoAcquisition125k_internal(true);
+		DoAcquisition125k_internal(-1,true);
 		size  = sizeof(BigBuf);
 
 		// FSK demodulator
 		size = fsk_demod(dest, size);
 
-		WDT_HIT();
-
 		// we now have a set of cycle counts, loop over previous results and aggregate data into bit patterns
-
 		// 1->0 : fc/8 in sets of 6
 		// 0->1 : fc/10 in sets of 5
 		size = aggregate_bits(dest,size, 6,5,5);
@@ -759,60 +735,60 @@ void CmdHIDdemodFSK(int findone, int *high, int *low, int ledcontrol)
 		// 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
 		uint8_t frame_marker_mask[] = {1,1,1,0,0,0};
+		int numshifts = 0;
+		idx = 0;
+		while( idx + sizeof(frame_marker_mask) < size) {
+			// search for a start of frame marker
+			if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
+			{ // frame marker found
+				idx+=sizeof(frame_marker_mask);
 
-		for( idx=0; idx < size-sizeof(frame_marker_mask); idx++) {
-
-			if (found) {
-				if(dest[idx] == dest[idx+1])
-				{// 1 1 or 00
-					found=0;
-					hi2=0;
-					hi=0;
-					lo=0;
-				}else
-				{
-					//Shift in a bit. Start by shifting high registers
+				while(dest[idx] != dest[idx+1] && idx < size-2)
+				{	
+					// Keep going until next frame marker (or error)
+					// Shift in a bit. Start by shifting high registers
 					hi2 = (hi2<<1)|(hi>>31);
 					hi = (hi<<1)|(lo>>31);
 					//Then, shift in a 0 or one into low
 					if (dest[idx] && !dest[idx+1])	// 1 0
 						lo=(lo<<1)|0;
 					else // 0 1
-						lo=(lo<<1)|1;
+						lo=(lo<<1)|
+								1;
+					numshifts ++;
+					idx += 2;
 				}
-				idx++;
-			}
-
-			// search for a start of frame marker
-			if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
-			{	// Found start of frame marker
-				found=1;
-				idx+=sizeof(frame_marker_mask);
-				if (found && (hi2|hi|lo)) {
-					if (hi2 != 0){
-						Dbprintf("TAG ID: %x%08x%08x (%d)",
-							 (unsigned int) hi2, (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
-					}
-					else {
-						Dbprintf("TAG ID: %x%08x (%d)",
-						 (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
-					}
-					/* if we're only looking for one tag */
-					if (findone)
+				//Dbprintf("Num shifts: %d ", numshifts);
+				// Hopefully, we read a tag and	 hit upon the next frame marker
+				if(idx + sizeof(frame_marker_mask) < size)
+				{
+					if ( memcmp(dest+idx, frame_marker_mask, sizeof(frame_marker_mask)) == 0)
 					{
-						*high = hi;
-						*low = lo;
-						return;
+						if (hi2 != 0){
+							Dbprintf("TAG ID: %x%08x%08x (%d)",
+								 (unsigned int) hi2, (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
+						}
+						else {
+							Dbprintf("TAG ID: %x%08x (%d)",
+							 (unsigned int) hi, (unsigned int) lo, (unsigned int) (lo>>1) & 0xFFFF);
+						}
 					}
-					hi2=0;
-					hi=0;
-					lo=0;
-					found=0;
+
 				}
+
+				// reset
+				hi2 = hi = lo = 0;
+				numshifts = 0;
+			}else
+			{
+				idx++;
 			}
 		}
 		WDT_HIT();
+
 	}
+	DbpString("Stopped");
+	if (ledcontrol) LED_A_OFF();
 }
 
 uint32_t bytebits_to_byte(uint8_t* src, int numbits)
@@ -830,29 +806,25 @@ uint32_t bytebits_to_byte(uint8_t* src, int numbits)
 void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
 {
 	uint8_t *dest = (uint8_t *)BigBuf;
-	int size=0, idx=0;
+
+	size_t size=0, idx=0;
 	uint32_t code=0, code2=0;
-	//uint32_t hi2=0, hi=0, lo=0;
 
-	setup_for_125khz();
+	// Configure to go in 125Khz listen mode
+	LFSetupFPGAForADC(95, true);
+
+	while(!BUTTON_PRESS()) {
+
 
-	for(;;) {
 		WDT_HIT();
-		if (ledcontrol)
-			LED_A_ON();
-		if(BUTTON_PRESS()) {
-			DbpString("Stopped");
-			if (ledcontrol)
-				LED_A_OFF();
-			return;
-		}
+		if (ledcontrol) LED_A_ON();
 
-		DoAcquisition125k_internal(true);
+		DoAcquisition125k_internal(-1,true);
 		size  = sizeof(BigBuf);
 
 		// FSK demodulator
 		size = fsk_demod(dest, size);
-		WDT_HIT();
+
 		// we now have a set of cycle counts, loop over previous results and aggregate data into bit patterns
 		// 1->0 : fc/8 in sets of 7
 		// 0->1 : fc/10 in sets of 6
@@ -860,6 +832,7 @@ void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
 
 		WDT_HIT();
 		
+		//Handle the data
  	    uint8_t mask[] = {0,0,0,0,0,0,0,0,0,1};
 		for( idx=0; idx < size - 64; idx++) {
 
@@ -890,8 +863,10 @@ void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
 				return;
 			}		
 		}
+		WDT_HIT();
 	}
-	WDT_HIT();
+	DbpString("Stopped");
+	if (ledcontrol) LED_A_OFF();
 }
 
 /*------------------------------
@@ -961,8 +936,9 @@ void CmdIOdemodFSK(int findone, int *high, int *low, int ledcontrol)
 // 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_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
 	if (bit == 0)
 		SpinDelayUs(WRITE_0);
 	else
@@ -976,8 +952,9 @@ void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t PwdMod
 {
 	unsigned int i;
 
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	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
@@ -1009,7 +986,7 @@ void T55xxWriteBlock(uint32_t Data, uint32_t Block, uint32_t Pwd, uint8_t PwdMod
 	// Now perform write (nominal is 5.6 ms for T55x7 and 18ms for E5550,
 	// so wait a little more)
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
 	SpinDelay(20);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
 }
@@ -1020,6 +997,7 @@ void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
 	uint8_t *dest = (uint8_t *)BigBuf;
 	int m=0, i=0;
   
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	m = sizeof(BigBuf);
   // Clear destination buffer before sending the command
 	memset(dest, 128, m);
@@ -1030,7 +1008,7 @@ void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
   
 	LED_D_ON();
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	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
@@ -1056,7 +1034,7 @@ void T55xxReadBlock(uint32_t Block, uint32_t Pwd, uint8_t PwdMode)
   
   // Turn field on to read the response
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
   
 	// Now do the acquisition
 	i = 0;
@@ -1084,6 +1062,7 @@ void T55xxReadTrace(void){
 	uint8_t *dest = (uint8_t *)BigBuf;
 	int m=0, i=0;
   
+	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	m = sizeof(BigBuf);
   // Clear destination buffer before sending the command
 	memset(dest, 128, m);
@@ -1094,7 +1073,7 @@ void T55xxReadTrace(void){
   
 	LED_D_ON();
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	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
@@ -1110,7 +1089,7 @@ void T55xxReadTrace(void){
   
   // Turn field on to read the response
 	FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
   
 	// Now do the acquisition
 	i = 0;
@@ -1799,8 +1778,9 @@ void SendForward(uint8_t fwd_bit_count) {
   LED_D_ON();
   
   //Field on
+  FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
   FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);
+  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
@@ -1812,7 +1792,7 @@ void SendForward(uint8_t fwd_bit_count) {
   FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
   SpinDelayUs(55*8); //55 cycles off (8us each)for 4305
   FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);//field on
+  FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
   SpinDelayUs(16*8); //16 cycles on (8us each)
   
   // now start writting
@@ -1824,7 +1804,7 @@ void SendForward(uint8_t fwd_bit_count) {
       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); // field off
       SpinDelayUs(23*8); //16-4 cycles off (8us each)
       FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
-      FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_READER);//field on
+      FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);//field on
       SpinDelayUs(9*8); //16 cycles on (8us each)
     }
   }