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ISO15693 device side improvements (#652)
* ISO15693 device side improvements * increase accuracy by doubling the sample frequency (hi_read_rx_xcorr.v) * adjust armsrc/iso15693.c and client/cmdhf15.c accordingly * use more accurate approximation for sqrt(ci^2 + cq^2) * improve EOF detection (was often mistaken for Logic0, resulting in "error, uneven octet! (extra bits!)") * hi_read_r_xcorr.v: avoid overflows during accumulation and truncation * explicitely cast unsigned ADC samples to signed
This commit is contained in:
pwpiwi
GitHub
parent
c80eb8ba79
commit
315e18e66c
4 changed files with 174 additions and 130 deletions
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@ -81,7 +81,10 @@
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#define AddCrc(data,datalen) Iso15693AddCrc(data,datalen)
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#define sprintUID(target,uid) Iso15693sprintUID(target,uid)
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int DEBUG=0;
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// approximate amplitude=sqrt(ci^2+cq^2)
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#define AMPLITUDE(ci, cq) (MAX(ABS(ci), ABS(cq)) + (MIN(ABS(ci), ABS(cq))>>1))
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static int DEBUG = 0;
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// ---------------------------
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@ -303,13 +306,9 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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// NOW READ RESPONSE
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FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
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//spindelay(60); // greg - experiment to get rid of some of the 0 byte/failed reads
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c = 0;
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getNext = false;
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for(;;) {
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
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AT91C_BASE_SSC->SSC_THR = 0x43;
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}
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
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int8_t b;
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b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
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@ -319,11 +318,11 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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// every other is Q. We just want power, so abs(I) + abs(Q) is
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// close to what we want.
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if(getNext) {
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uint8_t r = ABS(b) + ABS(prev);
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uint8_t r = AMPLITUDE(b, prev);
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dest[c++] = (uint8_t)r;
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dest[c++] = r;
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if(c >= 2000) {
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if(c >= 4000) {
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break;
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}
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} else {
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@ -341,12 +340,10 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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int i, j;
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int max = 0, maxPos=0;
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int skip = 4;
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// if(GraphTraceLen < 1000) return; // THIS CHECKS FOR A BUFFER TO SMALL
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int skip = 2;
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// First, correlate for SOF
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for(i = 0; i < 100; i++) {
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for(i = 0; i < 200; i++) { // usually, SOF is found around i = 60
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int corr = 0;
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for(j = 0; j < arraylen(FrameSOF); j += skip) {
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corr += FrameSOF[j]*dest[i+(j/skip)];
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@ -356,7 +353,7 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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maxPos = i;
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}
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}
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// Dbprintf("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));
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if (DEBUG) Dbprintf("SOF at %d, correlation %d", maxPos, max/(arraylen(FrameSOF)/skip));
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int k = 0; // this will be our return value
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@ -370,10 +367,15 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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memset(outBuf, 0, sizeof(outBuf));
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uint8_t mask = 0x01;
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for(;;) {
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int corr0 = 0, corr1 = 0, corrEOF = 0;
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int corr0 = 0, corr00 = 0, corr01 = 0, corr1 = 0, corrEOF = 0;
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for(j = 0; j < arraylen(Logic0); j += skip) {
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corr0 += Logic0[j]*dest[i+(j/skip)];
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}
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corr01 = corr00 = corr0;
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for(j = 0; j < arraylen(Logic0); j += skip) {
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corr00 += Logic0[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
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corr01 += Logic1[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
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}
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for(j = 0; j < arraylen(Logic1); j += skip) {
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corr1 += Logic1[j]*dest[i+(j/skip)];
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}
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@ -381,11 +383,14 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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corrEOF += FrameEOF[j]*dest[i+(j/skip)];
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}
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// Even things out by the length of the target waveform.
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corr00 *= 2;
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corr01 *= 2;
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corr0 *= 4;
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corr1 *= 4;
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if(corrEOF > corr1 && corrEOF > corr0) {
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// Dbprintf("EOF at %d", i);
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if(corrEOF > corr1 && corrEOF > corr00 && corrEOF > corr01) {
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if (DEBUG) Dbprintf("EOF at %d, correlation %d (corr01: %d, corr00: %d, corr1: %d, corr0: %d)",
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i, corrEOF, corr01, corr00, corr1, corr0);
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break;
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} else if(corr1 > corr0) {
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i += arraylen(Logic1)/skip;
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@ -398,7 +403,7 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
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k++;
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mask = 0x01;
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}
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if((i+(int)arraylen(FrameEOF)) >= 2000) {
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if((i+(int)arraylen(FrameEOF)/skip) >= 4000) {
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DbpString("ran off end!");
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break;
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}
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@ -446,9 +451,6 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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c = 0;
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getNext = false;
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for(;;) {
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
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AT91C_BASE_SSC->SSC_THR = 0x43;
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}
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
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int8_t b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
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@ -457,11 +459,11 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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// every other is Q. We just want power, so abs(I) + abs(Q) is
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// close to what we want.
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if(getNext) {
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uint8_t r = ABS(b) + ABS(prev);
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uint8_t r = AMPLITUDE(b, prev);
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dest[c++] = (uint8_t)r;
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dest[c++] = r;
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if(c >= 20000) {
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if(c >= BIGBUF_SIZE) {
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break;
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}
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} else {
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@ -479,12 +481,10 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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int i, j;
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int max = 0, maxPos=0;
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int skip = 4;
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// if(GraphTraceLen < 1000) return; // THIS CHECKS FOR A BUFFER TO SMALL
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int skip = 2;
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// First, correlate for SOF
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for(i = 0; i < 19000; i++) {
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for(i = 0; i < 38000; i++) {
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int corr = 0;
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for(j = 0; j < arraylen(FrameSOF); j += skip) {
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corr += FrameSOF[j]*dest[i+(j/skip)];
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@ -494,7 +494,7 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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maxPos = i;
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}
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}
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// DbpString("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));
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if (DEBUG) Dbprintf("SOF at %d, correlation %d", maxPos,max/(arraylen(FrameSOF)/skip));
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int k = 0; // this will be our return value
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@ -508,10 +508,15 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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memset(outBuf, 0, sizeof(outBuf));
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uint8_t mask = 0x01;
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for(;;) {
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int corr0 = 0, corr1 = 0, corrEOF = 0;
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int corr0 = 0, corr00 = 0, corr01 = 0, corr1 = 0, corrEOF = 0;
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for(j = 0; j < arraylen(Logic0); j += skip) {
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corr0 += Logic0[j]*dest[i+(j/skip)];
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}
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corr01 = corr00 = corr0;
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for(j = 0; j < arraylen(Logic0); j += skip) {
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corr00 += Logic0[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
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corr01 += Logic1[j]*dest[i+arraylen(Logic0)/skip+(j/skip)];
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}
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for(j = 0; j < arraylen(Logic1); j += skip) {
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corr1 += Logic1[j]*dest[i+(j/skip)];
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}
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@ -519,11 +524,14 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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corrEOF += FrameEOF[j]*dest[i+(j/skip)];
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}
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// Even things out by the length of the target waveform.
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corr00 *= 2;
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corr01 *= 2;
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corr0 *= 4;
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corr1 *= 4;
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if(corrEOF > corr1 && corrEOF > corr0) {
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// DbpString("EOF at %d", i);
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if(corrEOF > corr1 && corrEOF > corr00 && corrEOF > corr01) {
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if (DEBUG) Dbprintf("EOF at %d, correlation %d (corr01: %d, corr00: %d, corr1: %d, corr0: %d)",
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i, corrEOF, corr01, corr00, corr1, corr0);
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break;
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} else if(corr1 > corr0) {
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i += arraylen(Logic1)/skip;
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@ -536,7 +544,7 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
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k++;
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mask = 0x01;
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}
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if((i+(int)arraylen(FrameEOF)) >= 2000) {
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if((i+(int)arraylen(FrameEOF)/skip) >= BIGBUF_SIZE) {
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DbpString("ran off end!");
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break;
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}
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@ -602,10 +610,6 @@ void AcquireRawAdcSamplesIso15693(void)
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break;
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}
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}
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
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volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
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(void)r;
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}
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WDT_HIT();
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}
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@ -614,9 +618,6 @@ void AcquireRawAdcSamplesIso15693(void)
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c = 0;
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getNext = false;
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for(;;) {
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
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AT91C_BASE_SSC->SSC_THR = 0x43;
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}
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
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int8_t b;
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b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
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@ -626,11 +627,11 @@ void AcquireRawAdcSamplesIso15693(void)
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// every other is Q. We just want power, so abs(I) + abs(Q) is
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// close to what we want.
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if(getNext) {
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uint8_t r = ABS(b) + ABS(prev);
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uint8_t r = AMPLITUDE(b, prev);
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dest[c++] = (uint8_t)r;
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dest[c++] = r;
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if(c >= 2000) {
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if(c >= 4000) {
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break;
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}
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} else {
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@ -668,9 +669,6 @@ void RecordRawAdcSamplesIso15693(void)
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c = 0;
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getNext = false;
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for(;;) {
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
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AT91C_BASE_SSC->SSC_THR = 0x43;
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}
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if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
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int8_t b;
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b = (int8_t)AT91C_BASE_SSC->SSC_RHR;
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@ -680,11 +678,11 @@ void RecordRawAdcSamplesIso15693(void)
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// every other is Q. We just want power, so abs(I) + abs(Q) is
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// close to what we want.
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if(getNext) {
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uint8_t r = ABS(b) + ABS(prev);
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uint8_t r = AMPLITUDE(b, prev);
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dest[c++] = (uint8_t)r;
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dest[c++] = r;
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if(c >= 7000) {
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if(c >= 14000) {
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break;
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}
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} else {
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@ -836,7 +834,7 @@ int SendDataTag(uint8_t *send, int sendlen, int init, int speed, uint8_t **recv)
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if (init) Iso15693InitReader();
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int answerLen=0;
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uint8_t *answer = BigBuf_get_addr() + 3660;
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uint8_t *answer = BigBuf_get_addr() + 4000;
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if (recv != NULL) memset(answer, 0, 100);
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if (!speed) {
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@ -957,7 +955,7 @@ void ReaderIso15693(uint32_t parameter)
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int answerLen1 = 0;
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int answerLen2 = 0;
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int answerLen3 = 0;
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// int answerLen3 = 0;
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int i = 0;
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int samples = 0;
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int tsamples = 0;
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@ -967,11 +965,11 @@ void ReaderIso15693(uint32_t parameter)
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FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
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uint8_t *answer1 = BigBuf_get_addr() + 3660;
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uint8_t *answer2 = BigBuf_get_addr() + 3760;
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uint8_t *answer3 = BigBuf_get_addr() + 3860;
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uint8_t *answer1 = BigBuf_get_addr() + 4000;
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uint8_t *answer2 = BigBuf_get_addr() + 4100;
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// uint8_t *answer3 = BigBuf_get_addr() + 4200;
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// Blank arrays
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memset(answer1, 0x00, 300);
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memset(answer1, 0x00, 200);
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SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
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// Setup SSC
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@ -1025,21 +1023,21 @@ void ReaderIso15693(uint32_t parameter)
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TagUID[3],TagUID[2],TagUID[1],TagUID[0]);
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Dbprintf("%d octets read from SELECT request:", answerLen2);
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DbdecodeIso15693Answer(answerLen2,answer2);
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Dbhexdump(answerLen2,answer2,true);
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// Dbprintf("%d octets read from SELECT request:", answerLen2);
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// DbdecodeIso15693Answer(answerLen2,answer2);
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// Dbhexdump(answerLen2,answer2,true);
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Dbprintf("%d octets read from XXX request:", answerLen3);
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DbdecodeIso15693Answer(answerLen3,answer3);
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Dbhexdump(answerLen3,answer3,true);
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// Dbprintf("%d octets read from XXX request:", answerLen3);
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// DbdecodeIso15693Answer(answerLen3,answer3);
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// Dbhexdump(answerLen3,answer3,true);
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// read all pages
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if (answerLen1>=12 && DEBUG) {
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i=0;
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while (i<32) { // sanity check, assume max 32 pages
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BuildReadBlockRequest(TagUID,i);
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TransmitTo15693Tag(ToSend,ToSendMax,&tsamples, &wait);
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answerLen2 = GetIso15693AnswerFromTag(answer2, 100, &samples, &elapsed);
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TransmitTo15693Tag(ToSend,ToSendMax,&tsamples, &wait);
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answerLen2 = GetIso15693AnswerFromTag(answer2, 100, &samples, &elapsed);
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if (answerLen2>0) {
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Dbprintf("READ SINGLE BLOCK %d returned %d octets:",i,answerLen2);
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DbdecodeIso15693Answer(answerLen2,answer2);
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@ -1073,7 +1071,7 @@ void SimTagIso15693(uint32_t parameter, uint8_t *uid)
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FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
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uint8_t *buf = BigBuf_get_addr() + 3660;
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uint8_t *buf = BigBuf_get_addr() + 4000;
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memset(buf, 0x00, 100);
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SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
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@ -1177,7 +1175,7 @@ void DirectTag15693Command(uint32_t datalen,uint32_t speed, uint32_t recv, uint8
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if (recv) {
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LED_B_ON();
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cmd_send(CMD_ACK,recvlen>48?48:recvlen,0,0,recvbuf,48);
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cmd_send(CMD_ACK,recvlen>48?48:recvlen,0,0,recvbuf,48);
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LED_B_OFF();
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if (DEBUG) {
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@ -268,7 +268,7 @@ static char* TagErrorStr(uint8_t error) {
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case 0x02: return "The command is not recognised";
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case 0x03: return "The option is not supported.";
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case 0x0f: return "Unknown error.";
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case 0x10: return "The specified block is not available (doesn’t exist).";
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case 0x10: return "The specified block is not available (doesn't exist).";
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case 0x11: return "The specified block is already -locked and thus cannot be locked again";
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case 0x12: return "The specified block is locked and its content cannot be changed.";
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case 0x13: return "The specified block was not successfully programmed.";
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@ -286,12 +286,12 @@ int CmdHF15Demod(const char *Cmd)
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int i, j;
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int max = 0, maxPos = 0;
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int skip = 4;
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int skip = 2;
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if (GraphTraceLen < 1000) return 0;
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if (GraphTraceLen < 2000) return 0;
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// First, correlate for SOF
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for (i = 0; i < 100; i++) {
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for (i = 0; i < 200; i++) {
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int corr = 0;
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for (j = 0; j < arraylen(FrameSOF); j += skip) {
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corr += FrameSOF[j] * GraphBuffer[i + (j / skip)];
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@ -310,23 +310,30 @@ int CmdHF15Demod(const char *Cmd)
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memset(outBuf, 0, sizeof(outBuf));
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uint8_t mask = 0x01;
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for (;;) {
|
||||
int corr0 = 0, corr1 = 0, corrEOF = 0;
|
||||
for (j = 0; j < arraylen(Logic0); j += skip) {
|
||||
corr0 += Logic0[j] * GraphBuffer[i + (j / skip)];
|
||||
}
|
||||
for (j = 0; j < arraylen(Logic1); j += skip) {
|
||||
corr1 += Logic1[j] * GraphBuffer[i + (j / skip)];
|
||||
}
|
||||
for (j = 0; j < arraylen(FrameEOF); j += skip) {
|
||||
corrEOF += FrameEOF[j] * GraphBuffer[i + (j / skip)];
|
||||
}
|
||||
// Even things out by the length of the target waveform.
|
||||
corr0 *= 4;
|
||||
corr1 *= 4;
|
||||
int corr0 = 0, corr00 = 0, corr01 = 0, corr1 = 0, corrEOF = 0;
|
||||
for(j = 0; j < arraylen(Logic0); j += skip) {
|
||||
corr0 += Logic0[j]*GraphBuffer[i+(j/skip)];
|
||||
}
|
||||
corr01 = corr00 = corr0;
|
||||
for(j = 0; j < arraylen(Logic0); j += skip) {
|
||||
corr00 += Logic0[j]*GraphBuffer[i+arraylen(Logic0)/skip+(j/skip)];
|
||||
corr01 += Logic1[j]*GraphBuffer[i+arraylen(Logic0)/skip+(j/skip)];
|
||||
}
|
||||
for(j = 0; j < arraylen(Logic1); j += skip) {
|
||||
corr1 += Logic1[j]*GraphBuffer[i+(j/skip)];
|
||||
}
|
||||
for(j = 0; j < arraylen(FrameEOF); j += skip) {
|
||||
corrEOF += FrameEOF[j]*GraphBuffer[i+(j/skip)];
|
||||
}
|
||||
// Even things out by the length of the target waveform.
|
||||
corr00 *= 2;
|
||||
corr01 *= 2;
|
||||
corr0 *= 4;
|
||||
corr1 *= 4;
|
||||
|
||||
if (corrEOF > corr1 && corrEOF > corr0) {
|
||||
PrintAndLog("EOF at %d", i);
|
||||
break;
|
||||
if(corrEOF > corr1 && corrEOF > corr00 && corrEOF > corr01) {
|
||||
PrintAndLog("EOF at %d", i);
|
||||
break;
|
||||
} else if (corr1 > corr0) {
|
||||
i += arraylen(Logic1) / skip;
|
||||
outBuf[k] |= mask;
|
||||
|
|
|
|||
BIN
fpga/fpga_hf.bit
BIN
fpga/fpga_hf.bit
Binary file not shown.
|
|
@ -27,21 +27,11 @@ assign pwr_hi = ck_1356megb & (~snoop);
|
|||
assign pwr_oe1 = 1'b0;
|
||||
assign pwr_oe3 = 1'b0;
|
||||
assign pwr_oe4 = 1'b0;
|
||||
// Unused.
|
||||
assign pwr_lo = 1'b0;
|
||||
assign pwr_oe2 = 1'b0;
|
||||
|
||||
reg [2:0] fc_div;
|
||||
always @(negedge ck_1356megb)
|
||||
fc_div <= fc_div + 1;
|
||||
|
||||
(* clock_signal = "yes" *) reg adc_clk; // sample frequency, always 16 * fc
|
||||
always @(ck_1356megb, xcorr_is_848, xcorr_quarter_freq, fc_div)
|
||||
if (xcorr_is_848 & ~xcorr_quarter_freq) // fc = 847.5 kHz, standard ISO14443B
|
||||
adc_clk <= ck_1356megb;
|
||||
else if (~xcorr_is_848 & ~xcorr_quarter_freq) // fc = 423.75 kHz
|
||||
adc_clk <= fc_div[0];
|
||||
else if (xcorr_is_848 & xcorr_quarter_freq) // fc = 211.875 kHz
|
||||
adc_clk <= fc_div[1];
|
||||
else // fc = 105.9375 kHz
|
||||
adc_clk <= fc_div[2];
|
||||
assign adc_clk = ck_1356megb; // sample frequency is 13,56 MHz
|
||||
|
||||
// When we're a reader, we just need to do the BPSK demod; but when we're an
|
||||
// eavesdropper, we also need to pick out the commands sent by the reader,
|
||||
|
|
@ -69,15 +59,27 @@ begin
|
|||
end
|
||||
end
|
||||
|
||||
// Let us report a correlation every 4 subcarrier cycles, or 4*16=64 samples,
|
||||
// so we need a 6-bit counter.
|
||||
|
||||
// Let us report a correlation every 64 samples. I.e.
|
||||
// one Q/I pair after 4 subcarrier cycles for the 848kHz subcarrier,
|
||||
// one Q/I pair after 2 subcarrier cycles for the 424kHz subcarriers,
|
||||
// one Q/I pair for each subcarrier cyle for the 212kHz subcarrier.
|
||||
// We need a 6-bit counter for the timing.
|
||||
reg [5:0] corr_i_cnt;
|
||||
// And a couple of registers in which to accumulate the correlations.
|
||||
// We would add at most 32 times the difference between unmodulated and modulated signal. It should
|
||||
always @(negedge adc_clk)
|
||||
begin
|
||||
corr_i_cnt <= corr_i_cnt + 1;
|
||||
end
|
||||
|
||||
// And a couple of registers in which to accumulate the correlations. From the 64 samples
|
||||
// we would add at most 32 times the difference between unmodulated and modulated signal. It should
|
||||
// be safe to assume that a tag will not be able to modulate the carrier signal by more than 25%.
|
||||
// 32 * 255 * 0,25 = 2040, which can be held in 11 bits. Add 1 bit for sign.
|
||||
reg signed [11:0] corr_i_accum;
|
||||
reg signed [11:0] corr_q_accum;
|
||||
// Temporary we might need more bits. For the 212kHz subcarrier we could possible add 32 times the
|
||||
// maximum signal value before a first subtraction would occur. 32 * 255 = 8160 can be held in 13 bits.
|
||||
// Add one bit for sign -> need 14 bit registers but final result will fit into 12 bits.
|
||||
reg signed [13:0] corr_i_accum;
|
||||
reg signed [13:0] corr_q_accum;
|
||||
// we will report maximum 8 significant bits
|
||||
reg signed [7:0] corr_i_out;
|
||||
reg signed [7:0] corr_q_out;
|
||||
|
|
@ -86,11 +88,28 @@ reg ssp_clk;
|
|||
reg ssp_frame;
|
||||
|
||||
|
||||
always @(negedge adc_clk)
|
||||
begin
|
||||
corr_i_cnt <= corr_i_cnt + 1;
|
||||
end
|
||||
// The subcarrier reference signals
|
||||
reg subcarrier_I;
|
||||
reg subcarrier_Q;
|
||||
|
||||
always @(corr_i_cnt or xcorr_is_848 or xcorr_quarter_freq)
|
||||
begin
|
||||
if (xcorr_is_848 & ~xcorr_quarter_freq) // 848 kHz
|
||||
begin
|
||||
subcarrier_I = ~corr_i_cnt[3];
|
||||
subcarrier_Q = ~(corr_i_cnt[3] ^ corr_i_cnt[2]);
|
||||
end
|
||||
else if (xcorr_is_848 & xcorr_quarter_freq) // 212 kHz
|
||||
begin
|
||||
subcarrier_I = ~corr_i_cnt[5];
|
||||
subcarrier_Q = ~(corr_i_cnt[5] ^ corr_i_cnt[4]);
|
||||
end
|
||||
else
|
||||
begin // 424 kHz
|
||||
subcarrier_I = ~corr_i_cnt[4];
|
||||
subcarrier_Q = ~(corr_i_cnt[4] ^ corr_i_cnt[3]);
|
||||
end
|
||||
end
|
||||
|
||||
// ADC data appears on the rising edge, so sample it on the falling edge
|
||||
always @(negedge adc_clk)
|
||||
|
|
@ -103,36 +122,60 @@ begin
|
|||
if(snoop)
|
||||
begin
|
||||
// Send 7 most significant bits of tag signal (signed), plus 1 bit reader signal
|
||||
corr_i_out <= {corr_i_accum[11:5], after_hysteresis_prev_prev};
|
||||
corr_q_out <= {corr_q_accum[11:5], after_hysteresis_prev};
|
||||
if (corr_i_accum[13:11] == 3'b000 || corr_i_accum[13:11] == 3'b111)
|
||||
corr_i_out <= {corr_i_accum[11:5], after_hysteresis_prev_prev};
|
||||
else // truncate to maximum value
|
||||
if (corr_i_accum[13] == 1'b0)
|
||||
corr_i_out <= {7'b0111111, after_hysteresis_prev_prev};
|
||||
else
|
||||
corr_i_out <= {7'b1000000, after_hysteresis_prev_prev};
|
||||
if (corr_q_accum[13:11] == 3'b000 || corr_q_accum[13:11] == 3'b111)
|
||||
corr_q_out <= {corr_q_accum[11:5], after_hysteresis_prev};
|
||||
else // truncate to maximum value
|
||||
if (corr_q_accum[13] == 1'b0)
|
||||
corr_q_out <= {7'b0111111, after_hysteresis_prev};
|
||||
else
|
||||
corr_q_out <= {7'b1000000, after_hysteresis_prev};
|
||||
after_hysteresis_prev_prev <= after_hysteresis;
|
||||
end
|
||||
else
|
||||
begin
|
||||
// 8 bits of tag signal
|
||||
corr_i_out <= corr_i_accum[11:4];
|
||||
corr_q_out <= corr_q_accum[11:4];
|
||||
// Send 8 bits of tag signal
|
||||
if (corr_i_accum[13:11] == 3'b000 || corr_i_accum[13:11] == 3'b111)
|
||||
corr_i_out <= corr_i_accum[11:4];
|
||||
else // truncate to maximum value
|
||||
if (corr_i_accum[13] == 1'b0)
|
||||
corr_i_out <= 8'b01111111;
|
||||
else
|
||||
corr_i_out <= 8'b10000000;
|
||||
if (corr_q_accum[13:11] == 3'b000 || corr_q_accum[13:11] == 3'b111)
|
||||
corr_q_out <= corr_q_accum[11:4];
|
||||
else // truncate to maximum value
|
||||
if (corr_q_accum[13] == 1'b0)
|
||||
corr_q_out <= 8'b01111111;
|
||||
else
|
||||
corr_q_out <= 8'b10000000;
|
||||
end
|
||||
|
||||
corr_i_accum <= adc_d;
|
||||
corr_q_accum <= adc_d;
|
||||
// Initialize next correlation.
|
||||
// Both I and Q reference signals are high when corr_i_nct == 0. Therefore need to accumulate.
|
||||
corr_i_accum <= $signed({1'b0,adc_d});
|
||||
corr_q_accum <= $signed({1'b0,adc_d});
|
||||
end
|
||||
else
|
||||
begin
|
||||
if(corr_i_cnt[3])
|
||||
corr_i_accum <= corr_i_accum - adc_d;
|
||||
if (subcarrier_I)
|
||||
corr_i_accum <= corr_i_accum + $signed({1'b0,adc_d});
|
||||
else
|
||||
corr_i_accum <= corr_i_accum + adc_d;
|
||||
corr_i_accum <= corr_i_accum - $signed({1'b0,adc_d});
|
||||
|
||||
if(corr_i_cnt[3] == corr_i_cnt[2]) // phase shifted by pi/2
|
||||
corr_q_accum <= corr_q_accum + adc_d;
|
||||
if (subcarrier_Q)
|
||||
corr_q_accum <= corr_q_accum + $signed({1'b0,adc_d});
|
||||
else
|
||||
corr_q_accum <= corr_q_accum - adc_d;
|
||||
corr_q_accum <= corr_q_accum - $signed({1'b0,adc_d});
|
||||
|
||||
end
|
||||
|
||||
// The logic in hi_simulate.v reports 4 samples per bit. We report two
|
||||
// (I, Q) pairs per bit, so we should do 2 samples per pair.
|
||||
// for each Q/I pair report two reader signal samples when sniffing
|
||||
if(corr_i_cnt == 6'd32)
|
||||
after_hysteresis_prev <= after_hysteresis;
|
||||
|
||||
|
|
@ -167,8 +210,4 @@ assign ssp_din = corr_i_out[7];
|
|||
|
||||
assign dbg = corr_i_cnt[3];
|
||||
|
||||
// Unused.
|
||||
assign pwr_lo = 1'b0;
|
||||
assign pwr_oe2 = 1'b0;
|
||||
|
||||
endmodule
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue