fix false positive psk demod with fsk wave

also break out new find start of modulation routine.

diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index 35f220c0eff94bff4e504ca085e6b51fe1b57650..0bbd62c279670f21cec3afb0ab34cd631dfbd547 100644 (file)
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -1626,7 +1626,7 @@ void EM4xReadWord(uint8_t Address, uint32_t Pwd, uint8_t PwdMode) {
        fwd_bit_count += Prepare_Addr( Address );
 
        SendForward(fwd_bit_count);
-
+       SpinDelayUs(700);
        // Now do the acquisition
        DoPartialAcquisition(20, true, 5500);
        
@@ -1658,6 +1658,7 @@ void EM4xWriteWord(uint32_t flag, uint32_t Data, uint32_t Pwd) {
        //Wait for write to complete
        //SpinDelay(10);
 
+       SpinDelayUs(6500);
        //Capture response if one exists
        DoPartialAcquisition(20, true, 5500);
 

diff --git a/client/cmdlfem4x.c b/client/cmdlfem4x.c
index 7664978639fd425de6e752f327518d1f491962fa..d1245306ef00d0256de5ec23ea1163fa5fb5c9c7 100644 (file)
--- a/client/cmdlfem4x.c
+++ b/client/cmdlfem4x.c
@@ -530,14 +530,16 @@ bool downloadSamplesEM() {
 }
 
 bool EM4x05testDemodReadData(uint32_t *word, bool readCmd) {
-       // em4x05/em4x69 preamble is 00001010
+       // em4x05/em4x69 command response preamble is 00001010
        // skip first two 0 bits as they might have been missed in the demod
        uint8_t preamble[] = {0,0,1,0,1,0};
        size_t startIdx = 0;
-       // set size to 20 to only test first 14 positions for the preamble
-       size_t size = (20 > DemodBufferLen) ? DemodBufferLen : 20;
 
-       //test preamble
+       // set size to 20 to only test first 14 positions for the preamble or less if not a read command
+       size_t size = (readCmd) ? 20 : 11;
+       // sanity check
+       size = (size > DemodBufferLen) ? DemodBufferLen : size;
+       // test preamble
        if ( !onePreambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx) ) {
                if (g_debugMode) PrintAndLog("DEBUG: Error - EM4305 preamble not found :: %d", startIdx);
                return false;
@@ -548,7 +550,7 @@ bool EM4x05testDemodReadData(uint32_t *word, bool readCmd) {
                        if (g_debugMode) PrintAndLog("DEBUG: Error - End Parity check failed");
                        return false;
                }
-               //test for even parity bits.
+               // test for even parity bits.
                if ( removeParity(DemodBuffer, startIdx + sizeof(preamble),9,0,44) == 0 ) {             
                        if (g_debugMode) PrintAndLog("DEBUG: Error - Parity not detected");
                        return false;
@@ -808,6 +810,8 @@ int CmdEM4x05WriteWord(const char *Cmd) {
        int result = demodEM4x05resp(&dummy,false);
        if (result == 1) {
                PrintAndLog("Write Verified");
+       } else {
+               PrintAndLog("Write could not be verified");
        }
        return result;
 }
@@ -893,6 +897,12 @@ void printEM4x05info(uint8_t chipType, uint8_t cap, uint16_t custCode, uint32_t
        }
 }
 
+void printEM4x05ProtectionBits(uint32_t wordData) {
+       for (uint8_t i = 0; i < 14; i++) {
+               PrintAndLog("      Word:  %02u | %s", i, (((1 << i) & wordData ) || i < 2) ? "Is Locked" : "Is Not Locked");
+       }
+}
+
 //quick test for EM4x05/EM4x69 tag
 bool EM4x05Block0Test(uint32_t *wordData) {
        if (EM4x05ReadWord_ext(0,0,false,wordData) == 1) {
@@ -940,6 +950,26 @@ int CmdEM4x05info(const char *Cmd) {
                return 0;
        }
        printEM4x05config(wordData);
+
+       // read word 14 and 15 to see which is being used for the protection bits
+       wordData = 0;
+       if ( EM4x05ReadWord_ext(14, pwd, usePwd, &wordData) != 1 ) {
+               //failed
+               return 0;
+       }
+       // if status bit says this is not the used protection word
+       if (!(wordData & 0x8000)) {
+               if ( EM4x05ReadWord_ext(15, pwd, usePwd, &wordData) != 1 ) {
+                       //failed
+                       return 0;
+               }
+       }
+       if (!(wordData & 0x8000)) {
+               //something went wrong
+               return 0;
+       }
+       printEM4x05ProtectionBits(wordData);
+
        return 1;
 }
 

diff --git a/common/lfdemod.c b/common/lfdemod.c
index fbed6a9a8431fa913a4d56cba47b19297571ff4e..406b0445f462ec1b823607614a999ea2d6b746a2 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -187,6 +187,32 @@ bool onePreambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_
        return false;
 }
 
+// find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
+size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_t expWaveSize) {
+       size_t i = 0;
+       size_t waveSizeCnt = 0;
+       uint8_t thresholdCnt = 0;
+       bool isAboveThreshold = dest[i++] >= threshold_value;
+       for (; i < size-20; i++ ) {
+               if(dest[i] < threshold_value && isAboveThreshold) {
+                       thresholdCnt++;
+                       if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;                     
+                       isAboveThreshold = false;
+                       waveSizeCnt = 0;
+               } else if (dest[i] >= threshold_value && !isAboveThreshold) {
+                       thresholdCnt++;
+                       if (thresholdCnt > 2 && waveSizeCnt < expWaveSize+1) break;                     
+                       isAboveThreshold = true;
+                       waveSizeCnt = 0;
+               } else {
+                       waveSizeCnt++;
+               }
+               if (thresholdCnt > 10) break;
+       }
+       if (g_debugMode == 2) prnt("DEBUG: threshold Count reached at %u, count: %u",i, thresholdCnt);
+       return i;
+}
+
 //by marshmellow
 //takes 1s and 0s and searches for EM410x format - output EM ID
 uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_t *hi, uint64_t *lo)
@@ -496,7 +522,6 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 {
        size_t last_transition = 0;
        size_t idx = 1;
-       //uint32_t maxVal=0;
        if (fchigh==0) fchigh=10;
        if (fclow==0) fclow=8;
        //set the threshold close to 0 (graph) or 128 std to avoid static
@@ -506,28 +531,8 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
        size_t currSample = 0;
        if ( size < 1024 ) return 0; // not enough samples
 
-       // jump to modulating data by finding the first 4 threshold crossings (or first 2 waves)
-       // in case you have junk or noise at the beginning of the trace...
-       uint8_t thresholdCnt = 0;
-       size_t waveSizeCnt = 0;
-       bool isAboveThreshold = dest[idx++] >= threshold_value;
-       for (; idx < size-20; idx++ ) {
-               if(dest[idx] < threshold_value && isAboveThreshold) {
-                       thresholdCnt++;
-                       if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;                  
-                       isAboveThreshold = false;
-                       waveSizeCnt = 0;
-               } else if (dest[idx] >= threshold_value && !isAboveThreshold) {
-                       thresholdCnt++;
-                       if (thresholdCnt > 2 && waveSizeCnt < fchigh+1) break;                  
-                       isAboveThreshold = true;
-                       waveSizeCnt = 0;
-               } else {
-                       waveSizeCnt++;
-               }
-               if (thresholdCnt > 10) break;
-       }
-       if (g_debugMode == 2) prnt("threshold Count reached at %u",idx);
+       //find start of modulating data in trace 
+       idx = findModStart(dest, size, threshold_value, fchigh);
 
        // Need to threshold first sample
        if(dest[idx] < threshold_value) dest[0] = 0;
@@ -1509,42 +1514,26 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
        size_t numBits=0;
        uint8_t curPhase = *invert;
        size_t i=0, waveStart=1, waveEnd=0, firstFullWave=0, lastClkBit=0;
-       uint8_t fc=0, fullWaveLen=0, tol=1;
-       uint16_t errCnt=0, waveLenCnt=0;
-       fc = countFC(dest, *size, 0);
+       uint16_t fc=0, fullWaveLen=0, tol=1;
+       uint16_t errCnt=0, waveLenCnt=0, errCnt2=0;
+       fc = countFC(dest, *size, 1);
+       uint8_t fc2 = fc >> 8;
+       if (fc2 == 10) return -1; //fsk found - quit
+       fc = fc & 0xFF;
        if (fc!=2 && fc!=4 && fc!=8) return -1;
        //PrintAndLog("DEBUG: FC: %d",fc);
        *clock = DetectPSKClock(dest, *size, *clock);
        if (*clock == 0) return -1;
-       // jump to modulating data by finding the first 2 threshold crossings (or first 1 waves)
-       // in case you have junk or noise at the beginning of the trace...
-       uint8_t thresholdCnt = 0;
-       size_t waveSizeCnt = 0;
-       uint8_t threshold_value = 123; //-5
-       bool isAboveThreshold = dest[i++] >= threshold_value;
-       for (; i < *size-20; i++ ) {
-               if(dest[i] < threshold_value && isAboveThreshold) {
-                       thresholdCnt++;
-                       if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;                      
-                       isAboveThreshold = false;
-                       waveSizeCnt = 0;
-               } else if (dest[i] >= threshold_value && !isAboveThreshold) {
-                       thresholdCnt++;
-                       if (thresholdCnt > 2 && waveSizeCnt < fc+1) break;                      
-                       isAboveThreshold = true;
-                       waveSizeCnt = 0;
-               } else {
-                       waveSizeCnt++;
-               }
-               if (thresholdCnt > 10) break;
-       }
-       if (g_debugMode == 2) prnt("DEBUG PSK: threshold Count reached at %u, count: %u",i, thresholdCnt);
 
+       //find start of modulating data in trace 
+       uint8_t threshold_value = 123; //-5
+       i = findModStart(dest, *size, threshold_value, fc);
 
-       int avgWaveVal=0, lastAvgWaveVal=0;
-       waveStart = i+1;
        //find first phase shift
-       for (; i<loopCnt; i++){
+       int avgWaveVal=0, lastAvgWaveVal=0;
+       waveStart = i;
+       for (; i<loopCnt; i++) {
+               // find peak 
                if (dest[i]+fc < dest[i+1] && dest[i+1] >= dest[i+2]){
                        waveEnd = i+1;
                        if (g_debugMode == 2) prnt("DEBUG PSK: waveEnd: %u, waveStart: %u",waveEnd, waveStart);
@@ -1553,8 +1542,8 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
                                lastAvgWaveVal = avgWaveVal/(waveLenCnt);
                                firstFullWave = waveStart;
                                fullWaveLen=waveLenCnt;
-                               //if average wave value is > graph 0 then it is an up wave or a 1
-                               if (lastAvgWaveVal > threshold_value) curPhase ^= 1;  //fudge graph 0 a little 123 vs 128
+                               //if average wave value is > graph 0 then it is an up wave or a 1 (could cause inverting)
+                               if (lastAvgWaveVal > threshold_value) curPhase ^= 1;
                                break;
                        } 
                        waveStart = i+1;
@@ -1575,7 +1564,7 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
        //set start of wave as clock align
        lastClkBit = firstFullWave;
        if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);  
-       if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
+       if (g_debugMode==2) prnt("DEBUG PSK: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
        waveStart = 0;
        dest[numBits++] = curPhase; //set first read bit
        for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
@@ -1606,6 +1595,9 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
                                } else if (i+1 > lastClkBit + *clock + tol + fc){
                                        lastClkBit += *clock; //no phase shift but clock bit
                                        dest[numBits++] = curPhase;
+                               } else if (waveLenCnt < fc - 1) { //wave is smaller than field clock (shouldn't happen often)
+                                       errCnt2++;
+                                       if(errCnt2 > 101) return errCnt2;
                                }
                                avgWaveVal = 0;
                                waveStart = i+1;