lf t55xx and some lf demod fixes/adjustments

[proxmark3-svn] / armsrc / lfsampling.c

diff --git a/armsrc/lfsampling.c b/armsrc/lfsampling.c
index 4a968776a832b93b17ad1a7af9a8938a8cf1d9da..7c5412820b20ce065637c6af6d253345dba4ba5c 100644 (file)
--- a/armsrc/lfsampling.c
+++ b/armsrc/lfsampling.c
@@ -255,7 +255,7 @@ uint32_t SnoopLF()
 **/
 void doT55x7Acquisition(size_t sample_size) {
 
-       #define T55xx_READ_UPPER_THRESHOLD 128+40  // 50
+       #define T55xx_READ_UPPER_THRESHOLD 128+40  // 40 grph
        #define T55xx_READ_TOL   5
 
        uint8_t *dest = BigBuf_get_addr();
@@ -264,13 +264,11 @@ void doT55x7Acquisition(size_t sample_size) {
        if ( bufsize > sample_size )
                bufsize = sample_size;
 
-       //memset(dest, 0, bufsize);
-               
        uint16_t i = 0;
        bool startFound = false;
        bool highFound = false;
        uint8_t curSample = 0;
-       uint8_t firstSample = 0;
+       uint8_t lastSample = 0;
        uint16_t skipCnt = 0;
        while(!BUTTON_PRESS() && skipCnt<1000) {
                WDT_HIT();
@@ -282,25 +280,26 @@ void doT55x7Acquisition(size_t sample_size) {
                        curSample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
                        LED_D_OFF();
 
-                       // find first high sample
+                       // skip until the first high sample above threshold
                        if (!startFound && curSample > T55xx_READ_UPPER_THRESHOLD) {
-                               if (curSample > firstSample) 
-                                       firstSample = curSample;
+                               if (curSample > lastSample) 
+                                       lastSample = curSample;
                                highFound = true;
                        } else if (!highFound) {
                                skipCnt++;
                                continue;
                        }
-
-                       // skip until samples begin to change
-                       if (startFound || curSample < firstSample-T55xx_READ_TOL){
-                               if (!startFound) 
-                                       dest[i++] = firstSample;
-                               startFound = true;
+                       // skip until first high samples begin to change
+                       if (startFound || curSample < T55xx_READ_UPPER_THRESHOLD-T55xx_READ_TOL){
+                               // if just found start - recover last sample
+                               if (!startFound) {
+                                       dest[i++] = lastSample;
+                                       startFound = true;
+                               }
+                               // collect samples
                                dest[i++] = curSample;
                                if (i >= bufsize-1) break;
                        }
                }
-               //skipCnt++;
        }
 }