b4b1: more robust message detection.

RogueMaster · Jan 25, 2023 · cc32c5e · cc32c5e
1 parent 32b3f76
commit cc32c5e
Showing 1 changed file with 12 additions and 7 deletions.
diff --git a/protocols/b4b1.c b/protocols/b4b1.c
@@ -11,10 +11,15 @@
 
 static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo *info) {
     if (numbits < 30) return false;
-    const char *sync_patterns[3] = {
-        "10000000000000000000000000000001", /* 30 zero bits. */
-        "100000000000000000000000000000001", /* 31 zero bits. */
-        "1000000000000000000000000000000001", /* 32 zero bits. */
+
+    /* Test different pulse + gap + first byte possibilities. */
+    const char *sync_patterns[6] = {
+        "100000000000000000000000000000011101", /* 30 times gap + one. */
+        "100000000000000000000000000000010001", /* 30 times gap + zero. */
+        "1000000000000000000000000000000011101", /* 31 times gap + one. */
+        "1000000000000000000000000000000010001", /* 31 times gap + zero. */
+        "10000000000000000000000000000000011101", /* 32 times gap + one. */
+        "10000000000000000000000000000000010001", /* 32 times gap + zero. */
     };
 
     uint32_t off;
@@ -24,11 +29,11 @@ static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoView
         if (off != BITMAP_SEEK_NOT_FOUND) break;
     }
     if (off == BITMAP_SEEK_NOT_FOUND) return false;
-    if (DEBUG_MSG) FURI_LOG_E(TAG, "B4B1 preamble at: %lu",off);
+    if (DEBUG_MSG) FURI_LOG_E(TAG, "B4B1 preamble id:%d at: %lu",j,off);
     info->start_off = off;
 
-    // Seek data setction. Why -1? Last bit is data.
-    off += strlen(sync_patterns[j])-1;
+    // Seek data setction. Why -5? Last 5 half-bit-times are data.
+    off += strlen(sync_patterns[j])-5;
 
     uint8_t d[3]; /* 24 bits of data. */
     uint32_t decoded =