Ford TPMS.

protocols/ford_tpms.c

@@ -0,0 +1,64 @@
+/* Ford tires TPMS. Usually 443.92 Mhz FSK (in Europe).
+ *
+ * 52 us short pules
+ * Preamble: 0101010101010101010101010101
+ * Sync: 0110 (that is 52 us gap + 104 us pulse + 52 us gap)
+ * Data: 8 bytes Manchester encoded
+ * 01 = zero
+ * 10 = one
+ */
+
+#include "../app.h"
+
+static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo *info) {
+
+    const char *sync_pattern = "010101010101" "0110";
+    uint8_t sync_len = 12+4; /* We just use 12 preamble symbols + sync. */
+    if (numbits-sync_len < 8*8) return false;
+
+    uint64_t off = bitmap_seek_bits(bits,numbytes,0,numbits,sync_pattern);
+    if (off == BITMAP_SEEK_NOT_FOUND) return false;
+    FURI_LOG_E(TAG, "Fort TPMS preamble+sync found");
+
+    off += sync_len; /* Skip preamble and sync. */
+
+    uint8_t raw[8];
+    uint32_t decoded =
+        convert_from_line_code(raw,sizeof(raw),bits,numbytes,off,
+            "01","10"); /* Manchester. */
+    FURI_LOG_E(TAG, "Ford TPMS decoded bits: %lu", decoded);
+
+    if (decoded < 8*8) return false; /* Require the full 8 bytes. */
+
+    /* CRC is just the sum of the first 7 bytes MOD 256. */
+    uint8_t crc = 0;
+    for (int j = 0; j < 7; j++) crc += raw[j];
+    if (crc != raw[7]) return false; /* Require sane CRC. */
+
+    float psi = 0.25 * (((raw[6]&0x20)<<3)|raw[4]);
+
+    /* Temperature apperas to be valid only if the most significant
+     * bit of the value is not set. Otherwise its meaning is unknown.
+     * Likely useful to alternatively send temperature or other info. */
+    int temp = raw[5] & 0x80 ? 0 : raw[5]-56;
+    int flags = raw[5] & 0x7f;
+    int car_moving = (raw[6] & 0x44) == 0x44;
+
+    snprintf(info->name,sizeof(info->name),"%s","Ford TPMS");
+    snprintf(info->raw,sizeof(info->raw),"%02X%02X%02X%02X%02X%02X%02X%02X",
+        raw[0],raw[1],raw[2],raw[3],raw[4],raw[5],
+        raw[6],raw[7]);
+    snprintf(info->info1,sizeof(info->info1),"Tire ID %02X%02X%02X%02X",
+        raw[0],raw[1],raw[2],raw[3]);
+    snprintf(info->info2,sizeof(info->info2),"Pressure %.2f psi", (double)psi);
+    if (temp)
+        snprintf(info->info3,sizeof(info->info3),"Temperature %d C", temp);
+    else
+        snprintf(info->info3,sizeof(info->info3),"Flags %d", flags);
+    snprintf(info->info4,sizeof(info->info4),"Moving %s", car_moving ? "yes" : "no");
+    return true;
+}
+
+ProtoViewDecoder FordTPMSDecoder = {
+    "Ford TPMS", decode
+};

signal.c

@@ -386,6 +386,7 @@ extern ProtoViewDecoder RenaultTPMSDecoder;
 extern ProtoViewDecoder ToyotaTPMSDecoder;
 extern ProtoViewDecoder SchraderTPMSDecoder;
 extern ProtoViewDecoder CitroenTPMSDecoder;
+extern ProtoViewDecoder FordTPMSDecoder;
 
 ProtoViewDecoder *Decoders[] = {
     &Oregon2Decoder,        /* Oregon sensors v2.1 protocol. */
@@ -394,6 +395,7 @@ ProtoViewDecoder *Decoders[] = {
     &ToyotaTPMSDecoder,     /* Toyota TPMS. */
     &SchraderTPMSDecoder,   /* Schrader TPMS. */
     &CitroenTPMSDecoder,    /* Citroen TPMS. */
+    &FordTPMSDecoder,       /* Ford TPMS. */
     NULL
 };