Schrader EG53MA4 TPMS.

protocols/schrader_eg53ma4_tpms.c

@@ -0,0 +1,60 @@
+/* Schrader variant EG53MA4 TPMS.
+ * Usually 443.92 Mhz OOK, 100us pulse len.
+ *
+ * Preamble: alternating pulse/gap, 100us.
+ * Sync (as pulses and gaps): "01100101", already part of the data stream
+ * (first nibble) corresponding to 0x4
+ *
+ * A total of 10 bytes payload, Manchester encoded.
+ *
+ * 0 = 01
+ * 1 = 10
+ *
+ * Used in certain Open cars and others.
+ */
+
+#include "../app.h"
+
+static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo *info) {
+
+    const char *sync_pattern = "010101010101" "01100101";
+    uint8_t sync_len = 12+8; /* We just use 12 preamble symbols + sync. */
+    if (numbits-sync_len+8 < 8*10) 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, "Schrader EG53MA4 TPMS preamble+sync found");
+
+    off += sync_len-8; /* Skip preamble, not sync that is part of the data. */
+
+    uint8_t raw[10];
+    uint32_t decoded =
+        convert_from_line_code(raw,sizeof(raw),bits,numbytes,off,
+            "01","10"); /* Manchester code. */
+    FURI_LOG_E(TAG, "Schrader EG53MA4 TPMS decoded bits: %lu", decoded);
+
+    if (decoded < 10*8) return false; /* Require the full 10 bytes. */
+
+    /* CRC is just all bytes added mod 256. */
+    uint8_t crc = 0;
+    for (int j = 0; j < 9; j++) crc += raw[j];
+    if (crc != raw[9]) return false; /* Require sane CRC. */
+
+    float kpa = (float)raw[7]*2.5;
+    int temp_f = raw[8];
+    int temp_c = (temp_f-32)*5/9;
+
+    snprintf(info->name,sizeof(info->name),"%s","Schrader EG53MA4 TPMS");
+    snprintf(info->raw,sizeof(info->raw),"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
+        raw[0],raw[1],raw[2],raw[3],raw[4],raw[5],
+        raw[6],raw[7],raw[8],raw[9]);
+    snprintf(info->info1,sizeof(info->info1),"Tire ID %02X%02X%02X",
+        raw[4],raw[5],raw[6]); /* Only 28 bits of ID, not 32. */
+    snprintf(info->info2,sizeof(info->info2),"Pressure %.2f kpa", (double)kpa);
+    snprintf(info->info3,sizeof(info->info3),"Temperature %d C", temp_c);
+    return true;
+}
+
+ProtoViewDecoder SchraderEG53MA4TPMSDecoder = {
+    "Schrader EG53MA4 TPMS", decode
+};

signal.c

@@ -385,17 +385,19 @@ extern ProtoViewDecoder B4B1Decoder;
 extern ProtoViewDecoder RenaultTPMSDecoder;
 extern ProtoViewDecoder ToyotaTPMSDecoder;
 extern ProtoViewDecoder SchraderTPMSDecoder;
+extern ProtoViewDecoder SchraderEG53MA4TPMSDecoder;
 extern ProtoViewDecoder CitroenTPMSDecoder;
 extern ProtoViewDecoder FordTPMSDecoder;
 
 ProtoViewDecoder *Decoders[] = {
-    &Oregon2Decoder,        /* Oregon sensors v2.1 protocol. */
-    &B4B1Decoder,           /* PT, SC, ... 24 bits remotes. */
-    &RenaultTPMSDecoder,    /* Renault TPMS. */
-    &ToyotaTPMSDecoder,     /* Toyota TPMS. */
-    &SchraderTPMSDecoder,   /* Schrader TPMS. */
-    &CitroenTPMSDecoder,    /* Citroen TPMS. */
-    &FordTPMSDecoder,       /* Ford TPMS. */
+    &Oregon2Decoder,                /* Oregon sensors v2.1 protocol. */
+    &B4B1Decoder,                   /* PT, SC, ... 24 bits remotes. */
+    &RenaultTPMSDecoder,            /* Renault TPMS. */
+    &ToyotaTPMSDecoder,             /* Toyota TPMS. */
+    &SchraderTPMSDecoder,           /* Schrader TPMS. */
+    &SchraderEG53MA4TPMSDecoder,    /* Schrader EG53MA4 TPMS. */
+    &CitroenTPMSDecoder,            /* Citroen TPMS. */
+    &FordTPMSDecoder,               /* Ford TPMS. */
     NULL
 };