/* 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"); info->start_off = off; 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. */ info->pulses_count = (off + 8 * 8 * 2) - info->start_off; 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};