mirror of
https://github.com/DarkFlippers/unleashed-firmware.git
synced 2024-12-22 21:01:40 +03:00
71 lines
2.5 KiB
C
71 lines
2.5 KiB
C
/* Copyright (C) 2022-2023 Salvatore Sanfilippo -- All Rights Reserved
|
|
* See the LICENSE file for information about the license.
|
|
*
|
|
* Schrader TPMS. Usually 443.92 Mhz OOK, 120us pulse len.
|
|
*
|
|
* 500us high pulse + Preamble + Manchester coded bits where:
|
|
* 1 = 10
|
|
* 0 = 01
|
|
*
|
|
* 60 bits of data total (first 4 nibbles is the preamble, 0xF).
|
|
*
|
|
* Used in FIAT-Chrysler, Mercedes, ... */
|
|
|
|
#include "../../app.h"
|
|
|
|
#define USE_TEST_VECTOR 0
|
|
static const char* test_vector =
|
|
"000000111101010101011010010110010110101001010110100110011001100101010101011010100110100110011010101010101010101010101010101010101010101010101010";
|
|
|
|
static bool decode(uint8_t* bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo* info) {
|
|
if(USE_TEST_VECTOR) { /* Test vector to check that decoding works. */
|
|
bitmap_set_pattern(bits, numbytes, 0, test_vector);
|
|
numbits = strlen(test_vector);
|
|
}
|
|
|
|
if(numbits < 64) return false; /* Preamble + data. */
|
|
|
|
const char* sync_pattern = "1111010101"
|
|
"01011010";
|
|
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 TPMS gap+preamble found");
|
|
|
|
info->start_off = off;
|
|
off += 10; /* Skip just the long pulse and the first 3 bits of sync, so
|
|
that we have the first byte of data with the sync nibble
|
|
0011 = 0x3. */
|
|
|
|
uint8_t raw[8];
|
|
uint8_t id[4];
|
|
uint32_t decoded = convert_from_line_code(
|
|
raw, sizeof(raw), bits, numbytes, off, "01", "10"); /* Manchester code. */
|
|
FURI_LOG_E(TAG, "Schrader TPMS decoded bits: %lu", decoded);
|
|
|
|
if(decoded < 64) return false; /* Require the full 8 bytes. */
|
|
|
|
raw[0] |= 0xf0; // Fix the preamble nibble for checksum computation.
|
|
uint8_t cksum = crc8(raw, sizeof(raw) - 1, 0xf0, 0x7);
|
|
if(cksum != raw[7]) {
|
|
FURI_LOG_E(TAG, "Schrader TPMS checksum mismatch");
|
|
return false;
|
|
}
|
|
|
|
info->pulses_count = (off + 8 * 8 * 2) - info->start_off;
|
|
|
|
float kpa = (float)raw[5] * 2.5;
|
|
int temp = raw[6] - 50;
|
|
id[0] = raw[1] & 7;
|
|
id[1] = raw[2];
|
|
id[2] = raw[3];
|
|
id[3] = raw[4];
|
|
|
|
fieldset_add_bytes(info->fieldset, "Tire ID", id, 4 * 2);
|
|
fieldset_add_float(info->fieldset, "Pressure kpa", kpa, 2);
|
|
fieldset_add_int(info->fieldset, "Temperature C", temp, 8);
|
|
return true;
|
|
}
|
|
|
|
ProtoViewDecoder SchraderTPMSDecoder =
|
|
{.name = "Schrader TPMS", .decode = decode, .get_fields = NULL, .build_message = NULL};
|