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Add CRC to encoder

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Removed verbose debug logging and refactored CRC calculation for Ford V0 protocol, including a new function for CRC calculation during encoding and proper bit inversion for transmission and verification. Updated key2 construction to always use calculated CRC.
This commit is contained in:
RocketGod
2026-01-17 18:46:46 -08:00
parent f5e7c73b16
commit 0d043831ba
1 changed files with 41 additions and 104 deletions
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protocols/ford_v0.c
+41 -104
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@@ -15,18 +15,18 @@ static const SubGhzBlockConst subghz_protocol_ford_v0_const = {
// Ford V0 CRC Matrix (8x8 bytes) - extracted from firmware
static const uint8_t ford_v0_crc_matrix[64] = {
0xDA, 0xB5, 0x55, 0x6A, 0xAA, 0xAA, 0xAA, 0xD5, // Row 0
0xB6, 0x6C, 0xCC, 0xD9, 0x99, 0x99, 0x99, 0xB3, // Row 1
0x71, 0xE3, 0xC3, 0xC7, 0x87, 0x87, 0x87, 0x8F, // Row 2
0x0F, 0xE0, 0x3F, 0xC0, 0x7F, 0x80, 0x7F, 0x80, // Row 3
0x00, 0x1F, 0xFF, 0xC0, 0x00, 0x7F, 0xFF, 0x80, // Row 4
0x00, 0x00, 0x00, 0x3F, 0xFF, 0xFF, 0xFF, 0x80, // Row 5
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7F, // Row 6
0x23, 0x12, 0x94, 0x84, 0x35, 0xF4, 0x55, 0x84, // Row 7
0xDA, 0xB5, 0x55, 0x6A, 0xAA, 0xAA, 0xAA, 0xD5, // Row 0
0xB6, 0x6C, 0xCC, 0xD9, 0x99, 0x99, 0x99, 0xB3, // Row 1
0x71, 0xE3, 0xC3, 0xC7, 0x87, 0x87, 0x87, 0x8F, // Row 2
0x0F, 0xE0, 0x3F, 0xC0, 0x7F, 0x80, 0x7F, 0x80, // Row 3
0x00, 0x1F, 0xFF, 0xC0, 0x00, 0x7F, 0xFF, 0x80, // Row 4
0x00, 0x00, 0x00, 0x3F, 0xFF, 0xFF, 0xFF, 0x80, // Row 5
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7F, // Row 6
0x23, 0x12, 0x94, 0x84, 0x35, 0xF4, 0x55, 0x84, // Row 7
};
// ============================================================================
// CRC FUNCTIONS (for decoder verification)
// CRC FUNCTIONS
// ============================================================================
static uint8_t ford_v0_popcount8(uint8_t x) {
@@ -42,18 +42,6 @@ static uint8_t ford_v0_popcount8(uint8_t x) {
static uint8_t ford_v0_calculate_crc(uint8_t* buf) {
uint8_t crc = 0;
FURI_LOG_D(
TAG,
"CRC calc input: buf[1-8] = %02X %02X %02X %02X %02X %02X %02X %02X",
buf[1],
buf[2],
buf[3],
buf[4],
buf[5],
buf[6],
buf[7],
buf[8]);
for(int row = 0; row < 8; row++) {
uint8_t xor_sum = 0;
for(int col = 0; col < 8; col++) {
@@ -63,23 +51,29 @@ static uint8_t ford_v0_calculate_crc(uint8_t* buf) {
if(parity) {
crc |= (1 << row);
}
FURI_LOG_D(
TAG,
"CRC row %d: xor_sum=0x%02X popcount=%d parity=%d crc_so_far=0x%02X",
row,
xor_sum,
ford_v0_popcount8(xor_sum),
parity,
crc);
}
// XOR with 0x80 - Ford appears to invert bit 7
crc ^= 0x80;
FURI_LOG_D(TAG, "CRC calculated: 0x%02X", crc);
return crc;
}
// Calculate CRC for encoding: returns the value to transmit
static uint8_t ford_v0_calculate_crc_for_tx(uint64_t key1, uint8_t bs) {
uint8_t buf[16] = {0};
// Extract bytes from key1 into buf[0..7]
for(int i = 0; i < 8; ++i) {
buf[i] = (uint8_t)(key1 >> (56 - i * 8));
}
// BS goes into buf[8]
buf[8] = bs;
// Calculate CRC and XOR with 0x80 for transmission
uint8_t crc = ford_v0_calculate_crc(buf);
return crc ^ 0x80;
}
// Verify received CRC
static bool ford_v0_verify_crc(uint64_t key1, uint16_t key2) {
uint8_t buf[16] = {0};
@@ -91,34 +85,9 @@ static bool ford_v0_verify_crc(uint64_t key1, uint16_t key2) {
// BS is high byte of key2, goes into buf[8]
buf[8] = (uint8_t)(key2 >> 8);
FURI_LOG_I(
TAG,
"CRC verify: key1=0x%08lX%08lX key2=0x%04X",
(uint32_t)(key1 >> 32),
(uint32_t)(key1 & 0xFFFFFFFF),
key2);
FURI_LOG_I(
TAG,
"CRC verify: buf[0-8] = %02X %02X %02X %02X %02X %02X %02X %02X %02X",
buf[0],
buf[1],
buf[2],
buf[3],
buf[4],
buf[5],
buf[6],
buf[7],
buf[8]);
uint8_t calculated_crc = ford_v0_calculate_crc(buf);
uint8_t received_crc = (uint8_t)(key2 & 0xFF);
FURI_LOG_I(
TAG,
"CRC compare: calculated=0x%02X received=0x%02X match=%s",
calculated_crc,
received_crc,
(calculated_crc == received_crc) ? "YES" : "NO");
// Received CRC has bit 7 inverted
uint8_t received_crc = (uint8_t)(key2 & 0xFF) ^ 0x80;
return (calculated_crc == received_crc);
}
@@ -437,19 +406,23 @@ SubGhzProtocolStatus
}
instance->generic.cnt = instance->count;
// Read BS from file
uint32_t bs_temp = 0;
flipper_format_read_uint32(flipper_format, "BS", &bs_temp, 1);
uint8_t bs = (uint8_t)(bs_temp & 0xFF);
uint32_t crc_temp = 0;
flipper_format_read_uint32(flipper_format, "CRC", &crc_temp, 1);
// Calculate CRC from key1 and BS
uint8_t calculated_crc = ford_v0_calculate_crc_for_tx(instance->key1, bs);
// Build key2 from BS and calculated CRC
instance->key2 = ((uint16_t)bs << 8) | calculated_crc;
instance->key2 = ((bs_temp & 0xFF) << 8) | (crc_temp & 0xFF);
FURI_LOG_I(
TAG,
"Reconstructed key2: 0x%04X (BS=0x%02X, CRC=0x%02X)",
"Encoder key2: 0x%04X (BS=0x%02X, CRC=0x%02X calculated)",
instance->key2,
(uint8_t)bs_temp,
(uint8_t)crc_temp);
bs,
calculated_crc);
if(!flipper_format_read_uint32(
flipper_format, "Repeat", (uint32_t*)&instance->encoder.repeat, 1)) {
@@ -581,42 +554,15 @@ static bool ford_v0_process_data(SubGhzProtocolDecoderFordV0* instance) {
instance->key1 = ~combined;
instance->data_low = 0;
instance->data_high = 0;
FURI_LOG_I(
TAG,
"Got 64 bits, key1=0x%08lX%08lX",
(uint32_t)(instance->key1 >> 32),
(uint32_t)(instance->key1 & 0xFFFFFFFF));
return false;
}
if(instance->bit_count == 80) {
uint16_t key2_raw = (uint16_t)(instance->data_low & 0xFFFF);
uint16_t key2 = ~key2_raw;
FURI_LOG_I(TAG, "Got 80 bits, key2_raw=0x%04X key2=0x%04X", key2_raw, key2);
// Verify CRC
bool crc_ok = ford_v0_verify_crc(instance->key1, key2);
FURI_LOG_I(
TAG,
"Received: key1=0x%08lX%08lX key2=0x%04X CRC=%s",
(uint32_t)(instance->key1 >> 32),
(uint32_t)(instance->key1 & 0xFFFFFFFF),
key2,
crc_ok ? "OK" : "BAD");
decode_ford_v0(
instance->key1, key2, &instance->serial, &instance->button, &instance->count);
instance->key2 = key2;
FURI_LOG_I(
TAG,
"Decoded: Sn=0x%08lX Btn=%d Cnt=0x%05lX",
instance->serial,
instance->button,
instance->count);
return true;
}
@@ -819,7 +765,7 @@ SubGhzProtocolStatus
if(ret == SubGhzProtocolStatusOk) {
instance->key1 = instance->generic.data;
// Rewind and read all custom fields
// Rewind and read custom fields
flipper_format_rewind(flipper_format);
uint32_t bs_temp = 0;
@@ -828,15 +774,6 @@ SubGhzProtocolStatus
flipper_format_read_uint32(flipper_format, "CRC", &crc_temp, 1);
instance->key2 = ((bs_temp & 0xFF) << 8) | (crc_temp & 0xFF);
FURI_LOG_I(
TAG,
"Deserialize: key1=0x%08lX%08lX key2=0x%04X (BS=%02X CRC=%02X)",
(uint32_t)(instance->key1 >> 32),
(uint32_t)(instance->key1 & 0xFFFFFFFF),
instance->key2,
(uint8_t)bs_temp,
(uint8_t)crc_temp);
flipper_format_read_uint32(flipper_format, "Serial", &instance->serial, 1);
instance->generic.serial = instance->serial;
@@ -888,4 +825,4 @@ void subghz_protocol_decoder_ford_v0_get_string(void* context, FuriString* outpu
instance->count,
(instance->key2 >> 8) & 0xFF,
instance->key2 & 0xFF);
}
}