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/* 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. | ||
*/ | ||
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#include "../app.h" | ||
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static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo *info) { | ||
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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; | ||
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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"); | ||
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off += sync_len-8; /* Skip preamble, not sync that is part of the data. */ | ||
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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); | ||
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if (decoded < 10*8) return false; /* Require the full 10 bytes. */ | ||
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/* 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. */ | ||
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float kpa = (float)raw[7]*2.5; | ||
int temp_f = raw[8]; | ||
int temp_c = (temp_f-32)*5/9; | ||
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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; | ||
} | ||
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ProtoViewDecoder SchraderEG53MA4TPMSDecoder = { | ||
"Schrader EG53MA4 TPMS", decode | ||
}; |
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