mirror of
https://github.com/DarkFlippers/unleashed-firmware
synced 2024-12-19 01:03:22 +00:00
67 lines
2.4 KiB
C
67 lines
2.4 KiB
C
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/* Schrader variant EG53MA4 TPMS.
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* Usually 443.92 Mhz OOK, 100us pulse len.
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*
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* Preamble: alternating pulse/gap, 100us.
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* Sync (as pulses and gaps): "01100101", already part of the data stream
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* (first nibble) corresponding to 0x4
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*
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* A total of 10 bytes payload, Manchester encoded.
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*
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* 0 = 01
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* 1 = 10
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*
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* Used in certain Open cars and others.
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*/
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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";
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uint8_t sync_len = 12+8; /* We just use 12 preamble symbols + sync. */
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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);
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if (off == BITMAP_SEEK_NOT_FOUND) return false;
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FURI_LOG_E(TAG, "Schrader EG53MA4 TPMS preamble+sync found");
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info->start_off = off;
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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];
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uint32_t decoded =
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convert_from_line_code(raw,sizeof(raw),bits,numbytes,off,
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"01","10"); /* Manchester code. */
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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. */
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uint8_t crc = 0;
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for (int j = 0; j < 9; j++) crc += raw[j];
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if (crc != raw[9]) return false; /* Require sane CRC. */
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info->pulses_count = (off+10*8*2) - info->start_off;
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/* To convert the raw pressure to kPa, RTL433 uses 2.5, but is likely
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* wrong. Searching on Google for users experimenting with the value
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* reported, the value appears to be 2.75. */
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float kpa = (float)raw[7]*2.75;
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int temp_f = raw[8];
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int temp_c = (temp_f-32)*5/9; /* Convert Fahrenheit to Celsius. */
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snprintf(info->name,sizeof(info->name),"%s","Schrader EG53MA4 TPMS");
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snprintf(info->raw,sizeof(info->raw),"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
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raw[0],raw[1],raw[2],raw[3],raw[4],raw[5],
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raw[6],raw[7],raw[8],raw[9]);
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snprintf(info->info1,sizeof(info->info1),"Tire ID %02X%02X%02X",
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raw[4],raw[5],raw[6]); /* Only 28 bits of ID, not 32. */
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snprintf(info->info2,sizeof(info->info2),"Pressure %.2f kpa", (double)kpa);
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snprintf(info->info3,sizeof(info->info3),"Temperature %d C", temp_c);
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return true;
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}
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ProtoViewDecoder SchraderEG53MA4TPMSDecoder = {
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"Schrader EG53MA4 TPMS", decode
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};
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