mirror of
https://github.com/DarkFlippers/unleashed-firmware
synced 2024-12-21 02:03:18 +00:00
79 lines
2.6 KiB
C
79 lines
2.6 KiB
C
/* 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"
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"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 = convert_from_line_code(
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raw, sizeof(raw), bits, numbytes, off, "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(
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info->raw,
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sizeof(info->raw),
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"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
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raw[0],
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raw[1],
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raw[2],
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raw[3],
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raw[4],
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raw[5],
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raw[6],
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raw[7],
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raw[8],
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raw[9]);
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snprintf(
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info->info1,
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sizeof(info->info1),
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"Tire ID %02X%02X%02X",
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raw[4],
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raw[5],
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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 = {"Schrader EG53MA4 TPMS", decode};
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