mirror of
https://github.com/DarkFlippers/unleashed-firmware.git
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62 lines
2.3 KiB
C
62 lines
2.3 KiB
C
/* Copyright (C) 2022-2023 Salvatore Sanfilippo -- All Rights Reserved
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* See the LICENSE file for information about the license.
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*
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* Ford tires TPMS. Usually 443.92 Mhz FSK (in Europe).
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*
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* 52 us short pules
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* Preamble: 0101010101010101010101010101
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* Sync: 0110 (that is 52 us gap + 104 us pulse + 52 us gap)
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* Data: 8 bytes Manchester encoded
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* 01 = zero
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* 10 = one
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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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"0110";
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uint8_t sync_len = 12 + 4; /* We just use 12 preamble symbols + sync. */
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if(numbits - sync_len < 8 * 8) 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, "Fort TPMS preamble+sync found");
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info->start_off = off;
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off += sync_len; /* Skip preamble and sync. */
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uint8_t raw[8];
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uint32_t decoded = convert_from_line_code(
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raw, sizeof(raw), bits, numbytes, off, "01", "10"); /* Manchester. */
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FURI_LOG_E(TAG, "Ford TPMS decoded bits: %lu", decoded);
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if(decoded < 8 * 8) return false; /* Require the full 8 bytes. */
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/* CRC is just the sum of the first 7 bytes MOD 256. */
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uint8_t crc = 0;
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for(int j = 0; j < 7; j++) crc += raw[j];
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if(crc != raw[7]) return false; /* Require sane CRC. */
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info->pulses_count = (off + 8 * 8 * 2) - info->start_off;
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float psi = 0.25 * (((raw[6] & 0x20) << 3) | raw[4]);
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/* Temperature apperas to be valid only if the most significant
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* bit of the value is not set. Otherwise its meaning is unknown.
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* Likely useful to alternatively send temperature or other info. */
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int temp = raw[5] & 0x80 ? 0 : raw[5] - 56;
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int flags = raw[5] & 0x7f;
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int car_moving = (raw[6] & 0x44) == 0x44;
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fieldset_add_bytes(info->fieldset, "Tire ID", raw, 4 * 2);
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fieldset_add_float(info->fieldset, "Pressure psi", psi, 2);
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fieldset_add_int(info->fieldset, "Temperature C", temp, 8);
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fieldset_add_hex(info->fieldset, "Flags", flags, 7);
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fieldset_add_uint(info->fieldset, "Moving", car_moving, 1);
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return true;
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}
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ProtoViewDecoder FordTPMSDecoder =
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{.name = "Ford TPMS", .decode = decode, .get_fields = NULL, .build_message = NULL};
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