mirror of
https://github.com/Next-Flip/Momentum-Firmware.git
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90 lines
3.0 KiB
C
90 lines
3.0 KiB
C
/* Toyota tires TPMS. Usually 443.92 Mhz FSK (In Europe).
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*
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* Preamble + sync + 64 bits of data. ~48us short pulse length.
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*
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* The preamble + sync is something like:
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*
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* 10101010101 (preamble) + 001111[1] (sync)
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*
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* Note: the final [1] means that sometimes it is four 1s, sometimes
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* five, depending on the short pulse length detection and the exact
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* duration of the high long pulse. After the sync, a differential
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* Manchester encoded payload follows. However the Flipper's CC1101
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* often can't decode correctly the initial alternating pattern 101010101,
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* so what we do is to seek just the sync, that is "001111" or "0011111",
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* however we now that it must be followed by one differenitally encoded
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* bit, so we can use also the first symbol of data to force a more robust
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* detection, and look for one of the following:
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*
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* [001111]00
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* [0011111]00
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* [001111]01
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* [0011111]01
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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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if (numbits-6 < 64*2) return false; /* Ask for 64 bit of data (each bit
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is two symbols in the bitmap). */
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char *sync[] = {
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"00111100",
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"001111100",
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"00111101",
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"001111101",
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NULL
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};
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int j;
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uint32_t off = 0;
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for (j = 0; sync[j]; j++) {
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off = bitmap_seek_bits(bits,numbytes,0,numbits,sync[j]);
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if (off != BITMAP_SEEK_NOT_FOUND) {
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info->start_off = off;
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off += strlen(sync[j])-2;
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break;
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}
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}
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if (off == BITMAP_SEEK_NOT_FOUND) return false;
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FURI_LOG_E(TAG, "Toyota TPMS sync[%s] found", sync[j]);
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uint8_t raw[9];
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uint32_t decoded =
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convert_from_diff_manchester(raw,sizeof(raw),bits,numbytes,off,true);
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FURI_LOG_E(TAG, "Toyota TPMS decoded bits: %lu", decoded);
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if (decoded < 8*9) return false; /* Require the full 8 bytes. */
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if (crc8(raw,8,0x80,7) != raw[8]) return false; /* Require sane CRC. */
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/* We detected a valid signal. However now info->start_off is actually
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* pointing to the sync part, not the preamble of alternating 0 and 1.
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* Protoview decoders get called with some space to the left, in order
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* for the decoder itself to fix the signal if neeeded, so that its
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* logical representation will be more accurate and better to save
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* and retransmit. */
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if (info->start_off >= 12) {
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info->start_off -= 12;
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bitmap_set_pattern(bits,numbytes,info->start_off,"010101010101");
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}
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info->pulses_count = (off+8*9*2) - info->start_off;
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float psi = (float)((raw[4]&0x7f)<<1 | raw[5]>>7) * 0.25 - 7;
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int temp = ((raw[5]&0x7f)<<1 | raw[6]>>7) - 40;
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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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return true;
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}
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ProtoViewDecoder ToyotaTPMSDecoder = {
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.name = "Toyota TPMS",
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.decode = decode,
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.get_fields = NULL,
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.build_message = NULL
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};
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