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https://github.com/Next-Flip/Momentum-Firmware.git
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126 lines
4.5 KiB
C
126 lines
4.5 KiB
C
/* Microchip HCS200/HCS300/HSC301 KeeLoq, rolling code remotes.
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*
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* Usually 443.92 Mhz OOK, ~200us or ~400us pulse len, depending
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* on the configuration.
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*
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* Preamble: 12 pairs of alternating pulse/gap.
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* Sync: long gap of around 10 times the duration of the short-pulse.
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* Data: pulse width encoded data. Each bit takes three cycles:
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*
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* 0 = 110
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* 1 = 100
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*
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* There are a total of 66 bits transmitted.
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* 0..31: 32 bits of encrypted rolling code.
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* 32..59: Remote ID, 28 bits
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* 60..63: Buttons pressed
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* 64..64: Low battery if set
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* 65..65: Always set to 1
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*
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* Bits in bytes are inverted: least significant bit is first.
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* For some reason there is no checksum whatsoever, so we only decode
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* if we find everything well formed.
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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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/* In the sync pattern, we require the 12 high/low pulses and at least
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* half the gap we expect (5 pulses times, one is the final zero in the
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* 24 symbols high/low sequence, then other 4). */
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const char *sync_pattern = "101010101010101010101010" "0000";
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uint8_t sync_len = 24+4;
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if (numbits-sync_len+sync_len < 3*66) return false;
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uint32_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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info->start_off = off;
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off += sync_len; // Seek start of message.
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/* Now there is half the gap left, but we allow from 3 to 7, instead of 5
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* symbols of gap, to avoid missing the signal for a matter of wrong
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* timing. */
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uint8_t gap_len = 0;
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while(gap_len <= 7 && bitmap_get(bits,numbytes,off+gap_len) == 0)
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gap_len++;
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if (gap_len < 3 || gap_len > 7) return false;
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off += gap_len;
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FURI_LOG_E(TAG, "Keeloq preamble+sync found");
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uint8_t raw[9] = {0};
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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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"110","100"); /* Pulse width modulation. */
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FURI_LOG_E(TAG, "Keeloq decoded bits: %lu", decoded);
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if (decoded < 66) return false; /* Require the full 66 bits. */
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info->pulses_count = (off+66*3) - info->start_off;
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bitmap_reverse_bytes_bits(raw,sizeof(raw)); /* Keeloq is LSB first. */
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int buttons = raw[7]>>4;
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int lowbat = (raw[8]&0x1) == 0; // Actual bit meaning: good battery level
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int alwaysone = (raw[8]&0x2) != 0;
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fieldset_add_bytes(info->fieldset,"encr",raw,8);
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raw[7] = raw[7]<<4; // Make ID bits contiguous
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fieldset_add_bytes(info->fieldset,"id",raw+4,7); // 28 bits, 7 nibbles
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fieldset_add_bin(info->fieldset,"s[2,1,0,3]",buttons,4);
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fieldset_add_bin(info->fieldset,"low battery",lowbat,1);
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fieldset_add_bin(info->fieldset,"always one",alwaysone,1);
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return true;
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}
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static void get_fields(ProtoViewFieldSet *fieldset) {
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uint8_t remote_id[4] = {0xab, 0xcd, 0xef, 0xa0};
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uint8_t encr[4] = {0xab, 0xab, 0xab, 0xab};
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fieldset_add_bytes(fieldset,"encr",encr,8);
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fieldset_add_bytes(fieldset,"id",remote_id,7);
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fieldset_add_bin(fieldset,"s[2,1,0,3]",2,4);
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fieldset_add_bin(fieldset,"low battery",0,1);
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fieldset_add_bin(fieldset,"always one",1,1);
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}
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static void build_message(RawSamplesBuffer *samples, ProtoViewFieldSet *fieldset)
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{
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uint32_t te = 380; // Short pulse duration in microseconds.
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// Sync: 12 pairs of pulse/gap + 9 times gap
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for (int j = 0; j < 12; j++) {
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raw_samples_add(samples,true,te);
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raw_samples_add(samples,false,te);
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}
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raw_samples_add(samples,false,te*9);
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// Data, 66 bits.
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uint8_t data[9] = {0};
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memcpy(data,fieldset->fields[0]->bytes,4); // Encrypted part.
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memcpy(data+4,fieldset->fields[1]->bytes,4); // ID.
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data[7] = data[7]>>4 | fieldset->fields[2]->uvalue << 4; // s[2,1,0,3]
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int low_battery = fieldset->fields[3] != 0;
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int always_one = fieldset->fields[4] != 0;
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low_battery = !low_battery; // Bit real meaning is good battery level.
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data[8] |= low_battery;
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data[8] |= (always_one << 1);
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bitmap_reverse_bytes_bits(data,sizeof(data)); /* Keeloq is LSB first. */
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for (int j = 0; j < 66; j++) {
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if (bitmap_get(data,9,j)) {
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raw_samples_add(samples,true,te);
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raw_samples_add(samples,false,te*2);
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} else {
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raw_samples_add(samples,true,te*2);
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raw_samples_add(samples,false,te);
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}
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}
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}
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ProtoViewDecoder KeeloqDecoder = {
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.name = "Keeloq",
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.decode = decode,
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.get_fields = get_fields,
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.build_message = build_message
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};
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