/* Copyright (C) 2022-2023 Salvatore Sanfilippo -- All Rights Reserved * See the LICENSE file for information about the license. * * Microchip HCS200/HCS300/HSC301 KeeLoq, rolling code remotes. * * Usually 443.92 Mhz OOK, ~200us or ~400us pulse len, depending * on the configuration. * * Preamble: 12 pairs of alternating pulse/gap. * Sync: long gap of around 10 times the duration of the short-pulse. * Data: pulse width encoded data. Each bit takes three cycles: * * 0 = 110 * 1 = 100 * * There are a total of 66 bits transmitted. * 0..31: 32 bits of encrypted rolling code. * 32..59: Remote ID, 28 bits * 60..63: Buttons pressed * 64..64: Low battery if set * 65..65: Always set to 1 * * Bits in bytes are inverted: least significant bit is first. * For some reason there is no checksum whatsoever, so we only decode * if we find everything well formed. */ #include "../app.h" static bool decode(uint8_t* bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo* info) { /* In the sync pattern, we require the 12 high/low pulses and at least * half the gap we expect (5 pulses times, one is the final zero in the * 24 symbols high/low sequence, then other 4). */ const char* sync_pattern = "101010101010101010101010" "0000"; uint8_t sync_len = 24 + 4; if(numbits - sync_len + sync_len < 3 * 66) return false; uint32_t off = bitmap_seek_bits(bits, numbytes, 0, numbits, sync_pattern); if(off == BITMAP_SEEK_NOT_FOUND) return false; info->start_off = off; off += sync_len; // Seek start of message. /* Now there is half the gap left, but we allow from 3 to 7, instead of 5 * symbols of gap, to avoid missing the signal for a matter of wrong * timing. */ uint8_t gap_len = 0; while(gap_len <= 7 && bitmap_get(bits, numbytes, off + gap_len) == 0) gap_len++; if(gap_len < 3 || gap_len > 7) return false; off += gap_len; FURI_LOG_E(TAG, "Keeloq preamble+sync found"); uint8_t raw[9] = {0}; uint32_t decoded = convert_from_line_code( raw, sizeof(raw), bits, numbytes, off, "110", "100"); /* Pulse width modulation. */ FURI_LOG_E(TAG, "Keeloq decoded bits: %lu", decoded); if(decoded < 66) return false; /* Require the full 66 bits. */ info->pulses_count = (off + 66 * 3) - info->start_off; bitmap_reverse_bytes_bits(raw, sizeof(raw)); /* Keeloq is LSB first. */ int buttons = raw[7] >> 4; int lowbat = (raw[8] & 0x1) == 0; // Actual bit meaning: good battery level int alwaysone = (raw[8] & 0x2) != 0; fieldset_add_bytes(info->fieldset, "encr", raw, 8); raw[7] = raw[7] << 4; // Make ID bits contiguous fieldset_add_bytes(info->fieldset, "id", raw + 4, 7); // 28 bits, 7 nibbles fieldset_add_bin(info->fieldset, "s[2,1,0,3]", buttons, 4); fieldset_add_bin(info->fieldset, "low battery", lowbat, 1); fieldset_add_bin(info->fieldset, "always one", alwaysone, 1); return true; } static void get_fields(ProtoViewFieldSet* fieldset) { uint8_t remote_id[4] = {0xab, 0xcd, 0xef, 0xa0}; uint8_t encr[4] = {0xab, 0xab, 0xab, 0xab}; fieldset_add_bytes(fieldset, "encr", encr, 8); fieldset_add_bytes(fieldset, "id", remote_id, 7); fieldset_add_bin(fieldset, "s[2,1,0,3]", 2, 4); fieldset_add_bin(fieldset, "low battery", 0, 1); fieldset_add_bin(fieldset, "always one", 1, 1); } static void build_message(RawSamplesBuffer* samples, ProtoViewFieldSet* fieldset) { uint32_t te = 380; // Short pulse duration in microseconds. // Sync: 12 pairs of pulse/gap + 9 times gap for(int j = 0; j < 12; j++) { raw_samples_add(samples, true, te); raw_samples_add(samples, false, te); } raw_samples_add(samples, false, te * 9); // Data, 66 bits. uint8_t data[9] = {0}; memcpy(data, fieldset->fields[0]->bytes, 4); // Encrypted part. memcpy(data + 4, fieldset->fields[1]->bytes, 4); // ID. data[7] = data[7] >> 4 | fieldset->fields[2]->uvalue << 4; // s[2,1,0,3] int low_battery = fieldset->fields[3] != 0; int always_one = fieldset->fields[4] != 0; low_battery = !low_battery; // Bit real meaning is good battery level. data[8] |= low_battery; data[8] |= (always_one << 1); bitmap_reverse_bytes_bits(data, sizeof(data)); /* Keeloq is LSB first. */ for(int j = 0; j < 66; j++) { if(bitmap_get(data, 9, j)) { raw_samples_add(samples, true, te); raw_samples_add(samples, false, te * 2); } else { raw_samples_add(samples, true, te * 2); raw_samples_add(samples, false, te); } } } ProtoViewDecoder KeeloqDecoder = {.name = "Keeloq", .decode = decode, .get_fields = get_fields, .build_message = build_message};