Momentum-Apps/protocols/b4b1.c

/* PT/SC remotes. Usually 443.92 Mhz OOK.
 *
 * This line code is used in many remotes such as Princeton chips
 * named PT2262, Silian Microelectronics SC5262 and others.
 * Basically every 4 pulsee represent a bit, where 1000 means 0, and
 * 1110 means 1. Usually we can read 24 bits of data.
 * In this specific implementation we check for a prelude that is
 * 1 bit high, 31 bits low, but the check is relaxed. */

#include "../app.h"

static bool decode(uint8_t *bits, uint32_t numbytes, uint32_t numbits, ProtoViewMsgInfo *info) {
    if (numbits < 30) return false;
    const char *sync_patterns[3] = {
        "10000000000000000000000000000001", /* 30 zero bits. */
        "100000000000000000000000000000001", /* 31 zero bits. */
        "1000000000000000000000000000000001", /* 32 zero bits. */
    };

    uint32_t off;
    int j;
    for (j = 0; j < 3; j++) {
        off = bitmap_seek_bits(bits,numbytes,0,numbits,sync_patterns[j]);
        if (off != BITMAP_SEEK_NOT_FOUND) break;
    }
    if (off == BITMAP_SEEK_NOT_FOUND) return false;
    if (DEBUG_MSG) FURI_LOG_E(TAG, "B4B1 preamble at: %lu",off);
    info->start_off = off;

    // Seek data setction. Why -1? Last bit is data.
    off += strlen(sync_patterns[j])-1;

    uint8_t d[3]; /* 24 bits of data. */
    uint32_t decoded =
        convert_from_line_code(d,sizeof(d),bits,numbytes,off,"1000","1110");

    if (DEBUG_MSG) FURI_LOG_E(TAG, "B4B1 decoded: %lu",decoded);
    if (decoded < 24) return false;

    off += 24*4; // seek to end symbol offset to calculate the length.
    off++; // In this protocol there is a final pulse as terminator.
    info->pulses_count = off - info->start_off;

    fieldset_add_bytes(info->fieldset,"id",d,5);
    fieldset_add_uint(info->fieldset,"button",d[2]&0xf,4);
    return true;
}

/* Give fields and defaults for the signal creator. */
static void get_fields(ProtoViewFieldSet *fieldset) {
    uint8_t default_id[3]= {0xAB, 0xCD, 0xE0};
    fieldset_add_bytes(fieldset,"id",default_id,5);
    fieldset_add_uint(fieldset,"button",1,4);
}

/* Create a signal. */
static void build_message(RawSamplesBuffer *samples, ProtoViewFieldSet *fs)
{
    uint32_t te = 334; // Short pulse duration in microseconds.

    // Sync: 1 te pulse, 31 te gap.
    raw_samples_add(samples,true,te);
    raw_samples_add(samples,false,te*31);

    // ID + button state
    uint8_t data[3];
    memcpy(data,fs->fields[0]->bytes,3);
    data[2] = (data[2]&0xF0) | (fs->fields[1]->uvalue & 0xF);
    for (uint32_t j = 0; j < 24; j++) {
        if (bitmap_get(data,sizeof(data),j)) {
            raw_samples_add(samples,true,te*3);
            raw_samples_add(samples,false,te);
        } else {
            raw_samples_add(samples,true,te);
            raw_samples_add(samples,false,te*3);
        }
    }

    // Signal terminator. Just a single short pulse.
    raw_samples_add(samples,true,te);
}

ProtoViewDecoder B4B1Decoder = {
    .name = "PT/SC remote",
    .decode = decode,
    .get_fields = get_fields,
    .build_message = build_message 
};