Function isGapPulse

src/platforms/esp/32/drivers/rmt_rx/rmt_rx_channel.cpp.hpp:140–180

* @brief Check if symbol is a gap pulse (transmission gap like PARLIO DMA gap) * @param symbol RMT symbol to check * @param timing Timing thresholds * @param ns_per_tick Cached nanoseconds per tick * @return true if symbol is gap pulse (long low duration longer than reset but * within gap tolerance) * * Gap pulses are longer than normal bit LOW times but shorter than * gap_tolerance_ns. Th

 * errors. Common in PARLIO TX due to DMA transfer gaps (~20us).
 */
inline bool isGapPulse(RmtSymbol symbol, const ChipsetTiming4Phase &timing,
                       u32 ns_per_tick) {
    // No gap tolerance configured - treat as error
    if (timing.gap_tolerance_ns == 0) {
        return false;
    }

    // Cast RmtSymbol to rmt_symbol_word_t to access bitfields
    const auto rmt_sym = fl::bit_cast<rmt_symbol_word_t>(symbol);

    // Convert durations to nanoseconds
    u32 duration0_ns = ticksToNs(rmt_sym.duration0, ns_per_tick);
    u32 duration1_ns = ticksToNs(rmt_sym.duration1, ns_per_tick);

    // Gap pulse characteristics:
    // - Long LOW duration (longer than normal bit LOW timing)
    // - Shorter than reset threshold (not a frame reset)
    // - Within gap_tolerance_ns
    // - Should have level=0 (low) for the long duration
    //
    // The longest normal LOW pulse is t0l_max_ns, so gap must be longer than
    // that

    // Check duration1 (most common case - gap at end of bit sequence)
    if (rmt_sym.level1 == 0 && duration1_ns > timing.t0l_max_ns &&
        duration1_ns <= timing.gap_tolerance_ns) {
        FL_WARN("isGapPulse DETECTED: duration1=" << duration1_ns << "ns (level1=0), t0l_max="
               << timing.t0l_max_ns << "ns, gap_tolerance=" << timing.gap_tolerance_ns << "ns");
        return true;
    }

    // Check duration0 (less common - gap at start)
    if (rmt_sym.level0 == 0 && duration0_ns > timing.t0l_max_ns &&
        duration0_ns <= timing.gap_tolerance_ns) {
        FL_WARN("isGapPulse DETECTED: duration0=" << duration0_ns << "ns (level0=0), t0l_max="
               << timing.t0l_max_ns << "ns, gap_tolerance=" << timing.gap_tolerance_ns << "ns");
        return true;
    }

    return false;
}

/**
 * @brief Decode single symbol to bit value