Class ChannelEngineI2S

src/platforms/esp/32/drivers/i2s/channel_driver_i2s.h:109–249

@brief I2S LCD_CAM-based channel driver for parallel LED control on ESP32-S3 Implements IChannelDriver interface using ESP32-S3 LCD_CAM peripheral for LED data transmission. Uses dependency injection pattern for testability. ## Architecture - **Peripheral abstraction**: Uses II2sLcdCamPeripheral* for hardware delegation - **Transpose encoding**: Efficient bit-parallel waveform generation - **Mul

/// DRAINING → poll() → READY (transmission complete)
/// ```
class ChannelEngineI2S : public IChannelDriver {
public:
    /// @brief Constructor with dependency injection
    /// @param peripheral I2S LCD_CAM peripheral instance (real or mock)
    ///
    /// Stores a shared pointer to the peripheral to maintain proper lifetime.
    /// The peripheral will remain valid for the lifetime of this driver.
    explicit ChannelEngineI2S(fl::shared_ptr<detail::II2sLcdCamPeripheral> peripheral) FL_NOEXCEPT;

    /// @brief Destructor - waits for transmission completion
    ~ChannelEngineI2S() override;

    /// @brief Check if driver can handle channel data (clockless only)
    /// @param data Channel data to check
    /// @return true if clockless channel (rejects SPI), false otherwise
    bool canHandle(const ChannelDataPtr& data) const FL_NOEXCEPT override;

    /// @brief Enqueue channel data for transmission
    /// @param channelData Channel data to transmit
    ///
    /// Adds channel to internal queue. Transmission happens when show() is called.
    void enqueue(ChannelDataPtr channelData) FL_NOEXCEPT override;

    /// @brief Trigger transmission of enqueued data
    ///
    /// Groups channels by timing configuration and begins transmission of
    /// first group. Subsequent groups transmit sequentially via poll().
    void show() FL_NOEXCEPT override;

    /// @brief Query driver state and perform maintenance
    /// @return Current driver state (READY, BUSY, DRAINING, or ERROR)
    ///
    /// Must be called regularly to:
    /// - Check transmission completion status
    /// - Trigger sequential chipset group transmissions
    /// - Clean up completed transmissions
    DriverState poll() FL_NOEXCEPT override;

    void setPollNeededCallback(PollNeededCallback callback) FL_NOEXCEPT override;

    /// @brief Get the driver name for affinity binding
    /// @return "I2S"
    fl::string getName() const FL_NOEXCEPT override { return fl::string::from_literal("I2S"); }

    /// @brief Get driver capabilities (CLOCKLESS protocols only)
    /// @return Capabilities with supportsClockless=true, supportsSpi=false
    Capabilities getCapabilities() const FL_NOEXCEPT override {
        return Capabilities(true, false);  // Clockless only
    }

private:
    /// @brief Begin LED data transmission for current chipset group
    /// @param channelData Span of channel data to transmit
    /// @return true if transmission started successfully, false on error
    ///
    /// This method:
    /// 1. Validates channel data
    /// 2. Initializes LCD_CAM peripheral if needed