Class SPIDeviceProxy

src/platforms/arm/sam/spi_device_proxy.h:46–254

/// @tparam SPI_CLOCK_DIVIDER SPI clock divider (matches SAMHardwareSPIOutput)
template<u8 DATA_PIN, u8 CLOCK_PIN, u32 SPI_CLOCK_DIVIDER>
class SPIDeviceProxy {
private:
    SPIBusHandle mHandle;                    // Handle from SPIBusManager
    SPIBusManager* mBusManager;              // Pointer to global bus manager
    fl::unique_ptr<SAMDHardwareSPIOutput<DATA_PIN, CLOCK_PIN, SPI_CLOCK_DIVIDER>> mSingleSPI;
    fl::vector<u8> mWriteBuffer;        // Buffered writes (for Dual/Quad-SPI)
    bool mInitialized;                       // Whether init() was called
    bool mBusInitialized;                    // Whether bus manager has been initialized
    bool mInTransaction;                     // Whether select() was called

public:
    /// Constructor - just stores pins, actual setup happens in init()
    SPIDeviceProxy()
        : mHandle()
        , mBusManager(nullptr)
        , mInitialized(false)
        , mBusInitialized(false)
        , mInTransaction(false)
    {
    }

    /// Destructor - cleanup owned resources and unregister from bus manager
    ~SPIDeviceProxy() {
        // Unregister from bus manager (releases Dual/Quad-SPI if last device)
        if (mBusManager && mHandle.is_valid) {
            mBusManager->unregisterDevice(mHandle);
            mHandle = SPIBusHandle();  // Invalidate handle
        }

        mSingleSPI.reset();
    }

    /// Initialize SPI device and register with bus manager
    /// Called by LED controller's init() method
    void init() FL_NOEXCEPT {
        if (mInitialized) {
            return;  // Already initialized
        }

        // Get global bus manager
        mBusManager = &getSPIBusManager();

        // Register with bus manager
        // NOTE: Bus manager will determine if we use Single/Dual/Quad SPI
        // based on how many devices share our clock pin
        // Calculate SPI speed from clock divider: speed_hz = F_CPU / divider
        constexpr u32 spi_speed_hz = F_CPU / SPI_CLOCK_DIVIDER;
        mHandle = mBusManager->registerDevice(CLOCK_PIN, DATA_PIN, spi_speed_hz, this);

        if (!mHandle.is_valid) {
            FL_WARN("SPIDeviceProxy: Failed to register with bus manager (pin "
                    << static_cast<int>(CLOCK_PIN) << ":" << static_cast<int>(DATA_PIN) << ")");
            return;
        }

        // IMPORTANT: DO NOT initialize bus manager here!
        // We defer initialization until the first transmit() call (lazy initialization).
        // This allows all devices on the same clock pin to register before the bus