Atomic SPK Base Arduino 使用チュートリアル

#include <M5Unified.h>
#include <M5GFX.h>

// Define I2S audio pins connected to the speaker
#define PIN_DATA 38      // Data output pin for audio signal
#define PIN_BCLK 5       // Bit clock pin for I2S communication
#define PIN_LRCK 39      // Left/Right clock pin for channel selection

// Set audio output sample rate (44.1kHz is standard for audio)
static constexpr const size_t output_samplerate = 44100;

void setup() {
    M5.begin();
    M5.Display.setFont(&fonts::FreeMonoBold9pt7b);
    M5.Display.setTextDatum(middle_center);
    M5.Display.drawCenterString("SPK Example", 64, 60);

    // Configure speaker settings using I2S protocol
    m5::speaker_config_t spk_cfg = {
      .pin_data_out = PIN_DATA,          // Assign data pin
      .pin_bck = PIN_BCLK,               // Assign bit clock pin
      .pin_ws = PIN_LRCK,                // Assign left/right clock pin
      .sample_rate = output_samplerate,  // Set audio sample rate
      .dma_buf_len = 256,                // DMA buffer length (for smooth audio)
      .dma_buf_count = 6,                // Number of DMA buffers (double buffering)
      .i2s_port = i2s_port_t::I2S_NUM_0  // Specify I2S hardware port
    };
    M5.Speaker.config(spk_cfg);  // Apply the speaker configuration
    M5.Speaker.begin();  // Initialize the speaker hardware
    M5.Speaker.setVolume(128);
}

void loop() {
    // Play 6000Hz tone for 100ms
    M5.Speaker.tone(6000, 100);
    delay(1000);

    // Play 2000Hz tone for 20ms
    M5.Speaker.tone(2000, 20);
    delay(1000);
}

#include <driver/i2s_std.h>
#include <cmath>
#include <atomic>
#include <M5Unified.h>
#include <M5GFX.h>

// Define I2S audio pins connected to the speaker
#define PIN_DATA GPIO_NUM_38      // Data output pin for audio signal transmission
#define PIN_BCLK GPIO_NUM_5       // Bit clock pin for I2S timing synchronization
#define PIN_LRCK GPIO_NUM_39      // Left/Right clock pin for channel selection

// Audio configuration parameters
static constexpr const size_t output_samplerate = 44100;  // Audio sampling rate (Hz)
static constexpr const int amplitude = 32767;              // Max amplitude for 16-bit audio (-32768 ~ 32767)
static constexpr const int channels = 1;                   // MONO
static std::atomic<bool> isPlaying(false);                // Atomic flag for playback status
static std::atomic<uint8_t> volume(50);                    // Volume level (0-100%)

// I2S hardware handle for ESP32
i2s_chan_handle_t tx_handle = nullptr;
#define I2S_PORT  I2S_NUM_0

/**
 * @brief Set audio volume level
 * @param vol Volume level (0-100), 0 = mute, 100 = maximum
 */
void setVolume(uint8_t vol) {
    volume = constrain(vol, 0, 100);  // Constrain volume within valid range
}

void setup() {
    M5.begin();
    M5.Display.setFont(&fonts::FreeMonoBold9pt7b);
    M5.Display.setTextDatum(middle_center);
    M5.Display.drawCenterString("SPK Example", 64, 60);

    // Configure I2S channel parameters
    i2s_chan_config_t chan_cfg = {
        .id = I2S_NUM_AUTO,                // Automatically assign I2S peripheral
        .role = I2S_ROLE_MASTER,           // Operate as I2S master
        .dma_desc_num = 6,                 // Number of DMA descriptors
        .dma_frame_num = 256,              // Number of frames per DMA descriptor
        .auto_clear = true,                // Automatically clear DMA buffers
    };
    ESP_ERROR_CHECK(i2s_new_channel(&chan_cfg, &tx_handle, NULL));  // Create I2S channel

    // Configure standard I2S parameters - modified for mono
    i2s_std_config_t std_tx_cfg = {
        .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(output_samplerate),  // Clock configuration
        .slot_cfg = I2S_STD_MSB_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
        .gpio_cfg = {
            .mclk = I2S_GPIO_UNUSED,        // MCLK not used
            .bclk = PIN_BCLK,               // Bit clock pin
            .ws   = PIN_LRCK,               // Word select pin
            .dout = PIN_DATA,               // Data output pin
            .din  = I2S_GPIO_UNUSED,        // No input needed
            .invert_flags = {
                .bclk_inv = false,          // Do not invert BCLK
                .ws_inv   = false           // Do not invert WS
            },
        }
    };
    ESP_ERROR_CHECK(i2s_channel_init_std_mode(tx_handle, &std_tx_cfg));  // Initialize I2S mode
    ESP_ERROR_CHECK(i2s_channel_enable(tx_handle));                      // Enable I2S channel
}

void playTone(float frequency, uint32_t duration);

void loop() {

    playTone(6000, 100);  // 6000Hz for 100ms
    delay(1000);           // Pause 1 second

    playTone(2000, 20);   // 2000Hz for 20ms
    delay(1000);           // Pause 1 second
}

/**
 * @brief Generate sine wave tone and play through I2S (mono version)
 * @param frequency Tone frequency in Hz
 * @param duration Playback duration in milliseconds (0 = infinite)
 */
void playTone(float frequency, uint32_t duration) {
    if (tx_handle == NULL || frequency <= 0) return;  // Validate input

    isPlaying = true;
    const size_t samples_per_cycle = output_samplerate / frequency;  // Samples per sine wave cycle
    const size_t total_samples = (duration > 0) ?
        (output_samplerate * duration) / 1000 : UINT32_MAX;          // Total samples to generate

    // Audio buffer - mono 16-bit (modified from stereo)
    int16_t buffer[1024 * channels];  // 1024 samples
    size_t samples_written = 0;
    size_t bytes_written;
    float gain = volume / 100.0f;  // Calculate volume gain factor

    while (isPlaying && samples_written < total_samples) {
        // Calculate number of samples to write in this iteration
        size_t samples_to_write = std::min(1024, (int)(total_samples - samples_written));

        // Fill buffer with sine wave samples
        for (size_t i = 0; i < samples_to_write; i++) {
            // Calculate phase for continuous sine wave
            float phase = 2 * M_PI * (samples_written + i) / samples_per_cycle;
            int16_t sample = (int16_t)(amplitude * sin(phase));  // Generate raw sample

            sample = (int16_t)(sample * gain);  // Apply volume adjustment

            // Single channel output
            buffer[i] = sample;  // Only one channel needed
        }

        // Transmit audio data via I2S
        i2s_channel_write(tx_handle, buffer,
                         samples_to_write * channels * sizeof(int16_t),
                         &bytes_written, 100 / portTICK_PERIOD_MS);  // 100ms timeout

        // Update counter with actual written samples
        samples_written += bytes_written / (channels * sizeof(int16_t));
    }

    // Send silence after playback to prevent noise
    memset(buffer, 0, sizeof(buffer));  // Clear buffer with 0
    i2s_channel_write(tx_handle, buffer, sizeof(buffer), &bytes_written, portMAX_DELAY);
    isPlaying = false;
}

#include <SPI.h>
#include <SD.h>
#include <M5Unified.h>
#include <M5GFX.h>

// ------------------- Pin Definitions -------------------
// SPI pins for microSD card in speaker
#define SD_SPI_CS_PIN     -1   // CS pin not connected (hardware-enabled permanently)
#define SD_SPI_SCK_PIN    7    // SPI Clock pin
#define SD_SPI_MISO_PIN   8    // SPI MISO pin
#define SD_SPI_MOSI_PIN   6    // SPI MOSI pin

// I2S pins for speaker (audio output protocol)
#define SPK_I2S_PIN_DATA 38   // I2S audio data output pin
#define SPK_I2S_PIN_BCLK 5    // I2S bit clock pin
#define SPK_I2S_PIN_LRCK 39   // I2S LR clock pin

// ------------------- Audio Configuration -------------------
static constexpr const size_t output_samplerate = 44100;  // Standard audio sample rate (44.1kHz)
static bool isPlaying = false;                            // Flag to track audio play state (playing/stopped)

// ------------------- Global File/Buffer Variables -------------------
File wavFile;                 // File object for WAV audio file
uint8_t* wavBuffer = nullptr; // Buffer to store entire WAV file (header + audio data)
size_t wavBufferLen = 0;      // Total length of WAV data in buffer

void setup() {
    M5.begin();
    M5.Display.setFont(&fonts::FreeMonoBold9pt7b);
    M5.Display.setTextDatum(middle_center);
    Serial.begin(115200);

    // ------------------- SD Card Initialization -------------------
    SPI.begin(SD_SPI_SCK_PIN, SD_SPI_MISO_PIN, SD_SPI_MOSI_PIN, SD_SPI_CS_PIN);
    M5.Display.drawCenterString("SD Init...", 64, 0);
    Serial.println("SD Init...");

    // Attempt SD card init (25MHz SPI speed); halt on failure
    if (!SD.begin(SD_SPI_CS_PIN, SPI, 25000000)) {
        M5.Display.clear();
        M5.Display.drawCenterString("SD Error!", 64, 50);
        Serial.println("SD Error!");
        while (1);  // Infinite loop = halt if SD card fails
    } else {
        M5.Display.clear();
        M5.Display.drawCenterString("SD Ready", 64, 0);
        Serial.println("SD Ready");
    }

    // ------------------- Speaker Configuration (I2S) -------------------
    m5::speaker_config_t spk_cfg = {
        .pin_data_out = SPK_I2S_PIN_DATA,
        .pin_bck = SPK_I2S_PIN_BCLK,
        .pin_ws = SPK_I2S_PIN_LRCK,
        .sample_rate = output_samplerate,
        .dma_buf_len = 256,    // DMA buffer size (larger = smoother audio)
        .dma_buf_count = 6,    // Number of DMA buffers (double-buffering for stability)
        .i2s_port = i2s_port_t::I2S_NUM_0  // Use I2S hardware port 0
    };
    M5.Speaker.config(spk_cfg);  // Apply speaker settings

    // Initialize speaker; halt on failure
    if(!M5.Speaker.begin()){
        M5.Display.drawCenterString("SPK Error!", 64, 50);
        Serial.println("SPK Error!");
        while (1);
    } else {
        M5.Display.drawCenterString("SPK Ready", 64, 15);
        Serial.println("SPK Ready\n");
    }
    M5.Speaker.setVolume(128);
    delay(1000);

    // ------------------- Display Initial Instructions -------------------
    M5.Display.clear();
    M5.Display.setTextColor(TFT_YELLOW);
    M5.Display.drawCenterString("Press Screen", 64, 0);
    M5.Display.drawCenterString("to Play/Stop", 64, 15);
    M5.Display.setTextColor(TFT_WHITE);

    // ------------------- Load WAV File from SD Card -------------------
    wavFile = SD.open("/twinkle_twinkle.wav", FILE_READ);  // Open WAV file

    // Halt if WAV file not found
    if (!wavFile) {
        M5.Display.drawCenterString("Find wav Error!", 64, 40);
        Serial.println("Find wav Error!");
        while (1);
    } else {
        M5.Display.drawCenterString("Find wav", 64, 40);
        Serial.println("Find wav");
    }

    // Allocate buffer to store entire WAV file (avoids repeated SD reads)
    wavBufferLen = wavFile.size();  // Get total file size
    wavBuffer = (uint8_t*)malloc(wavBufferLen);  // Allocate memory

    // Halt if memory allocation fails
    if (wavBuffer == nullptr) {
        Serial.println("Memory Error!");
        wavFile.close();
        while (1);
    } else {
        wavFile.read(wavBuffer, wavBufferLen);  // Read entire file into buffer
        wavFile.close();                        // Close file (buffer has all data now)

        // Display WAV file size (convert bytes to KB)
        String str_buf = String("Size:") + wavBufferLen/1024 + "KB";
        M5.Display.drawCenterString(str_buf, 64, 55);
        Serial.printf("Size: %d KB\n", wavBufferLen/1024);
    }

    M5.Display.drawCenterString("Stopped", 64, 80);  // Show initial state (stopped)
}

void loop() {
    M5.update();  // Update M5 hardware state (detect button presses, etc.)

    if (M5.BtnA.wasClicked())
    {
        isPlaying = !isPlaying;  // Flip play state (playing ↔ stopped)
        M5.Display.fillRect(0, 80, 128, 48, TFT_BLACK);
        if (isPlaying) {
            M5.Display.drawCenterString("Playing", 64, 80);
            M5.Speaker.playWav(wavBuffer, wavBufferLen, -1, -1, false);// Infinite loop
        } else {
            M5.Display.drawCenterString("Stopped", 64, 80);
            M5.Speaker.stop();
        }
    }
}

#include <driver/i2s_std.h>
#include <endian.h>          // For byte-order conversion (handles WAV's little-endian format)
#include <SPI.h>
#include <SD.h>
#include <M5Unified.h>
#include <M5GFX.h>

// -------------------- Pin Definitions --------------------
// SPI pins for microSD card (connected to speaker module)
#define SD_SPI_CS_PIN     -1          // CS pin not connected (hardware-enabled permanently)
#define SD_SPI_SCK_PIN    GPIO_NUM_7  // SPI Clock pin
#define SD_SPI_MISO_PIN   GPIO_NUM_8  // SPI MISO pin
#define SD_SPI_MOSI_PIN   GPIO_NUM_6  // SPI MOSI pin

// I2S pins for speaker (audio output protocol)
#define SPK_I2S_PIN_DATA  GPIO_NUM_38  // I2S audio data output pin
#define SPK_I2S_PIN_BCLK  GPIO_NUM_5   // I2S bit clock pin
#define SPK_I2S_PIN_LRCK  GPIO_NUM_39  // I2S LR clock pin

// ------------------- Audio Configuration -------------------
static constexpr const size_t output_samplerate = 44100;  // Fixed audio sample rate (44.1kHz, standard for audio)
static bool isPlaying = false;                             // Flag to track play state (playing/stopped)
static std::atomic<uint8_t> volume(50);                    // Volume level (0-100%, atomic for thread safety)
static std::atomic<bool> isI2SEnabled(false);              // Tracks I2S channel state (enabled/disabled, thread-safe)

// -------------------- Global Variables --------------------
File wavFile;                 // File object for the target WAV audio file
uint8_t* wavBuffer = nullptr; // Buffer to store entire WAV file (header + raw audio data)
size_t wavBufferLen = 0;      // Total length of data in wavBuffer (bytes)
TaskHandle_t playTaskHandle = nullptr;  // Task handle for audio playback (manages playback thread)
std::atomic<bool> stopPlay(false);      // Playback stop flag (atomic to ensure thread safety)

// I2S hardware handle (ESP32-specific) for audio transmission
i2s_chan_handle_t tx_handle = nullptr;
#define I2S_PORT  I2S_NUM_0  // I2S peripheral port (uses port 0)

// ------------------- Structure Definitions -------------------
// Playback parameters struct (passed to playback task, avoids scope issues)
typedef struct {
    const uint8_t* data;       // Start address of raw audio data
    size_t data_len;           // Total length of audio data (bytes)
    uint16_t channel;          // Number of channels (1 = mono, 2 = stereo)
    uint16_t bit_per_sample;   // Audio bit depth (8 or 16 bits)
    uint32_t repeat;           // Playback repeat count (0xFFFFFFFF = infinite loop)
} PlayParams;

// WAV file header struct (for parsing WAV format metadata, packed to avoid memory alignment gaps)
typedef struct __attribute__((packed)) {
    char RIFF[4];         // File identifier ("RIFF" for WAV)
    uint32_t chunk_size;  // Total file size - 8 bytes (RIFF header size)
    char WAVEfmt[8];      // Format identifier ("WAVEfmt " with trailing space)
    uint32_t fmt_chunk_size; // Size of the format sub-chunk (16 for PCM format)
    uint16_t audiofmt;    // Audio format (1 = uncompressed PCM)
    uint16_t channel;     // Number of audio channels (1 = mono, 2 = stereo)
    uint32_t sample_rate; // Audio sample rate (Hz)
    uint32_t byte_per_sec;// Byte rate = sample_rate * channel * (bit_per_sample/8)
    uint16_t block_size;  // Block alignment = channel * (bit_per_sample/8)
    uint16_t bit_per_sample;// Audio bit depth (8 or 16 bits)
} WavHeader;

// WAV data chunk struct (stores raw audio data, packed for alignment)
typedef struct __attribute__((packed)) {
    char identifier[4];   // Chunk identifier ("data" for audio content)
    uint32_t chunk_size;  // Length of raw audio data (bytes)
    uint8_t data[1];      // Flexible array: start of raw audio data
} WavDataChunk;

// Function declarations
bool playWav(const uint8_t* wav_data, size_t data_len, uint32_t repeat = 1, int channel = -1, bool stop_current_sound = false);
void stop();
static void playTask(void* params);

/**
 * @brief Set audio volume level
 * @param vol Target volume (0-100, 0 = mute, 100 = maximum). Constrained to valid range automatically.
 */
void setVolume(uint8_t vol) {
    volume = constrain(vol, 0, 100);  // Ensure volume stays within 0-100 (prevents clipping or invalid values)
}

void setup() {
    M5.begin();
    M5.Display.setFont(&fonts::FreeMonoBold9pt7b);
    M5.Display.setTextDatum(middle_center);
    Serial.begin(115200);

    // ------------------- SD Card Initialization -------------------
    SPI.begin(SD_SPI_SCK_PIN, SD_SPI_MISO_PIN, SD_SPI_MOSI_PIN, SD_SPI_CS_PIN);
    M5.Display.drawCenterString("SD Init...", 64, 0);
    Serial.println("SD Init...");

    // Attempt SD card initialization (25MHz SPI speed for fast reads); halt on failure
    if (!SD.begin(SD_SPI_CS_PIN, SPI, 25000000)) {
        M5.Display.clear();
        M5.Display.drawCenterString("SD Error!", 64, 50);
        Serial.println("SD Error!");
        while (1);  // Infinite loop = halt system (SD card is critical for audio file access)
    } else {
        M5.Display.clear();
        M5.Display.drawCenterString("SD Ready", 64, 0);
        Serial.println("SD Ready");
    }

    // ------------------- I2S Speaker Configuration -------------------
    // Step 1: Configure I2S channel (master role, DMA settings)
    i2s_chan_config_t chan_cfg = {
        .id = I2S_NUM_AUTO,                // Auto-assign I2S peripheral (avoids port conflicts)
        .role = I2S_ROLE_MASTER,           // Act as I2S master (generates clock signals for speaker)
        .dma_desc_num = 6,                 // Number of DMA descriptors (reduces underruns)
        .dma_frame_num = 256,              // Frames per DMA descriptor (balances latency and stability)
        .auto_clear = true,                // Auto-clear DMA buffers after transmission (cleaner)
    };
    // Create I2S transmit channel (tx_handle = send channel, NULL = no receive channel)
    ESP_ERROR_CHECK(i2s_new_channel(&chan_cfg, &tx_handle, NULL));

    // Step 2: Configure standard I2S parameters (clock, slots, GPIO mapping)
    i2s_std_config_t std_tx_cfg = {
        .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(output_samplerate),  // Auto-generate clock for 44.1kHz
        .slot_cfg = I2S_STD_MSB_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
        // Use 16-bit data width, mono output (matches speaker hardware)
        .gpio_cfg = {
            .mclk = I2S_GPIO_UNUSED,        // MCLK not used (speaker doesn't require master clock)
            .bclk = SPK_I2S_PIN_BCLK,       // Map BCLK to configured GPIO
            .ws   = SPK_I2S_PIN_LRCK,       // Map LRCK to configured GPIO
            .dout = SPK_I2S_PIN_DATA,       // Map data output to configured GPIO
            .din  = I2S_GPIO_UNUSED,        // No audio input needed (playback-only)
            .invert_flags = {
                .bclk_inv = false,          // Do not invert BCLK (standard polarity)
                .ws_inv   = false           // Do not invert LRCK (standard polarity)
            },
        }
    };
    // Initialize I2S channel with standard mode settings
    ESP_ERROR_CHECK(i2s_channel_init_std_mode(tx_handle, &std_tx_cfg));
    M5.Display.drawCenterString("SPK Ready", 64, 15);
    delay(1000);  // Short delay to stabilize hardware

    // ------------------- Display Initial Instructions -------------------
    M5.Display.clear();
    M5.Display.setTextColor(TFT_YELLOW);  // Highlight instructions in yellow
    M5.Display.drawCenterString("Press Screen", 64, 0);
    M5.Display.drawCenterString("to Play/Stop", 64, 15);
    M5.Display.setTextColor(TFT_WHITE);   // Reset text color to white for status

    // ------------------- Load WAV File from SD Card -------------------
    wavFile = SD.open("/twinkle_twinkle.wav", FILE_READ);  // Open WAV file in read-only mode

    // Halt if WAV file is not found (critical error)
    if (!wavFile) {
        M5.Display.drawCenterString("Find wav Error!", 64, 40);
        Serial.println("Find wav Error!");
        while (1);
    } else {
        M5.Display.drawCenterString("Find wav", 64, 40);
        Serial.println("Find wav");
    }

    // Allocate buffer to store entire WAV file (avoids repeated SD card reads during playback)
    wavBufferLen = wavFile.size();  // Get total file size (bytes)
    wavBuffer = (uint8_t*)malloc(wavBufferLen);  // Allocate memory for buffer

    // Halt if memory allocation fails (not enough RAM for audio data)
    if (wavBuffer == nullptr) {
        Serial.println("Memory Error!");
        wavFile.close();
        while (1);
    } else {
        wavFile.read(wavBuffer, wavBufferLen);  // Read entire file into buffer
        wavFile.close();                        // Close file (buffer now holds all data)

        // Display WAV file size (convert bytes to KB for readability)
        String str_buf = String("Size:") + wavBufferLen/1024 + "KB";
        M5.Display.drawCenterString(str_buf, 64, 55);
        Serial.printf("Size: %d KB\n", wavBufferLen/1024);
    }

    M5.Display.drawCenterString("Stopped", 64, 80);  // Show initial state (stopped)
}

void loop() {
    M5.update();  // Update M5 hardware state (detect button presses, touch, etc.)

    // Toggle play/stop when Button A is clicked
    if (M5.BtnA.wasClicked())
    {
        isPlaying = !isPlaying;  // Flip play state (playing ↔ stopped)
        M5.Display.fillRect(0, 80, 128, 48, TFT_BLACK);  // Clear previous status text

        if (isPlaying) {
            M5.Display.drawCenterString("Playing", 64, 80);
            playWav(wavBuffer, wavBufferLen, -1, -1, true);// Infinite loop
        } else {
            M5.Display.drawCenterString("Stopped", 64, 80);
            stop();  // Stop ongoing playback
        }
    }
}

// ------------------- Playback Task Function -------------------
// Core audio playback task: Parses audio data, applies volume, and sends to I2S hardware
static void playTask(void* params) {
    // Unpack playback parameters (passed from playWav() function)
    PlayParams* p = (PlayParams*)params;

    // Calculate base audio parameters
    const size_t sample_byte = p->bit_per_sample / 8;  // Bytes per single sample (1 for 8-bit, 2 for 16-bit)
    const size_t total_samples = p->data_len / (sample_byte * p->channel);  // Total mono-equivalent samples
    size_t data_idx = 0;  // Current position in raw audio data (bytes)
    uint32_t repeat_cnt = 0;  // Number of completed playback loops

    // I2S output buffer (16-bit mono, 256 samples per buffer = reduces I2S call frequency)
    const size_t I2S_BUF_SAMPLES = 256;
    int16_t i2s_buf[I2S_BUF_SAMPLES] = {0};

    // Enable I2S channel (starts clock signals and prepares for data transmission)
    esp_err_t err = i2s_channel_enable(tx_handle);
    if (err == ESP_OK) {
        isI2SEnabled = true;  // Mark I2S as active (for thread-safe state checks)
    } else {
        Serial.printf("I2S Enable Failed: %s\n", esp_err_to_name(err));
        goto task_cleanup;  // Jump to resource cleanup if I2S enable fails
    }

    // Main playback loop (runs until stop flag is set or repeat count is reached)
    do {
        size_t buf_idx = 0;  // Current position in I2S output buffer

        // Fill I2S buffer with processed audio data (until buffer is full or stop is triggered)
        while (buf_idx < I2S_BUF_SAMPLES && !stopPlay) {
            // Check if end of audio data is reached; handle loop logic
            if (data_idx >= p->data_len) {
                // Exit loop if repeat count is exhausted (skip for infinite loop)
                if (p->repeat != 0xFFFFFFFF && repeat_cnt >= p->repeat - 1) {
                    break;
                }
                data_idx = 0;  // Reset data index to start of audio (loop)
                repeat_cnt++;  // Increment loop counter
            }

            // Step 1: Read raw sample and convert to 16-bit (uniform processing)
            int16_t sample = 0;
            if (p->bit_per_sample == 8) {
                // 8-bit WAV: Unsigned (0-255) → signed (-128-127) → scale to 16-bit (-32768-32767)
                uint8_t raw = p->data[data_idx];
                sample = (int16_t)(raw - 128) << 8;
            } else if (p->bit_per_sample == 16) {
                // 16-bit WAV: Little-endian → host byte-order (ESP32 is little-endian, but ensures compatibility)
                int16_t raw = le16toh(*(const int16_t*)(p->data + data_idx));
                sample = raw;
            }

            // Step 2: Convert stereo to mono (if needed)
            if (p->channel == 2) {
                int16_t sample_right = 0;
                // Read right channel sample (same conversion as left channel)
                if (p->bit_per_sample == 8) {
                    uint8_t raw_r = p->data[data_idx + 1];
                    sample_right = (int16_t)(raw_r - 128) << 8;
                } else if (p->bit_per_sample == 16) {
                    int16_t raw_r = le16toh(*(const int16_t*)(p->data + data_idx + 2));
                    sample_right = raw_r;
                }
                // Average left/right channels (avoids clipping, maintains volume)
                sample = (sample + sample_right) / 2;
                data_idx += sample_byte;  // Skip right channel data (already processed)
            }

            // Step 3: Apply volume control (0-100% → 0.0-1.0 gain factor)
            float vol = volume.load() / 100.0f;
            sample = (int16_t)(sample * vol);

            // Step 4: Store processed sample in I2S buffer
            i2s_buf[buf_idx] = sample;
            buf_idx++;
            data_idx += sample_byte;  // Move to next sample in raw data
        }

        // Send buffer to I2S hardware (only if buffer has data and stop is not triggered)
        if (buf_idx > 0 && !stopPlay) {
            size_t bytes_written = 0;
            err = i2s_channel_write(
                tx_handle,
                i2s_buf,
                buf_idx * sizeof(int16_t),  // Total bytes to write (samples × 2 bytes/sample)
                &bytes_written,
                pdMS_TO_TICKS(100)  // Timeout (100ms, prevents permanent blocking)
            );
            if (err != ESP_OK) {
                Serial.printf("I2S Write Failed: %s\n", esp_err_to_name(err));
                break;  // Exit playback on write failure
            }
        } else {
            break;  // Exit if no data or stop flag is set
        }
    } while (!stopPlay);

    // ------------------- Task Resource Cleanup -------------------
    // Ensure no memory leaks or hardware resource locks
task_cleanup:
    // Disable I2S only if it was previously enabled
    if (isI2SEnabled) {
        i2s_channel_disable(tx_handle);
        isI2SEnabled = false;  // Reset I2S state flag
    }
    vPortFree(p);                   // Free memory allocated for playback parameters
    playTaskHandle = nullptr;       // Reset task handle (indicates task is done)
    isPlaying = false;              // Reset global play state
    // Update display to show "Stopped" (matches user expectation)
    M5.Display.fillRect(0, 80, 128, 48, TFT_BLACK);
    M5.Display.drawCenterString("Stopped", 64, 80);
    vTaskDelete(nullptr);  // Delete the current task (frees task stack)
}

// ------------------- Public Interface: Play WAV File -------------------
/**
 * @brief Starts playback of a WAV file from a buffer
 * @param wav_data Pointer to WAV file data (header + audio)
 * @param data_len Total length of wav_data (bytes)
 * @param repeat Number of playback loops ( -1 = infinite, 1 = single play)
 * @param channel Force channel mode (unused here, retained for compatibility)
 * @param stop_current_sound Stop ongoing playback before starting new
 * @return true if playback starts successfully, false otherwise
 */
bool playWav(const uint8_t* wav_data, size_t data_len, uint32_t repeat, int channel, bool stop_current_sound) {
    // Step 1: Stop current playback if required (prevents audio overlap)
    if (stop_current_sound && playTaskHandle != nullptr) {
        stop();
        vTaskDelay(pdMS_TO_TICKS(10));  // Short delay to ensure task cleanup completes
    }

    // Step 2: Validate input parameters (prevent invalid data access)
    if (wav_data == nullptr || data_len < sizeof(WavHeader)) {
        Serial.println("Invalid WAV Data (null or too short)");
        return false;
    }

    // Step 3: Parse WAV header and validate format compatibility
    WavHeader* wav_hdr = (WavHeader*)wav_data;
    // Check if file is a valid WAV (RIFF and WAVEfmt identifiers)
    if (memcmp(wav_hdr->RIFF, "RIFF", 4) != 0 || memcmp(wav_hdr->WAVEfmt, "WAVEfmt ", 8) != 0) {
        Serial.println("Not a Standard WAV File");
        return false;
    }
    // Only support uncompressed PCM format (most common WAV type)
    if (wav_hdr->audiofmt != 1) {
        Serial.println("Only PCM Format WAV Supported");
        return false;
    }
    // Only support 8/16-bit depth (matches I2S configuration)
    if (wav_hdr->bit_per_sample != 8 && wav_hdr->bit_per_sample != 16) {
        Serial.println("Only 8/16-bit WAV Supported");
        return false;
    }
    // Ensure WAV sample rate matches I2S configuration (prevents pitch distortion)
    if (wav_hdr->sample_rate != output_samplerate) {
        Serial.printf("WAV Sample Rate Mismatch: WAV=%d, I2S=%d\n", wav_hdr->sample_rate, output_samplerate);
        return false;
    }

    // Step 4: Locate the "data" chunk (skip non-audio chunks like "LIST" or "INFO")
    WavDataChunk* data_chunk = (WavDataChunk*)(wav_data + sizeof(WavHeader));
    while (memcmp(data_chunk->identifier, "data", 4) != 0) {
        // Calculate offset to next chunk (account for chunk header + data)
        size_t next_offset = sizeof(WavDataChunk) - 1 + data_chunk->chunk_size;
        data_chunk = (WavDataChunk*)((uint8_t*)data_chunk + next_offset);
        // Prevent out-of-bounds access (stop if chunk exceeds input data length)
        if ((uint8_t*)data_chunk - wav_data >= data_len) {
            Serial.println("WAV Data Chunk Not Found");
            return false;
        }
    }

    // Step 5: Calculate actual usable audio data length (prevent buffer overflow)
    size_t actual_data_len = data_chunk->chunk_size;
    if ((uint8_t*)data_chunk + sizeof(WavDataChunk) - 1 + actual_data_len > wav_data + data_len) {
        actual_data_len = data_len - ((uint8_t*)data_chunk - wav_data + sizeof(WavDataChunk) - 1);
        Serial.printf("WAV Data Truncated to %d Bytes\n", actual_data_len);
    }
    if (actual_data_len == 0) {
        Serial.println("Empty WAV Data Chunk");
        return false;
    }

    // Step 6: Allocate memory for playback parameters (passed to task)
    PlayParams* params = (PlayParams*)pvPortMalloc(sizeof(PlayParams));
    if (params == nullptr) {
        Serial.println("Failed to Allocate Playback Params");
        return false;
    }
    // Populate playback parameters
    params->data = data_chunk->data;
    params->data_len = actual_data_len;
    params->channel = wav_hdr->channel;
    params->bit_per_sample = wav_hdr->bit_per_sample;
    params->repeat = (repeat == (uint32_t)-1) ? 0xFFFFFFFF : repeat;  // Map -1 to infinite loop

    // Step 7: Create playback task (runs on core 0, high priority for smooth audio)
    stopPlay = false;  // Reset stop flag before starting new task
    if (xTaskCreatePinnedToCore(
        playTask,          // Task function to execute
        "WavPlayTask",     // Task name (for debug)
        4096,              // Task stack size (4KB = enough for audio processing)
        params,            // Parameters passed to task
        5,                 // Task priority (higher than loop() to avoid underruns)
        &playTaskHandle,   // Task handle (tracks task state)
        0                  // Pin to core 0 (ESP32 core division for stability)
    ) != pdPASS) {
        Serial.println("Failed to Create Playback Task");
        vPortFree(params);  // Free params if task creation fails
        return false;
    }

    // Step 8: Update global state to indicate playback is active
    isPlaying = true;
    return true;
}

// ------------------- Public Interface: Stop Playback -------------------
/**
 * @brief Stops ongoing audio playback and cleans up resources
 */
void stop() {
    // Step 1: Trigger stop flag (playTask() will detect this and exit)
    stopPlay = true;

    // Step 2: Accelerate stop by disabling I2S (if active) and waiting for task cleanup
    if (playTaskHandle != nullptr) {
        if (isI2SEnabled) {
            i2s_channel_disable(tx_handle);
            isI2SEnabled = false;  // Reset I2S state to prevent re-enable
        }
        // Wait up to 100ms for task to delete (avoids blocking main loop)
        for (int i = 0; i < 10 && playTaskHandle != nullptr; i++) {
            vTaskDelay(pdMS_TO_TICKS(10));
        }
    }

    // Step 3: Reset global state and update display
    isPlaying = false;
    M5.Display.fillRect(0, 80, 128, 48, TFT_BLACK);  // Clear previous status
    M5.Display.drawCenterString("Stopped", 64, 80);   // Show stopped state
}