MIC

Example

#include <M5StickCPlus.h>
#include <driver/i2s.h>

#define PIN_CLK     0
#define PIN_DATA    34
#define READ_LEN    (2 * 256)
#define GAIN_FACTOR 3
uint8_t BUFFER[READ_LEN] = {0};

uint16_t oldy[160];
int16_t *adcBuffer = NULL;

void showSignal() {
    int y;
    for (int n = 0; n < 160; n++) {
        y = adcBuffer[n] * GAIN_FACTOR;
        y = map(y, INT16_MIN, INT16_MAX, 10, 70);
        M5.Lcd.drawPixel(n, oldy[n], WHITE);
        M5.Lcd.drawPixel(n, y, BLACK);
        oldy[n] = y;
    }
}

void mic_record_task(void *arg) {
    size_t bytesread;
    while (1) {
        i2s_read(I2S_NUM_0, (char *)BUFFER, READ_LEN, &bytesread,
                 (100 / portTICK_RATE_MS));
        adcBuffer = (int16_t *)BUFFER;
        showSignal();
        vTaskDelay(100 / portTICK_RATE_MS);
    }
}

void i2sInit() {
    i2s_config_t i2s_config = {
        .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM),
        .sample_rate = 44100,
        .bits_per_sample =
            I2S_BITS_PER_SAMPLE_16BIT,  // is fixed at 12bit, stereo, MSB
        .channel_format = I2S_CHANNEL_FMT_ALL_RIGHT,
#if ESP_IDF_VERSION > ESP_IDF_VERSION_VAL(4, 1, 0)
        .communication_format = I2S_COMM_FORMAT_STAND_I2S,
#else
        .communication_format = I2S_COMM_FORMAT_I2S,
#endif
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .dma_buf_count    = 2,
        .dma_buf_len      = 128,
    };

    i2s_pin_config_t pin_config;

#if (ESP_IDF_VERSION > ESP_IDF_VERSION_VAL(4, 3, 0))
    pin_config.mck_io_num = I2S_PIN_NO_CHANGE;
#endif

    pin_config.bck_io_num   = I2S_PIN_NO_CHANGE;
    pin_config.ws_io_num    = PIN_CLK;
    pin_config.data_out_num = I2S_PIN_NO_CHANGE;
    pin_config.data_in_num  = PIN_DATA;

    i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
    i2s_set_pin(I2S_NUM_0, &pin_config);
    i2s_set_clk(I2S_NUM_0, 44100, I2S_BITS_PER_SAMPLE_16BIT, I2S_CHANNEL_MONO);
}

void setup() {
    M5.begin();
    M5.Lcd.setRotation(3);
    M5.Lcd.fillScreen(WHITE);
    M5.Lcd.setTextColor(BLACK, WHITE);
    M5.Lcd.println("mic test");

    i2sInit();
    xTaskCreate(mic_record_task, "mic_record_task", 2048, NULL, 1, NULL);
}

void loop() {
    printf("loop cycling\n");
    vTaskDelay(1000 / portTICK_RATE_MS);

}