ESP32 Forum

Posted: **Sun Mar 19, 2023 10:41 pm**

Hello - I am trying to interface a mems I2C microphone to I2S0 - I have verified that the device is clocking and outputing data - The idea is to setup DMA buffers, to trigger an interrupt when DMA is complete, from the DMA ISR signal a task that will read out the last buffer, process it and notify other consumers for that data.

My problem seems to be that the DMA ISR is not getting set. I checked that the semaphores are setup properly, but I can't quite figure it out. Here is the code:

Code: [Select all] [Expand/Collapse]

 
static int16_t dma_buf[DMA_BUF_COUNT][DMA_BUF_LEN];
static int buf_ptr = 0;
SemaphoreHandle_t i2s_dma_sem;
static intr_handle_t i2s_isr_ret_handle;
 
void IRAM_ATTR i2s_isr_handler(void *arg)
{
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
 
    xSemaphoreGiveFromISR(i2s_dma_sem, &xHigherPriorityTaskWoken);
    if (xHigherPriorityTaskWoken) {
        portYIELD_FROM_ISR();
    }
}
 
 
void mic_task(void *arg)
{
    size_t bytesRead;
    color_t sample_colors[6] = { red, green, blue, yellow, purple, silver };
    printf("mic_task enabled\n\r");
    while (1)
    {
        if (xSemaphoreTake(i2s_dma_sem, portMAX_DELAY) == pdTRUE) {
            // Process the data in dma_buf[buf_ptr]
            // ...
            i2s_read(I2S_NUM, (void *)&dma_buf[buf_ptr], DMA_BUF_LEN * sizeof(int16_t), &bytesRead, 0);
            buf_ptr = (buf_ptr + 1) % DMA_BUF_COUNT;
            printf("Read %d bytes",bytesRead);
           
            // Signal the main application that new data is available
            // ...
        }
    }
}
 
void mic_init()
{
    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX,
        .sample_rate = 44100,
        .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
        .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
        .communication_format = I2S_COMM_FORMAT_I2S_MSB,
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .dma_buf_count = DMA_BUF_COUNT,
        .dma_buf_len = DMA_BUF_LEN,
        .use_apll = false,
        .tx_desc_auto_clear = false,
        .fixed_mclk = 0,
        
  
    };
    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_clk(I2S_NUM, 44100, I2S_BITS_PER_SAMPLE_16BIT, I2S_CHANNEL_MONO);
    i2s_pin_config_t pin_config = {
        .mck_io_num = I2S_PIN_NO_CHANGE,
        .bck_io_num = 3,
        .ws_io_num = I2S_PIN_NO_CHANGE,
        .data_out_num = I2S_PIN_NO_CHANGE,
        .data_in_num = 8
    };
    i2s_set_pin(I2S_NUM, &pin_config);
    i2s_zero_dma_buffer(I2S_NUM);
    
    i2s_dma_sem = xSemaphoreCreateBinary();
    esp_err_t err =esp_intr_alloc(ETS_I2S0_INTR_SOURCE, ESP_INTR_FLAG_LEVEL1 | ESP_INTR_FLAG_IRAM, i2s_isr_handler, NULL, &i2s_isr_ret_handle);
    if (err != ESP_OK)
        ESP_LOGE(TAG, "Error esp_intr_alloc %s", esp_err_to_name(err));
 
    
    err = esp_intr_enable(i2s_isr_ret_handle);
    ESP_LOGI(TAG, "INTERRUPT Enable:      %d ", err);
    xTaskCreate(mic_task, "mic_task", 4096, NULL, 5, NULL);
 
}

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Any ideas why i2s_isr_handler does not get called? Both esp_intr_alloc() and esp_intr_enable() return ESP_OK.

Thank you

Posted: **Mon Mar 20, 2023 12:38 am**

You cannot use both the driver as well as install your own ISR, and in your particular case, you don't need to. i2s_read() already suspends the calling task until the i2s peripheral has data available (that's why the driver needs the interrupt, it uses that to unblock the task calling i2s_read).

Posted: **Mon Mar 20, 2023 2:36 pm**

Thank you - I couldn't locate any documentation on it, but it makes sense. If the read will be blocking already, then I can forgo my interrupt and just running it on my thread directly.

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