ESP32 Forum

Posted: **Fri Oct 27, 2023 3:19 pm**

Hi everyone. I'm working with INMP441 and ESP32 Dev kit v1 in ESP-IDF 4.4.3. I set i2s 32 bit per sample and then using i2s_read function to read data from DMA and store in an array. I copy exactly what this guy do https://esp32.com/viewtopic.php?t=15185

Code: [Select all] [Expand/Collapse]

// Connections to INMP441 I2S microphone
#define I2S_WS 25
#define I2S_SD 33
#define I2S_SCK 32
 
// Use I2S Processor 0
#define I2S_PORT I2S_NUM_0
 
#define bufferCount 8
#define bufferLen 64
 
int16_t buffer16[bufferLen] = {0};
uint8_t buffer32[bufferLen * 4] = {0};
 
// Set up I2S Processor configuration
void i2s_install() {
  // Set up I2S Processor configuration
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    .sample_rate = 4000, // or 44100 if you like
    .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT, // Ground the L/R pin on the INMP441.
    .communication_format = (i2s_comm_format_t)(I2S_COMM_FORMAT_STAND_I2S),
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = bufferCount,
    .dma_buf_len = bufferLen,
    .use_apll = false,
    .tx_desc_auto_clear = false,
    .fixed_mclk = 0,
  };
 
  i2s_driver_install(I2S_PORT, &i2s_config, 0, NULL);
}
 
// Set I2S pin configuration
void i2s_setpin() {
    const i2s_pin_config_t pin_config = {
        .bck_io_num = I2S_SCK,
        .ws_io_num = I2S_WS,
        .data_out_num = -1,
        .data_in_num = I2S_SD
    };
 
    i2s_set_pin(I2S_PORT, &pin_config);
}

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The problem is after i2s_read funtion, my array value is zero. Below is how I read:

Code: [Select all] [Expand/Collapse]

while (1)
    {
        vTaskDelay(1); // Feed for watchdog, if not watchdog timer will be triggered!
 
        i2s_read(I2S_PORT, &buffer32, sizeof(buffer32), &bytesRead, 100);
        int samplesRead = bytesRead / 4;
 
        for (uint8_t i = 0; i < samplesRead; i++) {
            uint8_t mid = buffer32[i * 4 + 2];
            uint8_t msb = buffer32[i * 4 + 3];
            uint16_t raw = (((uint32_t)msb) << 8) + ((uint32_t)mid);
            memcpy(&buffer16[i], &raw, sizeof(raw)); // Copy so sign bits aren't interfered with somehow.
            printf("%d %d %d\n", 3000, -3000, buffer16[i]);
        }
    }

I changed to 16 bit per sample and it works. But I want 32 bit per sample. My code is totally fine when I use arduino (I'm using arduino 2.0.1).
Please help me to find the solution for this problem.

Posted: **Mon Nov 06, 2023 3:23 pm**

Update: I switched to esp-idf 5.1 and it worked quite well. Maybe idf 4.4.3 has problem with reading 32-bit samples with INMP441 ?

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