How to Use INMP441 I2S Microphone Module: Examples, Pinouts, and Specs

The INMP441 is a high-performance digital microphone module manufactured by Arduino. It uses the I2S (Inter-IC Sound) interface for transmitting audio data, making it an excellent choice for digital audio applications. This module is designed to deliver high signal-to-noise ratio (SNR) audio output while maintaining low power consumption. Its compact size and digital output make it ideal for integration into modern audio systems.

• Voice recognition systems
• Audio recording devices
• Smart home assistants
• IoT devices with audio input
• Digital audio processing and analysis

The INMP441 module is designed to provide reliable performance in a variety of audio applications. Below are its key technical details:

The INMP441 module has 5 pins, as described in the table below:

The INMP441 is straightforward to use in digital audio applications. Below are the steps and considerations for integrating it into a circuit:

1. Power Supply: Connect the VDD pin to a 3.3V regulated power source and the GND pin to the ground.
2. I2S Interface:
   • Connect the WS pin to the Word Select pin of the microcontroller.
   • Connect the SCK pin to the Serial Clock pin of the microcontroller.
   • Connect the SD pin to the Serial Data input pin of the microcontroller.
3. Pull-Up Resistors: Ensure that the I2S lines have appropriate pull-up resistors if required by your microcontroller.

• Voltage Levels: The INMP441 operates at 3.3V logic levels. Ensure your microcontroller is compatible or use a level shifter.
• Microphone Placement: Place the microphone in a location free from excessive noise or vibrations for optimal performance.
• I2S Configuration: Configure the microcontroller's I2S interface to match the INMP441's settings (e.g., data format, clock polarity).

The Arduino UNO does not natively support I2S, but you can use an external I2S interface or a compatible microcontroller like the ESP32. Below is an example code snippet for the ESP32:

#include <driver/i2s.h>

// I2S configuration for the INMP441 microphone
#define I2S_NUM         I2S_NUM_0  // Use I2S port 0
#define I2S_WS_PIN      15         // Word Select pin (WS)
#define I2S_SCK_PIN     14         // Serial Clock pin (SCK)
#define I2S_SD_PIN      32         // Serial Data pin (SD)

void setup() {
  // Configure the I2S driver
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX), // Master mode, receive only
    .sample_rate = 16000,                               // Sampling rate: 16 kHz
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,       // 16-bit audio data
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,        // Single channel (left)
    .communication_format = I2S_COMM_FORMAT_I2S,        // I2S format
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,           // Interrupt level
    .dma_buf_count = 8,                                 // Number of DMA buffers
    .dma_buf_len = 64                                   // Length of each DMA buffer
  };

  // Configure the I2S pins
  i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_SCK_PIN,  // Serial Clock (SCK)
    .ws_io_num = I2S_WS_PIN,    // Word Select (WS)
    .data_out_num = I2S_PIN_NO_CHANGE, // Not used for input
    .data_in_num = I2S_SD_PIN   // Serial Data (SD)
  };

  // Install and start the I2S driver
  i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
  i2s_set_pin(I2S_NUM, &pin_config);
}

void loop() {
  // Buffer to store audio data
  int16_t audio_buffer[1024];
  size_t bytes_read;

  // Read audio data from the INMP441
  i2s_read(I2S_NUM, audio_buffer, sizeof(audio_buffer), &bytes_read, portMAX_DELAY);

  // Process the audio data (e.g., send to a server, save to SD card, etc.)
}

1. No Audio Output:

   • Ensure the I2S interface is correctly configured on the microcontroller.
   • Verify the connections between the INMP441 and the microcontroller.
   • Check the power supply voltage (must be between 1.8V and 3.3V).

2. Distorted Audio:

   • Ensure the sampling rate and bit depth match the INMP441's capabilities.
   • Avoid placing the microphone near sources of electrical noise.

3. Microphone Not Detected:

   • Confirm that the I2S pins on the microcontroller are correctly assigned.
   • Check for loose or incorrect wiring.

• Use an oscilloscope to verify the I2S clock and data signals.
• Test the microphone with a known working I2S device to rule out hardware issues.
• Consult the microcontroller's datasheet for I2S configuration details.

By following this documentation, you can effectively integrate the INMP441 I2S Microphone Module into your audio projects.