How to Use i2s mic module : Examples, Pinouts, and Specs

The I2S microphone module is a digital microphone that utilizes the I2S (Inter-IC Sound) protocol for transmitting audio data. Unlike traditional analog microphones, which output analog signals requiring additional processing, the I2S microphone directly outputs digital audio data. This makes it ideal for applications requiring high-quality audio capture with minimal noise interference.

• Voice recognition systems (e.g., smart assistants)
• Audio recording and streaming
• Sound level monitoring
• IoT devices with audio input capabilities
• Noise-canceling systems

The following table outlines the key technical details of a typical I2S microphone module:

The I2S microphone module typically has the following pins:

1. Power the Module: Connect the VDD pin to a 1.8V to 3.6V power source and the GND pin to ground.
2. Connect I2S Lines:
   • Connect the SCK pin to the I2S clock line of your microcontroller.
   • Connect the WS pin to the word select line of your microcontroller.
   • Connect the SD pin to the I2S data input line of your microcontroller.
3. Configure the Microcontroller:
   • Set up the I2S peripheral on your microcontroller to match the microphone's sampling rate and data format.
   • If the module has an L/R Select pin, configure it to determine whether the microphone outputs data for the left or right audio channel.
4. Read Audio Data:
   • Use the microcontroller's I2S interface to capture audio data from the SD pin.

• Power Supply: Ensure a stable and clean power supply to avoid noise in the audio signal.
• Clock Signal: The SCK pin requires a stable clock signal. Verify that your microcontroller can generate the required clock frequency.
• Sampling Rate: Match the sampling rate of the I2S microphone with the configuration of your microcontroller.
• PCB Layout: Minimize noise by keeping the I2S lines short and avoiding interference from other high-frequency signals.

The Arduino UNO does not have a native I2S interface, but you can use an external I2S-compatible microcontroller (e.g., ESP32) to interface with the I2S microphone. Below is an example code snippet for an ESP32:

#include <driver/i2s.h>

// I2S configuration
#define I2S_NUM         I2S_NUM_0  // Use I2S port 0
#define I2S_WS_PIN      25         // Word Select pin
#define I2S_SCK_PIN     26         // Serial Clock pin
#define I2S_SD_PIN      22         // Serial Data pin

void setup() {
  // Configure I2S
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX), // Master mode, receive data
    .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,        // Left channel only
    .communication_format = I2S_COMM_FORMAT_I2S,       // I2S communication 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
  };

  // Install and configure I2S driver
  i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
  
  // Configure I2S pins
  i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_SCK_PIN,  // Serial Clock pin
    .ws_io_num = I2S_WS_PIN,    // Word Select pin
    .data_in_num = I2S_SD_PIN,  // Serial Data pin
    .data_out_num = I2S_PIN_NO_CHANGE // Not used
  };
  i2s_set_pin(I2S_NUM, &pin_config);
}

void loop() {
  // Buffer to store audio data
  uint8_t audio_data[1024];
  size_t bytes_read;

  // Read audio data from I2S
  i2s_read(I2S_NUM, audio_data, sizeof(audio_data), &bytes_read, portMAX_DELAY);

  // Process audio data (e.g., send to a server or save to storage)
}

1. No Audio Data Captured:

   • Verify that the SCK, WS, and SD pins are correctly connected to the microcontroller.
   • Ensure the I2S configuration (e.g., sampling rate, bit depth) matches the microphone's specifications.

2. Distorted or Noisy Audio:

   • Check the power supply for stability and noise.
   • Ensure proper grounding of the circuit.
   • Verify that the clock signal is stable and within the required frequency range.

3. Microphone Not Responding:

   • Confirm that the VDD pin is receiving the correct voltage.
   • Check for loose or incorrect connections.

Q: Can I use the I2S microphone with a Raspberry Pi?
A: Yes, the Raspberry Pi has a native I2S interface that can be used to connect the I2S microphone. You will need to enable the I2S interface in the Raspberry Pi's configuration settings.

Q: What is the maximum distance between the microphone and the microcontroller?
A: To minimize signal degradation, keep the I2S lines as short as possible (typically less than 10 cm). For longer distances, consider using shielded cables.

Q: Can I use multiple I2S microphones in a single system?
A: Yes, you can use multiple I2S microphones by configuring each microphone to output data on a different channel (left or right) or by using separate I2S interfaces.