M5 Stack PDM Microphone Unit (SPM1423)

M5 Stack PDM Microphone Unit (SPM1423) Documentation

The M5 Stack PDM Microphone Unit (SPM1423) is a digital microphone module designed for use with the M5 Stack series of microcontrollers. This module features a high-quality digital microphone, SPM1423, which is capable of capturing high-fidelity audio signals. The module is compatible with the M5 Stack system, making it easy to integrate into various projects.

Technical Specifications:

Microphone: SPM1423
 Bit Depth: 16-bit
 Sampling Rate: Up to 48 kHz
 Interface: I2S
 Power Supply: 3.3V
 Dimensions: 18.5 x 15.5 mm

Pinout:

The M5 Stack PDM Microphone Unit has the following pinout:

GND: Ground
 3V3: 3.3V Power Supply
 CLCK: I2S Clock
 WS: I2S Word Select
 SD: I2S Serial Data
 MIC_BIAS: Microphone Bias Voltage

Code Examples:

### Example 1: Basic Audio Recording using Arduino

This example demonstrates how to use the M5 Stack PDM Microphone Unit to record audio data using an Arduino-compatible board.

```cpp
#include <M5Stack.h>
#include <driver/i2s.h>

#define MIC_BIAS 25 // Microphone Bias Pin
#define I2S_CLK 0 // I2S Clock Pin
#define I2S_WS 2 // I2S Word Select Pin
#define I2S_SD 4 // I2S Serial Data Pin

void setup() {
  // Initialize the I2S interface
  i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_CLK,
    .ws_io_num = I2S_WS,
    .data_out_io_num = I2S_SD,
    .data_in_io_num = I2S_SD
  };
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    .sample_rate = 48000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = I2S_COMM_FORMAT_I2S_MSB,
    .dma_buf_count = 6,
    .dma_buf_len = 60
  };
  i2s_driver_install(I2S_PORT, &i2s_config, &pin_config);

// Set microphone bias voltage
  pinMode(MIC_BIAS, OUTPUT);
  digitalWrite(MIC_BIAS, HIGH);
}

void loop() {
  // Start I2S recording
  i2s_start(I2S_PORT);

// Read audio data from I2S interface
  int16_t audio_data[512];
  size_t bytes_read;
  i2s_read(I2S_PORT, (void)audio_data, 1024, &bytes_read, portMAX_DELAY);

// Process audio data (e.g., save to SD card or transmit over Wi-Fi)

// Stop I2S recording
  i2s_stop(I2S_PORT);
  delay(1000);
}
```

### Example 2: Voice Assistant Integration using MicroPython

This example demonstrates how to use the M5 Stack PDM Microphone Unit to capture audio data and integrate it with a voice assistant, such as Google Assistant or Alexa, using MicroPython.

```python
import machine
import utime
import i2s

# Initialize the I2S interface
i2s_obj = i2s.I2S(mode=i2s.MODE_MASTER_RX, baudrate=48000, dataformat=i2s.WORDLENGTH_16BIT)

# Configure microphone bias voltage
mic_bias = machine.Pin(25, machine.Pin.OUT)
mic_bias.value(1)

# Capture audio data
audio_data = bytearray(1024)
while True:
    # Read audio data from I2S interface
    i2s_obj.readinto(audio_data)

# Process audio data (e.g., send to voice assistant API)
    # ...

utime.sleep_ms(10)
```

Note: These examples are for illustration purposes only and may require modification to suit your specific application. Additionally, ensure that you have the necessary permissions and licenses to use the provided code and any third-party libraries or services.