nanoFramework.Iot.Device.Es7243e 1.0.8

ES7243E - Audio ADC (microphone capture codec)

The Everest Semiconductor ES7243E is a low-power audio ADC used on many ESP32 audio boards (ESP-BOX, ESP32-S3-Korvo, LyraT). It digitizes analog microphone inputs and outputs the captured audio as an I2S PCM stream.

This binding covers the I2C control plane only. It configures the codec (clocking, serial data format, microphone gain, mute and power state). The captured PCM audio samples are streamed out over I2S using System.Device.I2s and are not handled by this binding.

Documentation

• ES7243E is configured over I2C (control) and streams captured audio over I2S (data).
• Two chips make up a full-duplex audio path on boards such as the ESP32-S3-BOX-Lite: the ES7243E (ADC, capture) and the ES8156 (DAC, playback).
• Espressif esp_codec_dev component - the source of the register sequences used by this binding (ES7243E driver source).
• Espressif ESP32-S3-BOX-Lite hardware overview and the ESP-BOX repository.

Audio path on the ESP32-S3-BOX-Lite

The I2C bus carries register configuration only (sample rate, data format, mic gain, mute, power). No audio samples travel over I2C. The actual PCM audio streams over I2S.

Usage

Important: I2C pins for the ESP32 must be properly set up before creating the I2cDevice. For this, make sure you install the nanoFramework.Hardware.Esp32 NuGet and use the Configuration class to configure the pins:

using Iot.Device.Es7243e;
using nanoFramework.Hardware.Esp32;
using System;
using System.Device.I2c;
using System.Device.I2s;

// Setup ESP32-S3-BOX-Lite I2C control bus (SDA = GPIO8, SCL = GPIO18).
Configuration.SetPinFunction(8, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(18, DeviceFunction.I2C1_CLOCK);

I2cConnectionSettings settings = new I2cConnectionSettings(1, Es7243e.DefaultI2cAddress);
I2cDevice i2cDevice = new I2cDevice(settings);

Es7243e adc = new Es7243e(i2cDevice);

// Setup the ESP32 I2S receiver first so MCLK/BCLK/WS are running before the codec is configured.
// ESP32-S3-BOX-Lite I2S pin-out: BCLK = GPIO17, WS = GPIO47, DSIN = GPIO16, MCLK = GPIO2.
Configuration.SetPinFunction(17, DeviceFunction.I2S1_BCK);
Configuration.SetPinFunction(47, DeviceFunction.I2S1_WS);
Configuration.SetPinFunction(16, DeviceFunction.I2S1_MDATA_IN);
Configuration.SetPinFunction(2, DeviceFunction.I2S1_MCK);

I2sDevice i2s = new I2sDevice(new I2sConnectionSettings(1)
{
    Mode = I2sMode.Master | I2sMode.Rx,
    CommunicationFormat = I2sCommunicationFormat.I2S,
    ChannelFormat = I2sChannelFormat.RightLeft,
    BitsPerSample = I2sBitsPerSample.Bit16,
    SampleRate = 16_000,
});

// Bring the codec up and start capturing. Initialize() already puts the ES7243E into 16-bit I2S
// mode; set the mic gain after Start() (which resets it to a low value).
adc.Initialize();
adc.Start();
adc.SetMicGain(Es7243e.MaxMicGain);

// Read a block of audio and compute a simple peak amplitude. When you speak or tap near the
// microphones the reported value rises above the idle noise floor, confirming the ES7243E is
// configured correctly and streaming over I2S.
SpanByte buffer = new byte[1024];
i2s.Read(buffer);

int peak = 0;
for (int i = 0; i + 1 < buffer.Length; i += 2)
{
    short sample = (short)(buffer[i] | (buffer[i + 1] << 8));
    int magnitude = sample < 0 ? -sample : sample;
    if (magnitude > peak)
    {
        peak = magnitude;
    }
}

Debug.WriteLine($"Peak amplitude = {peak}");

The full sample loops the I2S read so you can watch the peak amplitude react to sound in real time.

For other targets (STM32, etc.) use the preset hardware I2C pins (no SetPinFunction call needed).