nanoFramework.Iot.Device.Aw88298

AW88298 - I2S Class-D smart audio amplifier (speaker output)

The Awinic AW88298 is a 16-bit I2S Class-D smart audio amplifier with an integrated boost converter and DSP. It drives a speaker directly from an I2S PCM stream and is used, for example, on the M5Stack CoreS3 to drive the built-in 1W speaker.

This binding covers the I2C control plane only. It configures the amplifier (reset, power/enable, output volume, mute and boost). The PCM audio samples are streamed over I2S using System.Device.I2s and are not handled by this binding.

The register sequences are ported from the Espressif esp_codec_dev component and should be validated should be validated on hardware other than the CoreS3. The AW88298 uses 16-bit registers. The default I2C address is 0x36.

Documentation

• AW88298 is configured over I2C (control) and streams audio over I2S (data).
• On the M5Stack CoreS3 the AW88298 (speaker) and the ES7210 (microphones) share the same internal I2C bus and I2S data lines.
• Espressif esp_codec_dev component - the source of the register sequences (AW88298 driver source).
• M5Stack CoreS3 documentation and the Espressif CoreS3 board support package.

Audio path on the M5Stack CoreS3

On the CoreS3 the internal bus and the speaker power are gated by the on-board AXP2101 PMIC and AW9523 IO expander (pin 2). The sample powers these up over I2C before configuring the amplifier; for a fuller implementation use the Iot.Device.Axp2101 / Iot.Device.Aw9523x bindings or the M5Stack CoreS3 board package.

Usage

using Iot.Device.Aw88298;
using nanoFramework.Hardware.Esp32;
using System.Device.I2c;
using System.Device.I2s;

// Setup the M5Stack CoreS3 internal I2C bus (SDA = GPIO12, SCL = GPIO11).
Configuration.SetPinFunction(12, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(11, DeviceFunction.I2C1_CLOCK);

I2cConnectionSettings settings = new I2cConnectionSettings(1, Aw88298.DefaultI2cAddress);
I2cDevice i2cDevice = new I2cDevice(settings);

Aw88298 amplifier = new Aw88298(i2cDevice);

// Setup the ESP32 I2S transmitter (MCLK = GPIO0, BCLK = GPIO34, WS = GPIO33, DOUT = GPIO13).
Configuration.SetPinFunction(34, DeviceFunction.I2S1_BCK);
Configuration.SetPinFunction(33, DeviceFunction.I2S1_WS);
Configuration.SetPinFunction(13, DeviceFunction.I2S1_DATA_OUT);
Configuration.SetPinFunction(0, DeviceFunction.I2S1_MCK);

I2sDevice i2s = new I2sDevice(new I2sConnectionSettings(1)
{
    Mode = I2sMode.Master | I2sMode.Tx,
    CommunicationFormat = I2sCommunicationFormat.I2S,
    ChannelFormat = I2sChannelFormat.RightLeft,
    BitsPerSample = I2sBitsPerSample.Bit16,
    SampleRate = 16_000,
    BufferSize = 40_000,
});

// Start the clocks, then configure the amplifier.
// Initialize takes the I2S sample rate so the amplifier's I2S control register matches the stream.
i2s.Write(new byte[512]);
amplifier.Initialize(16_000);
amplifier.Volume = 100;
amplifier.Muted = false;
amplifier.Start();

// Write interleaved stereo 16-bit PCM to i2s.Write(...) to play audio.