Audio System

The ESP32-P4-WIFI6-DEV-KIT includes a complete audio signal chain: an ES8311 audio codec, an NS4150B power amplifier for speaker output, a 3.5mm headphone jack, and an onboard SMD microphone. This guide covers hardware connections and I2S configuration for playback and recording.

Audio hardware overview

                    I2S Bus
  ESP32-P4  ──────────────────  ES8311 Codec
                                   │
                        ┌──────────┼──────────┐
                        │          │          │
                    Speaker    Headphone   Microphone
                   (NS4150B)   (3.5mm)     (SMD)
                    Amplifier    Jack      Onboard

Component	Details
Audio codec	ES8311 — 24-bit, 8—96 kHz sample rates, I2C control + I2S data
Power amplifier	NS4150B — 3W mono, Class D, drives the speaker connector
Speaker connector	MX1.25 2-pin, rated for 8 ohm 2W speakers
Headphone output	3.5mm stereo jack
Microphone	SMD MEMS microphone, soldered on-board

I2S pin mapping

The audio codec connects to the ESP32-P4 via I2S with the following GPIO assignments:

Signal	GPIO	Direction	Description
MCLK	GPIO13	Output	Master clock to codec
SCLK (BCLK)	GPIO12	Output	Bit clock
ASDOUT	GPIO11	Output	Audio data out (ESP32-P4 to codec)
LRCK (WS)	GPIO10	Output	Left/right word select
DSDIN	GPIO9	Input	Audio data in (codec to ESP32-P4)
PA_Ctrl	GPIO53	Output	Power amplifier enable (HIGH = on)

Speaker connection

Locate the MX1.25 2-pin speaker connector on the board (labeled SPK or SPEAKER on the silkscreen).
Connect an 8-ohm speaker rated at 2W or less. The connector accepts a standard MX1.25 plug.
Ensure correct polarity if your speaker is marked — reversed polarity will not damage the amplifier but will invert the audio phase.

Headphone jack

The 3.5mm jack provides stereo output directly from the ES8311 codec. It is active whenever the codec’s DAC output is enabled — no additional GPIO control is needed.

When headphones are inserted, you may want to disable the speaker amplifier (drive PA_Ctrl LOW) to avoid simultaneous output. The board does not have automatic headphone detection in hardware, so this must be handled in software if desired.

I2S playback setup (ESP-IDF)

Add the ES8311 component to your project:
Terminal window
```
idf.py add-dependency "espressif/es8311"
```

Configure and initialize the I2S interface and codec:

#include "driver/i2s_std.h"
#include "es8311.h"

#define I2S_NUM         I2S_NUM_0
#define SAMPLE_RATE     44100
#define PA_CTRL_GPIO    GPIO_NUM_53

// Enable the speaker amplifier
gpio_set_direction(PA_CTRL_GPIO, GPIO_MODE_OUTPUT);
gpio_set_level(PA_CTRL_GPIO, 1);

// I2S standard mode configuration
i2s_chan_handle_t tx_handle;
i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM, I2S_ROLE_MASTER);
i2s_new_channel(&chan_cfg, &tx_handle, NULL);

i2s_std_config_t std_cfg = {
    .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(SAMPLE_RATE),
    .slot_cfg = I2S_STD_PHILIPS_SLOT_DEFAULT_CONFIG(
        I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_STEREO),
    .gpio_cfg = {
        .mclk = GPIO_NUM_13,
        .bclk = GPIO_NUM_12,
        .ws   = GPIO_NUM_10,
        .dout = GPIO_NUM_11,
        .din  = GPIO_NUM_9,
    },
};
i2s_channel_init_std_mode(tx_handle, &std_cfg);
i2s_channel_enable(tx_handle);

Initialize the ES8311 codec over I2C:

es8311_handle_t es8311 = es8311_create(I2C_NUM_0, ES8311_ADDR);
es8311_init(es8311, &(es8311_codec_config_t){
    .sample_rate = SAMPLE_RATE,
    .bit_width = 16,
});
es8311_set_voice_volume(es8311, 70);  // 0-100

Write audio data to the I2S channel:

size_t bytes_written;
i2s_channel_write(tx_handle, audio_buffer, buffer_len,
                  &bytes_written, portMAX_DELAY);

I2S recording setup (ESP-IDF)

Recording from the onboard microphone uses the same I2S bus in receive mode.

Create an I2S receive channel (can coexist with the transmit channel on the same I2S peripheral):

i2s_chan_handle_t rx_handle;
i2s_new_channel(&chan_cfg, NULL, &rx_handle);
i2s_channel_init_std_mode(rx_handle, &std_cfg);
i2s_channel_enable(rx_handle);

Configure the ES8311 for ADC (recording) mode:

es8311_set_mic_gain(es8311, ES8311_MIC_GAIN_42DB);

Read audio samples:

uint8_t rec_buffer[1024];
size_t bytes_read;
i2s_channel_read(rx_handle, rec_buffer, sizeof(rec_buffer),
                 &bytes_read, portMAX_DELAY);

Troubleshooting

Symptom	Cause	Fix
No speaker output	PA_Ctrl not enabled	Set GPIO53 HIGH before writing audio data
Distorted audio	Speaker impedance too low or volume too high	Use 8-ohm speaker; reduce `es8311_set_voice_volume()`
No microphone input	Mic gain too low	Increase gain via `es8311_set_mic_gain()`
Crackling / clicks	Buffer underrun	Increase I2S DMA buffer size or reduce sample rate
I2C init fails	Wrong I2C address or bus	ES8311 default address is `0x18`; verify I2C bus number