Speakers

../../../../_images/axon-analog-speaker.webp

The axon users can connect broad range of speakers to the board. The axon board uses a ES8388 chip, which integrates a DAC (Digital-to-Analog Converter) and an ADC (Analog-to-Digital Converter) which provides a codec interfaces with the system via the I2S bus and is commonly used in designs requiring high-quality analog audio capture and playback.

Hardware Interface

../../../../_images/axon-audio.webp

  • Speaker Specifications: - Load Impedance: 4 ohm - Rated Power: 3W

How to Setup

Follow these steps to connect and use speakers with the Axon board.

1. Connect the Speaker

Connect your speaker to the Axon board:

  • Speaker positive → Speaker output pin on Axon (shown in image)

  • Speaker negative → Axon GND

Ensure connections are secure and properly seated.

2. Play Audio through Speaker

This section describes how to play audio through the speaker connected to the SBC using ALSA utilities.

Prerequisites

Ensure:

  • Speaker or headphones are properly connected to the SBC

  • ALSA utilities are installed

Install if needed:

sudo apt install alsa-utils

Step 1: Identify the Speaker Device

List available playback devices:

aplay -l

Example output:

     vicharak@vicharak:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: rockchipes8388 [rockchip-es8388], device 0: dailink-multicodecs ES8323.3-0011-0 [dailink-multicodecs ES8323.3-0011-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: rockchipdp0 [rockchip-dp0], device 0: rockchip-dp0 spdif-hifi-0 [rockchip-dp0 spdif-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: rockchipdp1 [rockchip-dp1], device 0: rockchip-dp1 spdif-hifi-0 [rockchip-dp1 spdif-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: rockchiphdmi0 [rockchip-hdmi0], device 0: rockchip-hdmi0 i2s-hifi-0 [rockchip-hdmi0 i2s-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 4: rockchiphdmi1 [rockchip-hdmi1], device 0: rockchip-hdmi1 i2s-hifi-0 [rockchip-hdmi1 i2s-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

  • See the chip name : rockchipes8388 it contains ES8388 which is an analog audio codec chip, which handles: audio

  • Note down the card and device number for this to be used in below commands

Note the:

  • card number

  • device number

Step 2: Play Audio File

Play an audio file using ( Note : Use the card and device number noted above, for eg: here hw:0,0 is used ):

speaker-test -D hw:0,0 -c 2

aplay -D plughw:0,0 test.wav
Parameter Explanation

Parameter

Meaning

-D plughw:0,0

Select playback device

test.wav

Audio file to play

Step 3: Verify Playback

You should hear audio from the connected speaker or headphones.

Step 4: Test Speaker with Built-in Sound

Play a test tone or system sound:

speaker-test -D plughw:0,0 -c 2 -t wav
Parameter Explanation

Parameter

Meaning

-D plughw:0,0

Playback device

-c 2

Stereo channels

-t wav

WAV test sound

Stop test with:

Ctrl + C

Supported Audio Formats

ALSA supports:

  • WAV (recommended)

  • 16-bit PCM

  • Mono or Stereo

  • Various sample rates (16 kHz, 44.1 kHz, 48 kHz)

Example:

aplay -D plughw:0,0 -f S16_LE -r 16000 -c 1 test.wav

Volume Control

Open ALSA mixer:

alsamixer

Use:

  • Arrow keys → adjust volume

  • F6 → select sound card

  • M → mute/unmute

Ensure output is not muted.

Troubleshooting

No sound output

Check device list:

aplay -l

Check volume:

alsamixer

Ensure:

  • Output channel is enabled

  • Volume is not muted

  • Test speaker hardware directly:

    speaker-test -c 2

—

Notes

  • Use plughw for automatic format conversion

  • WAV format is recommended for compatibility

  • Ensure speaker is properly powered (if external)

  • Load impedance must match speaker specifications (4 ohm for Axon)

  • Rated power is 3W per channel