Audio Input/Output Usage

The Rhino Pi IQ9N provides audio input (MIC, connected through the AEC interface) and audio output (SPK ×2) through the onboard audio module. Under the system, audio devices are exposed as ALSA sound cards, so standard ALSA tools can be used for configuration, playback, and recording tests.

Audio Channel Description

Channel	Description
MIC (AEC interface)	4Mic Array omnidirectional microphone array, connected through the AEC interface (WAFER-GH1.25-4PLB, signals LINE_LP / LINE_LM / LINE_RP / LINE_RM), supporting wake-up, beamforming noise reduction, echo cancellation, and directional sound pickup
SPK ×2	2 × 5W speaker output, connector model WAFER-PH2.0-2PWB
AEC reference channel	Internal USB2.0 audio channel, used for the echo cancellation reference signal

The audio module supports 4/6 MIC input and VOIP call noise reduction, and can achieve 5 m long-distance pickup with a recording distance adjustable from 1 to 5 m.

The above are specification values; measured metrics are subject to whole-machine testing.

Viewing Sound Cards and Devices

# View sound cards and device nodes (the onboard sound card is card 0)
aplay -l
arecord -l
cat /proc/asound/cards

# View PipeWire audio devices and routing
wpctl status

The measured device enumeration results are as follows:

Item	Name	Description
Playback device (ALSA)	card 0, device 0	Onboard playback device, outputting to the 2 × 5W speakers on the SPK interface
Recording device (ALSA)	card 0, device 2	Onboard digital microphone, mono, supporting 8~48 kHz
Default output (PipeWire)	pal sink speaker ll	Audio is output to the speaker by default
Default input (PipeWire)	pal source handset mic	Recording is taken from the onboard microphone by default

Note

Audio on the IQ9N is managed uniformly by PipeWire. When using aplay / arecord, do not use -D hw:x,y to occupy the hardware directly, otherwise it will conflict with PipeWire and report Device or resource busy; without -D, the commands automatically go through PipeWire's default input and output.

Volume Configuration

# View the default output device and current volume
wpctl status
wpctl get-volume @DEFAULT_AUDIO_SINK@

# Set the default output volume (0.0 ~ 1.0)
wpctl set-volume @DEFAULT_AUDIO_SINK@ 0.8

# You can also adjust the onboard smart amplifier directly through ALSA (the two channels correspond to the two speakers respectively; valid range 0~180)
amixer -c 0 sget 'aw_dev_0_volume'
amixer -c 0 sset 'aw_dev_0_volume' 80%
amixer -c 0 sset 'aw_dev_1_volume' 80%

Playback Test

# Play a wav file (through PipeWire's default output)
aplay test.wav

# Or use the PipeWire playback tool
pw-play test.wav

Recording Test

The onboard microphone is mono, so -c 1 must be specified when recording:

# Record a 5-second wav file (through PipeWire's default input)
arecord -f S16_LE -c 1 -r 16000 -d 5 -t wav mic_test.wav

# Or use the PipeWire recording tool (press Ctrl+C to stop)
pw-record --rate 16000 --channels 1 mic_test.wav

# Play back the recording
aplay mic_test.wav

Switching Input/Output Devices

When the system has multiple inputs and outputs (such as the onboard speaker and headphones), you can switch the default device through PipeWire:

# View device names and IDs
wpctl status

# Switch the default device to the specified ID (example)
wpctl set-default 44

# Adjust the default input volume
wpctl set-volume @DEFAULT_AUDIO_SOURCE@ 1.0

Notes

• Keep a certain distance between the microphone array and the speakers to avoid howling during pickup.
• When using AEC echo cancellation, make sure the reference signal channel and the recording channel are enabled at the same time.
• Pay attention to power matching when connecting external speakers; the maximum output per channel is 5W.
• Use PH2.0 2Pin specification cables for the audio interfaces; for specific interface definitions, see Interface Definitions and Applications.
• The commands above must be run in a terminal on the AidLux desktop (user aidlux); under the root environment of adb shell, PipeWire is unreachable and aplay / arecord report Host is down.

Related Documentation

• Audio Development
• I2S