Skip to main content

3.2.2 Audio Adapter Board On RDK X3 MD

Currently, the RDK X3 Module supports WM8960 Audio HAT. These boards are used to meet the functional requirements of different voice scenarios. The following will provide detailed instructions on how to use this audio board.

Note

If you are prompted that the Miniboot version is not the latest after installing the driver, please go to 1 System Options -> S7 Update Miniboot to update Miniboot.

WM8960 Audio HAT​

Product Introduction​

WM8960 Audio HAT is an audio adapter board produced by Waveshare Electronics. It adopts WM8960 Codec solution and can achieve dual-channel microphone recording and audio playback functions. The appearance of the adapter board is as shown in the figure below:

image-audio-wm8960

For detailed information about the audio adapter board, please refer to WM8960 Audio HAT.

Installation Method​

  1. Connect the adapter board to the 40-pin header of RDK X3 as shown in the figure below: image-wm8960-audio-hat-setup

  2. Configure the audio board using srpi-config: Enter 3 Interface Options->I5 Audio and select WM8960 Audio HAT: image-audio-driver-hat-config00

  3. Run the command sync && reboot to restart the development board. If the following device nodes appear under /dev/snd, it indicates that the adapter board is successfully installed:

    root@ubuntu:~# ls /dev/snd/
    by-path  controlC0  pcmC0D0c  pcmC0D0p  pcmC0D1c  pcmC0D1p  timer

Uninstallation Method​

  1. Configure the audio board using srpi-config: Enter 3 Interface Options->I5 Audio and select UNSET to uninstall the audio driver and related configurations.

Audio Nodes​

The playback node for this audio board on RDK X3 is pcmC0D0p, and the recording node is pcmC0D1c.

Recording and Playback Test​

To perform the test, we will be using the toolset provided by the tinyalsa library: tinycap for recording and tinyplay for playback.

Usage instructions for tinycap:

tinycap
Usage: tinycap {file.wav | --} [-D card] [-d device] [-c channels] [-r rate] [-b bits] [-p period_size] [-n n_periods] [-t time_in_seconds]

Use -- for filename to send raw PCM to stdout

Usage instructions for tinyplay:

tinyplay
usage: tinyplay file.wav [options]
options:
-D | --card   <card number>    The device to receive the audio
-d | --device <device number>  The card to receive the audio
-p | --period-size <size>      The size of the PCM's period
-n | --period-count <count>    The number of PCM periods
-i | --file-type <file-type >  The type of file to read (raw or wav)
-c | --channels <count>        The amount of channels per frame
-r | --rate <rate>             The amount of frames per second
-b | --bits <bit-count>        The number of bits in one sample
-M | --mmap                    Use memory mapped IO to play audio

For more information about the tinyalsa library, please refer to their repository.

  • 2-channel microphone recording:
tinycap ./2chn_test.wav -D 0 -d 1 -c 2 -b 16 -r 48000 -p 512 -n 4 -t 5
  • Dual-channel audio playback:
tinyplay ./2chn_test.wav -D 0 -d 0

Coexisting Audio Sub-board and USB Sound Card​

If you have a USB sound card and want it to coexist with the above-mentioned audio sub-board, please follow the tutorial below:

  1. Make sure the audio sub-board is enabled according to the instructions above.

  2. Connect the USB sound card and observe the newly added nodes under /dev/snd after the driver is loaded. Taking the WM8960 + USB full-duplex sound card as an example,

    root@ubuntu:~# ls /dev/snd/
    by-path  controlC0  pcmC0D0c  pcmC0D0p  pcmC0D1c  pcmC0D1p  pcmC1D0c  pcmC1D0p  timer

the nodes pcmC1D0c pcmC1D0p represent the USB sound card node, which is shared by full-duplex.

  1. Modify /etc/pulse/default.pa and add the corresponding node information below load-module module-alsa-source:
...

.ifexists module-udev-detect.so
load-module module-alsa-sink device=hw:0,1 mmap=false tsched=0 fragments=2 fragment_size=960 rate=48000 channels=2 rewind_safeguard=960
load-module module-alsa-source device=hw:0,0 mmap=false tsched=0 fragments=2 fragment_size=960 rate=48000 channels=2
load-module alsa device=hw:1,0 #corresponding to the above node
load-module module-alsa-source device=hw:1,0 #corresponding to the above node
.else

...
  1. Save the configuration and restart the development board.