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3.2.1 Audio Adapter Board On RDK X3

Video: https://www.youtube.com/watch?v=Jt7eaEe2QbQ&list=PLSxjn4YS2IuFUWcLGj2_uuCfLYnNYw6Ld&index=9

The RDK X3 currently supports WM8960 Audio HAT. This board are designed 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, using the 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

This audio sub-board is only compatible with RDK X3 version 2.0, and the version number can be queried as follows. The return value 8 indicates that the device is 2.0 version.

root@ubuntu:/userdata# cat /sys/class/socinfo/som_name
8

For a detailed introduction to 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 following picture
    image-wm8960-audio-hat-setup

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

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

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

Uninstalling Method​

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

Audio Nodes​

The playback node for this audio board on the RDK X3 is pcmC0D1p, and the recording node is pcmC0D0c

Recording and Playback Test​

The test uses the toolset of tinyalsa library: use tinycap for recording and tinyplay for playback

Usage of 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 of 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

If you want to learn more about the tinyalsa library, please refer to their repository

  • Recording with a 2-channel microphone:
tinycap ./2chn_test.wav -D 0 -d 0 -c 2 -b 16 -r 48000 -p 512 -n 4 -t 5
  • Playback of stereo audio:
tinyplay ./2chn_test.wav -D 0 -d 1

Coexistence of Audio Subboard and USB Sound Card​

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

  1. Make sure the audio subboard is functional according to the tutorial above.

  2. Connect the USB sound card and observe the newly added nodes under /dev/snd after the driver is loaded. Taking 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 pcmC1D0c pcmC1D0p nodes are for the USB sound card, and they share a full-duplex node.

  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 nodes
load-module module-alsa-source device=hw:1,0 #corresponding to the above nodes
.else

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