Page 3 of 6
Here’s an example of how command line drive of the audio board works. If, for example, you need to switch audio out through the black Headset socket (3.5mm stereo jack) mounted on the board to listen to music over headphones, you must bring up LXTerminal on the monitor screen by clicking on its icon, then type in:
Note in particular here that commands (shell scripts) are prefaced by ./ and that upper and lower cases (Capitals, non-Capitals) are recognised and important. With command lines all characters must be correct or an error message is returned – a frustration.
Get the command right, however, and down the screen spews a long command set, including conditions that can be changed – if you know how! What you need to know here, but is lacking from the User Manual, is that the board uses an ALSA mixer and you are in fact programming this item (amixer, arecord etc) when setting up the sound card. This is important when Googling questions, as Cirrus Logic advise for seeking help in the forums.
Commands are cumulative, so if you select Headset then Line Out you get both. If you want to switch one off, a Clear command must be used and new conditions re-programmed. It is tedious and taxing, but it works fine once you get the hang of it. Of course it does mean that to use the music player you must have Pi hooked up to a screen and connected to keyboard and mouse. Set-up conditions are stored and retained after switch off.
The tiny board carries a rank of audio connectors. The yellow phono socket is an
S/PDIF digital output, the white an S/PDIF digital input. Around the corner lies a black
3.5mm 'HeadSet' jack socket, a green analogue Line Out and a pink analogue Line In.
A 5V d.c. power input socket (black) is at far left.