Add GPIO output

[laurensoosting]

Add GPIO output which can be used to enable an amplifier when music is playing.

[tmigone]

Hi @laurensoosting this feature is already supported via bluetooth scripts:

• https://github.com/balenalabs/balena-sound#bluetooth-scripts-optional

Is this useful to you?

[laurensoosting]

Im mainly looking for this feature to use with spotify. I hink this could be a nice adition. On this moment the amplifier is always on.

[tmigone]

I see, in that case, yes, that is currently not possible. But it's a nice addition so we'll add it to the backlog. Thanks for the suggestion!

[AlexProgrammerDE]

@tmigone and @laurensoosting i found this wiki page of librespot: https://github.com/librespot-org/librespot/wiki/Options . It has an option named onevent. I will do some research now.

[tmigone]

This will be possible when 3.x is released with play/stop event hooks.

[AlexProgrammerDE]

This seems fixed then?

[shawaj]

@AlexProgrammerDE reckon it is worth adding some documentation about how to do this? I am not entirely sure of how to use the hooks. Haven't played around with it.

[AlexProgrammerDE]

@shawaj yeah docs on this would be good. @tmigone can you give us a look into how this works now?

[tmigone]

Added to the TODO in #393