I do have devices/code for the core/pc. They are written in Ruby. I do have one written in C++ but kept having problems with the device becoming disabled after a Quick Reload and switched back to Ruby. I know it's something I'm doing but just lost patience with myself. Everything is still pretty much event driven still with the hardware having a parent GSD device on any PC (including the RPI) handling the serial communication, then children under it like a door sensor or an on/off switch. This is pretty basic. I would like to put together an irrigation controller that would be a bit smarter. I was waiting to see what happens with the weather plugin and see if I can use that to effect zone times based on recent climate data. I am also adding functionality to handle analog inputs like temperature sensors.
The audio switch is a bit more complex but still basically event driven. The parent device handles serial communication with the hardware and then I adapted the audio zone template #1867 as child devices. The event would be something like "listening to music in bedroom - turn on audio switch bedroom input to bedroom output". I create some custom scenarios where I can set up a group of output zones to be connected to a single input. The last being the reason for building it.
For the RPI I use it in remote locations. At the end of my driveway (which is 600' long) I have one of my switches connected to it. The hardware is connected to roadway and photo eye sensors. I have a directional wifi bridge set up that also sends an IP camera's RTSP stream. (I wrote an adapter so LMCE could handle the RTSP stream). I have the same setup at the garden/green house.
Funny you mentioned the RPI A+ I saw that and I received a touch screen for the RPI ($25US) and plan on using it with the A+. It looks real interesting but I think it will need a custom J-box plate. Not the end of the world and it would be a lot more powerful than the micro controller type I was thinking of and I think a bit easier to get to the end product. I will keep you informed on the progress with that.