This is some Red Bear Lab BLE Nano code (requires Arduino core) for controlling a Sherwood Newcastle R-972 receiver via its serial port.
In my house, we use our stereo receiver (an R-972) with its many attached speakers to watch television. The receiver lives on a shelf behind our couch. The contraption below allows us to control the volume on the receiver using a knob rather than relying on a remote control.
I added a nice knob after taking the first pic.
Here you can see a bit more of the key parts.
I have a video demonstration on YouTube.
Eventually, if I ever get around to it, I will write an app that lets me control the volume (and perhaps some other features) from my phone.
