So I have spent quite a bit of time working on the firmware.

After linking the BT Audio module via serial to the Spark Core I put in the ability to control it via SNMP, this is not the most convenient method of skipping a song however.

Using the Spark Core API I made a web page that calls routines in the core, this lets me send play/skip and volume controls etc via the web, much easier.

I also added a "sleep" timer mode, I can activate a timer with 15,30,45 and 60 minute intervals that will issue the "stop" and "disconnect" commands to the BT Audio module at the end. This means I can put on a LONG playlist or an internet radio as the source and have it stop after an hour (when I am asleep) rather than keep playing all night.

The next stage is an "Alarm" that activates the BT link and plays a song at a set time to wake me up. This sadly requires the song is pre-queued on the phone because I can't control the track that is played over the BT audio link.