MP3Trigger by David Wicks (Edited for Particle by Tom) http://sansumbrella.com/

Simple wrapper for MP3Trigger serial communication from Particle devices. Also allows you to loop tracks.

When building your Particle solution, be sure to include this library.

For sample usage, see the examples/ folder (courtesy Carl Jensen)

Thanks to: Carl Jensen, http://dimsos.fridata.dk David Wicks, sansumbrella.com

Sparkfun product page has link to User Guide which they call Datasheet for some reason: http://www.sparkfun.com/products/9715

Updates on new firmware for MP3 Trigger V2 at: http://makerjam.com/support/