thanks Morgan. I've only been doing this a few month 
and probably jumping in at the deep end using eclipse ide and learning c++ on udemy - looking to grab a discovery or nucleo board! a little more research and ive discovered 'interrupt' so this may help me 
I've bought a few dsp books and c++ books and need to grab a few more. BasicSynth is helping me a lot to understand waveforms, sampling and sample rates but theres not much about sequencing. If anyone has any reading suggestions let me know