This is the prototype demo of the Xpression Controller that I made for Roland GR55 Guitar synthesizer. It captures the envelope of the tone (energy of the signal which is proportional to bowing) and controls the attack, amplitude of the sustain and release accordingly. It also minimises the false triggering of PCM tones due to the impulse nature of the response produced by it's source. The next step would be acquiring data from each string separately and controlling the parameters independently! I am also building the filter buffer and planning to put it all together as one ultimate "must have" accessory for GR55 especially for Violinists!