If you listen to music with synths from the 70s and 80s one sound you'll run into is an arpeggiator. Listen to the synth bass that comes in about 8s into: Rush - The Weapon

There are a lot of other interesting examples in this Vintage Synth discussion. The general idea is that you can make repeated patterns out of a series of notes, and the automation can move between notes faster than it would be practical or comfortable to play them.

I wanted to try this out with my rhythm stage setup, which meant I needed to teach my software about time. I don't want to be locked to one tempo, or even have to decide about tempo ahead of time, so I decided to start by teaching the system how to read the tempo off tapping my foot.

There are probably a lot of clever ways to do this, but I went with something brute force: each time I tap my foot I consider the past taps, and I compute how likely each potential tempo from 100 to 140 is. The tempo with the lowest error is the best one, and if the error is below an experimentally determined threshold the system decides it knows what speed I'm playing.

Between each beat it has eight opportunities to play things. If I were playing jigs six would be possible, but I haven't figured that out yet. For example, I can set it to play "1 1 8 8 1 1 8 8", which sounds like rocking octaves with each note doubled. Or I could play "1 - 8 - 13 - 16 -" , or any other pattern.

Once I have the ability to play notes a fraction of the way through the beat I can also use that for drums. My normal approach to drums is built around tapping a foot for each sound I want to trigger, but my feet are only so capable and there are a lot of patterns I can't play. With this I can set the system to play something like "K - - - H - H -", which is essentially French Canadian feet on drumkit. At some point I want to record some foot samples and make it do actual feet.

Putting this all together I can use it to fill out my mandolin playing: mandolin with arpeggiator

Or my piano playing: piano with arpeggiator

This opens up a bunch of possibilities, and I suspect there are a lot of things I'm going to want to do with it that I haven't thought of out yet.