Lately I've been learning about modular synths. One of the common things modular folks use to control things is a pulsed clock. This afternoon Tiina and I wandered down to Redfern to check out a meeting of the New Sound Waves modular synth group. The guys there had synced up their modulars and assorted other equipment with a shared clock source and were collaboratively making music. Pretty cool stuff.
Anyway, I decided to try to make my own clock divider. Didn't take long to get something working, and you can see the results in the video above. The genuine Arduino Uno is generating a simple square wave on pin 13, which you can observe with the built-in LED. The Freetronics clone is triggering on the rising edge of the square wave and operating a clock divider with /1 through /8 outputs. The /1 through /4 divider outputs are attached to a little test-LED board I made a while back. You can see that it has a bug caused by my forgetting to reset the tick counter.
To actually use this in a modular synth it would need to tolerate inputs in the range -12V to +12V, maybe via a bunch of MOSFETs. It might be easier to just ditch the AVR and use flip-flops