Recently in Arduino Category

post it in case anyone might find it useful. Feel free to use, CC-share alike, you know the routine. And here's the hacky PSD as well, enjoy!

I've decided to revisit my Arduino synth project from last September in hopes of creating a versatile synthesizer shield. I'm rather partial to the digitally-controlled-analog approach. I had an XR2206 function generator IC lying about, so I decided to put it to work as a possible core/VCO of this endeavor. It's quite easy to set up for accurate sine wave generation though driving the frequency with a convenient voltage is still something I'm figuring out.
Datasheets always seem to get a little vague just in the real clutch areas I need to focus on - a circumstance I find myself in often when getting to know a component, I suppose I'm a bit impatient and would rather experiment than attempt to decipher datasheet specs which I'm unfamiliar with. - And of course, why not? - the experimentation is the fun part! As a kid I remember acquiring new transformer figures and excitedly attempting to morph them without consulting the highly visible photo-instructions printed on each package. It's efficient to approach a new situation with proper procedure dictated to you - but that always leave me asking, "Why is that the proper method? and is it really the best way?" more to come . . .

The ArduinoSynth is my first attempt at microcontroller programming( and pretty much any coding at all beyond a little html). It took me a bit to get started but it's turning out to be a fun way to learn the language.
So far it's a 12-note monophonic synth with transposition selection via one 10K pot. I'm using a gutted toy keyboard for the switches and a simple low pass filter to smooth the output a bit. Here's the schematic:

Features I'd like to add:
- Another octave (maybe add a transpose switch on each of the next octave, then they can share pins with the first)
- Last note hit priority
- Portamento (note-slide)
- Real sine wave out (no external filter, please)
- Polyphony (I had it working badly, need better math)
- any real keyboard feature in existence(or not) attack, decay, waveform, vibrato, etc.

Source can be found here.
Audio sample here
Sample with no LPF here

I recently attended an Arduino class at Lemur here in Brooklyn. It was fun and moved at a brisk pace. The Arduino programming environment is pretty damn friendly and intuitive.
I'm a bit staggered by all the possibilities microcontrollers open up but keep wondering - how do I turn this thing into a synth? Well I seem to be making pretty good headway via hacking bits of others' sketches. Will report back soon.