Sonntag, 28. Dezember 2008

AVR-Based Synth

After finishing the Drumsynth Prototype i started another little synth project. It consisted in turning an atmega16 microcontroller in a simple 4-voice polyphonic synthesizer.
I've been working a lot with microcontrollers so i was curious to see if i could turn an atmega into a polyphonic synth. Another reason for this project was a lot of spare time at my dayjob since this project is much about programming which can be done ver easily in the office ;-)

By simple i mean that it only contains one oscillator per voice, no filter and a ADSR envelope per voice. Of course there are some other avr-based synth projects (,, in contrary to these projects i tried to focus on polyphony, with the aim of including it in a modular synthesizer.
What came out until now is a very cheap, cheap-sounding and cheap-sounding box. Technical data:
wave sampling rate: 31,25 kHz
resolution: 16bit
envelope (and possibly lfo) sampling rate: 244 Hz
midi: note on/note off
Extensions: basic wavetable capability, lfo

here is the video of this synth(sorry about the sound)

Sonntag, 14. Dezember 2008

PCB layouting

lots of thing have been going recently. I've started a new project: a digital polyphonic synth based on an atmega16 ic (pics and vids soon). I was looking for a good schematic and pcb designer software. After a long search and much hairpulling i finally decided to use an open-source package called gEDA. Although it has some small bugs it's much easier and less complex than many commercial options.
I've now (nearly) finished the layout of the sequencer master part. Here it is. I've noticed that (clever) layouting pcb's is a quite demanding task..
Please don't etch boards with that layout yet (that's why i didn't put the resistor values..) i have'nt checked and tested the layout yet