After making this I decided that only 3 different duty cycles were not enough so I upgraded it to 128 different cycles, so every possible cc value will now change the duty cycle.

Here is a recording of it: http://chipmusic.org/tmtgr/music/4bit-synth-duty-test

All I did was change the update_duty_cycle function to this:

void update_duty_cycle()
{
    OCR1B = OCR1A * (duty_cycle / 128.0f);
}

I've realised i have no way of programming the chip for this, someone want to mail me out a pre-flashed one?

I'll think of something to do in return. Like order a pizza to your house via the internet. pm me to work it out anyone?

Yeah programming the music was a very small portion of the project so there isn't much that's relevant to this forum, I just thought it would be worth sharing for people who like microcontrollers. Also, a while back MAKE Magazine contacted me because they were considering building a kit based on the project that people could buy, build and program themselves, and I sent them a bunch of info, and then they just never got back to me. I guess they ended up deciding it wasn't worthwhile

i saw the videos, they were cool. couldn't see what was going on too much.
reading the info now...

Somewhat related, I had to program the ATMega32 back in college...

http://blip.tv/file/201595

http://lab.christianmontoya.com/weeboy/

That's some low-bit music right there.

Where the sound quality differs from the NES, it is very likable in its own right!
This is cool.

i am pretty surprised by the sound samples he has.
some of the game cover tunes are spot on and the capabilities he implemented are not bad.
you can check out the sound samples here
http://code.google.com/p/4bitsynth/downloads/list

I know what ill be doing this long weekend.

sounds good too.

Or you could just output a voltage from the atmega into a voltage controlled oscillator, and that voltage into another oscillator...
And you can have your own modular analog synth with midi

this definitely seems like a fun little summer project for sure!

Looks great. Should'nt be too hard to make with an arduino.

i just saw this project on google code
a 4 bit MIDI synth based on the Atmel AVR ATMega48
it looks kind of cool, figured i would share.

here is the makers description

"4bitsynth is a MIDI-controlled digital synthesizer that uses the Atmel AVR ATMega48. Inspired by the NES, the sound is 4-bit. The digital output is put through an R-2R resistor ladder to get the analog waveform."

http://code.google.com/p/4bitsynth/