microcontroller for a digital synth

[pedrorf]

I use to lurk around here, but this is the first time I'm posting to the forum. And an off topic post at that... Oh well...

I've been looking at the opl3 and sid projects, and I was daydreaming about designing a midibox based synth with some modern microcontroller(s) working as a programmable synthesis engine. Now, I know next to nothing about microcontrollers, but I suppose nowadays one can get a reasonably priced chip strong enough to run a digital synth... Say, a dx-7 alike, or perhaps a waldorf-like wavetable synth. I was wondering if you nice people could point me to what you think might be an appropriate microcontroller for this sort of project. Something versatile, fast enough and powerful enough for the task, not too expensive and easy to integrate on a midibox project. Ideally it should be easy to program with C/C++, too. Any suggestions?

Thanks,

pedro

[TK.]

You could check the Chameleon specs - you are propably thinking about a similar device: http://www.chameleon.synth.net/english/index.shtml

Best Regards, Thorsten.

[DrBunsen]

Something versatile, fast enough and powerful enough for the task, not too expensive and easy to integrate on a midibox project. Ideally it should be easy to program with C/C++, too.

Well, the Parallax Propellor looks interesting, and there's already been some work on music synthesis for it.  It's an 8 core, 32 bit multiprocessor microcontroller, with each core doing 20 MIPS, for US$20, and development boards start at US$20 as well.  But it doesn't use C/C++; rather it has it's own languages for both high level and assembly work.

I've noticed some synthesis work on AVRs as well - if you check the Cornell University microcontrollers end-of-year project page for the last few years, various forms of music synthesis crop up there pretty regularly.  Dunno what the deal is on getting hold of source code from those projects, but there should be other AVR synthesis projects around.  Like AVRsynth, for example.

If you want serious grunt you might go for an ARM platform, although I think you are looking at pretty pricey dev boards for them.  Unless you pick up a cheap ($100) ARM based NAS box or other appliance and reflash it to run Linux or ucLinux.  Then you could install a stripped down Linux with a wide choice of already written synthesis applications.  But then it's more of a "real computer" than a uc.

Other suggestions: Shifty's Death Synth (based on a discontinued DSP dev board), dsPIC.

All of the above could be wildly inaccurate.  Your research is advised.

[TheAncientOne]

AVRx is an interesting hybrid, though assembling the board is seriously taxing my fading eyesight. The boards are very good quality, though due to a lack of parts buying savvy I ended up spending more than I should have done. I think 32 Euro for the boards is not bad considering the quality. A warning: if you're a soldering newbie don't even think about it - get some practice first.

www.avrx.se

Code is open source,which may help, though like Monowave the filters are analogue.

I think that the design could be fitted into the same PacTec as Wilba's. I'm doing my initial one as a 2U 19" rack module, though I now wish I'd modded the suggested design to give a headphone socket and a left hand 'shift' button.

[seppoman]

If you want to go all digital (no analog processing like the AVRx) and want to start from scratch, I´d recommend chosing either a DSP (the mentioned DSPic is quite cheap and easy to setup, DIP format) or using a 32 bit controller. The ARM7 series is quite powerful and there are cheap dev boards available. E.g. the SAM7-P256 from olimex.com has an Atmel SAM7S256 with 64kb of RAM, 60 MHz, USB, SD-card reader etc. onboard and costs only 70$. You could also go for ARM9 but as DrBunsen said, it´ll get more expensive and become kind of a real computer running Linux etc.

The Propeller is a funny idea and has some projects, but personally I dislike that there´s no C compiler and everything comes from a single small company. If they choose to stop making/supporting them because they´re not selling, you´re on a dead end. Stuff from Microchip or Atmel is at least somewhat future-proof, and ARMs you get from a dozen companies. I think I´d chose the ARM7 - it´s cheap, has good processing power and a free gnu C toolchain.

Seppoman

[DrBunsen]

Sparkfun have some interesting little ARM9 dev boards for not too expensive, and a range of add-on breakout boards.

You could also go for ARM9 but as DrBunsen said, it´ll get more expensive and become kind of a real computer running Linux etc.

By which time you might as well go for a GP2X, which has already had a fair bit of MIDI and synthesis work put in to it, and comes complete prebuilt, display, the works, for about US$199

The Propeller is a funny idea and has some projects, but personally I dislike that there´s no C compiler and everything comes from a single small company. If they choose to stop making/supporting them because they´re not selling, you´re on a dead end.

Somehow I don't see that happening; they've sunk a lot of R&D into it, they're about to release a second version, and the forums seem pretty active.

[pedrorf]

Thanks for your suggestions, folks. Plenty of stuff to research and read about. I'll let you know if I end up with something interesting.

pedro