[sdiy] DSP kits (was: Re: has anyone ever made their own Nord Modular?)

[Sean Costello]

Hi:

Check out http://blackfin.uclinux.org/. This is an open source project for developing for the Blackfin DSP from Analog Devices. Open source compiler, board design, etc. 

Generally speaking, the expensive part of working with ADI parts will be the cost of the VisualDSP++ compiler. The EZ-KITs come with a free version of the tool, but the free version of VisualDSP++ has limited memory access (only 1/4 of the given EZ-KIT). So the open source option above might be a good idea.

I work on the development team at ADI for VisualAudio, which is a visual compiler (think MAX/MSP, although it stems from projects that predate MSP) that generates code for SHARC and Blackfins, as well as allowing users to add their own modules in C or assembler. It is a nice tool, but it requires VisualDSP++ to compile the code, so it is unfortunately not a cheap option. 

Another option from Analog Devices: the SigmaDSP development boards. I think that they are $500, but that comes with a VERY nice visual compiler, similar to VisualAudio but with nicer graphics, so once you have spent your $500, you have all the tools you need to work with that platform. The newest SigmaDSPs are 48 pins, and have stereo ADCs and quad DACs built into the chip. Much better for building your own boards than the BGA you find on most Blackfins and SHARCs nowadays. The SigmaDSPs are a bit underpowered compared to the current SHARCs and Blackfins, but they are very low cost DSPs, so that is to be expected. 

As far as I know, none of these solutions have a MIDI interface, or code for MIDI. This doesn't mean that it is in any way impossible, just that you will need to create your own. I know that someone created a MIDI interface for the 21161 EZ-KIT, that was a very small daughter card. 

If you want to create a sampler, you need to make sure that the memory access pins are there to move samples from off-chip RAM to the DSP for processing as quickly as possible. Using DMAs will probably create too much of a bottleneck.

Sean Costello


  ----- Original Message ----- 
  From: Johannes Öberg 
  To: synth-diy at dropmix.xs4all.nl 
  Sent: Friday, October 21, 2005 9:19 PM
  Subject: [sdiy] DSP kits (was: Re: has anyone ever made their own Nord Modular?)


  Hijacking your thread: what (cheap) DSP kits are there? I only know of the EZ-SHARCs, and they don't seem that cheap anymore...

  The Soundart Chameleon would be great if only they would let you use the RS232 in your synth engine... As it is now, you can't really make a sampler out of it, can you? (And no; sample dumps over MIDI is not an option...)

  Are there any evaluation boards for DSP in ISA or PCI packages? Or any DIY projects for building a simple DSP board? Or anything you could put togheter with FPGAs?

  (what I would want to build isn't a Nord Modular, but a wavetable sound card in ISA form factor! I guess thats even more insane...)

  /J
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