[sdiy] The Chameleon Guitar

[paul.maddox.mail-list at synth.net]

Csaba,

> All right I had to look up what FWIW stands for :)

hehe, sorry.

> I had no idea DSP's can handle multiple registers. I thought only   
> like Microprocessors and higher, more complex µCUs. Interesting !

well not multiple registers.
Most instructions allow one or two simultaneous memory moves, be it  
between registers or a register and a memory location.

> So you're saying Assembler would be the way to go , for you. And
> therefore one would have to dig even deeper in the Datasheets not only
> set some registers. That makes sense.

:-)
There are only a few registers, if you get the motorola DSP 56xxx  
instruction book (free on request) it has a chapter at the front  
showing the registers. The for each instruction there are 2 or 3 pages  
explaining it's function, what registers it can work on and what  
parallel memory moves are allowed.
some of the Registers, like A are made of other registers, for example  
A0 and A1.

> But what about portability . Isn't a C-program much easier to port by
> simply changing the header  of the device. Sure you loose performance
> the code is not as optimized as it would be in Assembler .

Correct, C is far more portable, but the instruction set for the 56xxx  
range of freescale DSPs hasn't changed any :-)
So I'm not re-learning when I move from the chameleons 56303 to the  
soundbites 56721 or the new one I have with the 56372 on.

>  But the part
> runs @400MHz does it really matter ? Let's waste some of that DSP power
> :)

oooo, them's fighting words.
Tell you what, go and buy windows Vista, and the 2G of ram and 200Gb  
that are minimum recomended for it.

Just cause you have the speed and resource, doesn't mean you shoudl  
squander it.

> I'd like to see somebody write a Chorus, Flanger, Delay maybe even a
> Reverb application. So I can learn how that is being done in code.

delay lines with feedback paths and LFOs modulating the delay point.
Check out music DSP's archive - http://www.musicdsp.org/
There's code for a wah pedal, reverb, phaser, etc, etc and *MOST* are  
in C or C++

> My true problem with the SoundBite board is that there is not enough
> code around .So I can't even copycat snippets together and brew
> something that I can call my own.

forget that it's a soundbite.
remember its a 56xxx based core, search again :-)

> Paul,  you got the Monowave II and other synth created on the
> Chameleon's DSP(s) . Respect ! I am sure you will one of these days
> present us with some mint MultiEffects or something .

and you can take the code, from the monowave II and port it to a  
soundbite quite easily, the only thing missing is the control cpu (the  
chameleon has a coldfire for handling midi, control panel, etc).
My issue with the soundbite is, HOW do I get the control into it?

If I can figure out the hardware interface to control the soundbite or  
my new dsp evm board via say, SPI, then I can hook up a small micro to  
worry about midi and pass the details to the DSP to make the sound.

Paul