[sdiy] Wavetable Design Update

[Matthew Smith]

Quoth Paul Maddox at 03/02/11 18:11...
...
> bits? or bytes?
*headdesk* Bytes!

> 128 bytes of unsigned char should be 128bytes of unsigned char, you
> should use a couple of bytes more RAM for the pointer.
Yeah, that's what I figured. I'll look at it again at some point. Start 
with an empty but sized array - should be quick check to see if I've 
stuffed up the data. I need to recalculate all my tables anyway to 
account for the step up to 256 SAMPLES (that's where I got the bits 
confusion) and all the fun new shapes I've decided to chuck in, 
including arrays of totally random numbers (scaled 0-255, of course) to 
see what they sound like.

> actually, you can cheat.. I just remembered what I did with the monowave.
> forget the 32nd bit, use the carry over flow bit.
> so when the accumulator overflows (i.e. it gets bigger than 32 bits
> and resets) a carry/overflow flag is raised.
> Use that to "flip" (just like a flip flip) a pin on an IO port.
Not sure I've got any way to access that in C.

But the flip pin technique - if I used the next one as well, would that 
give me f/2, or am I understanding this wrong? Just be nice to get a 
"free" suboctave or two.

> See this page if it helps - http://ppg.synth.net/wave22/

Ta. Going to have to start copying these into a file so I can find them!

> it's one of those things that the moment you get it you'll kick
> yourself at how obvious it is :-)

I'm sure it is! I'm no mathematician (I struggle with it) but I'm 
getting the impression that this might be *really* simple stuff when I 
turn it around enough that I can get it to fit in my brain ;-)

Cheers

M

-- 
Matthew Smith
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