[sdiy] Wavetables

[Matthew Smith]

Quoth jon schatz at 22/01/11 16:20...
...
> if i'm understanding you correctly you already have most of the work 
> done for the saw / sine. the saw should just be the input value to your 
> sine function (ie, y=x from -1 to 1). the triangle is y=2x for -1 < x < 
> 0, y=1 for x = 0, and y = -2x for 0 < x < 1.

*headdesk* - at least as far as the sawtooth is concerned. Yes - that 
makes sense now!

> both the saw and triangle should cross 0 if you're talking about an ac 
> output. i expect your dac will take in 0 to 0xff as input values so your 
> tables will have to map -1 to 0 and 1 to 0xff but that's not so hard.

Yup. Positive integers 0x00 to 0xFF, my kinda numbers ;-)

Since I've got to write some (Perl) code to generate the tables, think 
I'll do it as a little web application where you can select waveform, 
number of bits, times oversampling, to spit out a text file that can be 
used howsoever.  I'll post a link when I'm done.

Many thanks for that!

Cheers

M

-- 
Matthew Smith
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