[sdiy] Wavetables

[Matthew Smith]

Quoth Gordon JC Pearce at 22/01/11 19:58...
...
> I'd just use a synchronous counter chip.  I appreciate that the whole
> idea is to build as much as possible from scratch, but I suspect the
> project will start to become Not Fun when you're chasing physics bugs do
> to with timing glitches ;-)

My flipflops (MC14027) are rated up to a mere 1.5MHz at 5V. I think, for 
the purposes of this exercise, I'll drive the DAC directly from the 
microcontroller, and put the tables in the FLASH programme storage area.

I've done the design on paper so know I *can* build a synchronous 
counter out of JK flipflops, so at least I've put the thought to it.

> As for doing it all in software, look at:
> http://www.gjcp.net/~gordonjcp/fmtoy.pde
> and the article much of it was derived from:
> http://interface.khm.de/index.php/lab/experiments/arduino-dds-sinewave-generator/

Thanks, I'll have a squiz.

> How accurately can you tune your clock frequency at 3.2MHz

Depends on the way the counters in the microcontroller work - if I 
really wanted accurate, I've got a 10MHz TTL output Rb oscillator buried 
on my bench somewhere. Maybe a BIT over the top for music, though!

Cheers

M

-- 
Matthew Smith
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