[sdiy] Korg DSS1 DMA oscillators, the old beast!

[Tom Wiltshire]

On 23 Jan 2010, at 16:49, Antti Huovilainen wrote:

> On Sat, 23 Jan 2010, Eric Brombaugh wrote:
>
>> If you want a DAC loaded at a variable rate controlled by a timer  
>> then you'd be better off using an external SPI DAC, driving the  
>> SPI TX from a DMA channel that's timer triggered.
>
> Or you could just resample to the output samplerate on the fly.  
> Relatively basic FIR interpolation.

How big a FIR filter would would you need, Antti? Can it be done with  
reasonable quality?
Presumably you'd have a much faster internal sample rate (say 4KHz  
max note frequency, with 256 sample wavetable = 1.024MHz (thanks  
paul..)) in which case this FIR filter is going to have to remove  
most of the higher frequencies to avoid aliasing.

Thanks,
Tom