[sdiy] Wavetable Design Update

[Matthew Smith]

Quoth Paul Maddox at 03/02/11 05:47...
...
> Will  you get the resolution you need from that timer?
> I have a feeling you may not.

I don't know. As soon as prescale is applied, that's when I think I 
could really get into trouble, hence the original issue.  As I'm not 
game for over-clocking, one option is to use the faster Dallas 
8051-based devices I have on hand, but this would involve going into an 
unfamiliar environment.

My preferred option, should this be a real issue, is one of 
re-configuration. As I've been thinking 'organ' from the word go, I 
might indeed split the device into ranges with one of the 6 sections 
becoming a stop covering the 'squeaky' notes at a reduced sample rate.

 From the input of Dave/Tom/Scott, I like the idea of breaking things 
down into octave+note (where note can be a fractional value rather than 
just plain 12 increments.) Furthermore, I'm thinking of taking away the 
job of working out the timer register values from devices doing the 
clock generation so that the master/assigner device takes on this task - 
the clock generators would then be fed the actual values to be plugged 
into the timer registers.

This complicates the controller software (per my response to Veronica) 
but, having thought about it, not that much. The assigner would also 
send note messages only to stops within whose range the note falls.

With the assigner only receiving MIDI and doing a calculation only at 
note-on, I don't think the maths will result in any audible delays. 
Heck, a 20-cycle calculation at 20MHz is only going to take 1us.

Cheers

M


-- 
Matthew Smith

Blog: www.smiffysplace.com  Business: www.smiffytech.com
www.linkedin.com/in/smiffy  www.flickr.com/photos/msmiffy
twitter.com/smiffy