[sdiy] Keyboard scanning rate

[Ullrich Peter]

Hi Neil!

In the Korg Poly800 I measured around 950Hz.

Ciao
Peter

http://come.to/synpro
http://go.to/datadial


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Neil Johnson
Sent: Wednesday, November 25, 2009 3:39 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Keyboard scanning rate

Hi,

The keyboard scanner for my Siel project is progressing well.  I'm at the point of deciding on the scanning rate, anything from 500us/scan upwards (2000 scan/s downwards).  Has anyone else built their own keyboard scanner and what scan rate did you use?

I'm also measuring note-on and note-off (release) velocity, so the scan rate affects the velocity (actually time-of-flight) measurement granularity.  A slower scan rate allows longer time measurement (slower velocity) vs. a faster scan rate gives greater resolution at fast playing, but not good at discriminating slower key actions.

The velocity range is limited by the 8-bit counters used to measure the time of flight.  

Comments welcome.

Cheers,
Neil
--
http://www.njohnson.co.uk
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