[sdiy] Keyboard scanning rate

[Neil Johnson]

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
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http://www.njohnson.co.uk