[sdiy] MIDI to Scanned Keyboard

Tom Arnold xyzzy at sysabend.org
Sun Jul 17 22:11:04 CEST 2016

I've been pondering a project and I'm looking for ideas to on how to do it
and perhaps not completely re-invent the wheel.

Have an old interface card for a music system.  The keyboards for the system
are ancient and j-wire and just not a huge amount of fun to keep maintained.
The card plugs into a standard computer bus.  I haven't drawn out the
schematic yet of the interface card ( very simple TTL logic ) or the small
board and diode arrays in the keyboard ( also simple TTL ) but I'm assuming
its just key scanning and some buffering.

Here's my question.   The keyboard is velocity sensitive.  So, the time
between contact release and second contact close is the velocity.

If I use a midi keyboard, I get a Note and a Velocity.  My first thought is
to just simulate ( to the bus ) the contact release and contact close, but
this will put it slightly behind when the key was actually struck.  Okay,
simple enough but I'm curious if anyone has done something like this and if
the delay was noticable.

I need to sit down and actually get the timings of everything, but this is
one of many projects in a far too vast pile of them I'm juggling, so I'm
hoping someone has some feedback I can add to my ponderings until it gets
enough momentum that I actually do it.


 - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
 - SynthGeek        -  "...is it a virus, a drug, or a religion?"
 - K6AET            -  Juanita Shrugs. "What's the difference? 
 --------------------         -- Neal Stephenson,  Snow Crash

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