ODP: digital keyboard controller...how to build one...?

[Roman Sowa]

Or something like I did with CD4000 series long time ago
(it was first board for my Poly) and connect DAC to it.
It outputs serial data (key number) and has a separate
signal indicating if key of number just sent is pressed.
I kinda abandoned the idea of explaining everything
on my webpage, so far there's only the scanner
schematic. If you're interested I can add output timings
and more info.
But I would never do it again this way, but with a micro.

and the scanner is there:
http://www.multimania.com/romcio/f_kbsc.gif

hope it helps (to keep you from making it with MSI)
Roman

-----Oryginalna wiadomooeæ-----
Od: Doug Ferrell [mailto:dougf at flashpnt.com]
Wys³ano: 2 wrzeoenia 1999 19:21
Do: 'Matti E. Leino'; 'SynthDIY'
Temat: RE: digital keyboard controller...how to build one...?


Matti,
	I've got a partially functioning prototype of such a device which I
built
last year.  I used TTL because I wanted to do some more interesting things
(there are a lot more variations of the basic MSI digital building blocks in
the TTL family than in 4xxx CMOS).  For a basic scanner, CMOS would probably
be best.
	Anyway, the basic idea is to have a fairly high speed clock (I used
something about 100kHz) to drive a digital counter.  The counter generates