Date   : Sun, 18 Oct 2009 23:31:41 +0100
From   : bbcmicro@... (Ian Stocks)
Subject: New storage system suggestinons?

Phill Harvey-Smith wrote:
> You've just described exactly how the AtomClone keyboard works, I have 
> an AVR that decodes the PS/2 keyboard and then feeds it's results to an 
> MT8816 crosspoint switch, which in turn is connected to the Atom 
> keyboard hardware.
> 
> The clever bit is the crosspoint switch, it's basically an array of 
> electrically switchable switches arranged as an 8x16 matrix you 
> basically feed it row and column, and a data bit, if the bit is 0 then 
> the switch at the row/col is opened, if it is 1 it is closed.


I was thinking it should be possible to decode the inputs to the 7445 
(IC26) for the current row being scanned, and then have an output port 
connected to the inputs of the 8255 (IC25) to set the relevant pressed 
key. One possible problem is the delay between decoding the row scan and 
setting the output for a key being pressed.

Did you try doing it that way before using the crosspoint switch?

Ian.