Keyboard scanner

[Hallgeir Helland]

Hi folks,

I've now designed a microcontroller based keyboard scanner
based on the diode matrix idea (thanks Paul!) but I have 
this one thought....

I'm using the Motorola 68HC705 µC and it has TTL architecture
(or so my teacher sez) and since I'll be using diodes on
each switch, there will be a voltage drop of about 0.6 V
on the input of the µC, right? Will it matter having 4.3 V
on the input instead of 5 V ?  Should I use buffers or 
something? 

BTW: I'm using Protel '98 (trial version) for PCB design. OK.

Thanks,
Hallgeir


BTW:: Check << www.netpower.no/~roarh/synth.htm >> if you care.
	Not much yet, but it'll all be there eventually.  :-)

-- 
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 Hallgeir Helland       hhelland at usa.net      
    Evlogia           http://fly.to/evlogia   
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