Keyboard scanner

[Beszedes Arpad]

Hallgeir Helland wrote:
> 
> 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.
> 

I've tried Protel98 also, but I'm not satisfied with it: I've been using
autotrax for ages and it was more than good (not a single problem with
it in >5 years). But when I first started Protel98 (importing my old
autotrax design) it crashed, and again, and again....
And there were other situations too when completely with no reason it
simply crashed.
Of course there are a lot of new features and a nice (maybe too nice)
user interface, but I have a feeling that I'd be more satisfied with a
smaller set of options but with a REALLY reliable and stabile tool.
That's my experience and opinion.

Regards,
  Arpad.



> Thanks,
> Hallgeir
> 
> BTW:: Check << www.netpower.no/~roarh/synth.htm >> if you care.
>         Not much yet, but it'll all be there eventually.  :-)
> 
> --
> .,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.
>  Hallgeir Helland       hhelland at usa.net
>     Evlogia           http://fly.to/evlogia
> '¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'

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*  Arpad Beszedes                             *
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*  Hungarian Academy of Sciences              *
*  Attila Jozsef University, Szeged, Hungary  *
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