Re: Keypad for Raduino...?

Mark Pilant
 

Hi Jack.

That whole idea of using voltage to determine keyer state makes me nervous.
Even something as simple as corrosion on the contacts can make a difference.
True.

But then again I figure if I know how it works, and with some appropriate
debug code always built in, it would be pretty easy to track down a keypad
problem. Partially to address this issue, my SNA code has a min and max for
each key value and includes a calibration menu item to determine the average
value to use (which is then used to calculate the min and max). Not only does
this work for resistors that are slightly different values (but still within
tolerance) and can handle a slight variation in contact resistance as well.

If I wanted to really minimize contact issues, I'd use something other than a
(USD) $5-$10 keypad :-) I used the cheap one because the SNA started out as
not much more than a simple proof of concept. Funny how proof of concept
projects become the final project :-P

You are right, however, in that the problem has caused people to rethink the
problem(s) and that's almost always good.
I couldn't agree more. Maybe other will get some ideas from my SNA code. (I
haven't done a whole lot more with it since I picked up an HP 8591E spectrum
analyzer with a tracking generator. Although I was pleased to see my little
SNA agreed with the HP SA :-)

73

- Mark N1VQW

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