Thank you all for the excellent information and resources. I
had checked Microchip and MikroElektronica sites and found
nothing. I missed the significance of the current rating for
the internal pullups.

I have been experimenting with a slightly different kind of
matrix keypad. Instead of shorting row and column, it
grounds both. This eliminates the need to scan and allows
the selection of multiple key presses although not all may
be unique. I think much of the problem I have seen has been
caused by capacitance. Earlier I didn't think about the R-C
timer effect. If I connect the keypad with a foot of cat-5
cable the 20k resistors work fine. If I use 6" of ribbon
cable 20k is too big but 4k7 or slightly less works fine.
There also appears to be a difference depending on which end
of the cable the resistors are attached although I have not
tested this very well.=20

Thanks again,
Allen



--=20
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