🚀 go-pugleaf

In article <92315.190637DI3QC@CUNYVM.BITNET> <DI3QC@CUNYVM.BITNET> writes:
>     I am planning to interface a keypad to the io lines of an hc11. Does anyon
>e have any suggestions on connecting a keypad. I was planning to scan the keypa
>d by driving one of the rows hi and testing the columns. I was planning on test
>ing this every 20ms. How would I take care of debouncing etc. Any suggestions.

You're on the right track...

Various places sell row/column encoded keypads.  Even Newark has some new
4x4 keypads that I like a lot (nice feel, you can get different colored
keys, etc.) for a very reasonable $10-$15.  Surplus places often have 
keypads for $1 or less, if you don't care what you're getting. :-)

If you scan every 20ms, you simply don't need to take care of debouncing --
switches don't bounce for anywhere _near_ that long!  (Consider that most
humans can hit a switch twice in somewhat <20ms -- go play with a stop
watch...).

If you're lucky, someone will have already done the code for this, since
it's a pretty common application (although it doesn't take very long to
do it yourself, either).  You might want to check the Motorola BBS for
this stuff.

						---Joel Kolstad