> are any better ways to go.  This is not unlike driving an LED matrix,
> and while I followed a bit of that thread, most of it seemed to relate
> to pulsing the individual LED banks and not actually latching them.

Well, if it's acceptable to have a short pulse on an output before it
settles, you could use shift registers. This circuit requires just 3 pins

http://home.clear.net.nz/pages/joecolquitt/message.html

You could filter the outputs to get rid of the pulses, unless the devices
you're controlling aren't too responsive. Worst case (I think) would be
output 1 going from on to off and 2-50 are on. 49 "ons" would pass
through output 1 before the "off". Each of these "ons" is a handful of
instructions. Say 6 @ 100ns (ie a 40MHz PIC) * 49 = ~ 3us pulse

Here's a circuit for measuring multiple inputs using a shift register and
4051s

http://home.clear.net.nz/pages/joecolquitt/0pots.html

Note that this accesses just one line at any time, but I'm wondering
if a modification could be made with flip-flops to turn this from a single
input reader to a multiple output driver. As the output of the 4051 is
selected with ABC there's no travelling pulse train, so an individual
flip-flop could be changed

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist