> What are some ways to go about this while keeping power low? I
> know I can poll each button until I find one high, but the processor
> will always be at full power doing this. What about using a simple logic
> gate to OR/NOR all the switches together to an interrupt pin to wake
> the processor up?

Scott,

that's what keyboard and button processing ICs (like infra-red remote
controls) do. An output pin goes low at any key press as an interrupt
line to a micro etc

A couple of something like the 4072 (dual 4-input OR) would do what
you're thinking of, or just 16 diodes. I've done this to make an INT
signal when using just a few buttons

The traditional way would be to arrange the 16 as a 4 x 4 and use IOC
(Interrupt-On-Change). If the PIC is inactive, the buttons will not be
being scanned so pull-ups (internal are available) on the columns (PortB
<4:7> ) and lows on the 4 row drive pins. On interrupt/wake-up, you'd
know only which column caused the IOC, so scan to get the row

>From the 2420/2520 datasheet

9.8 PORTB Interrupt-on-Change

An input change on PORTB<7:4> sets flag bit, RBIF (INTCON<0>).
The interrupt can be enabled/disabled by setting/clearing enable bit,
RBIE (INTCON<3>). Interrupt priority for PORTB interrupt-on-
change is determined by the value contained in the interrupt priority bit,
RBIP (INTCON2<0>)

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