David BALDWIN wrote:

>         As usual, I have some questions today... I am using the check_keys
> routine from Bob Blick. In fact, it only detects falling edges on portA.
> I am searching for a routine that could decide between a single press on
> a switch and a long press on a switch (more than 500ms or 1s).

David,

Check out my debouncing routine to capture both edges:

http://www.interstice.com/~sdattalo/technical/software/pic/debounce.html

A simple way to check if a key is pressed for a "long time" is with
the following untested code:

        MOVF    previous_state,W        ;Get the previous state of the
                                        ;switch (i.e. the last time it
was
                                        ;debounced).
        XORWF   latest_state,W          ;Get the latest state of the
switch
        XORWF   previous_state,F        ;Save latest state as previous
state
        ANDLW   BIT_POS_OF_SWITCH       ;We're interested in this bit.
        SKPNZ                           ;or SKPZ if input is low on key
press
         INCFSZ a_counter,F             ;Detected a pressed key count
it.
          CLRF  a_counter               ;No detection, so clear the
counter.

If this little chunk of code runs once every 5ms and you want to measure
key presses longer than one half of a second, then you simply need to
monitor when "a_counter" exceeds 100 (base 10). The state of the switch
is the "debounced state". In other words, the debounce routine would
first
execute before this one. Anyone see the subtlety in the skips?

Scott

PS. John, CLRF DOES affect the Z-bit on 16Cxx parts too. You will have
to make many, many, many more mistakes before any embarassment is
warranted
though.