So, it turns out, I'm an idiot (as I figured I would be).

After 24 hours of cogitating and trial-and-error, I discovered that in order
to successfully use the capture mode, it is *very* important to disable the
external clock oscillator circuit.

Would have been nice for the PIC to do that for me, if I set Timer 1 to
internal, but alas, it doesn't. That coupled with my misunderstanding of
just what that clock oscillator was (I was thinking: of course I want the
oscillator enabled, how else will Timer 1 increment?), and I kept
overlooking it.

One simple bit.

Well, if anyone had the answer, sorry to have beaten you to the punch, but
thanks anyway!



> Hi. I've been working on this all day, and I have no idea what I'm doing
> wrong.
>
> I want to capture falling edges on a PIC16F877 using CCP2 on pin PORTC:1. In
> an effort to narrow down why it wasn't working, I came up with this code:
>
> Loop
>   movfw   PORTC
>   movwf   PORTD
>   goto    Loop
>
> This code works, if the PIC is minimally configured. PORTD is a bunch of LEDs,
> PORTC is configured as b'11000010' (three inputs, the rest outputs, 7:0).
>
> If, however, I attempt to write a value to CCP2CON before executing this code,
> PORTC:1 is never read properly (always reads as 0). I've tried setting CCP2CON
> to b'00000100', capture every falling edge.
>
> If anyone has any insight, I'd really appreciate it. BTW, I've checked and
> re-checked things like proper bank, and so forth. I also tried multiple PICs.
>
> TIA,

--
Rick

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