Mike,

> The clock/MCU is running at 4Mhz and I am using RB6 as an output to an
> unrelated task. It is only RB7 that receives the input.

> > use pin RB7/T1OSI as an input pin for the counter. The pin is
> > receiving a
> > square wave signal between 13Khz and 15Khz of 0V to 5V.
> >
> > My dev settings are T1CON = 0x0F == Prescale 1:1, T1OSCEN =
> > 1, T1SYNC = 1,
> > TMR1CS = 1, TMR1ON.
>

I thik you can not do this, look on the page 41 (fig 5-14) of the F628 spec
(40300b.pdf) and you can see that TMR1 clock is feed via an Shmitt trigger
directly from the RB6 pin, so you can not use RB6 as output and timer input
at the same time. When you use RB7 as a timer1 input, the signal flows via
an inverter til the pin RB6. I Think there is some kind of contention in
this situation.

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