Datasheet page 6 (table 1, pin allocation table), shows INT is on RA2
and has quite a few other peripherals attached; are you confident you
aren't driving the pin from any of those other peripherals in the
chip?  I'd be worried about SRQ, C1OUT, and CCP3, per section 12.2.3.

Figure 12-1, Generic I/O Port Operation, doesn't show how peripherals
output to a shared pin.  I've no recent experience to share.

Interesting note on page 124, are you changing the input threshold
selection INLVLA at all?  If so, expect spurious input.

Reference:

http://datasheet.octopart.com/PIC16F1828-I/SS-Microchip-datasheet-12511458.=
pdf

On Wed, Dec 23, 2015 at 02:36:39PM +1100, K S wrote:
> Hi list.
>=20
> Apologies, I accidentally sent a truncated message prior to this one.
>=20
> I have a 100Hz square wave (from rectified mains) driving the INT0 pin on=
 a
> 16F1828. I'm after interrupts on a single edge only - don't care whether
> rising or falling.
>=20
> I can do this (v1) in my INT0 interrupt routine and it works as expected:
>=20
> InterruptIntPin
>     BANKSEL    OPTION_REG
> ;determine polarity of egde
>     btfsc    OPTION_REG,INTEDG
>     goto    InterruptIntPinRising
> InterruptIntPinFalling
>     bsf    OPTION_REG,INTEDG
> ;next interrupt on rising edge
>     BANKSEL    0
>     goto    InterruptIntPinEnd
> InterruptIntPinRising
>     bcf    OPTION_REG,INTEDG
> ;next interrupt on falling edge
>     BANKSEL    0
>     ;do stuff here
> InterruptIntPinEnd
>     bcf      INTCON,INTF
> ;allow INT interrupts again
>     retfie
>=20
> but if I do this (v2) it follows both edges on INT0:
>=20
> InterruptIntPin
>     BANKSEL    0
>     ;do stuff here
>     bcf      INTCON,INTF
> ;allow INT interrupts again
>     retfie
>=20
> That makes no sense to me. V2 should only be invoked on a single edge, no=
t
> both. No other changing of OPTION_REG occurs anywhere else.
>=20
> Does anyone have any idea why this may be happening?
>=20
> Cheers. Kris.
>=20
>=20
>=20
> On Wed, Dec 23, 2015 at 2:29 PM, K S <kresho@gmail.com> wrote:
>=20
> > I have a 100Hz square wave driving the INT0 pin on a 16F1828. I'm after
> > interrupts on a single edge only - don't care whether rising or falling=
..
> >
> > I can do this in my INT0 interrupt routine and it works as expected:
> >
> > InterruptIntPin
> >     BANKSEL    OPTION_REG
> > ;determine polarity of egde
> >     btfsc    OPTION_REG,INTEDG
> >     goto    InterruptIntPinRising
> > InterruptIntPinFalling
> >     bsf        OPTION_REG,INTEDG
> > ;next interrupt on rising edge
> >     BANKSEL    0
> >     goto    InterruptIntPinEnd
> > InterruptIntPinRising
> >     bcf        OPTION_REG,INTEDG
> > ;next interrupt on falling edge
> >     BANKSEL    0
> >
> >     incf    R_PSUPeaksCounter,F
> > ;increment the peak counter
> >     bsf        B_INTSignalDetected
> >
> >
> >
> --=20
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist

--=20
James Cameron
http://quozl.netrek.org/
--=20
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View/change your membership options at
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.