What you want are commonly called 'flags'.

Your interrupt routine sets a flag when it runs.

Then your non-interrupt routine periodically checks the flag to see if it i=
s set. When the flag is set the normal code then resets the flag and procee=
ds to do the procedure you want to run periodically. Then once the procedur=
e has completed it returns to whatever else your normal code is doing.

Note that you do need to protect against what is known as a 'race condition=
'. In the normal code before resetting the flag you need to disable the int=
errupt as the check and reset of the flag is not an atomic operation (i.e. =
it executes in one instruction that cannot be interrupted). I'll leave it t=
o others to provide example code for your chip.



>=20
> This should be a simple problem, but I've missed the solution.
>=20
> I'm programming a 16F684 in assembler.
>=20
> TMR0 interrupts every 4 milliseconds-1:16 prescaler.  It is used to time =
data
> input.
>=20
> A branch of the program processes in a few microseconds.  I want the
> program to wait until the next interrupt occurs.
>=20
> If I don't clear the TOIF flag before the RETFIE instruction the interrup=
t
> repeats in a continuous loop.
>=20
> I could monitor TMR0 and wait until it reaches 0xff--that would be close
> enough.
>=20
> But there should be some other way.  Any ideas?
>=20
> --
> Bob LeDoux <bobledoux@proaxis.com>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist

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