> =

> A nice way to solve this (and if the I/O pins do not have to
> e switched fast, such as e.g. indicator LEDs), is to only
> BSF/BCF the "shadow" bits in the main code, and only copy
> to the port in the ISR. That way you can manipulate the
> indicator-LED bits wherever there is a need, and have a
> safe update of the PORTx register in a single place in the
> ISR.
> =

> Jan-Erik.
> =

> =


Yes, and to make things even easier in the code and not need to bother abou=
t =

atomic operations there could be several shadow registers which each holds =
just =

a group of bits or even single bits (flags) where each shadow register is =

manipulated by different parts of the code, both isr and non isr code. The =

(timer-) isr then combines all shadow registers to one single byte and writ=
es =

them all at once to the port.

/Ruben

 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
-- =

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