Ben Hencke <PICLIST@mitvma.mit.edu> wrote:

> Unless I am losing my mind, I currently use IOC on a running 12f629 to
> detect pin changes. I constantly write to GPIO using MOVWF and have no
> problems.

    Newer PICs don't have the problems that older PICs do; perhaps
    the 12F629 is one of those newer PICs.

> IIRC on these chips, you can write to the port and it will not reset
> the IOC internal latch values (internal latch not GPIF interupt flag
> or whatever). However, BSF, BCF, ANDWF, etc are all read-modify-write
> instructions that will cause a "read" and reset the IOC latches. So
> you would have to use MOVWF to update your pins without messing up the
> IOC.

    On PICs with the Interrupt-on-Change problem, an internal read is
    performed even for MOVWF instructions, so reads AND writes reset
    the Interrupt-on-Change latches.

    -Andy

=== Andrew Warren -- aiw@cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics