On Mon, 24 Jun 2002 20:36:16 -0500, Nick Veys wrote:
>>Nick Veys wrote:
>This would work only I need individual control of each line.
>I've used
>BSF/BCF operations to do bit-banged SPI on a 16F84 before, and
>that
>worked just fine, it's hard to believe that I can't simply
>toggle some
>lines using those commands!

The difference is that you were probably driving logic inputs
when you bit banged that serial interface -- a very light load --
and the LED's load down the output pin because of the much
heavier output current. Big difference there!

>Should I use some kind of shadow register, set the bit in there
>and then
>move it to PORTA?  Sounds extremely backwards and kludgy.

Actually, it's the PIC's output port structure that's backwards
and kludgy. ;-)

Actually, it's a 6:1, half dozen the other scenario. There are
times when being able to read the actual port pin level vs. the
output register logic level can come in handy. You just have to
always be aware you are reading the output PIN level, not the
output register logic level.

Matt Pobursky
Maximum Performance Systems

P.S. More people have been skewered by this pitfall than probably
any other in the PIC world. Myself included...

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