On Fri, 2006-03-10 at 17:57 -0800, William Chops Westfield wrote:
> On Mar 10, 2006, at 11:51 AM, pic wrote:
> 
> > My C program for flashing leds is not working.
> >       /* Light the LEDs */
> >       LATD += 1;
> >
> 
> Both of your programs use this to 'toggle' the LEDs, but
> I'm not sure it's  a good idea due to the usual
> problems with Read/Modify/write on PICs.  Just because you
> wrote a 1 or 0 to a port pin doesn't mean that's what will
> be read back when you read the port...

Actually, that's the point of the LAT registers. The LAT registers map
directly to the latches that control the outputs. A read of these
registers reads the state of the actual latches for the outputs, there
is no influence from the outside world.

While a read-modify-write operation does occur, it will always read
correctly no matter what the port pins are at.

TTYL

-----------------------------
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http://repatch.dyndns.org:8383/pic_stuff/

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