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...

Try it with a shadow register...
	latd_shadow += 1;
     LATD = latd_shadow;

> void delay (void)
> {
>   for (i = 0; i < 10000; i++)
>     ;
> }
>
Depending on compiler specifics, this might be a very short
delay to pair to human perceptions.  I have a "flame" simulator
that changes the brightness of some LEDs with a 128 count inner
PWM loop and a 50 count outer loop (so, approximately equivilent
to a 6400 count single loop) that flickers at a reasonably
realistic rate (several times per second, at least), and it has
a lot more stuff in the inner loop than your code.  I seem to
recall that PICs at nominal frequency take 24 bits worth of
count to get delays in the one-second range.  (Hmm.  That was
implicit in your timer-based attempt.  prescale of 32 on a a
16 bit counter is ~2million cycles per second.)  I would hope
your compiler does the delay loop in far less than 100 cycles,
for a delay period of far less than 0.5 seconds...

BillW

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