Rafael:

It may be that you misunderstand the use of output_low().  The argument 
for this has to be a pin name.  Like output_low(PIN_A0).  And a pin name 
will be a constant.  I'm not sure how a value like 31744 could every be 
appropriate here.  You could use a switch or if construction to test a 
condition and set various different pins based on the test condition:

if (value == 31744) output_low(PIN_A0);
    else output_low(PIN_A1);

However, output_low(31744) would only make sense if 31744 referred to a pin.

You could also use the BIT_CLEAR command to accomplish this:

BIT_CLEAR(PORTA, 3);

Here, I believe the "3" could be a variable since it actually refers to 
a pin number, not a pin name.  However, I haven't tried this.

John Hansen

Rafael Vidal Aroca wrote:

>
>    Hi people,
>
>    i'd like to easily control all ports of my pic. I've been trying to 
> use output_low() and output_high() from ccs c, but seems that these 
> functions work only with constatns. Won't they work with variables?
>
>    I'm trying something like that
>
>    output_low(31744); // this works
>
>    value = 31744;
>    output_low(value);
>
>    ccs says that the expression must be a constant.
>
>    any ideas?
>
> thanks
>
> Rafael.



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