Checking to see if a pin is High or Low

[The Rookie]

I would like to develop a routine that checks to see if a pin is High or Low.

If the Pin is high it will do one thing of it is low it will do another.

Thanks

The Rookie

[Joyce]

if(input(PIN_Ax)) // pin high
{
do high
}
else
{
do low
}

[Suus]

Hello,

Can I make it shorter like:

if(PIN_Ax)
{
}

else
{
}

????

Susan

[Haplo]

Not in that format, but you can define a 'bit' like this:

#bit RA1=0x05.1 //On PIC16F877, 0x05 is the address of PORTA.

Now you can say:

RA1=1;

or

if(RA1)
{
...
}
else
{
...
}

[ckielstra]

Please note that the for the shorter version to work you will also have to define the I/O pin as input first! While in the 'longer' version the compiler will do this for you.

So, what is 'shorter'.... ???

Both examples lead to similar assembly code, so I guess it's a matter of taste.

[Haplo]

Actually the pin doesn't need to be configured as input. You can use this method to read/verify the state of an output pin as well.

[Suus]

And how to check if a pin is low?

(input(!PIN_B0))

or

(!input(PIN_B0))

Susan

[Haplo]

input() is a C function, so:

if(!input(PIN_B0))
{
...
}