Hi Sami (Sami Khawam), in <34A81FF3.65E5@unet.univie.ac.at> on Dec 29 you wrote:

> How can I detect, in an open-drain line,
> a High signal from a device while the PIC
> is outputing a Low signal?
> Can a pin be read when the TRIS is set to
> output?

I don't know why you would want to do this?

Insert a resistor serially into the line.  Choose its value with the pullup
value in mind.  Make sure the pullup is on the remote side, not the PIC
side.

When the PIC outputs low and the remote does too, you will find 0V on the
remote side.  If the remote outputs 1, you will find several hundred mVs,
depending on the shunt resistor value.


                        O
                        |
                     pullup
                        |
             _____      |
PIC --------|_____|-----*----- remote
                    ^
                    |
            measurement point