Thank you very much for your atention Mirter_e.
A "busy line" would work just fine but I´ve just realized that there´s need to know which computer has set which I/O. I am not sure if explain myself. Whenever PC1 sets an I/O port it is supposed to be shown in the PC2 and vice-versa. (USB Read and Write).
So here´s my idea from your tip. What if we have only one pic reading from or writing the I/O expander and whenever the second pic needs to do so, it just "tells" it to the pic number one through I2C ? Is it possible to have a bilateral comuniction with I2C ? See attached file.
I have no idea how the interruptions would work in this configuration
What do you say ???
Bookmarks