Hi,
In fact, I'm more of a PICAXE user and I transform my "simple" codes with PBP to program small PICs.
I was trying to use interrupts...
The subtleties of the PICs are therefore quite nebulous for me and my English is not flexible and subtle enough to understand the mysteries of the data sheets.
In fact what I wanted to do initially seemed easy to me... but it doesn't seem to be the case

I just want to vary a variable named MODE from 0 to 3, 0 to 3, ..., when port GP0 (which has a pull-up resistor to Vcc) goes to zero state.

If someone could help me out with just this little routine, that would be great.
Thanks in advance.