Our current design connects an external clock crystal to P12. The clock does not seem to be working when used with any of the chip resources. In fact, even if I route that back to an output pin, it is just sitting high. When wiring this clock to a P3 pin, I am able to use it just fine. I understand that the P12 pins are SIO...do they require some special type of setup? I read in another post that there was an issue if the input buffer was not enabled for the pin. When I corrected that, I was able to see the clock on the P3 pin, but still no dice on the P12 pin. I currently have the pin set up as a digital input, hw connection, high impedance digital. I also have CMOS threshold and input buffer enabled.