For some reason on the 16F1459 Microchip has chosen to put the external
interrupt  on the same pin as the in circuit serial programming clock.  The
PICKit 3 has a 4.7K pull down resistor on this line internally so Microchip
is pretty clear that you should not be adding an external pull up resistor
to this pin as you might do with an external interrupt if you were using
something like a push button.  Because there is a pull down resistor on
this line in the programmer, you could connect the push button to the
positive rail and detect a high when the button is pressed.  If you do this
with the PICKit 3, it will work when you are running the program, but this
disrupts debugger communication and so you can't use the in circuit
debugger with this set up.

Seems odd to me that Microchip would select this pin for the INT function,
but is there anyway to isolate this so you can use a PICKit 3 to do in
circuit debugging of firmware that uses the interrupt function?

John Hansen
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