The explanation of interrupt so you don't have to look is as follows interrupt: the number of the interrupt (int)
function: the function to call when the interrupt occurs; this function must take no parameters and return nothing. This function is sometimes referred to as an interrupt service routine.
mode defines when the interrupt should be triggered. Four contstants are predefined as valid values:
LOW to trigger the interrupt whenever the pin is low, CHANGE to trigger the interrupt whenever the pin changes value RISING to trigger when the pin goes from low to high, FALLING for when the pin goes from high to low.
The question is for CHANGE. It says whenever the pin changes values but this is vague. For my 1284p the interrupt is on the TX1 pin which is digital. This should mean it interrupts whenever there is a rising or falling edge. I have a qrd1114 encoder counter that gives an analog output to the INT1 input pin. So the final question is this. It ignores analog because it does not have the capability of a ADC and only changes when the pin drops over the high or low threshold for digital right? ... Or does this pin have a ADC?