How to set external clock source in PBP

[mister_e]

you can but if you check a specific DIGITAL pin, you can't do the Analog conversion on the same pin without changing something.
AND what is the use of converting a digital signal ... 0v or 5volt ADC=0 or 255

BUT if your waiting for a digital signal to do a analog conversion on another pin... for sure.

If PushButtonOnPORTABIT0 = 1 then
     ADCIN PORTA.1,Myvar
     SEROUT PORTC.0,N2400,[#Myvar]
endif

be sure of your setting of ADCONx register