Quote Originally Posted by Robotica1 View Post
As far as setting fuses I assume that when I choose 'EXTClk' as the oscillator fuse setting in ICProg that the correct settings will be applied. Perhaps I just didn't give the PIC time to fire. I will check the frequency of my 555 oscillator and try again. Please just clarify one thing: ?I totally vanish my XTAL setup (ie crystal and caps) and replace with a signal line in to RA7 from whatever oscillator setup I wish to use?
Yep, get rid of it all.
But, a 555 output will only work as an OSC1 input to the '628A if the 555 output swings far enough high and/or low. You might have to put some sort of buffer between the 555 and the PIC.