PIC Configuration Bits and Oscillator Setup

Settings that live outside your program.

PIC chips keep a few configuration words that select the oscillator type, watchdog, brown-out detection, code protection and pin functions. They are written when you program the chip, not by normal code.

If the oscillator setting does not match what is connected, the chip may not start at all. Choose internal oscillator while testing, then move to a crystal when timing matters.

Compilers usually provide directives to set these words in your source file, so they are recorded with the project.