Datasheet

PIC16F631/677/685/687/689/690
DS40001262F-page 54  2005-2015 Microchip Technology Inc.
3.7.3 CHECKING TWO-SPEED CLOCK
STATUS
Checking the state of the OSTS bit of the OSCCON
register will confirm if the microcontroller is running
from the external clock source, as defined by the
FOSC<2:0> bits in the Configuration Word register
(CONFIG), or the internal oscillator.
FIGURE 3-7: TWO-SPEED START-UP
0 1 1022 1023
PC + 1
TOSTT
HFINTOSC
OSC1
OSC2
Program Counter
System Clock
PC - N
PC