The oscillator type is selected by the FOSC bits of the configuration register:

11	RC oscillator
10	HS oscillator
01	XT oscillator
00	LP oscillator

Oscillator Types

HS, XT or LP Crystal or Ceramic Resonator Circuit

Resistor R1 may be required for AT strip cut crystals.

Ceramic Resonator Capacitor Selection
Mode	Freq	C1, C2
XT	455 kHz	47-100 pF
	2 MHz	15-33 pF
	4 MHz	15-33 pF
HS	8 MkHz	15-33 pF
	10 MHz	15-33 pF

Crystal Oscillator Capacitor Selection
Mode	Freq	C1, C2
LP	32 kHz	68-100 pF
	200 kHz	15-33 pF
XT	100 kHz	100-150 pF
	2 MHz	15-33 pF
	4 MHz	15-33 pF
HS	4 MHz	15-33 pF
	20 MHz	15-33 pF

RC Circuit

t = R * C


and


f=1 / T


t = time in Seconds
R = resistance in Ohms
C = capacitance in Farads
f = frequency in Hertz


recommended resistance value of 5K to 100K
recommended capacitance value of 20pF