PIC18F2450/4450
REGISTER 18-2: CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h)
R/P-0
IESO
R/P-0
U-0
—
U-0
—
R/P-0
FOSC3(1)
R/P-1
FOSC2(1)
R/P-1
FOSC1(1)
R/P-1
FOSC0(1)
FCMEN
bit 7
bit 0
Legend:
R = Readable bit
P = Programmable bit
U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed
u = Unchanged from programmed state
bit 7
bit 6
IESO: Internal/External Oscillator Switchover bit
1= Oscillator Switchover mode enabled
0= Oscillator Switchover mode disabled
FCMEN: Fail-Safe Clock Monitor Enable bit
1= Fail-Safe Clock Monitor enabled
0= Fail-Safe Clock Monitor disabled
bit 5-4
bit 3-0
Unimplemented: Read as ‘0’
FOSC3:FOSC0: Oscillator Selection bits(1)
111x= HS oscillator, PLL enabled (HSPLL)
110x= HS oscillator (HS)
1011= Internal oscillator, HS oscillator used by USB (INTHS)
1010= Internal oscillator, XT used by USB (INTXT)
1001= Internal oscillator, CLKO function on RA6, EC used by USB (INTCKO)
1000= Internal oscillator, port function on RA6, EC used by USB (INTIO)
0111= EC oscillator, PLL enabled, CLKO function on RA6 (ECPLL)
0110= EC oscillator, PLL enabled, port function on RA6 (ECPIO)
0101= EC oscillator, CLKO function on RA6 (EC)
0100= EC oscillator, port function on RA6 (ECIO)
001x= XT oscillator, PLL enabled (XTPLL)
000x= XT oscillator (XT)
Note 1: The microcontroller and USB module both use the selected oscillator as their clock source in XT, HS and
EC modes. The USB module uses the indicated XT, HS or EC oscillator as its clock source whenever the
microcontroller uses the internal oscillator.
DS39760A-page 192
Advance Information
© 2006 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
