PIC18F4550-IP Datasheet, PDF (296/438 Pages) Microchip Technology – 28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PIC18F2455/2550/4455/4550
REGISTER 25-2: CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h)
R/P-0
R/P-0
U-0
IESO
FCMEN
—
bit 7
U-0
R/P-0
R/P-1
R/P-0
R/P-1
—
FOSC3⁽¹⁾
FOSC2⁽¹⁾
FOSC1⁽¹⁾ FOSC0⁽¹⁾
bit 0
Legend:
R = Readable bit
P = Programmable bit
-n = Value when device is unprogrammed
U = Unimplemented bit, read as ‘0’
u = Unchanged from programmed state
bit 7
bit 6
bit 5-4
bit 3-0
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
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.
DS39632E-page 294
© 2009 Microchip Technology Inc.