Datasheet

PIC18(L)F2X/45K50
DS30684A-page 388  2012 Microchip Technology Inc.
REGISTER 26-2: CONFIG1H: CONFIGURATION REGISTER 1 HIGH
R/P-0 R/P-0 R/P-1 U-0 R/P-0 R/P-1 R/P-0 R/P-1
IESO FCMEN
PCLKEN
—
FOSC<3:0>
bit 7 bit 0
Legend:
R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘0’
-n = Value when device is unprogrammed x = Bit is unknown
bit 7 IESO
(1)
: Internal/External Oscillator Switchover bit
1 = Oscillator Switchover mode enabled
0 = Oscillator Switchover mode disabled
bit 6 FCMEN
(1)
: Fail-Safe Clock Monitor Enable bit
1 = Fail-Safe Clock Monitor enabled
0 = Fail-Safe Clock Monitor disabled
bit 5 PCLKEN: Primary Clock Enable bit
1 = Primary Clock is always enabled
0 = Primary Clock can be disabled by software
bit 4 Unimplemented: Read as ‘0’
bit 3-0 FOSC<3:0>: Oscillator Selection bits
1111 = Reserved
1110 = Reserved
1101 = EC oscillator (low power, <4 MHz)
1100 = EC oscillator, CLKO function on OSC2 (low power, <4 MHz)
1011 = EC oscillator (medium power, 4 MHz - 16 MHz)
1010 = EC oscillator, CLKO function on OSC2 (medium power, 4 MHz - 16 MHz)
1001 = Internal oscillator block, CLKO function on OSC2
1000 = Internal oscillator block
0111 = External RC oscillator
0110 = External RC oscillator, CLKO function on OSC2
0101 = EC oscillator (high power, 16 MHz - 48 MHz)
0100 = EC oscillator, CLKO function on OSC2 (high power, 16 MHz - 48 MHz)
0011= HS oscillator (medium power, 4 MHz - 16 MHz)
0010= HS oscillator (high power, 16 MHz - 25 MHz)
0001= XT oscillator
0000= LP oscillator
Note 1: When FOSC<3:0> is configured for HS, XT, or LP oscillator and FCMEN bit is set, then the IESO bit
should also be set to prevent a false failed clock indication and to enable automatic clock switch over from
the internal oscillator block to the external oscillator when the OST times out.