Datasheet

PIC16F818/819
DS39598F-page 38  2001-2013 Microchip Technology Inc.
FIGURE 4-6: PIC16F818/819 CLOCK DIAGRAM
REGISTER 4-2: OSCCON: OSCILLATOR CONTROL REGISTER (ADDRESS 8Fh)
PIC18F818/819
CONFIG (FOSC2:FOSC0)
OSC1
OSC2
Sleep
LP, XT, HS, RC, EC
CPU
Peripherals
Postscaler
MUX
MUX
8 MHz
4 MHz
2 MHz
1 MHz
500 kHz
125 kHz
250 kHz
OSCCON<6:4>
111
110
101
100
011
010
001
000
31.25 kHz
31.25 kHz
Source
Internal
Oscillator
Block
WDT
31.25 kHz
8 MHz
Internal Oscillator
(INTRC)
(INTOSC)
U-0 R/W-0 R/W-0 R/W-0 U-0 R-0 U-0 U-0
— IRCF2 IRCF1 IRCF0 —IOFS— —
bit 7 bit 0
bit 7 Unimplemented: Read as ‘0’
bit 6-4 IRCF2:IRCF0: Internal Oscillator Frequency Select bits
111 = 8 MHz (8 MHz source drives clock directly)
110 = 4 MHz
101 = 2 MHz
100 = 1 MHz
011 = 500 kHz
010 = 250 kHz
001 = 125 kHz
000 = 31.25 kHz (INTRC source drives clock directly)
bit 3 Unimplemented: Read as ‘0’
bit 2 IOFS: INTOSC Frequency Stable bit
1 = Frequency is stable
0 = Frequency is not stable
bit 1-0 Unimplemented: Read as ‘0’
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown