Datasheet

PIC16F631/677/685/687/689/690
DS41262E-page 48 © 2008 Microchip Technology Inc.
3.2 Oscillator Control
The Oscillator Control (OSCCON) register (Figure 3-1)
controls the system clock and frequency selection
options. The OSCCON register contains the following
bits:
• Frequency selection bits (IRCF)
• Frequency Status bits (HTS, LTS)
• System clock control bits (OSTS, SCS)
REGISTER 3-1: OSCCON: OSCILLATOR CONTROL REGISTER
U-0 R/W-1 R/W-1 R/W-0 R-1 R-0 R-0 R/W-0
— IRCF2 IRCF1 IRCF0 OSTS
(1)
HTS LTS SCS
bit 7 bit 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
bit 7 Unimplemented: Read as ‘0’
bit 6-4 IRCF<2:0>: Internal Oscillator Frequency Select bits
111 =8MHz
110 = 4 MHz (default)
101 =2MHz
100 =1MHz
011 = 500 kHz
010 = 250 kHz
001 = 125 kHz
000 = 31 kHz (LFINTOSC)
bit 3 OSTS: Oscillator Start-up Time-out Status bit
(1)
1 = Device is running from the clock defined by FOSC<2:0> of the CONFIG register
0 = Device is running from the internal oscillator (HFINTOSC or LFINTOSC)
bit 2 HTS: HFINTOSC Status bit (High Frequency – 8 MHz to 125 kHz)
1 = HFINTOSC is stable
0 = HFINTOSC is not stable
bit 1 LTS: LFINTOSC Stable bit (Low Frequency – 31 kHz)
1 = LFINTOSC is stable
0 = LFINTOSC is not stable
bit 0 SCS: System Clock Select bit
1 = Internal oscillator is used for system clock
0 = Clock source defined by FOSC<2:0> of the CONFIG register
Note 1: Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe
mode is enabled.