PIC16F737-I Datasheet, PDF (40/276 Pages) Microchip Technology – 28/40/44-Pin, 8-Bit CMOS Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC16F7X7
4.6.3 CLOCK TRANSITION AND WDT
When clock switching is performed, the Watchdog
Timer is disabled because the Watchdog Ripple
Counter is used as the Oscillator Start-up Timer (OST).
Note: The OST is only used when switching to
XT, HS and LP Oscillator modes.
Once the clock transition is complete (i.e., new oscilla-
tor selection switch has occurred), the Watchdog
Counter is re-enabled with the Counter Reset. This
allows the user to synchronize the Watchdog Timer to
the start of execution at the new clock frequency.
REGISTER 4-2:
OSCCON: OSCILLATOR CONTROL REGISTER (ADDRESS 8Fh)
U-0
R/W-0
R/W-0
R/W-0
R-0
R-0
R/W-0
—
IRCF2
IRCF1
IRCF0 OSTS⁽¹⁾ IOFS
SCS1
bit 7
R/W-0
SCS0
bit 0
bit 7
bit 6-4
bit 3
bit 2
bit 1-0
Unimplemented: Read as ‘0’
IRCF<2:0>: Internal RC Oscillator Frequency Select bits
000 = 31.25 kHz
001 = 125 kHz
010 = 250 kHz
011 = 500 kHz
100 = 1 MHz
101 = 2 MHz
110 = 4 MHz
111 = 8 MHz
OSTS: Oscillator Start-up Time-out Status bit⁽¹⁾
1 = Device is running from the primary system clock
0 = Device is running from the Timer1 oscillator (T1OSC) or INTRC as a secondary system clock
Note 1: Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the oscillator
mode.
IOFS: INTOSC Frequency Stable bit
1 = Frequency is stable
0 = Frequency is not stable
SCS<1:0>: Oscillator Mode Select bits
00 = Oscillator mode defined by FOSC<2:0>
01 = T1OSC is used for system clock
10 = Internal RC is used for system clock
11 = Reserved
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS30498C-page 38
 2004 Microchip Technology Inc.