Microchip Technology DM183037 Data Sheet
2012 Microchip Technology Inc.
DS30575A-page 39
PIC18F97J94 FAMILY
3.2
Oscillator Configuration
The oscillator source (and operating mode) that is used
at a device Power-on Reset (POR) event is selected
using Configuration bit settings. The Oscillator Configu-
ration bit settings are in the Configuration registers
located in the program memory (refer to
at a device Power-on Reset (POR) event is selected
using Configuration bit settings. The Oscillator Configu-
ration bit settings are in the Configuration registers
located in the program memory (refer to
for more information). The
Primary Oscillator Configuration bits, POSCMD<1:0>
(CONFIG3L<1:0>), and Oscillator Configuration bits,
(CONFIG3L<1:0>), and Oscillator Configuration bits,
FOSC<2:0> (CONFIG2L<2:0>), select the oscillator
source that is used at a POR. The FRC Oscillator with
Postscaler (FRCDIV) is the default (unprogrammed)
selection. The Secondary Oscillator, or one of the inter-
nal oscillators, may be chosen by programming these bit
locations.
The Configuration bits allow users to choose between
11 different clock modes, as shown in
source that is used at a POR. The FRC Oscillator with
Postscaler (FRCDIV) is the default (unprogrammed)
selection. The Secondary Oscillator, or one of the inter-
nal oscillators, may be chosen by programming these bit
locations.
The Configuration bits allow users to choose between
11 different clock modes, as shown in
.
TABLE 3-1:
CONFIGURATION BIT VALUES FOR CLOCK SELECTION
Oscillator Mode
Oscillator Source
POSCMD<1:0>
FOSC<2:0>
Notes
Fast RC Oscillator with
Postscaler (FRCDIV)
Postscaler (FRCDIV)
Internal
11
111
Fast RC Oscillator divided by 16
(FRC500kHz)
(FRC500kHz)
Internal
11
110
Low-Power RC Oscillator (LPRC)
Internal
11
101
Secondary (Timer1) Oscillator
(SOSC)
(SOSC)
Secondary
11
100
Primary Oscillator (HS) with PLL
Module (HSPLL)
Module (HSPLL)
Primary
10
011
Primary Oscillator (MS) with PLL
Module (MSPLL)
Module (MSPLL)
Primary
01
011
Primary Oscillator (EC) with PLL
Module (ECPLL)
Module (ECPLL)
Primary
00
011
Primary Oscillator (HS)
Primary
10
010
Primary Oscillator (MS)
Primary
01
010
Primary Oscillator (EC)
Primary
00
010
Fast RC Oscillator with PLL Module
(FRCPLL)
(FRCPLL)
Internal
11
001
Fast RC Oscillator (FRC)
Internal
11
000
Note 1:
OSC2 pin function is determined by the CLKOEN Configuration bit.
2:
Default oscillator mode for an unprogrammed (erased) device.