PIC24FJ16GA MICROCHIP [Microchip Technology], PIC24FJ16GA Datasheet - Page 91

• Manufacturer Part Number: PIC24FJ16GA
• Description: 28/44-Pin General Purpose, 16-Bit Flash Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

7.3
The operation of the oscillator is controlled by three
Special Function Registers:
• OSCCON
• CLKDIV
• OSCTUN
The OSCCON register (Register 7-1) is the main con-
trol register for the oscillator. It controls clock source
switching and allows the monitoring of clock sources.
REGISTER 7-1:
© 2008 Microchip Technology Inc.
bit 15
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 15
bit 14-12
bit 11
bit 10-8
Note 1:
CLKLOCK
R/SO-0
U-0
—
2:
3:
Control Registers
Reset values for these bits are determined by the FNOSC Configuration bits.
The state of the IOLOCK bit can only be changed once an unlocking sequence has been executed. In
addition, if the IOL1WAY Configuration bit is ‘1’ once the IOLOCK bit is set, it cannot be cleared.
Also resets to ‘0’ during any valid clock switch or whenever a non-PLL Clock mode is selected.
Unimplemented: Read as ‘0’
COSC2:COSC0: Current Oscillator Selection bits
111 = Fast RC Oscillator with Postscaler (FRCDIV)
110 = Reserved
101 = Low-Power RC Oscillator (LPRC)
100 = Secondary Oscillator (SOSC)
011 = Primary Oscillator with PLL module (XTPLL, HSPLL, ECPLL)
010 = Primary Oscillator (XT, HS, EC)
001 = Fast RC Oscillator with Postscaler and PLL module (FRCPLL)
000 = Fast RC Oscillator (FRC)
Unimplemented: Read as ‘0’
NOSC2:NOSC0: New Oscillator Selection bits
111 = Fast RC Oscillator with Postscaler (FRCDIV)
110 = Reserved
101 = Low-Power RC Oscillator (LPRC)
100 = Secondary Oscillator (SOSC)
011 = Primary Oscillator with PLL module (XTPLL, HSPLL, ECPLL)
010 = Primary Oscillator (XT, HS, EC)
001 = Fast RC Oscillator with Postscaler and PLL module (FRCPLL)
000 = Fast RC Oscillator (FRC)
IOLOCK
COSC2
R/W-0
R-0
OSCCON: OSCILLATOR CONTROL REGISTER
(2)
CO = Clear Only bit
W = Writable bit
‘1’ = Bit is set
COSC1
LOCK
R-0
R-0
(3)
COSC0
R-0
U-0
PIC24FJ64GA004 FAMILY
—
Preliminary
SO = Set Only bit
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
(1)
R/CO-0
The Clock Divider register (Register 7-2) controls the
features associated with Doze mode, as well as the
postscaler for the FRC oscillator.
The FRC Oscillator Tune register (Register 7-3) allows
the user to fine tune the FRC oscillator over a range of
approximately ±12%. Each bit increment or decrement
changes the factory calibrated frequency of the FRC
oscillator by a fixed amount.
U-0
CF
—
R/W-x
NOSC2
U-0
—
(1)
x = Bit is unknown
SOSCEN
R/W-x
NOSC1
R/W-0
(1)
DS39881C-page 89
R/W-x
OSWEN
NOSC0
R/W-0
(1)
bit 8
bit 0