PIC24FJ256GA106T-I Datasheet, PDF (107/292 Pages) Microchip Technology – 64/80/100-Pin, 16-Bit General Purpose Flash Microcontrollers with Peripheral Pin Select

PIC24FJ256GA110 FAMILY
7.3 Control Registers
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.
The CLKDIV register (Register 7-2) controls the
features associated with Doze mode, as well as the
postscaler for the FRC oscillator.
The OSCTUN register (Register 7-3) allows the user to
fine tune the FRC oscillator over a range of approxi-
mately ±12%. Each bit increment or decrement
changes the factory calibrated frequency of the FRC
oscillator by a fixed amount.
REGISTER 7-1: OSCCON: OSCILLATOR CONTROL REGISTER
U-0
R-0
R-0
R-0
U-0
R/W-x⁽¹⁾
—
COSC2
COSC1
COSC0
—
NOSC2
bit 15
R/W-x⁽¹⁾
NOSC1
R/SO-0
CLKLOCK
bit 7
R/W-0
IOLOCK⁽²⁾
R-0⁽³⁾
LOCK
U-0
R/CO-0
R/W-0
R/W-0
—
CF
POSCEN SOSCEN
R/W-x⁽¹⁾
NOSC0
bit 8
R/W-0
OSWEN
bit 0
Legend:
R = Readable bit
-n = Value at POR
CO = Clear Only bit
W = Writable bit
‘1’ = Bit is set
SO = Set Only bit
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 15
bit 14-12
bit 11
bit 10-8
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⁽¹⁾
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)
Note 1:
2:
3:
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.
© 2008 Microchip Technology Inc.
Preliminary
DS39905B-page 105