Microchip Technology PIC24FV16KM204 FAMILY, Техническое описание

Страница: 123 / 336


2013 Microchip Technology Inc.
Advance Information
DS33030A-page 123
PIC24FV16KM204 FAMILY
9.3 Control Registers
The operation of the oscillator is controlled by three
Special Function Registers (SFRs):
• OSCCON
• CLKDIV
• OSCTUN
The OSCCON register (
Register 9-1 ) is the main
control register for the oscillator. It controls clock
source switching and allows the monitoring of clock
sources.
The Clock Divider register ( Register 9-2 ) controls the
features associated with Doze mode, as well as the
postscaler for the FRC oscillator.
The FRC Oscillator Tune register (
Register 9-3 ) allows
the user to fine-tune the FRC oscillator over a range of
approximately ±5.25%. Each bit increment or decre-
ment changes the factory calibrated frequency of the
FRC oscillator by a fixed amount.
REGISTER 9-1: OSCCON: OSCILLATOR CONTROL REGISTER
U-0 R-0, HSC R-0, HSC R-0, HSC U-0 R/W-x
( 1 )
R/W-x
( 1 )
R/W-x
( 1 )
— COSC2 COSC1 COSC0 — NOSC2 NOSC1 NOSC0
bit 15 bit 8
R/SO-0, HSC U-0 R-0, HSC
( 2 )
U-0 R/CO-0, HS R/W-0
( 3 )
R/W-0 R/W-0
CLKLOCK — LOCK — CF SOSCDRV SOSCEN OSWEN
bit 7 bit 0
Legend: HSC = Hardware Settable/Clearable bit
HS = Hardware Settable bit CO = Clearable Only bit SO = Settable Only bit
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 15 Unimplemented: Read as ‘
0
’
bit 14-12 COSC<2:0>: Current Oscillator Selection bits
111
= 8 MHz Fast RC Oscillator with Postscaler (FRCDIV)
110
= 500 kHz Low-Power Fast RC Oscillator (FRC) with Postscaler (LPFRCDIV)
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
= 8 MHz FRC Oscillator with Postscaler and PLL module (FRCPLL)
000
= 8 MHz FRC Oscillator (FRC)
bit 11 Unimplemented: Read as ‘
0
’
bit 10-8 NOSC<2:0>: New Oscillator Selection bits
( 1 )
111
= 8 MHz Fast RC Oscillator with Postscaler (FRCDIV)
110
= 500 kHz Low-Power Fast RC Oscillator (FRC) with Postscaler (LPFRCDIV)
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
= 8 MHz FRC Oscillator with Postscaler and PLL module (FRCPLL)
000
= 8 MHz FRC Oscillator (FRC)
Note 1: Reset values for these bits are determined by the FNOSCx Configuration bits.
2: This bit also resets to ‘
0
’ during any valid clock switch or whenever a non-PLL Clock mode is selected.
3: When SOSC is selected to run from a digital clock input, rather than an external crystal (SOSCSRC =
0
),
this bit has no effect.