Microchip Technology dsPIC30F - Page 675

© 2004 Microchip Technology Inc.. DS70071C-page 24-3
Section 24. Device Configuration
Device
Configuration
24
Register 24-1: FOSC: Oscillator Configuration Register
Upper Byte:
UU UUUUUU
— — — — — — — —
bit 23 bit 16
Middle Byte:
R/P R/P U U U U R/P R/P
FCKSM<1:0>
— — — —FOS<1:0>
bit 15 bit 8
Lower Byte:
U U U U R/P R/P R/P R/P
— — — —FPR<3:0>
bit 7 bit 0
bit 23-16 Unimplemented: Read as ‘0’
bit 15-14 FCKSM<1:0>: Clock Switching Mode Selection Fuses bits
1x = Clock switching is disabled, Fail-Safe Clock Monitor is disabled
01 = Clock switching is enabled, Fail-Safe Clock Monitor is disabled
00 = Clock switching is enabled, Fail-Safe Clock Monitor is enabled
bit 13-10 Unimplemented: Read as ‘0’
bit 9-8 FOS<1:0>: Oscillator Source Selection on POR bits
11 = Primary Oscillator (Primary Oscillator mode selected by FPR<3:0>)
10 = Internal Low Power RC Oscillator
01 = Internal Fast RC Oscillator
00 = Low Power 32 kHz Oscillator (Timer1 oscillator)
bit 7-4 Unimplemented: Read as ‘0’
bit 3-0 FPR<3:0>: Primary Oscillator Mode Selection bits
1111 = EC w/ PLL 16x - External Clock mode with 16x PLL enabled. OSC2 pin is I/O.
1110 = EC w/ PLL 8x - External Clock mode with 8x PLL enabled. OSC2 pin is I/O.
1101 = EC w/ PLL 4x - External Clock mode with 4x PLL enabled. OSC2 pin is I/O.
1100 = ECIO - External Clock mode. OSC2 pin is I/O.
1011 = EC - External Clock mode. OSC2 pin is system clock output (F
OSC/4).
1010 = Reserved. Do not use.
1001 = ERC - External RC Oscillator mode. OSC2 pin is system clock output (F
OSC/4).
1000 = ERCIO - External RC Oscillator mode. OSC2 pin is I/O.
0111 = XT w/ PLL 16x - XT Crystal Oscillator mode with 16x PLL enabled (4 MHz-10 MHz crystal)
0110 = XT w/ PLL 8x - XT Crystal Oscillator mode with 8x PLL enabled (4 MHz-10 MHz crystal)
0101 = XT w/ PLL 4x - XT Crystal Oscillator mode with 4x PLL enabled (4 MHz-10 MHz crystal)
0100 = XT - XT Crystal Oscillator mode (4 MHz-10 MHz crystal)
001x = HS - HS Crystal Oscillator mode (10 MHz-25 MHz crystal)
000x = XTL - XTL Crystal Oscillator mode (200 kHz-4 MHz crystal)
Legend:
R = Readable bit P = Programmable bit U = Unimplemented bit