4.6.1 OSCCON1

Oscillator Control Register1
Note:
  1. The default value (f/f) is determined by the CONFIG1[RSTOSC] Configuration bits. See Table 4-2.
  2. If NOSC is written with a reserved value (Table 4-3), the operation is ignored and NOSC is not written.
  3. When CONFIG1[CSWEN] = 0, this register is read-only and cannot be changed from the POR value.
  4. EXTOSC must meet the PLL specifications.
  5. EXTOSC configured by CONFIG1[FEXTOSC].
  6. HFINTOSC frequency is set with the HFFRQ bits.
  7. EXTOSC must meet the PLL specifications.
Name: OSCCON1
Offset: 0xE43

Bit 76543210 
  NOSC[2:0]NDIV[3:0] 
Access R/WR/WR/WR/WR/WR/WR/W 
Reset fffffff 

Bits 6:4 – NOSC[2:0]  New Oscillator Source Request bits(1,2,3)

The setting requests a source oscillator and PLL combination per Table 4-3.

Table 4-2. Default Oscillator Settings
CONFIG1[RSTOSC] SFR Reset Values (fff ffff) Initial FOSC Frequency
NOSC/COSC NDIV/CDIV OSCFRQ
111 111 0000 4 MHz EXTOSC per FEXTOSC
110 110 0010 FOSC = 1 MHz (4 MHz/4)
101 101 0000 LFINTOSC
100 100 0000 SOSC
011 Reserved
010 010 0000 4 MHz EXTOSC + 4xPLL(4)
001 Reserved
000 110 0000 64 MHz FOSC = 64 MHz
Table 4-3. NOSC Bit Settings
NOSC[2:0] Clock Source
111 EXTOSC(5)
110 HFINTOSC(6)
101 LFINTOSC
100 SOSC
011 Reserved
010 EXTOSC + 4x PLL(7)
001 Reserved
000 Reserved

Bits 3:0 – NDIV[3:0]  New Divider Selection Request bits(2,3)

The setting determines the new postscaler division ratio per Table 4-1.

Table 4-1. NDIV Bit Settings
NDIV[3:0] Clock Divider
1111-1010 Reserved
1001 512
1000 256
0111 128
0110 64
0101 32
0100 16
0011 8
0010 4
0001 2
0000 1
The default value (f/f) is determined by the CONFIG1[RSTOSC] Configuration bits. See Table   1. If NOSC is written with a reserved value (Table   2), the operation is ignored and NOSC is not written. When CONFIG1[CSWEN] = 0, this register is read-only and cannot be changed from the POR value. EXTOSC must meet the PLL specifications.EXTOSC configured by CONFIG1[FEXTOSC]. HFINTOSC frequency is set with the HFFRQHFINTOSC Frequency Selection bits bits. EXTOSC must meet the PLL specifications.