Atmel XMEGA B, User Manual

Page: 90 / 415

90 XMEGA B [DATASHEET]
8291B–AVR–01/2013

Bit 0 – RC2MRDY: 2MHz Internal Oscillator Ready
This flag is set when the 2MHz internal oscillator is stable and is ready to be used as the system clock source.
7.10.3 XOSCCTRL – XOSC Control register

Bit 7:6 – FRQRANGE[1:0]: 0.4 - 16MHz Crystal Oscillator Frequency Range Select
These bits select the frequency range for the connected crystal oscillator according to Table 7-7 .
Table 7-7. 16MHz crystal oscillator frequency range selection.

Bit 5 – X32KLPM: Crystal Oscillator 32.768kHz Low Power Mode
Setting this bit enables the low power mode for the 32.768kHz crystal oscillator. This will reduce the swing on the TOSC2
pin.

Bit 4 – XOSCPWR: Crystal Oscillator Drive
Setting this bit will increase the current in the 0.4MHz - 16MHz crystal oscillator and increase the swing on the XTAL2
pin. This allows for driving crystals with higher load or higher frequency than specified by the FRQRANGE bits.
This function is enabled if the
0.4 - 16MHz Crystal Oscillator is selected.

Bit 4:0 – XOSCSEL[4:0]: Crystal Oscillator Selection
These bits select the type and start-up time for the crystal or resonator that is connected to the XTAL or TOSC pins. See
Table 7-8 on page 91 for crystal selections. If an external clock or external oscillator is selected as the source for the
system clock, see “CTRL – Control register” on page 89 . This configuration cannot be changed.
Bit 7 6 5 4 3 2 1 0
+0x02
FRQRANGE[1:0] X32KLPM
XOSCPWR
XOSCSEL[3:0]
XOSCSEL[4]
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
FRQRANGE[1:0] Group configuration
Typical frequency
range
Recommended range for
capacitors C1 and C2 (pF)
00 04TO2 0.4MHz - 2MHz 100-300
01 2TO9 2MHz - 9MHz 10-40
10 9TO12 9MHz - 12MHz 10-40
11 12TO16 12MHz - 16MHz 10-30