Atmel AVR XMEGA AU series User Manual

96
8331B–AVR–03/12
Atmel AVR XMEGA AU
7.10 Register Description – Oscillator
7.10.1 CTRL – Oscillator Control register
• Bit 7:5 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 4 – PLLEN: PLL Enable
Setting this bit enables the PLL. Before the PLL is enabled, it must be configured with the
desired multiplication factor and clock source. See ”STATUS – Oscillator Status register” on
page 97.
• Bit 3 – XOSCEN: External Oscillator Enable
Setting this bit enables the selected external clock source. Refer to ”XOSCCTRL – XOSC Con-
trol register” on page 97 for details on how to select the external clock source. The external clock
source should be allowed time to stabilize before it is selected as the source for the system
clock. See ”STATUS – Oscillator Status register” on page 97.
• Bit 2 – RC32KEN: 32.768kHz Internal Oscillator Enable
Setting this bit enables the 32.768kHz internal oscillator. The oscillator must be stable before it
is selected as the source for the system clock. See ”STATUS – Oscillator Status register” on
page 97.
• Bit 1 – RC32MEN: 32MHz Internal Oscillator Enable
Setting this bit will enable the 32MHz internal oscillator. The oscillator must be stable before it is
selected as the source for the system clock. See ”STATUS – Oscillator Status register” on page
97.
• Bit 0 – RC2MEN: 2MHz Internal Oscillator Enable
Setting this bit enables the 2MHz internal oscillator. The oscillator must be stable before it is
selected as the source for the system clock. See ”STATUS – Oscillator Status register” on page
97.
By default, the 2MHz internal oscillator is enabled and this bit is set.
Bit 76543210
+0x00 – – – PLLEN XOSCEN RC32KEN RC32MEN RC2MEN CTRL
Read/Write R R R R/W R/W R/W R/W R/W
Initial Value00000001

Atmel AVR XMEGA AU series Specifications

General

Brand	Atmel
Model	AVR XMEGA AU series
Category	Microcontrollers
Language	English