Datasheet

The OSCULP32K is enabled by default after a power-on reset (POR) and will always run except during

POR. The OSCULP32K has a 32.768kHz output and a 1.024kHz output that are always running.

The frequency of the OSCULP32K oscillator is controlled by the value in the 32kHz Ultra Low Power

Internal Oscillator Calibration bits (OSCULP32K.CALIB) in the 32kHz Ultra Low Power Internal Oscillator

Control register. OSCULP32K.CALIB is automatically loaded from Flash Factory Calibration during

startup, and is used to compensate for process variation, as described in the Electrical Characteristics.

The calibration value can be overridden by the user by writing to OSCULP32K.CALIB.

Related Links

37. Electrical Characteristics

15. GCLK - Generic Clock Controller

17.6.6 8MHz Internal Oscillator (OSC8M) Operation

OSC8M is an internal oscillator operating in open-loop mode and generating an 8MHz frequency. The

OSC8M is factory-calibrated under typical voltage and temperature conditions.

OSC8M is the default clock source that is used after a power-on reset (POR). The OSC8M can be used

as a source for the generic clock generators, as described in the GCLK – Generic Clock Controller.

In order to enable OSC8M, the Oscillator Enable bit in the OSC8M Control register (OSC8M.ENABLE)

must be written to one. OSC8M will not be enabled until OSC8M.ENABLE is set. In order to disable

OSC8M, OSC8M.ENABLE must be written to zero. OSC8M will not be disabled until OSC8M is cleared.

The frequency of the OSC8M oscillator is controlled by the value in the calibration bits (OSC8M.CALIB) in

the OSC8M Control register. CALIB is automatically loaded from Flash Factory Calibration during start-

up, and is used to compensate for process variation, as described in the Electrical Characteristics.

The user can control the oscillation frequency by writing to the Frequency Range (FRANGE) and

Calibration (CALIB) bit groups in the 8MHz RC Oscillator Control register (OSC8M). It is not

recommended to update the FRANGE and CALIB bits when the OSC8M is enabled. As this is in open-

loop mode, the frequency will be voltage, temperature and process dependent. Refer to the Electrical

Characteristics for details.

OSC8M is automatically switched off in certain sleep modes to reduce power consumption, as described

in the PM – Power Manager.