To improve accuracy of the LFRC oscillator, it can be calibrated using the HFXO as a reference oscillator.
The LFRC oscillator can be calibrated while it is running. The calibration is started by triggering the CAL task which temporarily requests the HFCLK with the HFXO as the source for calibration.
A DONE event will be generated when the calibration is finished.
If the CAL task is triggered while a calibration routine is already running (i.e. before the DONE event is generated), the CAL task has no effect and the calibration continues.
All cores can trigger the CAL task independently of each other. As a result, each core will receive a corresponding DONE event. If the calibration routine is already running (i.e. a core has triggered the CAL task), and the CAL task is triggered from another core, a DONE event is generated in both cores when the calibration of its corresponding LFRC oscillator is complete.