nrf_clock_lf_cfg_t Struct Reference

Type representing lfclk oscillator source. More...

#include <nrf_sdm.h>

Data Fields
uint8_t	source
uint8_t	rc_ctiv
uint8_t	rc_temp_ctiv
uint8_t	xtal_accuracy

Detailed Description

Type representing lfclk oscillator source.

Field Documentation

uint8_t nrf_clock_lf_cfg_t::rc_ctiv

     Only for NRF_CLOCK_LF_SRC_RC: Calibration timer interval in 1/4 second

units (nRF51: 1-64, nRF52: 1-32).

Note

To avoid excessive clock drift, 0.5 degrees Celsius is the maximum temperature change allowed in one calibration timer interval. The interval should be selected to ensure this.

Must be 0 if source is not NRF_CLOCK_LF_SRC_RC.

uint8_t nrf_clock_lf_cfg_t::rc_temp_ctiv

 Only for NRF_CLOCK_LF_SRC_RC: How often (in number of calibration

intervals) the RC oscillator shall be calibrated if the temperature hasn't changed. 0: Always calibrate even if the temperature hasn't changed. 1: Only calibrate if the temperature has changed (nRF51 only). 2-33: Check the temperature and only calibrate if it has changed, however calibration will take place every rc_temp_ctiv intervals in any case.

Note

Must be 0 if source is not NRF_CLOCK_LF_SRC_RC.

For nRF52, the application must ensure calibration at least once every 8 seconds to ensure +/-250ppm clock stability. The recommended configuration for NRF_CLOCK_LF_SRC_RC on nRF52 is rc_ctiv=16 and rc_temp_ctiv=2. This will ensure calibration at least once every 8 seconds and for temperature changes of 0.5 degrees Celsius every 4 seconds. See the Product Specification for the nRF52 device being used for more information.

uint8_t nrf_clock_lf_cfg_t::source

LF oscillator clock source, see Possible lfclk oscillator sources.

uint8_t nrf_clock_lf_cfg_t::xtal_accuracy

 External crystal clock accuracy used in the LL to compute timing windows.

Note

For the NRF_CLOCK_LF_SRC_RC clock source this parameter is ignored.