low frequency calibration interval

Question

Hi, 
 I have read the following posts and understand how low clock frequency mode can be selected 
 devzone.nordicsemi.com/.../ 
 I've also read in many posts that 4s calibration interval is fine for most case 
 What parameter/use case have impact for selecting the calibration interval ?
In which case we should reduce or increase the calibration interval ? 
 My goal is to have BLE working (advertising interval 1s + connected mode) and 1000 ppm accuracy on RTC timer 
 I am using sdk 9 and 10. Is the calibration based on temperature check experimental ?

Øyvind Karlsen · Accepted Answer

Hi, 
 Please see Stians more in depth answer on the calibration interval. The LFRC when calibrated runs at +/- 250 ppm. 
 What calibration in SDK 9 and 10 are you referring to? 
 RC clock calibration is implemented by the SoftDevice and is not experimental, it is required to make the chip work without a separate LF crystal in BLE mode. 
 Best regards, 
 Øyvind