SLAU847D October 2022 – May 2024 MSPM0L1105 , MSPM0L1106 , MSPM0L1227 , MSPM0L1228 , MSPM0L1228-Q1 , MSPM0L1303 , MSPM0L1304 , MSPM0L1304-Q1 , MSPM0L1305 , MSPM0L1305-Q1 , MSPM0L1306 , MSPM0L1306-Q1 , MSPM0L1343 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346 , MSPM0L2227 , MSPM0L2228 , MSPM0L2228-Q1
The RTC module provides calibration mechanisms for reducing timekeeping error due to crystal offset error and crystal temperature drift. Crystal offset error can be corrected by measuring the crystal frequency through the RTC_OUT output and adjusting calibration registers in the RTC. Crystal temperature drift can be corrected by measuring the system temperature with software, computing a correction factor in ppm based on the measured temperature, and applying the correction factor to the RTC.
Up to ±240 ppm of offset correction or up to ±240 ppm of temperature compensation correction can be applied individually, but the total correction allowed when both offset correction and temperature compensation are used together is ±240 ppm. This means that the signed addition of offset error and temperature compensation should not exceed the maximum of ±240 ppm, else the values in excess of ±240 ppm will be ignored by hardware.