SLAZ534U June   2013  – August 2021 MSP430F5257

 

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6.30 RTC6

RTC Module

Category

Functional

Function

the step size of the RTC frequency adjustment is twice the specified size.

Description

In BCD mode of operation, the step size of the RTC frequency adjustment is =+8ppm/-4ppm. This is twice the size specified in the User's Guide.
In BCD mode, for up calibration this results in a step size per step of 8ppm (1024 cycles) instead of 4ppm (512 cycles). For down calibration this results in a step size per step of 4ppm (512 cycles) instead of 2ppm (256 cycles).
In Binary mode, the step size = +4ppm/-2ppm as per the spec.

Workaround

In BCD mode of operation, half the calibration value could be written into RTCCAL register to compensate the doubled step size.