MSP430FR6889: Can I input an external clock as the internal RTC clock source?

Section 23.2.2 of the User's Guide says that

RT0PS is sourced from the low-frequency oscillator XT1.

To use an external clock instead of the crystal oscillator, set the LFXTBYPASS bit. The datasheet allows any frequency between 10.5 kHz and 50 kHz for that.

Hi Clemens Ladisch,

Thank you for your reply.

But in the User Guide the input clock has a description called Crystal Oscillators and there is no description of external clock etc,

so I worried and asked a question.

I am glad if external clock can be used with RTC as you said...

I'm also waiting for the answers from TI employees

Regards,

uchida-k

The label in figure 23-1 assumes that you're using LFXT in crystal oscillator mode (because it wouldn't make much sense to run the RTC with any other clock frequency), but the RTC_C module is independent from the CS module, and when the LFXT is in bypass mode, then that is the clock signal that other modules get.

The external clock is described in section 3.2.2.