<![CDATA[Method to know that the RTC was initialized and has valid time/date]]>If there a method to know that the RTC (on an M5 Core2 or M4 CoreInk) was initialized and does not need to be updated in a scenario where Internet (NTP) access is not available ?

Thanks.

]]>https://community.m5stack.com/topic/3667/method-to-know-that-the-rtc-was-initialized-and-has-valid-time-dateRSS for NodeThu, 30 Apr 2026 03:11:19 GMTThu, 21 Oct 2021 18:07:40 GMT60<![CDATA[Reply to Method to know that the RTC was initialized and has valid time/date on Thu, 21 Oct 2021 19:18:58 GMT]]>@felmue Thanks for the pointer !

]]>https://community.m5stack.com/post/15196https://community.m5stack.com/post/15196Thu, 21 Oct 2021 19:18:58 GMT<![CDATA[Reply to Method to know that the RTC was initialized and has valid time/date on Thu, 21 Oct 2021 18:43:00 GMT]]>Hello @IndianaTux

have a look at the PCF8563 datasheet chapter 8.4.1 Register VL_seconds. In addition to the seconds, register 0x02 also holds a bit (7), which gets set if the voltage dropped too much.

I don't see a ready made method / function to read this bit in the M5Core2 library on github, but it should be relatively easy to add.

Thanks
Felix

]]>https://community.m5stack.com/post/15195https://community.m5stack.com/post/15195Thu, 21 Oct 2021 18:43:00 GMT