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6 months ago.

RTC at FRDMK64F did no longer work since mbed-os 5.10.0

Yesterday I realized, that the RTC on my K64F did no longer work. Since several years I use this function. We have modified the hardware of K64F and add a battery, so we could save date and time during switch off. As I realized this, I search for other requests and saw the request of Koen Kempeneers. Following this I updated to 5.10.1, but no result. I can set date and time and as long as the board is powered on, I can read correct values. But after reset or power off, the RTC again start at 1.1.1970 00:00. Is there any idea in the community ? Best Regards, Peter Schrems

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1 Answer

6 months ago.

Hi Peter, I found an entry in the file rtc_api.c in the sub folder api of the folder TARGET_MCUExpresso_MCUS named "static bool rtc_time_set". When I compare these with the sources of older versions, I see, that this entry is not existing earlier. This value is default set to false and it seems, that it will used to detect, if the RTX is set or not. But it seems, that is don't works correct. I checked and these value to true and then the clock of the FRDM K64F will no longer set too default during power off or reset. I'm not shure, if these change is correct but it may a hint for you to continue your tests. Regards, Kevman

Hi Kevman, thank's for your help. Indeed, I followed your suggestion and can confirm what you said. In the meantime version 5.10.2 is available and I hoped, the bug is fixed. I saw some changes in the source file you recomment, but it's still the same. You still need to set the rtc_time_set to true to get a well working RTC without fall back during reset or power down. Best Regards, Peter

posted by Peter S. 26 Oct 2018

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