RTC clock source issues

[rwemyss]

Posted on December 25, 2008 at 01:07

RTC clock source issues

[rwemyss]

Posted on May 17, 2011 at 12:54

Hey!

I'm having some problems with the RTC on the STM32. When I use the LSE everything works as desired, but when I try to use the HSE or LSI it only works until there's a reset then stops working. I would expect it to work the same way for any of the clock sources. Any ideas why this is happening? It seems to hang on RTC_WaitForSynchro(); I'm using a keil development board, the fwlib and basically a copy of the example given in the fwlib examples folder. Thanks! [ This message was edited by: rwemyss on 26-11-2008 18:56 ]

[dschneeweis]

Posted on May 17, 2011 at 12:54

Hi

I have the same problem, when using the LSI as RTC source. If I stop the debugger after I reseted the SEC-flag from the RTC and perform a reset with the debugger the LSEON bit is set automaticly and the LSE starts working. Now the RTC-source is choosen as LSI (because the input channel selector is in the backup-domain). The LSI itself is stopped with reset. The command WaitForSynchro() needs at least on tick on the RTC. But without a clocksource it waits forever. Why starts the LSE after clearing the SEC-flag and reset the CPU? If it wouldn't start I only had to check the LSEON bit and if not set and RTC is on start LSI.

[pandoraems]

Posted on May 17, 2011 at 12:54

i am only starting with RTC stuff, but according to documentation only LSE can stay on during reset (or power off, while Vbatt is present)

other oscillators are not a part of RTC core and therefore aren't operational in the stand-by mode. maybe thats the explanation to the behavior you observe?