STM CircleOS forum / RTC clock source

rw · 2008-11-28 10:01:17

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!

Francis · 2008-11-28 13:53:56

With the very first batch of Primers, we used to have some problems with the 32K oscillators. The subcontractors soldered different sources for the crystals, and the capacitors were not well adapted to these different devices. For some crystals, the oscillators didn't start. The problem could be the same for the Keil boards..

rw · 2008-12-08 13:07:50

Hi,

thanks for the reply. the 32k oscillator was always working fine for me, it was the HSE that was the issue.

I managed to find a solution, I hacked up the fwlib example until it worked by slowly moving operations out of 'one shot' function until it worked after reset.

To be honest I don't know why, but it works. The drawback is that it won't keep time during power down (not a problem for me), but will resume after reset.

Cheers,
Richard

snetmonster · 2008-12-30 17:18:48

Hi, What is the frequency of the HSE oscillator you are using?
Normally it should be between 4 Mhz and 16Mhz and the nominal value is 8Mhz and be careful, if you want to get full speed 72Mhz, just choose a frequency that can be multiplied to get the 72Mhz (it is recommended to be 8Mhz since it can be multiplied to provide 72Mhz).

I hope this helps.

# 1 2008-11-28 10:01:17 RTC clock source

RTC clock source

# 2 2008-11-28 13:53:56 RTC clock source

Re: RTC clock source

# 3 2008-12-08 13:07:50 RTC clock source

Re: RTC clock source

# 4 2008-12-30 17:18:48 RTC clock source

Re: RTC clock source

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