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rohitpai77
rohitpai77
Associate
April 9, 2014
Question

Use of RTC in back up domain

  • April 9, 2014
  • 12 replies
  • 2497 views
Posted on April 09, 2014 at 11:33

Hello All,

I have read from STM324xx data sheet that the RTC is registers are still valid and running when Vdd is off and Vbat is present. I am not sure how the microcontroller manges normal running mode and standby mode (Vdd is off and Vbat is present). 

I have two questions

1. Is it responsibility of FW to manage the switch or is is managed by the MCU hardware.? When Vdd is off and Vbat is present does the microcontroller automatically goes to standby mode..? Do we need any kind of configuration for this...?

2. How to know after power start whether the product up from a stand by mode or a power down reset. 

Thnaks for any kind of suggestion.

BR,

Rohit 

#rtc #rtc #rtc #stm32 #stm32
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chen
chen
Associate II
June 6, 2014
Posted on June 06, 2014 at 11:19

Hi

As I said - it looks like you are using the internal low speed oscillator.

''I wonder Y the RTC is just storing the time and not ticking in back up domain.''

I agree, the documentation suggests that it should work BUT one of the other experienced posters (who has experience with the RTC) has said that the RTC does not get clocked by the LSI when running off the battery.

''Is there any special configuration required to eable this feature.''

He said the only solution (he knows about) is to use an external oscillator (LSE)

chen
chen
Associate II
June 6, 2014
Posted on June 06, 2014 at 11:21

Hi

As I said - it looks like you are using the internal low speed oscillator.

''I wonder Y the RTC is just storing the time and not ticking in back up domain.''

I agree, the documentation suggests that it should work BUT one of the other experienced posters (who has experience with the RTC) has said that the RTC does not get clocked by the LSI when running off the battery.

''Is there any special configuration required to eable this feature.''

He said the only solution (he knows about) is to use an external oscillator (LSE)

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