Leaving Standby by WakeUp pin and RTC Alarm

kris2399 · ‎2012-02-17

Posted on February 17, 2012 at 17:37

We use a strategy to wake up the STM32F103 from standby mode by means of the wakeup pin and/or from the RTC alarm. In our implementation it appears that the wakeup from the RTC alarm does occur when the wakeup pin is in a high state during standby. When the wakeup pin is in a low state this functions perfectly. Is it possible to have a wakeup from standby with the wakeup pin enabled and in a high state during standby? What are the necessary conditions to achieve this?

#stm32l151-standby-wakeup #rtc-standby-wakeup #wakeyp #rtc-alarm #standby

brianshankland9 · ‎2013-04-05

Posted on April 05, 2013 at 10:13

I submitted sample code demonstrating this based on ST's own example running on the STM32L152-EVAL via our ST distributer and so far I've had no reply.

ST are either not bothered to confirm the error in their device or explain this functionality of their interface.

I do feel let down as a UK manufacturer trying to build up our industry if this is the support we face.

So for a low power solution I suggest looking at what Atmel of TI have to offer.

brianshankland9 · ‎2013-04-16

Posted on April 16, 2013 at 12:04

A bit of progress,

ST have now confirmed that they are able to replicate this fault using the project I sent on the eval board. Here's hoping for either confirmation of silicon problem that may get fixed in a new die spin, or even better no silicon problem but a description on how to configure this feature without getting the problem.

waclawek.jan · ‎2013-04-16

Posted on April 16, 2013 at 12:32

Thanks for reporting the progress.

Care to publish the example you gave to ST?

JW

Nickname12657_O · ‎2013-04-21

Posted on April 21, 2013 at 18:18

Dear all,

Here is the official ST statement on this issue : To avoid having the application blocked in Standby mode in this use case, please apply this specific wakeup clearing sequence:

1) Disable wakeup sources first, before clearing the wake-up flag.

2) Then re-enabling the wakeup sources before going into standby.

If the wake-up line is still present ( maintained to 1), the above sequence will regenerate a rising edge and the device will not not be blocked in standby mode for ever.

We will update you on our action plan for corrective actions and documentation follow-up later on.

Cheers,

STOne-32.

jono-tree · ‎2014-04-06

Posted on April 06, 2014 at 13:39

Hello,

Thanks for this solution. The encountered the same problem using the stm32f4 discovery board, and using the PWR_STANDBY example. When I pushed the button, it entered standby mode (indicating by the LED ceasing to toggle), and woke up after the 5s alarm due to the RTC. Pushing the button again before that 5ms failed to wake it up however.

As suggested, I moved the line PWR_WakeUpPinCmd(ENABLE); from the main function, to the line after the line clearing the wake up flag, PWR->CR |= PWR_CR_CWUF;

After this it worked

Jonathan

Amel NASRI · ‎2014-04-10

Posted on April 10, 2014 at 17:40

Hi Jonathan,

For F4 devices, the workaround is already described in the

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/errata_sheet/DM00037591.pdf

(2.1.5 subsection).

-Mayla-

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

marcmarc9 · ‎2014-05-13

Posted on May 14, 2014 at 04:36

Interesting thread. Does this apply to the STM32F072 as well?