What is connected to the ''internal wakeup line''

[Uwe Bonnes]

Posted on February 02, 2017 at 10:59

Hello,

reference manuals for the L4 series in the power section talk about a EIWUL bit in the PWR->CR3 register, enabling an 'internal wakeup line'. A search in the manuals and with google does not bring up any further explanation of what is connected to this 'internal wakeup line'. Some explanation in the reference manuals would help.

Thanks

[Khouloud GARSI]

Posted on February 02, 2017 at 11:36

Hello

Bonnes.Uwe

,

I will highlight this internally.

Thanks a lot for your contribution and sorry for any inconvenience this may have caused.

Khouloud.

[Khouloud GARSI]

Posted on February 06, 2017 at 16:48

Hi

Bonnes.Uwe

,

I have reviewed the reported point. The information about the 'internal wakeup line' could be obtained from tables:

• Functionalities depending on the working mode
• EXTI lines connections

The internal wake up lines are the ones coming from RTC or a peripheral with wakeup capabilities.

Khouloud.

[JGerb]

I don't believe you have answered the question. I too have the same question, and am struggling to get my STM32L475 to wake up from RTC, and would like to know if I need to enable this bit.

To further add to the confusion, the revision note shows that this bit has been renamed recently from EIWF to EIWUL. Neither of those 2 bit definitions are further explained anywhere else in any diagram or table.

Please state clearly which table you are referring to. Insisting we RTFM when the FM is clearly F not explaining doesn't help - the reference manual needs to be fixed.

[Ijoui.1]

I think I solved it:

This 'internal wakeup line' is connected to everything with Standby wakeup capability. It is the only way it makes sense since most wakeups are through EXTI but that is for Stop modes only. There must be some line that signals the wakeup even when EXTI is inactive (Standby and Shutdown modes).

If you look at the register (PWR_SR1 in my case) with WUFI (flag bit for a wakeup through the 'internal wakeup line') you can see that there are flag bits for PVD and WKUPx which both have Standby and Shutdown wakeup capability but aren't really peripherals with their own registers etc. I think this is a strong clue that I'm right, not 100% sure though.