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HW Timer Server Wakeup Period / Low Power Manager / Sequencer


I am trying to use the HW Timer Server Library, Low Power Manager and Sequencer on an STM32WB to wakeup/sleep my system to/from STOP2 mode. It seems that the system checks the timer once per second. I am monitoring the STM32WB power using STM32CUBEMonitorPower and the XNUCLEOLPM01A. 

In the image below I have set a timer server for 5000ms and then go to STOP2. It is expected behaviour to have the system wake up once per second to check the state and then go back to sleep?


PS: More info on Low Power Manager, Timer Server and Sequencer in AN5289 Section 4.

EDIT: In this example I am just going to SLEEP power state not STOP2 as I wanted to use the debugger.



ST Employee

Hi TomC,
Could you please take a screenshot centered on one of these spikes to see their shape?


Hi Joe,

Below is a zoomed in spike



ST Employee

Hi TomC,

You should not be seeing these kinds of spikes.
I think the easiest way would be to start from BLE_HeartRate, which is optimized for low power and will allow you to follow the correct process of the power manager.

Keep me updated on your progress 😉

Hi Joe,

I've been leaning on the Heart Rate example quite heavily to get this far however it isn't clear to me the difference between my codebase and the example that would cause this behavior, no doubt there is one I just can't find it. Is there any specific area of the Heart Rate example you could recommend I look at. Noting that my project's RTC configuration (MX_RTC_Init( ) ) is identical to the Heart Rate example.

Kind regards,

ST Employee

Hello @TomC 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.