STM32WB55 shutdown CPU2 - low power

[F F]

Hi,

I'm struggling to add low-power features to my device application, hopefully I can get some help here.

What do I want?

My device is sampling sensor data (52Hz) and saving it periodically to external flash memory. When the device is running in sampling mode I do not want to do anything with Bluetooth (CPU2). If possible I want to have it fully disabled!

What have I tried?

Read the Low Power manager description in this manual.

Add the following to my application:

• Create a user Id (CFG_LPM_Id_t) in app_conf.h
• Call UTIL_LPM_SetOffMode()
• Call void UTIL_LPM_EnterLowPower()

Result

This will indeed significantly decrease my power consumption, but it looks like CPU1 is set to OFF as well. My sensor processing stops as well as my interrupt triggers (DRDY) coming from a MEMS sensor. Similar behavior I have with UTIL_LPM_SetStopMode().

Is there any way to have CPU2 power consumption to a minimum, independently from CPU1, which should sample data and input it to an AI model (so I guess it's not possible to run a low power mode here).

Thanks in advance!

[Remy ISSALYS]

Hello,

According to your previous post, I think the best mode in your case in the STOP2 low power mode. The CPU2 power consumption is very close to the minimum if there isn't RF activity. If you are using the sequencer, you don't need to call UTIL_LPM_EnterLowPower, it's done automatically when the CPU has nothing to do if your data processing is under a task.

Best Regards