Proper way to enter & exist STOP2 mode?

[StephanMair]

Hi, I'd like know how I should enter stop2 in the most thorough way.

I'm using STM32WB55x series, to enter STOP2 mode, all GPIO bands apparently needs to be initialized as analog.

The problem is, I need BANK A to use EXTI to wake the chip back up into normal running mode, but if I leave the BANK A on, the power consumption will increase from a mere 3 to 4 uA to a whopping 980 uA.

I seem to remember there is a mode where you CAN use a limited set of pins to wake up the chip and still reduce the stop mode power consumption to below 10 uA?

Can anyone please tell me if that's possible? If so how to accomplish that?

[TDK]

That info is spelled out in the RM. See "6.4.9 Stop2 mode".

https://www.st.com/content/ccc/resource/technical/document/reference_manual/group0/83/cf/94/7a/35/a9/43/58/DM00318631/files/DM00318631.pdf/jcr:content/translations/en.DM00318631.pdf

[Tim.N]

The biggest thing is to make sure none of your I/O configurations are drawing extra power. E.g.:

• GPIOs set to input with a floating input voltage will cause extra leakage and switching current
• GPIOs set to output which drive a load will cause extra current from driving the load

Try remuxing all of your bank A GPIOs as disconnected and see if you still have the extra power draw. Also, if you're using a debugger, those pins can draw extra too. If you want to leave the debugger attached, remux PA13-PA15 as disconnected when you want to test those out (you'll lose your debugger when doing so), and make sure that your debugger didn't set anything in the DBGMCU registers (e.g. DBGMCU->APB1FZR1, DBGMCU->APB1FZR2, and DBGMCU->CR) which would leave the debugger circuitry on in stop modes.

[Christophe Arnal]

​Hello,

The limited set of wakeup pin is used to exit either from standby or shutdown mode. As specified in the reference manual ( RM0434), there are five wakeup pins ( WKUPx).

To exit from Stop Mode, any GPIO configured as EXTI can be used to wakeup the device.

Assuming you started from BANKA being fully configured as analog input ( please make sure you did that in software as PA13, PA14, PA15 are not configured in analog mode out of reset), it is likely that the GPIO you selected is either wrongly configured or connected to something on your board.

Please check the PullUp/PullDown configuration and if there are anything connected on this GPIO on your board and make sure that when the GPIO is idle, there is no current leakage.

Regards.

[Scott Löhr]

I second the answer from @Christophe Arnal​ .

I am running a custom IAR app developed by starting with an ST sample app on their STM32WB Nucleo dev board and I have all 3 of the buttons configured to wake from STOP2 and I'm measuring 4-uA in STOP2 across JMP2.