Power meas. - How to put PA13 and PA14 to analog no pull up and no pull down?

[DS.4]

Hi

I am using X-NUCLEO-LPM01A to measure some currents on P-NUCLEO-WB55 according to video:
https://www.youtube.com/watch?v=7IVs-nuoXj8.

To keep ST Link enbaled the commentator asks to put some pins to analog state , no internal pull-up , and pull-down state

 

See here:

How do I do that?

 

[Andrew Neil]

You can link to a specific time in a YouTube video:

eg, https://youtu.be/7IVs-nuoXj8?t=736

 

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@DS.4 wrote:

To keep ST Link enbaled the commentator asks to put some pins to analog state

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I think you may have misunderstood what he meant: that will still break the debug connection - it just saves you having to physically fit & remove the jumpers.

Also, if you're trying to get your application down to really the lowest possible current level, this will still leave some leakage - so you'll still need to physically disconnect.

Anyhow ...

 

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@DS.4 wrote:

How do I do that?

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Something like this:

 

 GPIO_InitTypeDef GPIO_InitStruct;

 GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Pin = GPIO_PIN_All;

 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

 

 

[DS.4]

"that will still break the debug connection" - why?

Prior to adding PIN13 and PIN5 to be analog, I Ran a quick test , programmed the WB55 in debug mode (CubeIDE) , and ran.

Have some weird base current of 1 mA on advertising during sleep.  (BleHeartRate example)
But then,  I do get to hold a breakpoint on connection event  , debug doesn't break. But I see the current jump high to 3mA while I am holding the break point. here:

Exiting debug:

Pressing the" Reset button" on WB55 does not exit debug.

Only if I press "RESET TARGET" on STM32CubeMonitor-Power than I lose it. And only then I see datasheet sleep currents. (3uA). See here:

 

So what's going on? and what is then the correct way to keep debug with sleep if I need it?

 

 

 

 

[Andrew Neil]

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@DS.4 wrote:

"that will still break the debug connection" - why?

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Because you are disconnecting the SWD connection - which goes through those pins.

 

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@DS.4 wrote:

So what's going on? and what is then the correct way to keep debug with sleep if I need it?

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You will never get true low power readings with a debugger connected - the debugger keeps the CPU awake.

Also, as mentioned earlier, the physical connection will give you some leakage/stray currents.

As well as the SWD connections, also check:

• Reset from the ST-Link
• Target voltage sense
• UART connection
• Trace connection
• Connections to other "features" on the dev board.

It is a non-trivial exercise to find & disconnect all these things, and the ST documentation is often incomplete; eg:

https://community.st.com/t5/stm32-mcus-wireless/current-consumption-in-stop-mode-using-b-l072z-lrwan1/m-p/448139/highlight/true#M14437

(unfortunately the link in that post seems to be broken)

EDIT: I found what it should link to:

https://community.st.com/t5/stm32-mcus-wireless/excess-current-consumption-running-b-l072z-lrwan1-from-battery/m-p/322961

 

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@DS.4 wrote:

what is then the correct way to keep debug with sleep if I need it?

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You can't have both sleep and debug - choose one.

 

[Andrew Neil]