High Current Consumption in Stop2 mode STM32L4

Forum|Forum|7 years ago
May 30, 2019
4 replies
2116 views

I am trying to achieve the lowest power consumption possible when entering Stop2 mode with the STM32L476. I have verified that all of my GPIO are in the correct state before entering Stop2 mode. I am also very confident that it is not any external circuitry on my board at this point as I have done extensive testing.

My current consumption is about 280 uA when entering stop2 mode. About 35 uA can me accounted for with the current draw of a couple of my external circuits. However, the MCU itself should be drawing around 3-5 uA.

Are there any things someone can point me to to check in order to see what might be causing the problem?

In my sleep projects code, I initialize the system clock, all gpios, and several peripherals. Then, I deinitialize all said peripherals, set my GPIOs to the proper settings, and then enter sleep mode.

Any guidance would be greatly appreciated. I have been stuck on this for weeks.

This topic has been closed for replies.

Best answer by Aaron McNeil

After a few weeks of fighting with this I finally fixed my current consumption problem. Apparently, when using the HAL library to initialize a few GPIO that I am using as interrupts, as well as the FMC controller for external SRAM, you have to call HAL_GPIO_DeInit() before you are able to reconfigure the GPIO to prepare it for Stop2 mode. Once I added HAL_GPIO_DeInit() before I reinitialized them, I was able to get my overall current down to 39 uA, which is exactly what I was expecting.

I'm not sure if there is a more efficient way to go about this, as I will have to reinitialize all the GPIO and SRAM upon wake up, but at least I am now able to get the low power I was expecting.

Piranha

Principal III

Take a look at DBGMCU_CR register. Try setting it to zero before entering low-power mode. Debugging connection will be lost, of course. Also disconnect debugger physically, because it's pins can also draw some current.

Aaron McNeilAuthor

Associate III

Thank you for the reply. My DBGMCU_CR register is 0 before entering low power mode. Also, when my debugger is physically connecting i am drawing around 430 uA. When I disconnect it is when I get my current of 280 uA.

Aaron McNeilAuthor

Associate III

Is there a way to see what my register settings are after I enter stop2 mode? I am thinking the best way to move on from here is to compare registers on my board to the nucleo board using the sleep example and see if I can find any differences. Once I get to the point in code that sets the SLEEPDEEP but of Cortex System control register, my debugger stops working so I cannot see my register settings.

If I compare all my registers just before that point, they all look the same.

I'm at my wits end here...

Aaron McNeilAuthorBest answer

Associate III

After a few weeks of fighting with this I finally fixed my current consumption problem. Apparently, when using the HAL library to initialize a few GPIO that I am using as interrupts, as well as the FMC controller for external SRAM, you have to call HAL_GPIO_DeInit() before you are able to reconfigure the GPIO to prepare it for Stop2 mode. Once I added HAL_GPIO_DeInit() before I reinitialized them, I was able to get my overall current down to 39 uA, which is exactly what I was expecting.

I'm not sure if there is a more efficient way to go about this, as I will have to reinitialize all the GPIO and SRAM upon wake up, but at least I am now able to get the low power I was expecting.

Sign up

Login with SSO

Login to the community

Login with SSO