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PNeub.2
PNeub.2
Associate
July 14, 2021
Question

Nucleo stm32WL55 LoRaWAN_Endnode SMPS, current in STOP2 is between 160uA and not 2uA

  • July 14, 2021
  • 2 replies
  • 3884 views

Hey there, i have a problem with the Nucleo STM32WL55 Board, i'm trying to reduce the current of the board in the LoRaWAN_EndNode application. When the uc is running i got something between 160uA, but in the datasheet it says that the typical current in stop2 is ~2uA. I tried it to reduce it with the SMPS. I added the resistor of zero OHM to R33 and the pinheader. I also changed the software the define DCDC_IS_SUPPORTED to zero.

 

In Sys_conf.h i changed the the defines to no debug, trace Level to off.

 

The only changes that are visible are that the current durring sending is raised from 25mA to 40mA. But the stop2 is still between 160-170uA.

 

After i put the Jumper on the VLXSMPS header i got weird current measuring, like in the third picture descripted. Is there something i don't see ?

 

I'm measuring with the X-Nucleo_LPM01A, i put the GND line to GND and the Aref+ to AVDD.

 

Please help me, i don't get any further with it. 0693W00000BdcYDQAZ.png0693W00000BdccKQAR.png0693W00000BdcXyQAJ.png0693W00000BdcXtQAJ.png0693W00000BdcXoQAJ.png

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2 replies

YBOUV.1
YBOUV.1
ST Employee
July 19, 2021

Hello,

using the stm32wl nucleo board (without hw modification) with the lorawan endnode project as is. I just disabled the JoinLedtimer (commenting out UTIL_TIMER_SetPeriod(&JoinLedTimer, 500);) to not have the led current consumption

I can measure the expected figure:

 0693W00000CzxGSQAZ.png 

0693W00000CzxGhQAJ.pngFrom the X-Nucleo-LPM01A, I use: AREF as source connected to VDD_MCU. (available on the JP1jumper pin)

Note also that the board remains supplied by the USB cable to supply the rest of the board (STLINK etc)

Aside comment :

-DCDC is switched off in stop2 mode, hence not consuming current in stop2

-make sure all the input of the stm32wl are properly driven while in stop2. For example, UART_RX (on the PA3/VCP_RX) if not driven, will have an undefined voltage and hence will toggle the input buffer creating unwanted current sink

mohamed chawki chamsi
mohamed chawki chamsi
Associate
April 6, 2022

Hello,

I had the same problem, it turned out to be due to the I2C GPIOs.

I solved it by turning off these GPIOs.

Check you settings, you maybe have some active peripherals GPIOs.

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