B-U585I-IOT02A very high power consumption during active and stop2 modes

[henry_kay]

Hello,

I am trying to implement an edge AI application on the B-U585I-IOT02A board alternating between active mode for inference and stop2 mode. I based the implementation on the PWR_LPMODE_RTC example for the U575 board, I have attached main.c below.

I am using Power Profiler Kit II in source meter mode to measure energy consumption. I have disabled ST-LINK via the SWD MCU switch. I power the board with 3.3V using the 3V3 pin through PPKII. I left the jumper at 5V_USB_STLK and I am using the default values in PPKII. During measurements, I observe a current of approx. 100mA in active mode and 80mA (instead of a few μΑ) in stop2 mode. I wanted to check whether:

• There is a bug in my implementation and the board never enters Stop2 correctly
• There is a bug in my implementation and there are still peripherals or clocks active during Stop2 mode
• The B-U585I-IOT02A is not really meant to be used for energy consumption measurements since there are components that consume power even during stop2 (i.e. wifi radio or pull-ups/pull/downs). In that case would a Nucleo U575 be more suitable for representative measurements or the only way would be to design a custom PCB from scratch?
• There is a way to perform a more accurate measurement of the MCU energy consumption on the B-U585I-IOT02A. i.e through the VDD_MCU JP3?

Thank you!

[henry_kay]

Hello all,

I still can't make the current consumption during stop2 mode on the B-U585I-IOT02A SoC go below ~80mA. I've reviewed the configuration (RTC wakeup, WFI, clocks, etc.), and I'm increasingly leaning toward non-MCU components being responsible for the high current. I have confirmed the MCU enters STOP2, but the current barely drops from active mode (~100mA) to STOP2 (~80mA), which seems way too high for STM32U5 alone.

Would using the Nucleo U575 be a solution? Or measuring directly the MCU consumption through JP3 (I am not even sure this is possible, haven't tried yet)? Or is there something else that I am currently missing to turn energy consumption down?

Thank you very much!

[jacks004]

The B-U585I-IOT02A may have high power consumption due to active peripherals or misconfigured low-power settings. Check clocks, GPIO states, and disable unused modules.

[henry_kay]

@jacks004 I am only enabling GPIO port H6/7 and clocks (if you see from the attached source files) and have also disabled RT-LINK through the relevant hardware switch. I am not explicitly disabling the rest of the on-board ICs, including BLE and WiFi but shouldn't they be set to off by default?