standby on stm32u375 not reaching low power state

[Geoffrey1]

I have no problem reaching a low power state with stop3.  All the Pull Up/Down registers are configured correctly.  However, simply changing the low power mode from STOP3 to STANDBY results in a 1.5mA current sink.  What could this be?  The debugger support is off in both cases.

[MM..1]

Try show more info primary current in STOP3? And i see you bare metal in next thread, Use LL examles STM32CubeU3/Projects/NUCLEO-U385RG-Q/Examples_LL/RTC/RTC_ExitStandbyWithWakeUpTimer_Init/Src/main.c at main · STMicroelectronics/STM32CubeU3 · GitHub

[Jason Miller234]

A 1.5 mA current in STANDBY usually means the MCU isn't entering true standby. Check wake-up sources, RTC, external peripherals, and verify your standby entry code. Sharing the MCU model and code will help identify the exact cause.

[Geoffrey1]

It’s an stm32u375.  I can see (with test pins) that it’s entering this code and I can see, via the Pull up/down that it’s definitely not transitioning to standby, but it’s definitely waiting in the wfi

 

Here’s the entry code (stm32u375). 

 

 tagDevicesDisableWakeupSources();
  tagPowerClearWakeFlags();
  DBGMCU->CR = 0;
  MODIFY_REG(PWR->CR1, PWR_CR1_LPMS, 4U);

  //tagPowerSelectStop3();

  SET_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));

  __DSB();
  __WFI();

 

[MM..1]

Maybe when your read reference manual (2800 pages) and next appnotes and docs, you can write bare code, but in real life dont ask here about your bare code miss. And after only maybe read basics, you get info , that 375 and 385 is same except encrytion engine.

[Geoffrey1]

That's a rather rude response.  You assume I haven't read the reference manual, I have, that I haven't read st hal, I have, or that I'm somehow unqualified to write "bare code", I'm not.   As usual, the st documentation leaves edge cases as an exercise to the reader.

 

I started with a basic question, why would stop3 work, and standby not.  Btw, I've used standby on the stm32l432 for years .  There is nothing evident in the st code or documentation that points to an obvious got you.  I only posted code in response to previous feedback.