STM32WB5MM not reaching deep sleep (STOP2/Standby) – still consuming 20 mA

[dineDK2]

Hello,

I am working on STM32WB5MM custom hardware and trying to implement deep sleep mode using RTC wakeup interrupt.

What I want to achieve:

• MCU should stay active for ~30 seconds after reset.

• Then enter deep sleep / STOP2 mode.

• Wake up automatically every 30 seconds using RTC wakeup timer interrupt.

• Expected current in STOP2 / Standby mode = < 1 mA (microamp level).

What is happening:

• In normal running mode, MCU current ≈ 30 mA (okay).

• When I put MCU into STOP2 mode, it still consumes ≈ 20 mA, instead of going down to microamps.

• I am not sure if MCU is really entering STOP2/Standby or staying partially active.

• while (1)
  {
  HAL_Delay(30000);

  HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);
  HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 30, RTC_WAKEUPCLOCK_CK_SPRE_16BITS);

  HAL_SuspendTick();
  HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);

  SystemClock_Config();
  HAL_ResumeTick();

  HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);

  if (wakeupFlag == 1)
  {
  wakeupFlag = 0;
  // Do something on wakeup
  }
  }

Question:

1. Is this the correct way to put STM32WB5MM into deep sleep (STOP2) with RTC wakeup?

2. Why is the current still ~20 mA instead of microamps?

3. Do I need to disable any peripherals/clocks (e.g., HSI, HSE, GPIO, debug, etc.) before STOP2?

4. Any hardware considerations for STM32WB5MM to achieve low-power STOP2?