STM32WB55 Shutdown mode

[VM]

Ciao,

I am trying to put my STM32wb55 in shutdown mode and wake it up using 2 external pins.

Wake-up sources are on PA0 (active high) and PC12 (active low). Those should be PIN1 and PIN3 wake-up sources.

This is the code I use to put the device in shutdown mode:

void EnterLowPower()
{
  __disable_irq();
  __disable_fault_irq();
 
    LL_C2_PWR_SetPowerMode(LL_PWR_MODE_SHUTDOWN);
 
    HAL_PWREx_DisableBLEActivityIT();
    HAL_PWREx_Disable802ActivityIT();
 
    HAL_RTCEx_DeactivateWakeUpTimer(&RTC_Handle);
 
    HAL_PWREx_EnablePullUpPullDownConfig();
 
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_A, GPIO_PIN_1);   
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_A, GPIO_PIN_7);   
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_A, GPIO_PIN_15); 
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_B, GPIO_PIN_4);   
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_B, GPIO_PIN_7);   
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_B, GPIO_PIN_13);  
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_B, GPIO_PIN_15);  
    HAL_PWREx_EnableGPIOPullDown(PWR_GPIO_D, GPIO_PIN_0);  
 
    HAL_PWREx_ClearWakeupFlag(PWR_FLAG_WU);
 
    HAL_PWREx_EnableWakeUpPin(PWR_WAKEUP_PIN1_HIGH,PWR_CORE_CPU1);
    HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2);
    HAL_PWREx_EnableWakeUpPin(PWR_WAKEUP_PIN3_LOW,PWR_CORE_CPU1);
    HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN3);
    HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN4);
 
    HAL_PWREx_DisableInternalWakeUpLine();
 
    HAL_PWREx_ClearWakeupFlag(PWR_FLAG_WU);
 
    HAL_PWREx_EnterSHUTDOWNMode();
}
 

I have some simple code that just enters shutdown mode a few seconds after boot (just toggling some LEDs to give me a hint of the current state).

What I see is that the device seems to enter shutdown mode (I see the outputs I set as pull-down changing their state) but almost immediately (50ms) resuming. It may also be just a reset instead of a shutdown, but I checked nRST_SHDW in FLASH_OPTR and it's set to 1 and so this should not happen).

I check the state of PWR->SR1, PWR->SR2 and RCC->CSR after this "resume" and values are 0x0000 0x0101 and 0x0C000000 like for a normal boot-up.

This is how clocks are initialized:

PeriphClkInitStruct.PeriphClockSelection  = RCC_PERIPHCLK_SMPS | 
       RCC_PERIPHCLK_RFWAKEUP |
       RCC_PERIPHCLK_RTC | RCC_PERIPHCLK_CLK48SEL |
       RCC_PERIPHCLK_RNG | RCC_PERIPHCLK_I2C3;
 
PeriphClkInitStruct.RngClockSelection   = RCC_RNGCLKSOURCE_HSI48;
PeriphClkInitStruct.RTCClockSelection   = RCC_RTCCLKSOURCE_LSE;
PeriphClkInitStruct.RFWakeUpClockSelection = RCC_RFWKPCLKSOURCE_LSE;
PeriphClkInitStruct.SmpsClockSelection   = RCC_SMPSCLKSOURCE_HSE;
PeriphClkInitStruct.SmpsDivSelection    = RCC_SMPSCLKDIV_RANGE1;
PeriphClkInitStruct.I2c3ClockSelection   = RCC_I2C3CLKSOURCE_SYSCLK;
 
HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) ;

I mention this because if I remove RCC_PERIPHCLK_RFWAKEUP and set RFWakeUpClockSelection to RCC_RFWKPCLKSOURCE_NONE the device seems to enter shutdown mode but then does not seem to be able to recover (one of the two inputs is a button, so pushing-releasing it would generate multiple rising and falling edges, excluding a configuration problem for the wake-up source polarity, I think. I anyway tried to change those with no success.

It's there something I am missing in my EnterLowPower function?

I checked STMicroelectronics/STM32CubeWB on github but can't find any sample using HAL_PWREx_EnterSHUTDOWNMode. I found some for the L4 and I think I do the same things they do in their code, but ATM it does not seem to work.

[Remy ISSALYS · Accepted solution]

Hello,

It's not possible to do shutdown when BLE is activated. To do shutdown, you must turn off the CPU2 before going shutdown mode and when you recover from shutdown, you need to do all the CPU2 initialization again before starting BLE activity. To stop RF activity, you can perform a reset with hci_reset function.

When CPU2 is running, you shall not use LL_C2 command like the following: LL_C2_PWR_SetPowerMode(LL_PWR_MODE_SHUTDOWN);

Best Regards

[Aurentiaco]

Hello Remy,

I have one more question how can I set both CPU's in shutdown mode because I need to put both of them in shutdown mode. I want to put my system in shutdown mode for example 5 minutes of inactive then when I press the button want to wake it up. How can I make initialization when I wake it up could you give more information please. 
So:
1. How can I put my entire system in shutdown mode?
2. How can I turn off my ble than when it wakes up set the ble again?

Could you help me about it?