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USART_ISR_WUF is not set after wake up from STOP2 by LPUART

Charles_Li
Associate II

I've enabled STOP2 mode with the below code statement

 

void PWR_EnterStopMode(void) { /* USER CODE BEGIN PWR_EnterStopMode_1 */ UART_WakeUpTypeDef WakeUpSelection; WakeUpSelection.WakeUpEvent = UART_WAKEUP_ON_STARTBIT; if (HAL_UARTEx_StopModeWakeUpSourceConfig(&hlpuart1, WakeUpSelection)!= HAL_OK) { Error_Handler(); } __HAL_UART_ENABLE_IT(&hlpuart1, UART_IT_WUF); HAL_UARTEx_EnableStopMode(&hlpuart1); /* USER CODE END PWR_EnterStopMode_1 */ /** * When HAL_DBGMCU_EnableDBGStopMode() is called to keep the debugger active in Stop Mode, * the systick shall be disabled otherwise the cpu may crash when moving out from stop mode * * When in production, the HAL_DBGMCU_EnableDBGStopMode() is not called so that the device can reach best power consumption * However, the systick should be disabled anyway to avoid the case when it is about to expire at the same time the device enters * stop mode (this will abort the Stop Mode entry). */ HAL_SuspendTick(); /** * This function is called from CRITICAL SECTION */ EnterLowPower(); /************************************************************************************ * ENTER STOP MODE ***********************************************************************************/ LL_PWR_SetPowerMode(LL_PWR_MODE_STOP2); LL_LPM_EnableDeepSleep(); /**< Set SLEEPDEEP bit of Cortex System Control Register */ /** * This option is used to ensure that store operations are completed */ #if defined (__CC_ARM) __force_stores(); #endif __WFI(); /* USER CODE BEGIN PWR_EnterStopMode_2 */ /* USER CODE END PWR_EnterStopMode_2 */ return; } /** * @brief Exits Low Power Stop Mode * @note Enable the pll at 32MHz * none * @retval none */ void PWR_ExitStopMode(void) { /* USER CODE BEGIN PWR_ExitStopMode_1 */ /* USER CODE END PWR_ExitStopMode_1 */ /** * This function is called from CRITICAL SECTION */ ExitLowPower(); HAL_ResumeTick(); /* USER CODE BEGIN PWR_ExitStopMode_2 */ HAL_UARTEx_DisableStopMode(&hlpuart1); /* USER CODE END PWR_ExitStopMode_2 */ return; }
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LPUART could wake up MCU that I verifed by set a break point on 

 

void LPUART1_IRQHandler(void)

 

But USART_ISR_WUF is not set causing I can't handle RX message after resuming from STOP2 mode, is there anything I missed?

Charles_Li_0-1733991734504.png

 

3 REPLIES 3
Roger SHIVELY
ST Employee

Hello @Charles_Li ,

 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

 

Regards,

Roger

Fabi1
Associate

Hello @Charles_Li @Roger SHIVELY 

I have exactly the same problem,

The frame is processed only when the MCU exits STOP2 mode.

I have the impression that the problem comes from the LPUART==>ISR==> IDLE bit which seems hardware and takes a while to go from 0 to 1.

Fabi1_0-1734708622064.png

 


I added a small delay right after the interrupt and everything works perfectly, but I don't think it's the best solution.

Very roughly, I tried a while loop

 

 

 

while (LL_LPUART_IsActiveFlag_IDLE(LPUART1) == 0) { }

 

 

 

This allowed me to understand that the problem was indeed coming from the LPUART==>ISR==> IDLE flag which was triggered a little after the IDLE interruption of my DMA.

@Roger SHIVELY  have you a solution?

 

Regards,

Fabien,

I got expected flags after removing the below lines in PWR_ExitStopMode, 

 

__HAL_UART_DISABLE_IT(huart,UART_IT_WUF); HAL_UARTEx_DisableStopMode(huart);

 

 

It goes to WakeupCallback when UART wakes MCU from STOP mode but not RxEventCallback

/* UART wakeup from Stop mode interrupt occurred ---------------------------*/ if (((isrflags & USART_ISR_WUF) != 0U) && ((cr3its & USART_CR3_WUFIE) != 0U))