STM32L4A6 Exiting Stop Mode 1 using UART

[jlsw30]

Hi, 

Using references from 

1) STML496 UART Wake up from Stop Example - https://github.com/STMicroelectronics/STM32CubeL4/blob/master/Projects/NUCLEO-L496ZG/Examples/UART/UART_WakeUpFromStop/Src/main.c#L78 

2) STM Getting started with PWR Guide - https://wiki.st.com/stm32mcu/wiki/Getting_started_with_PWR#Stop0.2C_Stop1.2C_and_Stop2_modes

I have the following code that tries to wake up from STOP1 via UART. 

 

 /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
 HAL_Init();
 /* USER CODE BEGIN Init */
 /* USER CODE END Init */
 /* Configure the system clock */
 SystemClock_Config();
 /* USER CODE BEGIN SysInit */
 /* USER CODE END SysInit */
 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_I2C1_Init();
 MX_UART5_Init();
 /* USER CODE BEGIN 2 */
 HAL_PWREx_EnableLowPowerRunMode();
 /* USER CODE END 2 */
 __HAL_RCC_WAKEUPSTOP_CLK_CONFIG(RCC_STOP_WAKEUPCLOCK_MSI);
 /* make sure that no UART transfer is on-going */
 while(__HAL_UART_GET_FLAG(&huart5, UART_FLAG_BUSY) == SET);
 /* make sure that UART is ready to receive
 * (test carried out again later in HAL_UARTEx_StopModeWakeUpSourceConfig) */
 while(__HAL_UART_GET_FLAG(&huart5, UART_FLAG_REACK) == RESET);
 WakeUpSelection.WakeUpEvent = UART_WAKEUP_ON_READDATA_NONEMPTY;
 if (HAL_UARTEx_StopModeWakeUpSourceConfig(&huart5, WakeUpSelection)!= HAL_OK)
 {
 Error_Handler();
 }
 /* Enable the UART Wake UP from STOP1 mode Interrupt */
 __HAL_UART_ENABLE_IT(&huart5, UART_IT_WUF);
 /* enable MCU wake-up by UART */
 HAL_UARTEx_EnableStopMode(&huart5);
 /* enter STOP1 mode */
 DEBUG_Transmit((uint8_t *)"Entering stop mode\r\n", 20);
 HAL_SuspendTick();
 HAL_PWREx_EnterSTOP1Mode(PWR_SLEEPENTRY_WFI);
 HAL_ResumeTick();
 DEBUG_Transmit((uint8_t *)"success\r\n", 9);
 /* at that point, MCU has been awoken: the LED has been turned back on */
 SystemClock_Config();
 /* Wake Up based on RXNE flag successful */
 HAL_UARTEx_DisableStopMode(&huart5);

 

 However, the interrupt does not seem to trigger and i am always stuck in stop mode.

I have also attached my clock configuration as follows.

Appreciate any advise on what I am doing wrong. Thank you. 

[Sarra.S]

Hello @jlsw30, welcome to ST Community, 

To be sure that the UART is not busy with any ongoing transmission or reception and the UART receiver is enabled and ready to receive data: 

 while(__HAL_UART_GET_FLAG(&UartHandle, USART_ISR_BUSY) == SET);
 /* make sure that UART is ready to receive
 * (test carried out again later in HAL_UARTEx_StopModeWakeUpSourceConfig) */
 while(__HAL_UART_GET_FLAG(&UartHandle, USART_ISR_REACK) == RESET)

 

[jlsw30]

Hello Sarra, thank you for the reply. 

Initially thought I had to use a different flag as it was UART5 instead of USART5 on STML4A6. 

Either way, I have tried the code as recommmended but was still unable to wake up from stop mode.  

 while(__HAL_UART_GET_FLAG(&UartHandle, USART_ISR_BUSY) == SET);
 /* make sure that UART is ready to receive
 * (test carried out again later in HAL_UARTEx_StopModeWakeUpSourceConfig) */
 while(__HAL_UART_GET_FLAG(&UartHandle, USART_ISR_REACK) == RESET)

In the datasheet, UART 5 is able to wake stop1, so i believe that it should be possible 

I have also attached my callbacks as follows for reference:

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
 if (huart->Instance == UART5)
 {
		HAL_ResumeTick();
		/* at that point, MCU has been awoken: the LED has been turned back on */
		SystemClock_Config();
 /* Handle received data */
 DEBUG_Transmit((uint8_t *)"Data received\r\n", 15);
 }
}

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
 if (huart->Instance == UART5)
 {
 DEBUG_Transmit((uint8_t *)"Data transmitted\r\n", 18);
 }
}

void HAL_UART_ErrorCallback(UART_HandleTypeDef *huart)
{
 if (huart->Instance == UART5)
 {
 DEBUG_Transmit((uint8_t *)"UART Error\r\n", 12);
 }
}

Thank you!

[jlsw30]

I have attached my .ioc file and main.c file for reference

[jlsw30]

Solved this by adjusting clock to not use MSI, though this is not an optimal solution as i would prefer a lower clock speed configuration for my usage. Will try to see how i can modify the code to work with MSI clock configuration.