How do I wake from Stop mode using UART?

[JKing.8]

Hello all,

After successfully entering Stop mode with my STM32F051, I cannot wake it up. I have referenced this article heavily, but cannot get it to work for me (I see that it is for an F072B): https://github.com/STMicroelectronics/STM32CubeF0/blob/master/Projects/STM32F072B-Discovery/Examples/UART/UART_WakeUpFromStop/Src/main.c

I have been using this method of wakeup:

WakeUpSelection.WakeUpEvent = UART_WAKEUP_ON_ADDRESS; WakeUpSelection.AddressLength = UART_ADDRESS_DETECT_7B;

WakeUpSelection.Address = 0x29;

__HAL_UART_ENABLE_IT(&UartHandle, UART_IT_WUF);

HAL_UARTEx_EnableStopMode(&UartHandle);

After entering Stop mode by sending "stop", how can I wake it up? I cannot get "HAL_UART_RxCpltCallback" to call again. Is that even how I can wake it up, or how do I send 0x29?

uint8_t Rx_data[4];  //  creating a buffer of 4 bytes
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
	  HAL_UART_Receive_IT(&huart1, Rx_data, 4);
		if (Rx_data[0] == 's' && Rx_data[1] == 't' && Rx_data[2] == 'o' && Rx_data[3] == 'p') {
			  HAL_PWR_EnterSTOPMode(PWR_LOWPOWERREGULATOR_ON, 
                          PWR_STOPENTRY_WFI);
		}
 
		if (Rx_data[0] == 'w' && Rx_data[1] == 'a' && Rx_data[2] == 'k' && Rx_data[3] == 'e') {
			SystemClock_Config();
			HAL_UARTEx_DisableStopMode(&huart1);
		}
}

Any help or tips are appreciated. Thank you in advance!

[S.Ma]

I think wakeup pin connected to rx maybe needed in clock stopped.mode, as unclocked or self clocked peripheral maybe needed to kick back the main oscillator. In STM33L or U series, there is LPUART as low.power uart which can wakeup on incoming RX data byte and catch it value. If bitrate remains reasonable.

[Piranha]

https://github.com/STMicroelectronics/STM32CubeF0/blob/830a0e950d421c17abff57a2ea1e977870355519/Projects/STM32F072B-Discovery/Examples/UART/UART_WakeUpFromStop/Src/main.c#L103

https://github.com/STMicroelectronics/STM32CubeF0/blob/830a0e950d421c17abff57a2ea1e977870355519/Projects/STM32F072B-Discovery/Examples/UART/UART_WakeUpFromStop/Src/main.c#L189

And who will call these?

[JKing.8]

1: USARTx_RCC_CONFIG(RCC_USARTxCLKSOURCE_HSI);

This command is not applicable to the STM32F051, but I still set the UART clock source to HSI using PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_HSI;

2: if (HAL_UARTEx_StopModeWakeUpSourceConfig(&UartHandle, WakeUpSelection)!= HAL_OK){

I do have this command, but I forgot to include that in my question. I was trying to not flood the page with code:)