STM32CubeMX serial port receives data (interrupt mode, HAL library)

System: Linux Mint 18.3 xfce 64bit 
Software: 
STM32CubeMX 4.24 
SW4STM32 2.4

Development board chip: STM32F103RCT6, STM32F407VET6 
Implementation effect: Open two serial port assistant windows, one for USART1 and one for USART2. Data sent from any serial port (serial port 1 or serial port 2) will be immediately returned through this serial port 
.

Advantages of using STM32CubeMX and SW4STM32: 
(1) Advantage of cross-platform development, there are ready-made installation packages for both Windows and Linux systems, and the installation process of sw4stm32 will automatically install the STLINK driver 
(2) Version upgrades are active, which I think is a good phenomenon, indicating that developers attach great importance to it 
(3) The most important thing is free! ! ! No need to look for crack activation everywhere

(1) Use STM32CubeMX to configure TIM3, PA8, PD2 (LED light), USART1, USART2 in Pinout.

(2) Keep the clock configuration as default 

(3) Set the TIM1 clock to interrupt once every 1s 

(4) Keep the baud rates of USART1 and USART2 unchanged, set NVIC as shown below, pay attention to the priority 
 
 
(5) and then generate the SW4STM32 project 

(6) Use sw4stm32 to open the project and 
add three codes in main.c. Please refer to the prompts for the specific locations. The entire main.c file is too long to post.

/* USER CODE BEGIN PV */

/* Private variables ---------------------------------------------------------*/

uint8_t aTxBuffer[]="*********Serial port sends data ××××××××××××\r\n";

uint8_t aRxBuffer1[1]; // used to receive data sent by serial port 1

uint8_t aRxBuffer2[1]; // used to receive data sent by serial port 2

/* USER CODE END PV */

  /* Infinite loop */

  /* USER CODE BEGIN WHILE */

    HAL_UART_Receive_IT(&huart1,aRxBuffer1,1);          // Enable the USART1 Interrupt

    HAL_UART_Receive_IT(&huart2,aRxBuffer2,1);          // Enable the USART2 Interrupt

    HAL_UART_Transmit(&huart1,aTxBuffer,sizeof(aTxBuffer),100);

    HAL_UART_Transmit(&huart2,aTxBuffer,sizeof(aTxBuffer),100);

    HAL_TIM_Base_Start_IT(&htim3); // Start timer 3

  while (1)

  {

  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */

  }

  /* USER CODE END 3 */

/* USER CODE BEGIN 4 */

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)

{

    if(huart->Instance == USART1) // Determine which serial port triggered the interrupt

    {

        HAL_UART_Transmit(&huart1,aRxBuffer1,1,100); // Send the received data immediately using serial port 1

        HAL_UART_Receive_IT(&huart1,aRxBuffer1,1); // Re-enable serial port 1 receive interrupt

    }

    if(huart->Instance == USART2)

    {

        HAL_UART_Transmit(&huart2,aRxBuffer2,1,100); // Send the received data immediately using serial port 1

        HAL_UART_Receive_IT(&huart2,aRxBuffer2,1); // Re-enable serial port 2 receive interrupt

    }

}

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)

{

    if(htim->Instance == TIM3) // Determine which timer triggered the interrupt

    {

        HAL_GPIO_TogglePin(GPIOA,GPIO_PIN_8);

    }

}

/* USER CODE END 4 */

If you find that the effect cannot be achieved, please check whether your hardware connection is correct, and whether the USB to TTL converter is normal. I encountered that my USB to TTL converter could receive data from STM32 but could not send data. I tossed it all night and changed the serial port line the next day to test it. It was normal