UART WITH STM32L476

[ACekm.1]

i was planning to do an experiment i need to insert two numbers and calculate the sum of that two inserted number. Then i need to see them in terminal. However i have confused a bit. Could anyone help me? I get stuck over here.

 /* USER CODE END 2 */

 int First_Digit;

 int Second_Digit;

 int Sum_Digits;

 /* Infinite loop */

 /* USER CODE BEGIN WHILE */

 while (1)

 {

   /* USER CODE END WHILE */

uint8_t First_Digit[] = "first digit \r\n"; // data to send

HAL_UART_Transmit(&huart2, First_Digit, 18, 100);

HAL_Delay(2000);

uint8_t Second_Digit[] = "second digit \r\n"; // data to send

HAL_UART_Transmit(&huart2, Second_Digit, 18, 100);

HAL_Delay(2000);

uint8_t Sum_Digits[] = "sum \r\n"; // data to send

HAL_UART_Transmit(&huart2, Sum_Digits, 12, 100);

HAL_Delay(2000);

   /* USER CODE BEGIN 3 */

 }

 /* USER CODE END 3 */

}

[Bob S]

"experiment" == "homework" ? 🙂

First thing, do not hard-code string lengths into HAL_UART_Transmit() calls. Use strlen() (**NOT** sizeof()) instead:

HAL_UART_Transmit(&huart2, First_Digit, strlen(First_Digit), 100);

So how are you stuck? What is your program doing that you don't expect? Or what is it NOT doing that you want it to do?

[Tesla DeLorean]

You'll need to receiver characters, and perhaps a RETURN/ENTER character to mark the end of the input, and then convert those characters into a numeric form you can do math on.

[S.Ma]

A console example using interrupts and sw fifo would probably help a significant number of coders....

[ACekm.1]

i can not printed the sum of two numbers. i can print first digit, second digit. however i can not be able to print sum and dont know how to make calculation in uart

[ACekm.1]

int main(void)

{

 /* USER CODE BEGIN 1 */

 /* USER CODE END 1 */

 /* MCU Configuration--------------------------------------------------------*/

 /* 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_USART2_UART_Init();

 /* USER CODE BEGIN 2 */

 /* USER CODE END 2 */

 int First_Digit;

 int Second_Digit;

 int Sum_Digits;

 /* Infinite loop */

 /* USER CODE BEGIN WHILE */

 while (1)

 {

   /* USER CODE END WHILE */

uint8_t First_Digit[] = "first digit \r\n"; // data to send

HAL_UART_Transmit(&huart2, "\r\n First_Digit:", 18, 100);

read_inputs();

//L_Delay(1500);

uint8_t Second_Digit[] = "second digit \r\n"; // data to send

HAL_UART_Transmit(&huart2, "\r\n Second_Digit:", 18, 100);

read_inputs();

//L_Delay(1500);

uint8_t Sum_Digits[] = "sum \r\n"; // data to send

HAL_UART_Transmit(&huart2, "\r\n Sum_Digits:", 50, 100);

convert_cton();

//L_Delay(1500);

   /* USER CODE BEGIN 3 */

 }

 /* USER CODE END 3 */

}

int read_inputs() {

   char button_pressed = "";

   char buffer[255];

   int i=0;

   while(button_pressed != '\r')

   {

      HAL_UART_Receive(&huart2, &button_pressed, 1, 100000000);

      HAL_UART_Transmit(&huart2, &button_pressed, 1, 100000000);

      buffer[i++] = button_pressed;

   }

   return atoi(buffer);

}

//int read_outputs() {

//   char button_pressed = "";

   //char buffer[255];

   //int i = 0;

//   while(button_pressed !='\r')

   //{

      //HAL_UART_Receive(&huart2, &button_pressed, 1, 100000000);

         //   HAL_UART_Transmit(&huart2, &button_pressed, 1, 100000000);

         //   buffer[i++] = button_pressed;

   //}

   //return atoi(buffer);

//}

int convert_cton() {

   char button_pressed = "";

   int Sum_Digits = (int)(button_pressed)+0;

   printf("%d", Sum_Digits);

   return 0;

}

[ACekm.1]

could u explain me more please if u check i have also posted full code that i have developed.

[Bob S]

Not IRQ but DMA: https://github.com/MaJerle/stm32-usart-uart-dma-rx-tx

[Piranha]

For educational purposes one should actually go through all of those approaches: polling, IRQ, IRQ+DMA and IRQ with software FIFO.

[Tesla DeLorean]

Make sure to NUL terminate input you are feeding to string functions.

Perhaps also watch the values returned by functions, and buffer length

int read_inputs(void)
{
   char buffer[255];
   int i=0;
 
   while(1)
   {
     char button_pressed;
     if (HAL_UART_Receive(&huart2, &button_pressed, 1, 100000000) == HAL_OK)
     {
       HAL_UART_Transmit(&huart2, &button_pressed, 1, 100000000);
       if ((button_pressed == '/r') || (button_pressed == '/n') || (i >= (sizeof(buffer) - 2)))
         break;
       buffer[i++] = button_pressed;
     }
   }
 
   buffer[i++] = 0; // NUL terminate
 
   return atoi(buffer);
}