cancel
Showing results for 
Search instead for 
Did you mean: 

UART WITH STM32L476

ACekm.1
Associate II

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 */

}

11 REPLIES 11
Bob S
Principal

"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?

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.

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..
S.Ma
Principal

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

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

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;

}

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

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

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);
}

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..