Record 5 - the serial port of stm32f411ceu6 realizes the sending and receiving of fixed length data and variable length data

1. Fixed length data transceiver

Mission

utilize UART Realize the sending of data of any length , After receiving the data, the single chip microcomputer sends the data to the computer as it is

Code implementation

/* USER CODE BEGIN PV */
uint8_t RxBuffer[10];// Define the buffer size of the receive area 
/* USER CODE END PV */

while (1)
  {
    
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
    HAL_UART_Receive(&huart2,RxBuffer,5,0xFFFF);
    HAL_UART_Transmit(&huart2,RxBuffer,5,0xFFFF);
  }
  /* USER CODE END 3 */

2. Variable length data sending and receiving

Mission

utilize UART Realize the sending of data of any length , After receiving the data, the single chip microcomputer adds a newline character at the end and sends it to the computer .

stm32cubemx To configure

UART And DMA The opening method is described in the previous corresponding section
For details, please see ：

https://blog.csdn.net/weixin_65489379/article/details/122783396

Code implementation

main.c in

/* USER CODE BEGIN PV */
uint8_t RxBuffer[100];// Define the buffer size of the receive area 
/* USER CODE END PV */

/* USER CODE BEGIN PD */
#include "string.h"// For later use strcat Concatenate two arrays 
/* USER CODE END PD */

/* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();
  /* USER CODE BEGIN 2 */
	HAL_UART_Receive_DMA(&huart2,RxBuffer,50);// Open the DMA
	__HAL_UART_ENABLE_IT(&huart2 ,UART_IT_IDLE);// Enable idle interrupt 

  /* USER CODE END 2 */

stm32f4xx_it.c in
Manually add the content of idle interrupt

/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */
extern uint8_t RxBuffer[100];
/* USER CODE END PV */

( stay C In language , Modifier extern Used before the declaration of a variable or function , To illustrate “ This variable / Functions are defined elsewhere , To quote... Here ")

void USART2_IRQHandler(void)
{
    
  /* USER CODE BEGIN USART2_IRQn 0 */
	if(__HAL_UART_GET_FLAG(&huart2,UART_FLAG_IDLE) != RESET )// The idle interrupt flag bit obtained is not 0, This indicates that the idle interrupt is triggered 
	{
    
	    char str[]="\r\n";\\ The newline array contains carriage return plus newline 
		__HAL_UART_CLEAR_IDLEFLAG(&huart2); Clear the free interrupt flag bit 
		HAL_UART_DMAStop(&huart2);// Data transfer ended , stop it DMA receive 
		uint8_t len= 50- __HAL_DMA_GET_COUNTER(huart2.hdmarx);// total - Number of bytes left = The actual number of bytes received 
		strcat((char*)RxBuffer ,str );
        HAL_UART_Transmit_DMA(&huart2,RxBuffer,len+2);// Resend the number of bytes received back to the computer 
		HAL_UART_Receive_DMA(&huart2,RxBuffer,50);// Turn it on again DMA receive 
	}

  /* USER CODE END USART2_IRQn 0 */

Add ：
DOS and Windows： need \r\n Only then can it be resolved to a valid carriage return line feed , Otherwise, there is only a return to the beginning of the line or a newline .

Unix and Mac OS X： take \n Resolve to a valid carriage return line feed .

Macintosh/OS 9： take \r Resolve to a valid carriage return line feed .

\r representative Carriage Return;
\n representative Line Feed.

effect