STM32 serial port based on Hal library accepts interrupts and idle interrupts

Preface

In communications .UART Due to full duplex communication , It can accept data and send data at the same time and is widely used .

There are many ways to accept data

such as :

<1> Judge according to the terminator , Data is in string form , So generally, the receiver accepted by the serial port is "\r\n"  Switch to 16 Base number ascil Code display is 0X0D   0X0A ( Corresponding \r\n)

 <2> Timer interrupt , Design " Dog feed semaphore " That is, the idle time of the serial port , The timer after serial port acceptance is continuously decreasing , If it is reduced to zero, it is judged that the acceptance is complete , When receiving the data, feed the dog to refresh the decreasing time .（ This is also the common serial port acceptance idea of MCU ）

Refer to me 51 The engineering of ：

MCU serial port interrupt and message sending and receiving processing —— Judge and control the received information _ Hao Yuehua's blog -CSDN Blog _ How to trigger SCM serial port interrupt

 <3>STM32 There are many ways , The first two can be used in some cases .

But the first one only applies to the judgment terminator . I recently made RF module （RF） Data sent by serial port （ A kind of 16 The format of hexadecimal , No, \r\n The terminator ） It's Limited , In addition, the second type needs to be matched with a timer . And I am satisfied with the serial port accepting interrupt and idle interrupt introduced in this writing   YYDS!!!

understand

Serial port accepts interrupt ：

Enable serial port to accept interrupt RXEN after , The serial port accepts a packet , One frame （ Usually 8 Digit bit , One end bit ） Then enter interrupt .

With a timer 2 For example

Can make

__HAL_UART_ENABLE_IT(&huart2,UART_IT_RXNE);

  The actual processing function

USART2_IRQHandler(void)

  stay HAL The library function cannot be redefined , stay stm32f1xx_it.c in Add __weak Indicates that the weak definition can be rewritten

__weak void USART2_IRQHandler(void)

Serial port idle interrupt ：

  In enabling IDLE  , After receiving a frame of data through the serial port , If the serial port remains idle within a byte, the serial port idle interrupt will be triggered   

Once again into the   USART2_IRQHandler(void)   

Can make  

 __HAL_UART_ENABLE_IT(&huart2,UART_IT_IDLE);

It is the same as the interrupt processing function of serial port receiving data . Like the improvement of the second method above , Because the second method doesn't know how long it takes , Because the size of the data transmission interval is unknown , Only one value can be estimated to pass the attenuation “ Dog feed semaphore ” To judge . Again , If the data is too large and keeps sending, it will not be idle .

It is worth noting that , After the serial port is accepted, the idle flag bit must be cleared . Through reading serial port DR Register to clear IDLE Sign a , Otherwise, the program will always trigger idle interrupt .

For example, serial port interrupt processing code （ Take serial port 3 as an example ） Be careful ( use __weak modification hal library stm32f1x_it.c In this rewrite ）

void USART3_IRQHandler(void){
      uint8_t temp;
    if(huart3.Instance->SR & UART_FLAG_RXNE){
         Rx_uart3_signal=2;
         temp=huart3.Instance->DR;
        Rx_uart3_buf[Rx_uart3_cnt++]=temp; 
    }
    
    else if(huart3.Instance->SR & UART_FLAG_IDLE){
         temp=huart3.Instance->DR;
        Rx_uart3_signal=0;
		
		 
		
    }

}

adopt Rx_uart3_signal=0 Judge that one acceptance is over , stay while Print data in . The effect is very good for me , The second method is in the form of hardware （stm32 Built in idle interrupt ） Instead of a timer, it realizes packet acceptance .

Reference resources

STM32 Idle interrupt of serial port _csdn_dx The blog of -CSDN Blog _ Serial port idle interrupt