Realize serial port receiving data based on STM32 ring queue

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原文链接：https://blog.csdn.net/qq_36413982/article/details/103836946

说在前面

Those who code should learn data structures and have learned about queues.A circular queue is a special form of queue,It is widely used.Because there are so many articles about this,Theoretical knowledge can be seen by others,The following is well written：STM32进阶之串口环形缓冲区实现

代码实现

• Ring queue data structure

typedef struct ringBuff{
    unsigned int in;               //写入的位置
    unsigned int out;              //读出的位置
    unsigned char buffer[RING_BUFF_SIZE];     //数据域
}stRingBuff;

• Write one byte of data to the queue

/**
 - @brief:         Write one byte of data to the circular queue
 - @param[in]:     None
 - @retval[out]:   None
 - @note:            
 - @author:       AresXu
 - @version:      v1.0.0
*/
char WriteOneByteToRingBuffer(stRingBuff *ringBuf,char data)
{
 if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    if(IsRingBufferFull(ringBuf))   //Before writing, check whether the queue is full
    {
        return FALSE;
    }

    ringBuf->buffer[ringBuf->in] = data;
    ringBuf->in = (++ringBuf->in) % RING_BUFF_SIZE;    //防止越界
 return TRUE;
}

When writing data, it is necessary to judge whether the queue is full,When it is full, it cannot be written.

• Determine if the queue is full

/**
 - @brief:         Check whether the ring queue is full
 - @param[in]:     None
 - @retval[out]:   None
 - @note:            
 - @author:       AresXu
 - @version:      v1.0.0
*/
bool IsRingBufferFull(stRingBuff *ringBuf)
{
  if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    if(((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out)
    {
//  printf("Ring buffer is Full\r\n");
        return TRUE;
    }
    return FALSE;
}

当写满时,The read and write positions are also equal,Can't tell if it's full.There are two solutions to this situation：

The data structure adds a variable to count the number of data written

像这种((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out,Free up a byte to not write data

• Read one byte of data

/**
 - @brief:         Read one byte of data from the circular queue
 - @param[in]:     None
 - @retval[out]:   None
 - @note:            
 - @author:       AresXu
 - @version:      v1.0.0
*/
char ReadOneByteFromRingBuffer(stRingBuff *ringBuf,char *data)
{
 if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    if(IsRingBufferEmpty(ringBuf))    //Check if the queue is empty before reading
    {
        return FALSE;
    }

    *data = ringBuf->buffer[ringBuf->out];
    ringBuf->out = (++ringBuf->out) % RING_BUFF_SIZE;    //防止越界

    return TRUE;
}

• 判断队列是否为空 Empty when the write position and the read position are equal

/**
 - @brief:        Check if the ring queue is empty
 - @param[in]:     None
 - @retval[out]:   None
 - @author:       AresXu
 - @version:      v1.0.0
*/
bool IsRingBufferEmpty(stRingBuff *ringBuf)
{ 
 if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    if(ringBuf->in == ringBuf->out)   //Empty when the write position and the read position are equal
    {
//  printf("Ring buffer is Empty\r\n");
        return TRUE;
    }
    return FALSE;
}

• Write multiple bytes to the queue

/**
 * @brief:         寫lenbytes of data to the circular queue
 * @param[in]:     None
 * @retval[out]:   None
 * @note:            
 * @author:        AresXu
 * @version:       v1.0.0
*/
void WriteRingBuffer(stRingBuff *ringBuf,char *writeBuf,unsigned int len)
{
    unsigned int i;
 
 if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    for(i = 0; i < len; i++)
    {
        WriteOneByteToRingBuffer(ringBuf,writeBuf[i]);
    }
}

• Read multiple bytes from the queue

/**
 * @brief:         Read from the circular queuelenbytes of data
 * @param[in]:     None
 * @retval[out]:   None
 * @note:            
 * @author:       AresXu
 * @version:      v1.0.0
*/
void ReadRingBuffer(stRingBuff *ringBuf,char *readBuf,unsigned int len)
{
    unsigned int i;
    
 if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }
    
    for(i = 0; i < len; i++)
    {
        ReadOneByteFromRingBuffer(ringBuf,&readBuf[i]);
    }
}

• Get the length of data that has been written to the queue It is convenient to know how much data to read from the queue after receiving.

/**
  * @brief:         Get the length that has been written
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @version:       v1.0.0
*/
int GetRingBufferLength(stRingBuff *ringBuf)
{
    if (ringBuf == NULL)
    {
        printf("pointer is null\r\n");
        return;
    }

    return (ringBuf->in - ringBuf->out + RING_BUFF_SIZE) % RING_BUFF_SIZE;
}

画个图,You can know why by drawing and you can judge the length of the write.

到STM32上测试

• Serial port receiving part：

static stRingBuff g_stRingBuffer = {0,0,0};
static u8 g_recvFinshFlag = 0;

stRingBuff *GetRingBufferStruct(void)
{
 return &g_stRingBuffer;
}

u8 *IsUsart1RecvFinsh(void)
{
 return &g_recvFinshFlag;
}

void USART1_IRQHandler(void)                 //串口1中断服务程序
{
 u8 res;

 if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)  //接收中断(接收到的数据必须是0x0d 0x0a结尾)
 {
  res = USART_ReceiveData(USART1); //读取接收到的数据
  WriteOneByteToRingBuffer(GetRingBufferStruct(),res); 
    }
 if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)        //空闲中断
 {
  USART_ReceiveData(USART1);           //清除空闲中断
  g_recvFinshFlag = 1;                  //接收完成
 }
}

• 主函数：

int main(void)
{  
 char readBuffer[100];
 u16 t;  
 u16 len; 
 u16 times = 0;
 delay_init();       //延时函数初始化   
 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置NVIC中断分组2:2位抢占优先级,2位响应优先级
 uart_init(115200);  //串口初始化为115200
 LED_Init();        //LED端口初始化
 KEY_Init();          //初始化与按键连接的硬件接口
 
 while(1)
 {
  times++;
  if(*IsUsart1RecvFinsh())
  {
   ReadRingBuffer(GetRingBufferStruct(),readBuffer,GetRingBufferLength(GetRingBufferStruct()));
   printf("%s",readBuffer);
   memset(readBuffer,0,100);
   *IsUsart1RecvFinsh() = 0;
  }
  if(times%500==0)
   LED0=!LED0;
  delay_ms(1);   
 }  
}

• 串口收发测试

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