原文链接:STM32串口之环形队列接收数据
码代码的应该学数据结构都学过队列。环形队列是队列的一种特殊形式,应用挺广泛的。
因为有太多文章关于这方面的内容,理论知识可以看别人的,下面写得挺好的:
STM32进阶之串口环形缓冲区实现
代码实现
环形队列数据结构
typedef struct ringBuff{
unsigned int in;
unsigned int out;
unsigned char buffer[RING_BUFF_SIZE];
}stRingBuff;
写一字节数据到队列
char WriteOneByteToRingBuffer(stRingBuff *ringBuf,char data)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(IsRingBufferFull(ringBuf))
{
return FALSE;
}
ringBuf->buffer[ringBuf->in] = data;
ringBuf->in = (++ringBuf->in) % RING_BUFF_SIZE;
return TRUE;
}
写入数据时要判断队列是否满,满了肯定就不能写入。
判断队列是否写满
bool IsRingBufferFull(stRingBuff *ringBuf)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out)
{
return TRUE;
}
return FALSE;
}
当写满时,读写位置也是相等,无法判断是否写满。这种情况有两种办法解决:
。数据结构增加一个变量来计数写入数据的个数
。像这种 ((ringBuf->in+1) % RING_BUFF_SIZE) == ringBuf->out,空出一个字节来不写数据
读一字节的数据
char ReadOneByteFromRingBuffer(stRingBuff *ringBuf,char *data)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(IsRingBufferEmpty(ringBuf))
{
return FALSE;
}
*data = ringBuf->buffer[ringBuf->out];
ringBuf->out = (++ringBuf->out) % RING_BUFF_SIZE;
return TRUE;
}
判断队列是否为空
写入位置和读出位置相等时为空
bool IsRingBufferEmpty(stRingBuff *ringBuf)
{
if (ringBuf == NULL)
{
printf("pointer is null\r\n");
return;
}
if(ringBuf->in == ringBuf->out)
{
return TRUE;
}
return FALSE;
}
写多个字节到队列
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]);
}
}
从队列中读出多个字节
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]);
}
}
获取已经写入队列的数据长度
有这个方便知道接收完了要从队列中读出多少个数据。
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,画画就可以知道为什么这样可以判断写入的长度。
到STM32上测试
串口接收部分:
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)
{
u8 res;
if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
{
res = USART_ReceiveData(USART1);
WriteOneByteToRingBuffer(GetRingBufferStruct(),res);
}
if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)
{
USART_ReceiveData(USART1);
g_recvFinshFlag = 1;
}
}
主函数:
int main(void)
{
char readBuffer[100];
u16 t;
u16 len;
u16 times = 0;
delay_init();
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
uart_init(115200);
LED_Init();
KEY_Init();
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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