如何從UART正確接收字符串

Question

我發送一個這樣的字符串：$ 13，-14,283,4，-4,17,6，-240，-180＃

但是沒有顯示因為緩沖區是“重載”，我怎樣才能收到整個字符串或者如何在讀取每個字節后清除它？

// get a character string 
char *getsU2(char *s, int len) { 
    char *p = s; // copy the buffer pointer 
    do {
        *s = getU2(); // get a new character 
        if (( *s=='\r') || (*s=='\n')) // end of line... 
            break; // end the loop s++;

        // increment the buffer pointer 
        len--;
    } while (len>1); // until buffer is full 

    *s = '\0'; // null terminate the string 

    return p; // return buffer pointer
} 


// get a character string
char *getsU2(char *s, int len) { 
    char *p = s; // copy the buffer pointer 
    do {
        *s = getU2(); // get a new character 

        if (( *s=='\r') || (*s=='\n')) // end of line... 
            break; // end the loop 

        s++;     

        // increment the buffer pointer 
        len--; 
    } while (len>1); // until buffer is full

    *s = '\0'; // null terminate the string      

    return p;    // return buffer pointer
}



char getU2(void) { 
if(U2STAbits.OERR == 1) 
{     U2STAbits.OERR = 0; } 
while (!U2STAbits.URXDA);    // wait for new character to arrive return U2RXREG;
                             // read character from the receive buffer }

getsU2(buffer,sizeof(buffer));

Answer 1

嘗試使用UART接收中斷。 以下代碼適用於PIC24H; 適當修改。

在你的init函數中：

IFS0bits.U1RXIF = 0;        // clear rx interrupt flag
IFS0bits.U1TXIF = 0;        // clear tx interrupt flag

IEC0bits.U1RXIE = 1;        // enable Rx interrupts
IPC2bits.U1RXIP = 1;
IEC0bits.U1TXIE = 1;        // enable tx interrupts
IPC3bits.U1TXIP = 1;   

創建一個中斷處理程序，將字節放入緩沖區或隊列：

void __attribute__((__interrupt__, auto_psv)) _U1RXInterrupt(void)
{
    char bReceived;

    // Receive Data Ready
    // there is a 4 byte hardware Rx fifo, so we must be sure to get all read bytes    
    while (U1STAbits.URXDA)
    {
        bReceived = U1RXREG;

        // only usethe data if there was no error
        if ((U1STAbits.PERR == 0) && (U1STAbits.FERR == 0))
        {
             // Put your data into a queue
             FIFOPut(bReceived);

        }

    }    

    IFS0bits.U1RXIF = 0;        // clear rx interrupt flag 
}

您的隊列代碼如下：

#define FIFO_SIZE 64

char pbBuffer[FIFO_SIZE];
char *pbPut;
char *pbGet;

void FIFOInit(void)
{
    pbPut = pbBuffer;
    pbGet = pbBuffer;
}

void FIFOPut(char bInput)
{
    *pbPut = bInput;
    pbPut++;

    if (pbPut >= (pbBuffer + FIFO_SIZE))
        pbPut = pbBuffer;
}

char FIFOGet(void)
{
    char bReturn;

    bReturn = *pbGet;
    pbGet++;

    if (pbGet>= (pbBuffer + FIFO_SIZE))
        pbGet= pbBuffer;
}   

顯然，應該加強FIFO功能以防止溢出，在空隊列上返回錯誤等。