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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

A UART question related to character READ

Hello,

I'm new to to this forum and here's a UART related question.

Im using a polling loop like this one to read a byte from the UART register:

1. status = IORD_ALTERA_AVALON_UART_STATUS(UART_DEBUG_BASE);

if (status == 0x60) then goto step# 2 else go back to step# 1

2. ch = (char)IORD_ALTERA_AVALON_UART_RXDATA(UART_DEBUG_BASE);

3. What do I do here to reset something in the UART before going back to step# 1 so as NOT to get the last character that I just read in step# 2?

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    17 years ago

    Try this: 

    
int uart_read(int base, char *ptr, int len, int flags){
    int block;
    unsigned int status;
    block = 1;//!(flags & O_NONBLOCK);
    do{
        status = IORD_ALTERA_AVALON_UART_STATUS(base);
        /* clear any error flags */
        IOWR_ALTERA_AVALON_UART_STATUS(base, 0);
        if (status & ALTERA_AVALON_UART_CONTROL_RRDY_MSK){
            ptr = IORD_ALTERA_AVALON_UART_RXDATA(base);
            if (!(status & (ALTERA_AVALON_UART_STATUS_PE_MSK | 
                ALTERA_AVALON_UART_STATUS_FE_MSK))){
                return 1;
            }
        }
    }while (block);
    return 0;
}

    It's not a completed function but I believe it illustrates what you're missing.