Re: Problem with UART using register

Altera_Forum · ‎09-02-2009

Hello,

I made a project with a Nios II processor, and I am currently trying to get data from UART.

I tried using the getc function and it works fine, I received all the data. I also tried using register (checking the bit RRDY of the status register) but I don't get all the data (in average, I received a third of the data I send, but it is not constant). For the test, I use a simple rs232 terminal (Termite), and send byte by byte manually, so it is not a problem of speed. In my code, I just get data from uart and display the value on leds, I think my code is correct (I put the two methods used below), but I don't see why it doesnot work correctly, if anyone has an idea.

Thanks in advance.

Jérôme


    // Reading uart using HAL (works all the time)
    FILE* file;
    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, ~0x00);
    file = fopen (UART_NAME, "r+");
    do
    {
        data = getc(file);
        IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, ~data);
    }while(1);
    // Reading uart using register (works sometimes)
    do
    {
        status = IORD_ALTERA_AVALON_UART_STATUS(UART_BASE);
        if( (status & ALTERA_AVALON_UART_STATUS_RRDY_MSK) != 0)
        {
            data = IORD_ALTERA_AVALON_UART_RXDATA(UART_BASE);
            IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, ~data);
        }
    }while(1);

Altera_Forum · ‎09-02-2009

hi, same mistake

try with ALTERA_AVALON_UART_STATUS_tRDY_MSK.

I don't know why it works for me.

EDIT : Sorry, wrong way

Altera_Forum · ‎09-02-2009

Here I don't send data, so the bit TRDY is always at 1.

Else, this phenomenon is strange because, if I enable interrupt on reception, when I have an interrupt I get all bytes correctly using the same method.

Altera_Forum · ‎09-02-2009

I use this in "interrupt on reception", it works well.

In a superloop, reading if RRDY is active is not recommended I think.

It is a mistake for me too.