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Altera_Forum's avatar
Altera_Forum
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20 years ago

Problem detecting data no Serial Port

Hello,

I´ve built the folowing code:

while (1)

{

fprintf(fp, "%c", B_PACK);

for (j = 0; j < 10000000; j++)

{

//testadado = (testadado | tembyte()); // tem dado http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

if(IORD_ALTERA_AVALON_UART_STATUS(ENDSERIAL) & 0x080)

{

printf("I got data");

testadado = 1;

getchar();

break;

}

}

}

Where fp is a pointer to my uart1.

Well, I´m testing this code with Hyperterminal.

I can receive the B_PACK byte there with no problems. But when I send one byte thru the Hyperterminal, the code keeps running and it do not enter in the

if(IORD_ALTERA_AVALON_UART_STATUS(ENDSERIAL) & 0x080)

condition.

If I send a lot of data, then sometimes it enters in the condition. But it do not work to the first data.

Can someone help me?

And isn´t there another way to detect if there is data on the serial?

Thanks!

4 Replies

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

    --- Quote Start ---

    originally posted by hoffpistolao@Dec 21 2005, 08:27 AM

    hello,

    i´ve built the folowing code:

    while (1)

    {

    fprintf(fp, "%c", b_pack);

    for (j = 0; j < 10000000; j++)

    {

    //testadado = (testadado | tembyte()); // tem dado http://forum.niosforum.com/work2/style_emoticons/<#emo_dir#>/smile.gif

    if(iord_altera_avalon_uart_status(endserial) & 0x080)

    {

    printf("i got data");

    testadado = 1;

    getchar();

    break;

    }

    }

    }

    where fp is a pointer to my uart1.

    well, i´m testing this code with hyperterminal.

    i can receive the b_pack byte there with no problems. but when i send one byte thru the hyperterminal, the code keeps running and it do not enter in the

    if(iord_altera_avalon_uart_status(endserial) & 0x080)

    condition.

    if i send a lot of data, then sometimes it enters in the condition. but it do not work to the first data.

    can someone help me?

    and isn´t there another way to detect if there is data on the serial?

    thanks!

    <div align='right'><{post_snapback}> (index.php?act=findpost&pid=11692)

    --- quote end ---

    --- Quote End ---

    Hello,

    maybe the problem here is that you are using high-level HAL functions with low-level macros (driver level) to access your UART. If you only use one of these methods, it should work. May be if you fclose() the UART before using the low-level macros could help.

    We had a similar problem because we wanted to use the high-level HAL functions only, but then the getchar() function blocked until there was data received. So we decided to write our own UART driver with a non-blocking read() function.

    I hope this helps!
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    I got that.

    And is there a way to detect if there is data on serial using High level functions?

    Because if I use getc to read a data the program stops until the data comes.

    So I would like to be sure that there is data, and then use the getc().

    Thank you for replying! =]
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    I haven&#39;t found a way to detect if there is a byte in the receive buffer of the UART with high-level HAL functions (like read(), getc()...) only. This was the reason why we created our own low-level driver for the UART which has a different read() function which returns immediately even if there was no data received. If this is the case, our function simply returns a value which indicates that 0 bytes are received and the calling code can continue.

    Unfortunately I cannot give you the code of our driver because there is some other functionality in this driver which is very application-specific.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    try this code , it check how much char are in the uart buffer

    # include "altera_avalon_uart.h"# include <fcntl.h># include <unistd.h># include "priv/alt_file.h"

    int getUartBufferCnt()

    {

    //alt_fd* fd=&alt_fd_list[fdterm];

    //fd is the uart&#39;s file discreptor

    alt_avalon_uart_dev* dev = (alt_avalon_uart_dev*) fd->dev;

    int bufferCnt=dev->rx_end-dev->rx_start;

    if(bufferCnt<0)

    bufferCnt+=ALT_AVALON_UART_BUF_LEN;

    return bufferCnt;

    }