QextSerialPort question

[sidenelen]

Hello, I'm trying to establish a communication between a microprocessor and my Ubuntu PC.

I'm using Qextserialport library. But some error occured I don't know why.

I tested the portname and it's like that attached "ttyACM0"

QextSerialPort *deneme = new QextSerialPort();
    deneme->setPortName("/dev/ttyACM0");
    deneme->setBaudRate(BAUD9600);
    deneme->setParity(PAR_NONE);
    deneme->setDataBits(DATA_8);
    deneme->setStopBits(STOP_1);
 
    if ( !(deneme->open(QIODevice::ReadWrite)) )
    {
        qDebug("error");    }
    if(deneme->isOpen())
    {
        qDebug("opened");
        deneme->close();
    }

QextSerialPort *deneme = new QextSerialPort();
    deneme->setPortName("/dev/ttyACM0");
    deneme->setBaudRate(BAUD9600);
    deneme->setParity(PAR_NONE);
    deneme->setDataBits(DATA_8);
    deneme->setStopBits(STOP_1);

    if ( !(deneme->open(QIODevice::ReadWrite)) )
    {
        qDebug("error");    }
    if(deneme->isOpen())
    {
        qDebug("opened");
        deneme->close();
    }

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When I run it, It just waits and "error" occured. What I am missing you think?

Thanks in advance

[norobro]

Possibly a permissions problem?

[sidenelen]

Probably. How should i overcome it?

[norobro]

I use QextSerialPort on my Debian box to communicate with a weather station console. Had to add my user account to the dialout group.

$ ls -l /dev/ttyS0
crw-rw---T 1 root dialout 4, 64 May 10 18:01 /dev/ttyS0

sudo adduser user dialout

[sidenelen]

onur@onur-pc:~$ ls -l /dev/ttyACM0
crw-rw---- 1 root dialout 166, 0 2012-05-11 14:11 /dev/ttyACM0

and then i try to run

onur@onur-pc:~$ sudo adduser onur dialout

the output is

The user `onur' is already a member of `dialout'.

sorry for the such noob questions.

[norobro]

sorry for the such noob questions.

No prob, this is the newbie forum after all.

Try your code without the "if" on the open statement:

. . . 
deneme->open(QIODevice::ReadWrite)
if(deneme->isOpen())
{ 
. . .

. . . 
deneme->open(QIODevice::ReadWrite)
if(deneme->isOpen())
{ 
. . .

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Edit:

Obviously I'm stabbing in the dark with the above.

Did your microprocessor docs specify the port settings you are using? Here are the settings that I use:

port = new QextSerialPort("/dev/ttyS0");
    port->setBaudRate(BAUD19200);
    port->setFlowControl(FLOW_OFF);
    port->setParity(PAR_NONE);
    port->setDataBits(DATA_8);
    port->setStopBits(STOP_2);
    port->open(QIODevice::ReadWrite)

port = new QextSerialPort("/dev/ttyS0");
    port->setBaudRate(BAUD19200);
    port->setFlowControl(FLOW_OFF);
    port->setParity(PAR_NONE);
    port->setDataBits(DATA_8);
    port->setStopBits(STOP_2);
    port->open(QIODevice::ReadWrite)

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[sidenelen]

I've changed the code like that

QextSerialPort *deneme = new QextSerialPort();
    deneme->open(QIODevice::ReadWrite);
    deneme->setQueryMode(QextSerialPort::EventDriven);
    deneme->setPortName("/dev/ttyACM0");
    deneme->setBaudRate(BAUD9600);
    deneme->setParity(PAR_NONE);
    deneme->setDataBits(DATA_8);
    deneme->setStopBits(STOP_1);
 
    if (deneme->isOpen()) qDebug("connection established");
        else                  qDebug("failed to connect");
    if (deneme->bytesAvailable()>0) {
        qDebug("byte=",deneme->bytesAvailable());
    }
    else
    {
        qDebug("theres nothing");
    }
}

QextSerialPort *deneme = new QextSerialPort();
    deneme->open(QIODevice::ReadWrite);
    deneme->setQueryMode(QextSerialPort::EventDriven);
    deneme->setPortName("/dev/ttyACM0");
    deneme->setBaudRate(BAUD9600);
    deneme->setParity(PAR_NONE);
    deneme->setDataBits(DATA_8);
    deneme->setStopBits(STOP_1);

    if (deneme->isOpen()) qDebug("connection established");
        else                  qDebug("failed to connect");
    if (deneme->bytesAvailable()>0) {
        qDebug("byte=",deneme->bytesAvailable());
    }
    else
    {
        qDebug("theres nothing");
    }
}

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Now it always says "connection established", even if i write some wrong port name like "tty12334324".

But bytesAvailable() returns "-1" when i'm trying to learn how many bytes are available to read.

By the way, I'm sure some data coming from the microprocessor with parameters that i wrote. Cause i've try it with another desktop program which is reading data from the same microprocessor truly.

[norobro]

Do you not need to send data to your device to get a response?

Try something like this:

QString cmd("a command for your device");
deneme->write(cmd.toAscii(), cmd.length());
deneme->waitForReadyRead();
qDebug() << "Bytes availible:" << deneme->bytesAvailible() << "data:" << deneme->readAll();

QString cmd("a command for your device");
deneme->write(cmd.toAscii(), cmd.length());
deneme->waitForReadyRead();
qDebug() << "Bytes availible:" << deneme->bytesAvailible() << "data:" << deneme->readAll();

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[sidenelen]

i tried it, still the same dunno wheres the missing.

[norobro]

Sorry I haven't been any help. Sending LF to my device wakes it up and it responds with CRLF, then you can start sending commands.

You might try the QSerialDevice library. The author is a member of this site: thread

[sidenelen]

I don't know how but i finally got it! thank you so much for your patient help