[SOLVED] Qserialport sending data when opened without action

fred_douille

Yes, I used the same code on arduino for QextSerialPort and QSerialPort.
It's for that I don't understand what happened.
And I think that both of them use Qiodevice?

SGaist

Which version of QSerialPort and Qt are you using ?

fred_douille

I use Qt 5.1.1 and QSerialPort built-in

SGaist

IIRC there's been some work on the QSerialPort module recently, can you test the 5.2 version to see whether it's still happening ?

fred_douille

thanks, I am downloading the RC version.
I can't try this week end but I will on monday.
thank you and I'll tell you if it works

kuzulis

2 fred_douille,

first, you can check it on the "standard" Terminal example from the QtSerialPort, because maybe you do something wrong.

fred_douille

In fact I used the terminal example from QtSerialPort. It is a very good help to explain how to use the library. But with it I had the problem, so I simplify the code to find where is the problem but in vain. I will try again with Qextserialport to be sure and maybe I should use an other arduino board. And I hope Qt 5.2 solved the problem

fred_douille

Hi,

I just tried with Qt 5.2 RC and the problem is still there.
Now I'm trying again with QextSerialPort

fred_douille

So, with QextSerialPort, no problem.
With QSerialPort I solved half the problem, if I open the port before setup the ui there is not data sent. But when I close my app, datas are sent.
It's look like there is a problem in the management of the port.
Maybe I have to put a specific flag when I open the port but I don't know wihch one.

Edit: In fact if no data are sent when I open the port with QSerialPort it's because I used QextSerialPort before.
It's look like the buffer is not empty, QextSerialPort empty it when opening and QserialPort isn't.

I think the difference is that QextSerialPort is not asynchronous while QSerialPort is.
And it's for that I can't use readyread signal with QextSerialPort.
I don't know what to do

kuzulis

In this case you can use QSerialPort::clear() method after opening.

BTW: Also your provided code do a multiple signal/slot connections after multiple clicks to the "open" button. It can lead to some problems for you.

fred_douille

I just tried QSerialPort::clear() but with no effect, very strange..

@serial->clear(QSerialPort::AllDirections);@

And now I changed my code, I open the port at the program launch without button, and close and reopen the program each time

kuzulis

You do clear() after opening? Please check a clear() return value.

Need to do like:

[code]
...
bool ret = port->open();
if (ret)
ret = port->clear();
if (ret) {
// do something
}
[/code]

fred_douille

I tried this:
@
if( serial->open(QIODevice::ReadWrite) )
{
if (serial->clear(QSerialPort::AllDirections))
{
QMessageBox::information(this,"test","cleared");
}
}
@

I have my QMessageBox saying "cleared" but still datas sent.

fred_douille

I tried to open the port in ReadOnly mode and datas are still sent.
It's so strange...

With QextSerialPort I can't use ReadyRead signal, so I'm stuck.

SOLVED!
It was ridiculous. It's look like there is a problem in QSerialPort for baudrate at 115200.
I adapted my code and my arduino to run at 9600 and it's fine.