QSerialPort data missing while reading

mostefa

Adding to what @mrjj said

When readall is called you may received just part of your frame,

For example , we are going to send "HELLO WORLD" on the serial port

this can be sent in two times :

at time t0 "HEL" is received
at time t1 "O WORLD" is received

If you are doing your readall, at time t0 you can receive just part of data

To avoid this you can use readyRead signal, and QByteArray buffer

connect(nameOfyourSerialPort,SIGNAL(readyRead(),this,SLOT(onPartOfFrameAvailable());

QByteArray mWholeData;//var member this is our buffer

void onPartOfFrameAvailable()
{
     mWholeData.append(nameOfyourSerialPort->readAll());
     qDebug() << "for the moment wholeData contains" << mWholeData;
}

If you send "HELLO WORLD" the result will be for example:

First output : for the moment wholedata contains "HEL";
Second output : for the moment wholedata contains "HELLO WORL"
Thirs output : for the moment wholedata contains "HELLO WORLD";

biomed12

@mostefa
Yes, I have this trouble definitely. I will try and share the results.

mostefa

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

biomed12

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

mostefa

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

Getting larger than what?

I don't understand could you provide more details please?

biomed12

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

Getting larger than what?

I don't understand could you provide more details please?

like
axx
axxxaxa
axaxaxxxx

I am trying now this algorithm, what is your opinion?

QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    if(serialData.length()<4 || serialData[0] != 'a' || serialData[3] != 'b')
    {
        return;
    }

    serData.bytes[0] = serialData[1];
    serData.bytes[1] = serialData[2];
    qDebug()<<QString::number(serData.intPart);
    serData.intPart = 0;
    //qDebug()<<QString::number(data.length());
    console->append(QString::fromLatin1(serialData));
    serialData.clear();
}

mostefa

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

Getting larger than what?

I don't understand could you provide more details please?

like
axx
axxxaxa
axaxaxxxx

I am trying now this algorithm, what is your opinion?
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    if(serialData.length()<4 || serialData[0] != 'a' || serialData[3] != 'b')
    {
        return;
    }

    serData.bytes[0] = serialData[1];
    serData.bytes[1] = serialData[2];
    qDebug()<<QString::number(serData.intPart);
    serData.intPart = 0;
    //qDebug()<<QString::number(data.length());
    console->append(QString::fromLatin1(serialData));
    serialData.clear();
}

I am not able to understand all what you are doing

Why don't we start with simple things:

So

When you readData is CALLED ? , is it a SLOT ? , is it connected to readyRead signal?
What is the output of this code?

For example we keep only this part of the code :


// i am trying only to keepthe basic lines for reading serial port
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    qDebug() << "receivedthat for the moment = " << serialData;
}

biomed12

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:
@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

Getting larger than what?

I don't understand could you provide more details please?

like
axx
axxxaxa
axaxaxxxx

I am trying now this algorithm, what is your opinion?
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    if(serialData.length()<4 || serialData[0] != 'a' || serialData[3] != 'b')
    {
        return;
    }

    serData.bytes[0] = serialData[1];
    serData.bytes[1] = serialData[2];
    qDebug()<<QString::number(serData.intPart);
    serData.intPart = 0;
    //qDebug()<<QString::number(data.length());
    console->append(QString::fromLatin1(serialData));
    serialData.clear();
}
I am not able to understand all what you are doing

Why don't we start with simple things:

So

When you readData is CALLED ? , is it a SLOT ? , is it connected to readyRead signal?

What is the output of this code?

For example we keep only this part of the code :
// i am trying only to keepthe basic lines for reading serial port
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    qDebug() << "receivedthat for the moment = " << serialData;
}

Guy,

Of course the signal slot mechanism such you mention.
The code is always append received data to buffer. But, I need just four bytes. My microcontroller send datas like that:

starts with 'a' char and, 2 data bytes which include what i want, and terminates with 'b'

for example; "affb", i need the ff data.

So, your codes output like that:

affb
affbaffb
affbaffbaffb

because you are appending new datas consistently the buffer.

kuzulis

Foo::onReadyRead()
{
    for (;;) {
        if (serial->bytesAvailable() <  4)
            return; 
       const QByteArray peeked = serial-> peek(4);
       QDataStream ds(peeked);
       qint8 a;
       qint8 b;
       qint16 data;
       ds >> a >> data >> b;   
       if (a == 'a' && b == 'b') {
           // all good, data variable contains ADC value
           serial->read(4); // dummy read whole frame
       } else {
           serial->read(1);  // try to synchronise
       }
    }  //end for
}

mostefa

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:
@biomed12 said in QSerialPort data missing while reading:
@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

@biomed12 said in QSerialPort data missing while reading:

Yes, I have this trouble definitely. I will try and share the results.

Ok keep us informed ;)

ooppss.. Qbyte array is getting larger always.

Getting larger than what?

I don't understand could you provide more details please?

like
axx
axxxaxa
axaxaxxxx

I am trying now this algorithm, what is your opinion?
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    if(serialData.length()<4 || serialData[0] != 'a' || serialData[3] != 'b')
    {
        return;
    }

    serData.bytes[0] = serialData[1];
    serData.bytes[1] = serialData[2];
    qDebug()<<QString::number(serData.intPart);
    serData.intPart = 0;
    //qDebug()<<QString::number(data.length());
    console->append(QString::fromLatin1(serialData));
    serialData.clear();
}
I am not able to understand all what you are doing

Why don't we start with simple things:

So

When you readData is CALLED ? , is it a SLOT ? , is it connected to readyRead signal?

What is the output of this code?

For example we keep only this part of the code :
// i am trying only to keepthe basic lines for reading serial port
QByteArray serialData;
union
{
    unsigned char bytes[2];
    unsigned int intPart;

}serData;
//! [7]
void MainWindow::readData()
{
    serialData.append(serial->readAll());
    qDebug() << "receivedthat for the moment = " << serialData;
}
Guy,

Of course the signal slot mechanism such you mention.

The code is always append received data to buffer. But, I need just four bytes. My microcontroller send datas like that:

starts with 'a' char and, 2 data bytes which include what i want, and terminates with 'b'

for example; "affb", i need the ff data.

So, your codes output like that:

affb
affbaffb
affbaffbaffb

because you are appending new datas consistently the buffer.

Ok , it's clear for now

QByteArray dataToTreat;
void MainWindow::readData()
{
    serialData.append(serial->readAll());

    if(serialData.startWith('a')
    {
	if(serialData.length() > 4)
	{
		 dataToTreat = serialData.left(4);
		serialData.remove(0,4);
	}
    }
    else
    {
           // Not a normal case
     }

// DO WHAT YOU WANT
    serData.bytes[0] = serialData[1];
    serData.bytes[1] = serialData[2];
    qDebug()<<QString::number(serData.intPart);
    serData.intPart = 0;
    //qDebug()<<QString::number(data.length());
    console->append(QString::fromLatin1(serialData));
    serialData.clear();
}

biomed12

@mostefa

I want to get the second and third byte of data to in another union type TO MAKE it unsigned int like 4095.

mostefa

even with the last code i proposed?
Or you can try to use the code of @kuzulis , this can be the best way to achieve what you want

biomed12

@mostefa said in QSerialPort data missing while reading:

even with the last code i proposed?
Or you can try to use the code of @kuzulis , this can be the best way to achieve what you want

baü
baü
baÿ
baÿ
baÿ
baÿ
baþ
baþ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ

Again. always framing error.

biomed12

@kuzulis said in QSerialPort data missing while reading:

//your code here
```Foo:onReadyRead()
{
    for (;;) {
        if (serial->bytesAvailable() <  4)
            return; 
       QByteArray peeked = serial-> peek(4);
       QDataStream ds(peeked);
       qint8 a;
       qint8 b;
       qint16 data;
       ds >> a >> data >> b;   
       if (a == 'a' && b == 'b') {
           // all good, data variable contains ADC value
           serial-> read(4); // dummy read whole frame
       } else {
           serial-> read(1);  // try 
       }
  }  //end for
}

how to leave from for(;;)?

mostefa

@biomed12 said in QSerialPort data missing while reading:

@mostefa said in QSerialPort data missing while reading:

even with the last code i proposed?
Or you can try to use the code of @kuzulis , this can be the best way to achieve what you want

baü
baü
baÿ
baÿ
baÿ
baÿ
baþ
baþ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ
baÿ

Again. always framing error.

baÿ

Looks like ba is correctly in hex , but ÿ is in ascii

The hex code equivalent to ÿ is ff

http://www.rapidtables.com/convert/number/ascii-to-hex.htm

this will lead actually to baffbaffbaff... and i think that this is what you need?

So there is a conversion problem in your code( or maybe just a display problem)

kuzulis

@biomed12 said in QSerialPort data missing while reading:

how to leave from for(;;)?

if (serial->bytesAvailable() <  4)
            return;

@biomed12 said in QSerialPort data missing while reading:

Again. always framing error.

Are you sure, your setting:

serial->setStopBits(QSerialPort::TwoStop);

were applied?

@biomed12 said in QSerialPort data missing while reading:

baÿ
baÿ
baÿ

Try to output the data variable instead...

PS1: QSerialPort is a buffered class and nothing missed.

PS2:

serial->setReadBufferSize(4);

need to remove it if you do not know what for..

biomed12

@mostefa

I solved framing errror problem with this algorithm:

Device send datas like:

sendData[0] = (char)'a';
sendData[1] = (char)'k';
sendData[2] = adcValue.bytes[0];
sendData[3] = (adcValue.bytes[1] & 15);

Read data algorithm:

union{
    unsigned char bytes[2];
    unsigned int intPart;
    unsigned char *ptr;
}serData;

void MedicalSoftware::serialReadData()
{

    if(serial->bytesAvailable()<4)
    {
        return;
    }

    QByteArray serialInData = serial->readAll();

    //my algorithm
    if(serialInData[0] == 'a' && serialInData[1] == 'k')
    {
        serData.bytes[0] = serialInData[2];
        serData.bytes[1] = serialInData[3];

    }else if(serialInData[2] == 'a' && serialInData[3] == 'k')
    {
        serData.bytes[0] = serialInData[0];
        serData.bytes[1] = serialInData[1];
    }
    else if(serialInData[1] == 'a' && serialInData[2] == 'k')
    {
        serial->read(1);
        return;
    }else if(serialInData[0] == 'k' && serialInData[3] == 'a')
    {
        serData.bytes[0] = serialInData[1];
        serData.bytes[1] = serialInData[2];

    }
  
    if(plotDataButtonStatus == true)
    {
        plotMainGraph(serData.intPart);
    }
    serData.intPart = 0;
}

I have another problem now:) but it is another topic. Thanks

my new problem if you wonder:

http://stackoverflow.com/questions/42742033/qcustomplot-huge-amount-of-data-plotting