Sending Packet through QSerialport ?

[bhargav]

how to convert quint8 startbyte = 0xF0;

to QByteArray ?

[aha_1980]

@bhargav

E.g. the same way you already used:

QByteArray send;
send.append('0xF0');

Or use the constructor: QByteArray ba(1, char(startbyte));

Regards

[bhargav]

transmit data: "\xF0\x12\x96\x96krishnalkjkl;d\xF1"
data size: "\xF0\x12\x96\x96kris"

why my receiver is not receiving all data?

receiver code:

QByteArray data ;
data = m_pcSerialport->readAll();

qDebug() <<"data size:"<< data;

tx code:

QByteArray sending;

QString str = ui->textEdit->toPlainText();

QByteArray send = str.toUtf8();

int size_packet_length = str.size();

qDebug() << "size of payload:"<< size_packet_length;

quint16 req_code = 0xFD96;
char reqbytes[2];
reqbytes[0] = (req_code >> 8) & 0xff;
reqbytes[1] = req_code & 0xff;
QByteArray 

qDebug() <<"bytes of reqcode:"<<req;

int size_reqcode = sizeof(req_code);

qDebug() << "size of reqcode:"<< size_reqcode;


quint8 startbyte = 0xF0;

int size_startbyte = sizeof(startbyte);

qDebug() << "size of startbyte:"<< size_startbyte;

quint8 endbyte = 0xF1;

 int size_endbyte = sizeof(endbyte);

 qDebug() << "size of endbyte:"<< size_endbyte;


 int total_datalength = size_reqcode + size_startbyte + size_endbyte + size_packet_length;

// QByteArray totallength = QByteArray::number(total_datalength);

 qDebug() << "size of total datalength:"<< total_datalength;

sending.append(startbyte);
sending.append(total_datalength);
sending.append(req);
sending.append(send);
sending.append(endbyte);

m_pcSerialport->write(sending,total_datalength);

qDebug() << "transmit data:"<< sending;

tell me why my receiver not receiving all data ?

any mistakes if found in code suggest me to better?

[aha_1980]

@bhargav

Serial ports are slow, therefore your receive the answer in chunks.

If you look at my answer above again, I said you need a member variable and you append to it.

In your code you have a local variable, and you assign to it. That's why its not working for you :)

Regards

[bhargav]

my receiver code:

QByteArray data ;
data += m_pcSerialport->readAll();

 qDebug() <<"data size:"<< data;
 

 QByteArray received = data.toHex();

 qDebug()<<"testing :"<<received;
 

 for (int i = 0; i < received.size(); i++)
 {
    queue.enqueue(received[i]);
 }

 qDebug() <<"queue:"<<queue;

how to compare queue with 0xF0(STX), 0xF1(ETX)? how to extract data or payload?

[aha_1980]

Hi @bhargav,

as you still insist using a queue, then you should ask the person who told you so.

If you wanne go my way, I can surely help you, but if you want to go your way, you're on your own.

Regards

[bhargav]

ok sir ,

QByteArray data;
data +=m_pcserialport->readall();

qDebug() <<"data received "<<data;

/// after that i got output like this

\xF0\x0E\xFD\x96haihelloeveryone\xF1

from that i have to check the conditions above mention

if(data == 0xF0)
{
qDebug()<<"STX is received ";
}

if(data == 0xF1)
{
qDebug()<<"ETX is received";
}

and how to extract data "haihelloeveryone"? from the received .

help me code without Queue?

[aha_1980]

@bhargav

1. As said above, you need a member variable. data is local, appending to it does not make sense.
2. I found out that you only need to check if both STX and ETX are in the frame, otherwise you exit the slot and just wait for more data come in (the slot will be
   called again).
3. Note that parts of your protocol are not used yet (and maybe not needed?): data lenght and request code.

void MainWindow::slotDataReceived(void)
{
    m_buf += m_port->readAll();

    for (;;) {
        int posStx = m_buf.indexOf(char(0xF0));
        int posEtx = m_buf.indexOf(char(0xF1));

        if (posStx >= 0 && posEtx >= 0) {
            // extract payload
            QByteArray data = m_buf.mid(posStx + 4, posEtx - posStx - 4);
            // remove frame from receive buffer
            m_buf.remove(0, posEtx + 1);
            qDebug() << "Data =" << data;
        } else {
            break;
        }
    }
}

Regards

[kuzulis]

@aha_1980 ,

I admire for your patience. )))

[bhargav]

thank you so much for your support.

output of code:
transmit data: "\xF0\x0F\xFD\x96hai krishna\xF1"
data received : "\xF0\x0F\xFD\x96hai "
data received : "krishna

in receiver last byte is not receiving .so,it is not going to if condition for further operations.

tnsmitter code:

// sending through serialport
sending.append(startbyte);
sending.append(total_datalength);
sending.append(req);
sending.append(send);
sending.append(endbyte);

 m_pcSerialport->write(sending,total_datalength);

 qDebug() << "transmit data:"<< sending;

how to receive last byte?

[bhargav]

hmm got it.

[bhargav]

transmit data: "\xF0\x0B\xFD\x96krishna\xF1"
data received : "\xF0\x0B\xFD\x96kris"
for STX 0
for ETX -1
data received : "hna\xF1"
for STX -1
for ETX 3

like this ,it fail to check the condition?

[aha_1980]

Hi @bhargav

Please show your receive slot code.

Also, I thought a bit more about it and got questions you can ask yourself:

1. What happens if size or function code contains the chars STX or ETX?
2. In your send function, you convert a QString toUtf8(). Potentially there might be characters that map to STX or ETX too.

Regards

[bhargav]

my output is :
Port is open: "Unknown error"
size of payload: 23
size of reqcode: 2
size of startbyte: 1
size of endbyte: 1
size of total datalength: 27
transmit data: "\xF0\x1B\xFD\x96krishnalkgkjhkjddhaksjd\xF1"
data received : "\xF0\x1B\xFD\x96kris"
data size : 8
Minimum length is received
received payload "kri"
data received : "hnalkgk"
data size : 7
Minimum length is received
both stx and etx recived
received payload "krikg"
data received : "jhkjddha"
data size : 8
Minimum length is received
both stx and etx recived
received payload "krikgddh"
data received : "ksjd\xF1"
data size : 5
Minimum length is received
both stx and etx recived
received payload "krikgddh"

my receiver code is:

//just checking for bytes available
if(m_pcSerialport->bytesAvailable() == 0 ) {

    qDebug() << "no data to Receive : bad signal?";
    return;
 }


// reading data in serial port
 QByteArray m_buf;

m_buf = m_pcSerialport->readAll();

// char *buff;

// int size = m_pcSerialport->bytesAvailable();

// int byte = peek();

// qDebug() <<"data received :"<< byte;

qDebug() <<"data received :"<< m_buf;
qDebug() <<"data size :"<< m_buf.size();


 // check for minimum length
 int minbytes = 3;

 if(m_buf.size() >= minbytes)
 {
     qDebug() << "Minimum length is received";
 }

 int stx = m_buf.indexOf(char(0xF0));
 int etx = m_buf.indexOf(char(0xF1));


if(stx && etx) {

    qDebug() << "both stx and etx recived";
}

 //   calc full len
 //   check full len data avail or not

// if(etx)
// {
// qDebug() <<"full length is received";

// qDebug() <<"full length:"<< m_buf.size();
// }

 // Extracting the data to show in GUI
 for (int i = 4; i < m_buf.size() - 1; i++) {

     ba.append(m_buf[i]);
 }

  qDebug() <<"received payload"<< ba;

  ui->textEdit_2->setPlainText(ba);

}

how to calculate full packet length and extract payload to show in GUI?

help me , i am getting payload in gui but some data is losing ? i want without loosing data i want to show in GUI.

[aha_1980]

Hi @bhargav,

please read my post with the example again.

1. m_buf needs to be a member variable. (Why?)
2. you need to append to m_buf. (Why?)

Regards

[bhargav]

thank you for your support ,just got the output.