Serial Data "reading" disorder

ftsm

Hi everyone !

It's my first program on Qt, so please be understanding ... (for my english too)

It have an arduino uno card, and some potentiometers on it. I made a small Dialog window just to see if I can receive everything by serial buffer. I managed to receive and see all the informations (basicaly 6 numbers with 1 or 4 digits each).
In order to separate them (they arrived like "12359542288752145"), I put a letter betwen each value with arduino, so datas arrive like "A1235AB954BC2288CD75DE2145E".
Then i make some sections with the right letter and got the separate datas like i need.

But the problem is I never receive data the same way, it could be either:
"A1235AB954BC2288CD75DE2145E"
or
"A12"
or even
""

Do you know how to fiw that ? Here is a part of my (poor) code:

#include "dialog.h"
#include "ui_dialog.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include <string>
#include <QDebug>
#include <QMessageBox>
#include <QTime>

Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
ui->InclinoD_lcdNumber->display("----");
ui->InclinoG_lcdNumber->display("----");
ui->Godet_lcdNumber->display("----");
ui->Balancier_lcdNumber->display("----");
ui->Fleche_lcdNumber->display("----");
ui->Tourelle_lcdNumber->display("----");

arduino = new QSerialPort(this);
serialBuffer = "";

bool arduino_is_available = false;
QString arduino_uno_port_name;

foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts()){
    if(serialPortInfo.hasProductIdentifier() && serialPortInfo.hasVendorIdentifier()){
        if((serialPortInfo.productIdentifier() == arduino_uno_product_id)
                && (serialPortInfo.vendorIdentifier() == arduino_uno_vendor_id)){
            arduino_is_available = true; 
            arduino_uno_port_name = serialPortInfo.portName();
        }
    }
}

if(arduino_is_available){
    qDebug() << "Found the arduino port...\n";
    arduino->setPortName(arduino_uno_port_name);
    arduino->open(QSerialPort::ReadOnly);
    arduino->setBaudRate(QSerialPort::Baud9600);
    arduino->setDataBits(QSerialPort::Data8);
    arduino->setFlowControl(QSerialPort::NoFlowControl);
    arduino->setParity(QSerialPort::NoParity);
    arduino->setStopBits(QSerialPort::OneStop);
    QObject::connect(arduino, SIGNAL(readyRead()), this, SLOT(readSerial()));
}else{
    qDebug() << "Couldn't find the correct port for the arduino.\n";
    QMessageBox::information(this, "Serial Port Error", "Couldn't open serial port to arduino.");
}

}

Dialog::~Dialog()
{
if(arduino->isOpen()){
arduino->close(); // Close the serial port if it's open.
}
delete ui;
}

void Dialog::readSerial()
{

    QStringList buffer_split;

    serialData = arduino->readAll();
    serialBuffer = QString::fromStdString(serialData.toStdString());

    parsed_data = serialBuffer.section("D", 1,1); 
    buffer_split.insert(0,parsed_data);
    parsed_data = serialBuffer.section("G", 1,1); 
    buffer_split.insert(1,parsed_data);
    parsed_data = serialBuffer.section("o", 1,1); 
    buffer_split.insert(2,parsed_data);
    parsed_data = serialBuffer.section("B", 1,1); 
    buffer_split.insert(3,parsed_data);
    parsed_data = serialBuffer.section("F", 1,1); 
    buffer_split.insert(4,parsed_data);
    parsed_data = serialBuffer.section("T", 1,1); 
    buffer_split.insert(5,parsed_data);

    qDebug() << buffer_split << "\n";

    serialData.clear();
    serialBuffer = "";


    Dialog::updateInclinoD(buffer_split[0]);
    Dialog::updateInclinoG(buffer_split[1]);
    Dialog::updateGodet(buffer_split[2]);
    Dialog::updateBalancier(buffer_split[3]);
    Dialog::updateFleche(buffer_split[4]);
    Dialog::updateTourelle(buffer_split[5]);

// And after come my functions ...

Thank you all !

SGaist

Hi and welcome to devnet,

The usual way to handle incoming data is to store them in a buffer until there's enough of them to form a complete package and only then parse the packet.

mrjj

Hi
Data most often comes in pieces so as @SGaist says, you must keep reading
like
m_readData.append( m_serialPort->readAll());
until you got whole "line" of data
you can check
if (m_readData.size() >= EXPECTED_BYTES)
Parse()
or have kind of stop marker in the data.

Other note. you could maybe use same separator between numbers, like | and then
just say
serialBuffer = QString::fromStdString(serialData.toStdString());
QStringList list = serialBuffer .split ( "|" );
then you have list of each number.
list[0] being the first.

Just a though. might not suit your needs.

ftsm

@SGaist Thank you or your answer. Yes i suppose that's what I have to do, but I don't really know how. I tried with "waitForReadyRead()" but he doesn't work, my code just stop and crash on it, despite what I read I don't really know how to use it properly.

ftsm

@mrjj Thank you.
I used differents letters as separator because i wanted to reconize each data. Indeed I can just use one separator but it means that I have to gather all the data in the good order.
".append" seams like a good way but my problem is that I can't know the size of my expected bytes. Each potentiometer can send 1 to 4 digits. I assume there are already solutions for that, but I don't know what ...

mrjj

@ftsm
Ah ok, yes if they can come out of order then same separator is not a option.

-Each potentiometer can send 1 to 4 digits
so maybe there comes 1 byte or maybe 4 ?

ftsm

@mrjj Indeed. And so if I try ".append" I will have a huge disorder in datas ...
I'm still trying to figure out a way to get everything in order but nothing work fine yet

mrjj

@ftsm
but how does the potentiometer send its data ?
you have no control over the format?

ftsm

@mrjj The potentiometer send its data via Arduino. I can write how I want to send it. First I tried with "," to separate, but I could'nt reconize wich data was what. So I tried with a specific letter before and after each potentiometer value. In this case it is really hard for me to extract the potentiometer value from the line (from serial) because I only know the "split" technic

SGaist

Mix both techniques: an ID to know what kind of data you have and the "special" char to know where to split.

ftsm

@SGaist Yes I think that is my best move, that's what I'm currently trying to do.
But I have a last problem: how can I try the existence of a string from QstringList ? For example I need to know if after spliting "buffer_split[1]" exist ?

SGaist

You can use a while loop and take the first element at each iteration so no need for a particular check.

mrjj

@ftsm
also QstringList has a size() that tells the number of elements. (strings)
That also gives hints to valid index.

ftsm

@SGaist @mrjj Thank you for that, I managed to split correctly and find the right data.
But I am still able to do that only on debug mode, when I try to run the program it's like i'm going too fast and my "->ReadAll()" don't gather enought data. (I saw that with some qDebug()).
So I go back to my first problem, if I use a while loop with "append" I will mix the data.
Can't I use "waitForReadyRead()" ?

ftsm

OH MY GOD that was the solution since the begining !! It's 1:30am and it's perfectly working !!

THank you guys I love you so much !!

YAAaaaaaayyy my first beautiful program on Qt and it rules !! THANK YOU

mrjj

@ftsm
Congratulations with the baby ;)