Unable to read the proper data through UART.

[Mohit Tripathi]

Hi,

I am trying to communicate with my hardware through UART and trying to store in a text file. But, I am getting the garbage data.

dialog.h

#include "dialog.h"
#include "ui_dialog.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QDebug>
#include <QtWidgets>
#include <QString>
#include <QObject>
#include <QApplication>
#include <QtSerialPort>
#include <QTimer>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    //ui->temp1_lcdNumber->display("-------");
    serial_is_available = false;
    port_name = "";
    serial =new QSerialPort(this);
    serialBuffer = "";
    parsed_data = "";
    temperature_value = 0.0;
    qDebug()<<"No of available ports"<<QSerialPortInfo::availablePorts().length();

        serial->setPortName(port_name);
        serial->open(QSerialPort::ReadWrite);
        serial->setBaudRate(QSerialPort::Baud19200);
        serial->setDataBits(QSerialPort::Data8);
        serial->setParity(QSerialPort::NoParity);
        serial->setStopBits(QSerialPort::OneStop);
        serial->setFlowControl(QSerialPort::NoFlowControl);
        connect(serial,&QSerialPort::readyRead,this,&Dialog::serialReceived);
}


Dialog::~Dialog()
{
    if(serial->isOpen()){
        serial->close();
    }
    delete ui;
}

template <class T> bool hasError(const QIODevice & d) {
    return qobject_cast<const T *>(&d) && static_cast<const T &>(d).error() != T::NoError;
}

void chkError(const QIODevice & d) {
    if (hasError<QFile>(d) || hasError<QSerialPort>(d))
        qFatal("I/O Error on %s: %s", d.objectName().toLocal8Bit().constData(),
               d.errorString().toLocal8Bit().constData());
}

void logData(QTextStream & log, const QByteArray & data) {
    log << data.toHex() << "\nLength: " << data.size() << "\n\n";
    log.flush();
    chkError(*log.device());
}

void transmit(QSerialPort & port, const QByteArray & data, QTextStream & log) {
    port.write(data);
    qDebug() << "\nWrote" << data.size() << ":" << data.toHex().constData();
    chkError(port);
    logData(log, data);
}

void receive(QSerialPort & port, QTextStream & log) {
    QByteArray data = port.readAll();
    qDebug() << "\nRead" << data.size() << ":" << data.toHex().constData();
    chkError(port);
    logData(log, data);
}

void Dialog::on_write_pushButton_clicked()
{
    QFile logFile("Data.txt");
    if (!logFile.open(QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text))
        qFatal("Can't open the log file: %s", logFile.errorString().toLocal8Bit().constData());
    QTextStream log(&logFile);

    serial =new QSerialPort(this);
    serial->setPortName("COM4");
    serial->setBaudRate(QSerialPort::Baud19200);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::EvenParity);
    serial->setStopBits(QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);

    if (!serial->open(QIODevice::ReadWrite))
        qFatal("Can't open the serial port: %s", serial->errorString().toLocal8Bit().constData());

    logFile.setObjectName("Log File");
    serial->setObjectName("Serial Port");
    //QTimer *timer = new QTimer(this);
 QMessageBox::information(this,"Motor Controller","Write data");
 QByteArray sendPacket = QByteArrayLiteral("\x01\x02");
// sendPacket.resize(2);
// transmit(*serial, sendPacket, log);
// while (serial->waitForReadyRead(400))
// {
//     receive(*serial, log);
//     QTimer::singleShot(300, this, SLOT(quit()));
// }

 if(serial->isWritable())
 {

     //serial->write(output1.toStdString().c_str());
     serial->flush();
     serial->waitForBytesWritten(100);
 }
 else
 {
     qDebug()<<"write to serial";
 }

 while (true) {
     transmit(*serial, sendPacket, log);
     do {
         receive(*serial, log);
     } while (serial->waitForReadyRead(3000));


 //qDebug()<<output1;
}
}
void Dialog::serialReceived()
{
    /*int data1  =0;
     char *dataBuffer;
     int size = arduino->bytesAvailable();
     dataBuffer = new char[size+1];
     data1 = arduino->read(dataBuffer,size);
     dataBuffer[data1]='\0';
     //delete dataBuffer;*/

    QStringList buffer_split = serialBuffer.split(",");
     if(buffer_split.length() < 3){
         serialData = serial->readAll();
         serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());
         serialData.clear();
     }else{
         serialBuffer = "";
        qDebug() << buffer_split << "\n";
         //   Dialog::updatelcd1(buffer_split[0]);
            qDebug()<<"No reading";
     }
}

main.cpp

#include "dialog.h"
#include <QApplication>
#include <QIcon>
#include <QPixmap>


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Dialog w;
    w.setFixedSize(960,520);
    w.setWindowIcon(QIcon(QPixmap("C:/Users/BALARAJU/Documents/icon1.png").scaled(320,300,Qt::KeepAspectRatio,Qt::SmoothTransformation)));
    w.setWindowTitle("Motor Controller");
    w.show();
    return a.exec();
}

dialog.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QSerialPort>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
    void serialReceived();
     void updateLCD(const QString);
     void updatelcd1(QString);



private:
    Ui::Dialog *ui;
    QSerialPort *serial;
    static const quint16 serial_uno_vendorid =9025;
    static const quint16 serial_uno_productid =67;
    QString port_name;
    QByteArray serialData;
    QByteArray sendPacket;
    QString serialBuffer;
    QString parsed_data;
    double temperature_value;
    bool serial_is_available;
   // void updateLCD(QString);

private slots:

    void on_write_pushButton_clicked();

public:

};

#endif // DIALOG_H

motor_controller.pro

#-------------------------------------------------
#
# Project created by QtCreator 2018-03-15T17:29:54
#
#-------------------------------------------------

QT       += core gui  serialport

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = motor_controller
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        dialog.cpp

HEADERS += \
        dialog.h

FORMS += \
        dialog.ui

DISTFILES += \
    moh.qml

Can I know where I am doing wrong?
I should get the like this format. I have stored into Hercules Terminal.

***Timestamp RTC: 1563194715
[GENERAL EVENT] - ID=[-109] Sender=[5]
Watchdog int occured :: 3

Connection to server created successfully
Time status 200

Timestamp Server: 1563194716
Freeing allocated databuffer

WRITE TS 1563194715
"duration":"0",
"remember_me":true***

[SGaist]

Hi,

What do you mean by garbage ?
What does it look like ?

serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());

Don't do that kind of conversion. Make serialBuffer a QByteArray and only convert it to QString if needed and when needed.

while (true) {
transmit(*serial, sendPacket, log);
do {
receive(*serial, log);
} while (serial->waitForReadyRead(3000));

//qDebug()<<output1;
}

You are creating an infinite loop without any way to exit from it. That's bad design.

Since it looks like you want to use the blocking API, then take a look at the QSerialPort related examples to implement that.

[aha_1980]

@Mohit-Tripathi If you really get garbage, then you should first check the baud rate, data bits, stop bits and parity settings.

Also, as @SGaist said, try one of the examples, like the terminal example first.

Once that is running, modify it to your needs.

Regards