Arduino analog input to QT Gauge.

[SGaist]

Why are you going through all these transformation ? QString has a constructor taking a QByteArray ?

Then you need to parse the data you received and with that update the gauge.

You might be interested by the CirculaGauge element.

[StevieGardiner]

Thank you for your reply, ive continued some research today and came up quite well apart from the updating of the gauge needle.

void Dialog::analogRead2()
{
    QStringList buffer_split = serialBuffer.split(",");
    if(buffer_split.length() < 3)
    {
        serialData = arduino->readAll();
        serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());
        serialData.clear();
    }else{
        serialBuffer = "";
        qDebug() << buffer_split << "\n";
        parsed_data = buffer_split[1];
        oil_pressure_bar = (0.008) * (parsed_data.toDouble());
        oil_pressure_volt = (0.0048) * (parsed_data.toDouble());
        qDebug() << "Pressure: " << oil_pressure_volt << "\n";

        Dialog::updateOilPressure(parsed_data);
    }
}

void Dialog::updateOilPressure(QString sensor_reading)
{
    ui->oilpress_LCD1->display(oil_pressure_bar);
    ui->oilpressraw_LCD2->display(oil_pressure_volt);
    mSpeedNeedle->setDegreeRange(oil_pressure_bar);
}

I did as you said and parsed the data, I managed to get a raw voltage reading from the sensor, and then converted it to pressure. But when I tried to update the needle rotation, I failed.

[SGaist]

What exactly fails ?

[StevieGardiner]

Thank you for your help, it turns out all I had to do was restart QT Creator.

I'm not stuck on another problem and could I ask for your help?

Ive removed the C++ gauge example and replaced it with a simple QML gauge, I would like to take my serial signal and place it in the needleAngle slot.

Could you tell me the best way to do this as my code seems to emit a lot of errors.
*.pro

QT       += core gui serialport qml
QT += quick

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = 300zx
TEMPLATE = app

DEFINES += QT_DEPRECATED_WARNINGS

SOURCES += main.cpp\
        dialog.cpp

HEADERS  += dialog.h

FORMS    += dialog.ui

DISTFILES += \
    main.qml \
    QtQuickViewManager/View.pri \
    QtQuickViewManager/README.md \
    oiltemp.qml

include(./QtQuickViewManager/View.pri)

RESOURCES += \
    resource.qrc

QML_IMPORT_PATH =

*.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QSerialPort>
#include <QByteArray>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();

signals:
    void oil_pressure_bar(QVariant num);

public slots:
void analogRead2();
void analogRead3();
void updateOilPressure(QString);
void updateOilTemperature(QString);
void needleAngle(QVariant num);

private:
    Ui::Dialog *ui;

    QSerialPort *arduino;
    static const quint16 arduino_uno_vendor_id = 0x2341;
    static const quint16 arduino_uno_product_id = 0x0001;
    QByteArray serialData;
    QString serialBuffer;
    QString parsed_data;
    double oil_pressure_volt;
};

#endif // DIALOG_H

*.cpp

#include "dialog.h"
#include "ui_dialog.h"
#include <QSerialPort>
#include <QSerialPortInfo>
#include <string>
#include <QDebug>
#include <QMessageBox>
#include <QQuickView>
#include <QQmlApplicationEngine>
#include <QtQuickWidgets/QQuickWidget>


Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    setWindowFlags(Qt::Dialog | Qt::FramelessWindowHint);
    ui->oilpress_LCD1->display("-------");
    ui->oilpressraw_LCD2->display("-------");
    ui->oiltemp_LCD1->display("-------");
    ui->oiltempraw_LCD2->display("-------");
   
    QQuickView *view = new QQuickView();
        QWidget *container = QWidget::createWindowContainer(view, this);
        container->setMinimumSize(250, 250);
        container->setMaximumSize(250, 250);
        container->setFocusPolicy(Qt::TabFocus);
        view->setSource(QUrl("qrc:/new/prefix1/main.qml"));
        ui->verticalLayout->addWidget(container);
       
     *italicised text*   auto Dialog = new QDialog(this);
            auto quickWidget = new QQuickWidget(QUrl("main.qml"), this);
            auto Rectangle = quickWidget->rootObject();

                    // Connect C++ signal to QML slot
                        QObject::connect(Dialog, SIGNAL(oil_pressure_bar(QVariant num)),Rectangle, SLOT(needleAngle(QVariant num)));

    arduino = new QSerialPort(this);
    serialBuffer = "";
    parsed_data = "";
    oil_pressure_volt = 0.0;
    //oil_pressure_bar = 0.0;


    bool arduino_is_available = false;
    QString arduino_uno_port_name;

    foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts()){
        //  check if the serialport has both a product identifier and a vendor identifier
        if(serialPortInfo.hasProductIdentifier() && serialPortInfo.hasVendorIdentifier()){
            //  check if the product ID and the vendor ID match those of the arduino uno
            if((serialPortInfo.productIdentifier() == arduino_uno_product_id)
                    && (serialPortInfo.vendorIdentifier() == arduino_uno_vendor_id)){
                arduino_is_available = true; //    arduino uno is available on this port
                arduino_uno_port_name = serialPortInfo.portName();
            }
        }
    }

    /*
     *  Open and configure the arduino port if available
     */
    if(arduino_is_available){
        qDebug() << "Found the arduino port...\n";
        arduino->setPortName(arduino_uno_port_name);
        arduino->open(QSerialPort::ReadOnly);
        arduino->setBaudRate(QSerialPort::Baud57600);
        arduino->setDataBits(QSerialPort::Data8);
        arduino->setFlowControl(QSerialPort::NoFlowControl);
        arduino->setParity(QSerialPort::NoParity);
        arduino->setStopBits(QSerialPort::OneStop);
        QObject::connect(arduino, SIGNAL(readyRead()), this, SLOT(analogRead2()));
        QObject::connect(arduino, SIGNAL(readyRead()), this, SLOT(analogRead3()));

    }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::analogRead2()
{
    QStringList buffer_split = serialBuffer.split(",");
    if(buffer_split.length() < 3)
    {
        serialData = arduino->readAll();
        serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());
        serialData.clear();
    }else{
        serialBuffer = "";
        qDebug() << buffer_split << "\n";
        parsed_data = buffer_split[1];
        //oil_pressure_bar = (0.008) * (parsed_data.toDouble());
        oil_pressure_volt = (0.0048) * (parsed_data.toDouble());
        qDebug() << "Pressure: " << oil_pressure_volt << "\n";

        Dialog::updateOilPressure(parsed_data);
    }
}

void Dialog::updateOilPressure(QString sensor_reading)
{
    //ui->oilpress_LCD1->display(oil_pressure_bar);
    ui->oilpressraw_LCD2->display(oil_pressure_volt);

}

main.cpp

#include "dialog.h"
#include <QApplication>
#include <QWidget>
#include <QCoreApplication>
#include <QFile>
#include <QString>
#include <QDebug>
#include <QTextStream>
#include <ViewManagement.h>
#include <QGuiApplication>
#include <QScopedPointer>
#include <QQmlApplicationEngine>
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QObject>


void read(QString filename)
{
    QFile file(filename);
    if(!file.open(QFile::ReadOnly |
                  QFile::Text))
    {
        qDebug() << " Could not open the file for reading";
        return;
    }

    QTextStream in(&file);
    QString myText = in.readAll();

    // put QString into qDebug stream
    qDebug() << myText;

    file.close();
}

int main(int argc, char *argv[])

{
    QApplication a(argc, argv);
    QWidget widget(0);
    Dialog w;
    w.setWindowTitle("Temperature Sensor Reading");
    w.setFixedSize(800,480);
    w.show();

    return a.exec();
}

*.qml

import QtQuick 2.1
import QtQuick.Controls 2.0
import QtQuick.Extras 1.4
import QtSensors 5.7

Rectangle {
    id: gauge
    width: 500
    height: 250
    property alias btnMinus: btnMinus
    property alias needle: needle
    property alias btnPlus: btnPlus

    property double needleAngle: 0;

    Image {
        id: background
        x: 0
        y: 0
        width: 250
        height: 250
        source: "Img/background.png"

        Image {
            id: needle
            x: 92
            y: 121
            width: 150
            height: 8
            source: "Img/needle.png"
            transform: Rotation {origin.x: 35; origin.y: 5; angle: needleAngle}

            smooth: true
        }

        Button {
            id: btnPlus
            x: 8
            y: 192
            width: 50
            height: 50
            text: qsTr("+")
            onClicked: needleAngle +=10
        }

        Button {
            id: btnMinus
            x: 192
            y: 192
            width: 50
            height: 50
            text: qsTr("-")
            onClicked: needleAngle -=10
        }
    }
}

And again any help and advice would be much appreciated.

[SGaist]

What errors is it emitting ?

[StevieGardiner]

C:\Users\Stephn\Documents\300zx\dialog.cpp:37: error: no matching function for call to 'Dialog::connect(QDialog*&, const char*, QQuickItem*&, const char*)'
QObject::connect(Dialog, SIGNAL(oil_pressure_bar(QVariant)),Rectangle, SLOT(needleAngle(QVariant)));
^

This is the error I'm getting. much appreciated.

[SGaist]

You are trying to connect classes. You have to connect instances of these classes.

[StevieGardiner]

And by classes you mean "dialog" when I should be connecting " updatedoilpress"?
And instead of "Rectangle" I should be connecting Rotation"?

Also would this QObject::Connect be the easiest and simplest way of connecting a C++ signal (analogread2, oil_press_bar) to a QML Slot (Neeedle, needleAngle)?

[SGaist]

You'd have to search for the objects you are interest in in your engine and then connect them.

By the way, why not make this dialog also with QtQuick ?

[StevieGardiner]

Ok so id search for the instances, I can google how to do that.

What are the benefits of using QtQuick, over my method?

[SGaist]

That was just curiosity. Nothing wrong in mixing both. If you go with a QtQuick only GUI you should be able to drop the dependency on the QtWidgets module which makes your application lighter weight.

[StevieGardiner]

Hi,

I took your advice and used the cpp for serial data collection and the qml for the GUI, but I'm having a problem with this error.

C:\Users\Stephn\Documents\nissan300zx\serialport.h:50: error: 'double SerialPort::oil_pressure_volt' conflicts with a previous declaration
double oil_pressure_volt;
^

I know that the code is duplicating names, but id like to read that name in Q_Property and then send it to QML.

#ifndef SERIALPORT_H
#define SERIALPORT_H

#include <QObject>
#include <QQuickItem>
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QByteArray>

class SerialPort : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString oil_pressure_volt READ oil_pressure_volt WRITE set_oil_pressure_volt NOTIFY oil_pressure_volt_Changed)

public:
    SerialPort(QObject *parent = 0);
            SerialPort(QString);


            QString oil_pressure_volt() const
            {
                return m_oil_pressure_volt;
            }

public slots:
    void analogRead2();
    void updateOilPressure(QString);


    void set_oil_pressure_volt(QString oil_pressure_volt)
    {
        if (m_oil_pressure_volt == oil_pressure_volt)
            return;

        m_oil_pressure_volt = oil_pressure_volt;
        emit oil_pressure_volt_Changed(oil_pressure_volt);
    }

signals:

    void oil_pressure_volt_Changed(QString oil_pressure_volt);

private:
    QSerialPort *arduino;
    static const quint16 arduino_uno_vendor_id = 0x2341;
    static const quint16 arduino_uno_product_id = 0x0001;
    QByteArray serialData;
    QString serialBuffer;
    QString parsed_data;
    double oil_pressure_volt;

    QString m_oil_pressure_volt;
};

#endif // SERIALPORT_H

Could I rename the oil_pressure_volt in the CPP

void SerialPort::updateOilPressure(QString sensor_reading)
{
    //oil_pressure_volt(double) = data;

}

[SGaist]

Why are you declaring a oil_pressure_volt property QString then the matching variable as double and still use QString everywhere ?

[StevieGardiner]

Sorry, that was me trying different ideas out.

#ifndef SERIALPORT_H
#define SERIALPORT_H

#include <QObject>
#include <QQuickItem>
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QByteArray>

class SerialPort : public QObject
{
    Q_OBJECT
    Q_PROPERTY(double oil_pressure_volt READ oil_pressure_volt WRITE set_oil_pressure_volt NOTIFY oil_pressure_volt_Changed)

public:
    SerialPort(QObject *parent = 0);
            SerialPort(QString);

            double oil_pressure_volt() const
            {
                return m_oil_pressure_volt;
            }

public slots:
    void analogRead2();
    void updateOilPressure(QString);

    void set_oil_pressure_volt(double oil_pressure_volt)
    {
        if (m_oil_pressure_volt == oil_pressure_volt)
            return;

        m_oil_pressure_volt = oil_pressure_volt;
        emit oil_pressure_volt_Changed(oil_pressure_volt);
    }

signals:

    void oil_pressure_volt_Changed(double oil_pressure_volt);

private:
    QSerialPort *arduino;
    static const quint16 arduino_uno_vendor_id = 0x2341;
    static const quint16 arduino_uno_product_id = 0x0001;
    QByteArray serialData;
    QString serialBuffer;
    QString parsed_data;
    double oil_pressure_volt;

    double m_oil_pressure_volt;
};

#endif // SERIALPORT_H

This is the error,

C:\Users\Stephn\Documents\nissan300zx\serialport.h:48: error: 'double SerialPort::oil_pressure_volt' conflicts with a previous declaration
     double oil_pressure_volt;
            ^

[StevieGardiner]

Hi, So after making a few suggested changes I cant now display a "0" on my qml text field, I think this zero is the first reading of the analogRead 2.

I changed to this in the main.

engine.rootContext()->setContextProperty("serialport", &serialport);

and this in the header.

Q_PROPERTY( double oilPressureVoltage MEMBER m_oil_pressure_volt WRITE set_oil_pressure_volt NOTIFY oil_pressure_volt_Changed )

I think I need to add some code into a string,

#ifndef SERIALPORT_H
#define SERIALPORT_H

#include <QObject>
#include <QQuickItem>
#include <QSerialPort>
#include <QSerialPortInfo>
#include <QByteArray>

class SerialPort : public QObject
{
    Q_OBJECT
    Q_PROPERTY( double oilPressureVoltage MEMBER m_oil_pressure_volt WRITE set_oil_pressure_volt NOTIFY oil_pressure_volt_Changed )

public:
    SerialPort(QObject *parent = 0);
            SerialPort(QString);

public slots:
    void analogRead2();
    void updateOilPressure(QString);

    void set_oil_pressure_volt(double oilPressureVoltage)
    {
        if (m_oilPressureVoltage == oilPressureVoltage)
            return;

        m_oilPressureVoltage = oilPressureVoltage;
        emit oil_pressure_volt_Changed(oilPressureVoltage);
    }

signals:

    void oil_pressure_volt_Changed(double oilPressureVoltage);

private:
    QSerialPort *arduino;
    static const quint16 arduino_uno_vendor_id = 0x2341;
    static const quint16 arduino_uno_product_id = 0x0001;
    QByteArray serialData;
    QString serialBuffer;
    QString parsed_data;
    double oil_pressure_volt;
    double m_oilPressureVoltage;
};

#endif // SERIALPORT_H

[SGaist]

Can you how how you are using that class in QML ?

[StevieGardiner]

yes its...

import QtQuick 2.5
import QtQuick.Window 2.2
import QtQuick.Extras 1.4
import QtQuick.Controls 2.0
import SerialPortlib 1.0

Window {
    id: gauge
    visible: true
    width: 640
    height: 480

    TextEdit {
        id: textEdit
        text: SerialPort.newValue
        verticalAlignment: Text.AlignVCenter
        horizontalAlignment: Text.AlignCenter
        }
}

and...

int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
SerialPort serialport;
qmlRegisterType<SerialPort>("SerialPortlib", 1, 0, "SerialPort");
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

return app.exec();

[SGaist]

What's that newValue ?

You seem to be trying to use a SerialPort object but you are currently accessing it's class (or Type in QML).

You either need to create a SerialPort object in QML or give an instance from it to the engine.

Did you already read the QML CPP integration chapter of Qt's documentation ?

[StevieGardiner]

I tried to create an object by doing;

import QtQuick 2.5
import QtQuick.Window 2.2
import QtQuick.Extras 1.4
import QtQuick.Controls 2.0
import SerialPortlib 1.0

Window {
    visible: true
    width: 640
    height: 480
    id: gauge

    SerialPort{
        OnOil_pressure_volt_Changed:(console.log(newValue));
    }
}

with no joy, is this what your referring too?

[SGaist]

Your QML slot name is wrong.

AFAIK it should be onOil_pressure_volt_changed Note that Qt's naming style is camelCase, that might help you match your code with the documentation.

You should maybe take a look at http://qmlbook.org