Передача данных из цикла С++ в QML

#ifndef DATAPORT_H
#define DATAPORT_H

#include <QObject>
#include <QDebug>
#include <QTime>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <string.h>
#include <time.h>

#define I2C_SLAVE	0x0703
#define I2C_SMBUS	0x0720

#define I2C_SMBUS_READ	1
#define I2C_SMBUS_WRITE	0

#define I2C_SMBUS_QUICK		    0
#define I2C_SMBUS_BYTE		    1
#define I2C_SMBUS_BYTE_DATA	    2
#define I2C_SMBUS_WORD_DATA	    3
#define I2C_SMBUS_PROC_CALL	    4
#define I2C_SMBUS_BLOCK_DATA	    5
#define I2C_SMBUS_I2C_BLOCK_BROKEN  6
#define I2C_SMBUS_BLOCK_PROC_CALL   7	
#define I2C_SMBUS_I2C_BLOCK_DATA    8

#define I2C_SMBUS_BLOCK_MAX	    32	
#define I2C_SMBUS_I2C_BLOCK_MAX	32	

class dataport : public QObject
{
    Q_OBJECT

public:
    explicit dataport(QObject *parent = 0);

signals:
    //void sendToQml(QString skz);

public slots:
    void start();

private:
    QString dataX;
    int i,k,l;
    int16_t val1, val2;
    int accX;
    double massive[2048];
    double massiveX[2048];
    char ch1, ch2;
    double sumkv;
    double sum;
QString skz;

    union i2c_smbus_data
    {
      uint8_t   byte;
      uint16_t  word;
      uint8_t   block [I2C_SMBUS_BLOCK_MAX + 2] ;
    };

    struct i2c_smbus_ioctl_data
    {
      char                  read_write;
      uint8_t               command ;
      int                   size;
      union i2c_smbus_data  *data;
    };

    static inline int i2c_smbus_access (int fd, char rw, uint8_t command, int size, union i2c_smbus_data *data)
    {
      struct i2c_smbus_ioctl_data args ;

      args.read_write = rw ;
      args.command    = command ;
      args.size       = size ;
      args.data       = data ;
      return ioctl (fd, I2C_SMBUS, &args) ;
    }

    int i2c_smbus_read_byte_data(int fd, int reg)
    {
      union i2c_smbus_data data;

      if (i2c_smbus_access (fd, I2C_SMBUS_READ, reg, I2C_SMBUS_BYTE_DATA, &data))
        return -1 ;
      else
        return data.byte & 0xFF ;
    }

    void data_update (void);
    int system_init(void);

    const char *i2cHandleNode = "/dev/i2c-1";
    int i2c_fd = -1;

};

#endif // DATAPORT_H

#include "dataport.h"

    dataport::dataport(QObject *parent) : QObject(parent)
    {

    }

    void dataport::data_update(void)
    {
        if(ioctl(i2c_fd, I2C_SLAVE, 0x68) < 0)  {
            fprintf(stdout, "%s : ioctl I2C_SLAVE Setup Error!\n", __func__);
            return;
        }
        ch1 = i2c_smbus_read_byte_data(i2c_fd, 0x3b);
        ch2 = i2c_smbus_read_byte_data(i2c_fd, 0x3c);
        val1 = ch1<<8|ch2;
    }

    int dataport::system_init(void)
    {
        if((i2c_fd = open(i2cHandleNode, O_RDWR)) < 0)  {
            fprintf(stdout, "%s : %s Open Error!\n", __func__, i2cHandleNode);
            return  -1;
        }
        return  0;
    }

    void dataport::start()
    {
        QObject* textX1 = this->parent()->findChild<QObject*>("textX");
        if (system_init() < 0)
            {
                fprintf (stderr, "%s: System Init failed\n", __func__); fflush(stdout);
                //return -1;
            }
        for(l=0;l<8;l++){
QTime start = QTime::currentTime();
                   for(i=0;i<2048;i++){
                       usleep(70);
                        if(ioctl(i2c_fd, I2C_SLAVE, 0x68) < 0)  {
                            fprintf(stdout, "%s : ioctl I2C_SLAVE Setup Error!\n", __func__);
                            return;
                        }
                        ch1 = i2c_smbus_read_byte_data(i2c_fd, 0x3b);
                        ch2 = i2c_smbus_read_byte_data(i2c_fd, 0x3c);
                        val1 = ch1<<8|ch2;
                        massive[i]=val1;
                    }
qDebug()<< "time "<< start.elapsed();
sumkv = 0;
for(k=0;k<2048;k++){
    massiveX[k]=(fabs(massive[k]/16384) - 1)*9.81;
    sum = massiveX[k]*massiveX[k];
    sumkv = sumkv + sum;
}
            qDebug()<<massive[15];
            qDebug()<<massiveX[15];
            skz = QString::number(sqrt(sumkv/2048));///(l+1);
            qDebug()<<skz;
            textX1->setProperty("text",skz);
        }          
}

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3
import QtCharts 2.0

ApplicationWindow {
    id: tex
    objectName: "tex"
    visible: true
    width: 640
    height: 480
    title: qsTr("TEST2")

signal startSignal()
    
    Button{
        text: "START"
        onClicked: startSignal()
    }

    TextField{
        id: textX
        objectName: "textX"
        width: parent.width/3
        height: parent.height/10
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.top: parent.top
    }
    Text {
        id: textXx
        objectName: "textXx"
        //text: qsTr("text")
    }
    ChartView{
        title: "SKZ"
        anchors.top: textX.bottom
        anchors.left: parent.left
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        antialiasing: true       
    }
}