Question

I’m attempting to code an application that reads in the values from an IMU. I’m trying to get the different values of the attitude (i.e. direction) of the IMU for 1 second when using the getAtr_Click method. However, while this is calling the Get_Attitude function, it only changes the textbox values once on my form. How do I make it change each time? (I want to see 10 different values flash by on the textbox).

Here’s my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.Timers;
using VectorNav.Devices;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    public static Vn100 vn100 = new Vn100("COM5", 9600);
    // New Vn100 on COM5

    private void Get_Attitude()
        //gets the current yaw, pitch, roll in degrees, and displays
    {
        var attitude = vn100.CurrentAttitude;
        yaw.Text = Convert.ToString(attitude.Ypr.YawInDegs);
        pitch.Text = Convert.ToString(attitude.Ypr.PitchInDegs);
        roll.Text = Convert.ToString(attitude.Ypr.RollInDegs);
    }
    public Form1()
        //connect to the Vn100, set its output to YPR, output at 10Hz
    {
        InitializeComponent();
        vn100.Connect();
        vn100.SetAsyncDataOutputType(Vn100.AsyncOutputType.Ypr, true);
        vn100.SetAsyncDataOutputFreq(10, true);
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        Get_Attitude();
    }

    private void tare_Click(object sender, EventArgs e)
    {
        vn100.Tare(true);
        vn100.Tare(true); //for some reason it doesn't display the correct Attitude     values w/out a double Tare
        Get_Attitude();
    }

    private void getAtr_Click(object sender, EventArgs e)
    {
        for (int i = 1; i <= 10; i++)
        {
            while (vn100.CurrentAttitude == null)
                Thread.Sleep(10);
            Get_Attitude();
        }
    }

    protected override void OnFormClosing(FormClosingEventArgs e)
        //disconnect from the Vn100 when the box is closed
    {
        vn100.Disconnect();
        base.OnFormClosing(e);
    }

    }
}

Answer 1

Do you want to see 10 (possibly) different values displayed in your textboxes during 1s, at an interval of 10ms, once you call getAttr_Click()?

If yes, then that would be the way to do it:

private void getAtr_Click(object sender, EventArgs e)
{
    for (int i = 1; i <= 10; i++)
    {
        while (vn100.CurrentAttitude == null)
            Thread.Sleep(10);
        Get_Attitude();

        Thread.Sleep(10);
    }
}

In your version, the thread that called the getAttr_Click() method just checks vn100.CurrentAttutude at 10ms intervals. Once that has a non-null value, I suspect it remains non-null, meaning your while() loop will be skipped in every for() iteration so Get_Attitude() will be called 10 times in a row (probably) so fast that you only get to see the last values on the screen.

Thing is, this will keep your UI unresponsive each 10ms during the click, so you might consider calling this getAtr_Click() asynchronously or other trivial solution.

EDIT: Actually, it would help knowing the behaviour of the vn100 component. In the case it is unpredictable, the only thing you can be sure of is displaying 10 different values at no less than 10ms distance in time, regardless if you do everything on the UI thread or on a different thread. It is all related to that vn100.CurrentAttitude behaviour…