Timer

    ' Programme to verify resolution of the timer ticks.
    ' modified version of posted solution by PC 2004-01-01
    Dim count As Integer = 0
    Dim strNow As String
    Dim m_intNInt As Integer
    Dim ts1 As TimeSpan, ts2 As TimeSpan
    Dim dt1 As DateTime, dt2 As DateTime
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        ' determine current time
        dt2 = Date.Now
        ' convert to string
        strNow = String.Format("{0:hh':'mm':'ss'.'fff}", dt2)
        If count = 0 Then
            ' save start time in string and in TimeSpan
            TextBox1.Text = strNow
            dt1 = dt2
        End If
        ' display current time
        ListBox1.Items.Add(strNow)
        count += 1
        If count > m_intNInt Then  'end of test
            dt2 = Date.Now      ' dt2=end time
            TextBox2.Text = strNow
            Timer1.Enabled = False  ' stop clock
            count = 0       ' reset count for further tests
            Button1.Text = "Execute"  ' reset button display
            ts1 = dt2.Subtract(dt1) 'calculate time diff.
            Label3.Text = "Time Difference=" & ts1.ToString
            ' calculate and display error
            ts2 = TimeSpan.FromMilliseconds(Timer1.Interval * m_intNInt)
            Label3.Text &= vbCrLf & "  Error=" & ts2.Subtract(ts1).ToString
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ' validate time interval
        Timer1.Interval = Val(TextBox3.Text)
        If Timer1.Interval < 10 Or Timer1.Interval > 5000 Then
            MsgBox("Please keep interval between 10 and 5000 ms")
        End If
        ' validate total duration
        m_intNInt = Val(TextBox4.Text)
        Dim MaxDuration As Integer = 3    ' in minutes
        If Timer1.Interval * m_intNInt / 1000 > MaxDuration * 60 Then
            MsgBox("Please keep total duration to less than " & MaxDuration & " minutes")
        End If
        ' reset button function
        Button1.Text = "Please Wait..."
        Button1.Refresh()
        ' reset displays
        TextBox1.Text = ""
        TextBox2.Text = ""
        Label3.Text = ""
        ListBox1.Items.Clear()
        ' enable timer
        Timer1.Enabled = True
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ' turn off timer
        Timer1.Enabled = False
    End Sub