Timer in VB.NET

Public Class Form1
    Private _elapseTimerRunning As Boolean = False
    Private _elapseStartTime As DateTime

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        Timer1.Interval = 1000
        Timer1.Enabled = True
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        txtTime.Text = Now.ToString("h:mm:ss tt")
        If _elapseTimerRunning = True Then
            Dim elapsedtime = DateTime.Now.Subtract(_elapseStartTime)
            txtElapsed.Text = String.Format("{0}hr : {1}min : {2}sec", elapsedtime.Hours, elapsedtime.Minutes, elapsedtime.Seconds)
        End If
    End Sub

    Private Sub btnStart_Click(sender As Object, e As EventArgs) Handles btnStart.Click
        _elapseStartTime = DateTime.Now
        _elapseTimerRunning = True
    End Sub

    Private Sub btnStop_Click(sender As Object, e As EventArgs) Handles btnStop.Click
        _elapseTimerRunning = False
    End Sub
End Class

Timer to count down in VB.Net 2010

This is an example of using VB.NET to count down time:

Public Class frmSinglePlayer

    Private TargetDT As DateTime
    Private CountDownFrom As TimeSpan = TimeSpan.FromMinutes(3)

    Private Sub frmSinglePlayer_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        tmrCountdown.Interval = 500
        TargetDT = DateTime.Now.Add(CountDownFrom)
        tmrCountdown.Start()
    End Sub

    Private Sub tmrCountdown_Tick(sender As Object, e As System.EventArgs) Handles tmrCountdown.Tick
        Dim ts As TimeSpan = TargetDT.Subtract(DateTime.Now)
        If ts.TotalMilliseconds > 0 Then
            lblTime.Text = ts.ToString("mm\:ss")
        Else
            lblTime.Text = "00:00"
            tmrCountdown.Stop()
            MessageBox.Show("Done")
        End If
    End Sub
End Class