Counting Impulses

[ravoll]

Hi All,
Still working on my R/C Dyno software(see my other threads).

Have dug up my very first code that I wrote for reading impulses.
It didn't work the way I intended.
It reads the incoming impulses for one second,and writes them to a TextBox.
Problem was,during the 1 second timer interval,you could see the impulses being counted.1,2,3,4,5............101,102,103 and so on until the timer interval was finished,then it would start over at zero,and count up again.Slightly unreadable.

But now I think I can use this to my advantage.
What I would like to accomplish is to have it still visably read the impulses,like it does now,but instead of starting over at zero it should hold it's last count until the impulses change.Like if impulses count up to 25 and level off,I want to see it count 1,2,3,4.....23,24,25,25,25,25,.And if the count goes up or down I want to see it,as in 25,26,27,27,27 or 25,24,23,23,23.If a change occurs from "steady" state,it should'nt start over counting at zero.
If at all possible I would like to utilise the Timer I already have,and not use a 2nd timer .I already have working code that uses 2 timers to hold the last interval count but it counts in the background ,so I don't see the count between intervals.
Is this even possible to do?

(I know this code is ragged looking ,but I'll fine tune it later.)

Public Class Form1
    Dim Rev As Double
    Dim updatetext As Integer
    Dim impulse As Integer = 1
    Dim imp_count As Integer = 0
    Dim RPM As Integer
    Dim time_sec As Integer
    Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Timer1.Enabled = False
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        SerialPort1.Open() 'open the port for access 
        Timer1.Enabled = True
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        SerialPort1.Close()
        Timer1.Enabled = False
    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Timer1.Interval = 1000 'set the time interval 
        While Timer1.Interval < 1000
            TextBox1.Text = imp_count


        End While
        imp_count = 0
    End Sub


    Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

        time_sec = time_sec + 1
        'imp_count = 0
        time_sec = 0

        If impulse > 0 Then
            imp_count = imp_count + 1
        End If
        RPM = imp_count

        Rev = imp_count / 3
        updatetext = RPM
        Me.Invoke(New EventHandler(AddressOf TextUpdate))
    End Sub
    Private Sub TextUpdate(ByVal sender As Object, ByVal e As EventArgs)
        TextBox1.Text = updatetext
        TextBox2.Text = updatetext

    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub

    Private Sub TextBox2_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged
        TextBox2.Text = Rev
    End Sub
End Class