serial coms - again

[malc-c]

To be honest I'm not sure either - I thought if you sent A,B,C through the port it would just loop that over and over again... do PICs have buffers ? I thought they sent data straight out and in ? but then I'm really getting out of my depth with this.

[malc-c]

Whilst undertaking several hours googling I came across a forum that contained a simple example from a two year old post of using VB.net to communicate with a PIC micro using PBP. So far I'm managing to adapt it to include a combo box to choose the comm port and retrieve a set of data from my PIC.

For reference here is the VB code

Imports System.IO
Imports System.IO.Ports
Imports System.Net
Imports System.Data
Imports System
Imports System.Windows.Forms
Imports System.Threading
Imports System.Text


Public Class mMain

    Dim WithEvents serPort As New IO.Ports.SerialPort
    Dim myStringBuilder As New StringBuilder

    Private Sub mMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        For i As Byte = 0 To My.Computer.Ports.SerialPortNames.Count - 1
            Me.ComboBox1.Items.Add(My.Computer.Ports.SerialPortNames(i))
        Next i

        serPort.BaudRate = 115200
        serPort.DataBits = 8
        serPort.Parity = Parity.None
        serPort.StopBits = StopBits.One

        butConnect.Enabled = True
        butDisConnect.Enabled = False
    End Sub

    Private Sub butConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butConnect.Click
        If (serPort.IsOpen = False) Then
            Try
                serPort.Open()

                lstData.Items.Clear()
                myStringBuilder = New StringBuilder  'Clear any old data

                butConnect.Enabled = False
                butDisConnect.Enabled = True
            Catch ex As Exception
                'Routine to process exceptions like port already open etc.
                MsgBox("Exception error")
            End Try
        End If
    End Sub

    Private Sub butDisConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butDisConnect.Click
        If (serPort.IsOpen = True) Then
            serPort.Close()
            butDisConnect.Enabled = False
            butConnect.Enabled = True
        End If
    End Sub

    Private Sub serPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles serPort.DataReceived
        Try
            myStringBuilder.Append(serPort.ReadExisting())
            Me.Invoke(New EventHandler(AddressOf update_Data))
        Catch ex As Exception
            MsgBox("Data Error")
        End Try
    End Sub

    Private Sub update_Data()
        lstData.Items.Add(myStringBuilder.ToString)
        myStringBuilder = New StringBuilder  'Flush the old data
    End Sub
End Class

I designed a form to suit the different buttons and combo boxes and this was the result.



The data in the list box came from this section of PBP code

Hserout [DEC Temperatures(0)]
Hserout [DEC Temperatures(1)]
Hserout [DEC Temperatures(2)]
Hserout [DEC Temperatures(3)]
hserout [10]

And as I only have one sensor out of four connected to the input associated with Temperature(2) in use the value of 002610, 002680 etc is right and reflects the 26.1C (rising).

However I would like to split this and place the result into 4 separate text boxes, ie so textbox1 will be updated with just Temperature(0), Textbox2 with Temperature(1) etc. Is there any modification I can do to the PBP code to separate the string to do this.

I know there has been some concerns about discussing VB code on this forum, but IMO when it's related to such a topic this thread covers I feel that it's justified.

[HenrikOlsson]

Hi Malc,
My VB is very rusty at the moment but have a look at the Split function in VB. It can be used to split a single string into separate strings (an array of strings actually) and you can specify the delimiter used. So if you send your values as text (which you are at the moment) separated by a comma you can use split the recived string into separate strings which you can the us to populate the textboxes.

If your string as read from the serial port object (let's call it RxString) looks like:
002610,002660,002680,002680
Then something like MyArrayOfStrings = Split (RxString, ",") will return 002610 in the first element of MyArrayOfStrings, 002660 in the second and so on. You can then do something like myTextBox1.Text=MyArrayOfStrings(0)

This is all untested but lookup Split in MSDN and string handling/parsing in general.

/Henrik.

[malc-c]

Thanks Henrik,

I get the gist of what you have said, and I'll have a search for that expression. I must admit the syntax of VB is somewhat alien to me

[malc-c]

Guys, one further thing... when there is no sensor connected the value for say Temperatures(0) will be 0. When present it sends the temperature as a three digit value, eg 25.7c would be sent as 257. I really need to send a zero value as 000 and not a single 0,

any ideas ?

[HenrikOlsson]

Hi,
If you HSEROUT DEC3 Temperatures(0) it will write three digits, ie. 000 if the value is 0.

/Henrik.

[malc-c]

Thankyou - works a treat

[gadelhas]

Hi malc-c;

Hi use a function in VB, that does do the job, that you want, but you must send to VB more things;

You are sending 4 temperatures, i supose from 4 diferent sensors, 1 temperatura measure for each sensor.
So if you put something before sendig the temperatures to identify de sensor, like this for exemple;
You are Sending;
002610
002660
002680
002680

Ff you send;
S1002610
S2002660
S3002680
S4002680

The 2 first chars, are the ID of the sensor, and the 6 next chars are the temperature.

Now it's easy to separate them in VB, with the function "Mid",
On the event Data Received, you must do something like this;

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

        buffer = SerialPort1.ReadExisting

      If Mid(buffer, 1, 2) = "S1" Then
            Label1.Text = Mid(buffer, 3, 6) ' label to show the temperature of 1º sensor
       End If

      If Mid(buffer, 1, 2) = "S2" Then
            Label2.Text = Mid(buffer, 3, 6) ' label to show the temperature of 2º sensor
       End If

      If Mid(buffer, 1, 2) = "S3" Then
            Label3.Text = Mid(buffer, 3, 6) ' label to show the temperature of 3º sensor
       End If

      If Mid(buffer, 1, 2) = "S4" Then
            Label4.Text = Mid(buffer, 3, 6) ' label to show the temperature of 4º sensor
       End If
End Sub

You can use it too in a Select case, and you should put a try....cath too.

If you don't understanding something, please tell me.