[RESOLVED] Corrupted data from arduino on my app

[arcyde]

Hello guys, i have a CAM module ov7670 (arduino) which makes this:
1- converts the image taken to bytes and saves on SD card ... working... 38kb file size, .yuv format.
2- converts the image taken to bytes and I receive on a richtextbox on my VS2010 app...not working 20~50KB filesize.
My app: A combobox which show all available Serial Ports., a RichTextBox which shows the received data and a button to save the content into a .YUV file.

If (comPORT <> "") Then
                SerialPort1.Close()
                SerialPort1.PortName = comPORT
                SerialPort1.BaudRate = 9600
                SerialPort1.DataBits = 8
                SerialPort1.Parity = Parity.None
                SerialPort1.StopBits = StopBits.One
                SerialPort1.Handshake = Handshake.None
                SerialPort1.Encoding = System.Text.Encoding.Default
                SerialPort1.ReadTimeout = 10000

                SerialPort1.Open()
                Button1.Text = "Desconectar"
                Timer1.Enabled = True
                ComboBox1.Enabled = False

 Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick
        receivedData = ReceiveSerialData()
        richtextbox1.Text &= receivedData
    End Sub


    Function ReceiveSerialData() As String
        Dim Incoming As String
        Try
            Incoming = SerialPort1.ReadExisting()
            If Incoming Is Nothing Then
                Return "nothing" & vbCrLf
            Else
                Return Incoming
            End If
        Catch ex As TimeoutException
            Return "Error: Serial Port read timed out."
        End Try

    End Function

On SD card the file have exact 38kb (correct size) but on my richtextbox i receive between 20kb~50kb but never 38kb :/
What i can do?

[Mc_VB]

Try this example and see if it will capture your incoming data. In the example there is one Form containing one RichTextBox

I did not show the serial port configuration so that is left for you to do, just make sure the port is open before the Arduino transmits.

  Public Delegate Sub myDelegate(ByVal sData As Byte)

    Private Sub Text_Out(ByVal sData As Byte)

        RichTextBox1.AppendText(sData.ToString & " ")
       
    End Sub

 Private Sub SerialPort1_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        Dim sData As Byte
        SerialPort1.ReadTimeout = 20
      
        Do While SerialPort1.BytesToRead > 0
            Try
                sData = CByte(SerialPort1.ReadByte)
                Me.BeginInvoke((New myDelegate(AddressOf Text_Out)), sData)

            Catch ex As Exception

            End Try
        Loop
    End Sub

[Mc_VB]

What I didn't mention was that the example above will receive the transmitted bytes and display those bytes as a byte value which is a value between 0 and 255. I am thinking that the byte value is what you require yet your example is trying to capture and display an ASCII string of characters. If I am wrong the conversion from byte value to ASCII character is an easy process, so providing the example captures all the byte values then all will be good.

[arcyde]

Hello, i tried this and results numbers...ok, but i treid to converty byte into ANSI (System.text.encoding.default) and returns a error, "value of type 1-dimensional array of byte cannot be converted to string". Can you help with decoding?

[jmcilhinney]

i treid to converty byte into ANSI (System.text.encoding.default) and returns a error

Then you did it wrong. If you show us what you did, we would have a much better chance of showing you what's wrong with it.

[dbasnett]

If the arduino is sending an image WHY are you putting the received data in a string???? Try it this way(you'll need to get rid of the timer code)

    Private buffer As New List(Of Byte)
    Private Sub SerialPort1_DataReceived(sender As Object,
                                         e As IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

        Dim BytesRead As Integer = 0

        Dim numberOfBytesToRead As Integer = SerialPort1.BytesToRead
        ' Create a byte array large enough to hold the bytes to be read.
        Dim newReceivedData(numberOfBytesToRead - 1) As Byte
        ' Read the bytes into the byte array.
        BytesRead = SerialPort1.Read(newReceivedData, 0, numberOfBytesToRead)
        If BytesRead > 0 Then
            If BytesRead <> numberOfBytesToRead Then
                Array.Resize(newReceivedData, BytesRead)
            End If
            buffer.AddRange(newReceivedData) 'accumulate in buffer
        End If
    End Sub

You'll need to figure out when the arduino is done sending, but once you do the entire image should be in 'buffer'

[digitalShaman]

be aware that the DataReceived event runs in a different thread than the rest of your code. so to stick with dbase example, make sure you synchronize access to the "buffer" variable otherwise ugly things will happen sooner or later.

[arcyde]

I'll try this last code, but is a very simple app, https://imgur.com/a/y74Hwhf I send only one command and i receive the image data, the .yuv file need to have 38kb. And i receive only 1 image per command.

[arcyde]

This is the full first code:

Public Class Form1
    Dim comPORT As String
    Dim receivedData As String = ""

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Timer1.Enabled = False
        comPORT = ""
        For Each sp As String In My.Computer.Ports.SerialPortNames
            ComboBox1.Items.Add(sp)
        Next
    End Sub


    Private Sub comPort_ComboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles ComboBox1.SelectedIndexChanged
        If (ComboBox1.SelectedItem <> "") Then
            comPORT = ComboBox1.SelectedItem
        End If
    End Sub


    Private Sub connect_BTN_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
        If (comPORT <> "") Then
                SerialPort1.Close()
                SerialPort1.PortName = comPORT
                SerialPort1.BaudRate = 9600
                SerialPort1.DataBits = 8
                SerialPort1.Parity = Parity.None
                SerialPort1.StopBits = StopBits.One
                SerialPort1.Handshake = Handshake.None
                SerialPort1.Encoding = System.Text.Encoding.Default
                SerialPort1.ReadTimeout = 10000

                SerialPort1.Open()
                Button1.Text = "Desconectar"
                Timer1.Enabled = True
                ComboBox1.Enabled = False
Else
                MsgBox("Select a COM port first")
            End If
        Else
            SerialPort1.Close()
            Button1.Text = "Conectar"
            timer1.enabled=false
        End If
end sub

Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick
        receivedData = ReceiveSerialData()
        richtextbox1.Text &= receivedData
    End Sub


    Function ReceiveSerialData() As String
        Dim Incoming As String
        Try
            Incoming = SerialPort1.ReadExisting()
            If Incoming Is Nothing Then
                Return "nothing" & vbCrLf
            Else
                Return Incoming
            End If
        Catch ex As TimeoutException
            Return "Error: Serial Port read timed out."
        End Try

    End Function

Private Sub clearbtn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles clearbtn.Click
        richtextbox1.Text = ""
    End Sub


    Private Sub sendbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles sendbtn.Click
        SerialPort1.WriteLine(TextBox1.Text)
    End Sub

    
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim imgtxt As String = richtextbox1.Text
        Dim wrttxt As New StreamWriter(Application.StartupPath & "/test.YUV")
        wrttxt.Write(imgtxt)
        wrttxt.Close()
    End Sub
End Class

[Mc_VB]

First we need to clear up that your captured image is not meant to be read as text or a string of ASCII characters, it is 38K byte values between 0 and 255, this kind of file is called a binary file. Your code is wrong for this application so you need to look at my example or the example of dbasnett.

I modified my example to use a Queue to hold the incoming serial data, there is a place to write in your own folder path ( notice the correct syntax is "\test.YUV" and not "/test.YUV" ) and finally I added a button with the code to write the data in the Queue to an array and then write a binary file to disk. For the example you must wait until you have received all data before trying to write to disk.

  Dim mypath = My.Computer.FileSystem.CombinePath(Application.StartupPath, "\test.YUV")
    Dim myq As Queue(Of Byte) = New Queue(Of Byte)

    Public Delegate Sub myDelegate(ByVal sData As Byte)

    Private Sub Text_Out(ByVal sData As Byte)
        RichTextBox1.AppendText(sData.ToString & " ")
        myq.Enqueue(sData)
    End Sub

    Private Sub SerialPort1_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        Dim sData As Byte
        SerialPort1.ReadTimeout = 20

        Do While SerialPort1.BytesToRead > 0
            Try
                sData = CByte(SerialPort1.ReadByte)
                Me.BeginInvoke((New myDelegate(AddressOf Text_Out)), sData)

            Catch ex As Exception

            End Try
        Loop
    End Sub


    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click


        Dim mydata(myq.Count - 1) As Byte
        myq.CopyTo(mydata, 0)
        My.Computer.FileSystem.WriteAllBytes(mypath, mydata, False)


    End Sub

[arcyde]

Unbelievable, perfect hahaha worked 100%, the only problem now is the foccus on camera(just turn left-right), and the app design. Ty so much, all. I will change to resolved. ^.^

[Mc_VB]

Remember in your final application you will need to clear the contents of the Queue between each capture or write directly to an array and skip the Queue alltogether.

[arcyde]

Yeah, its working good now, ty so much.