Control real world devices with your PC

Step 12 Add some code

Over on the right circled in green are several useful buttons - the second from the right is the View Code button and the right button is the View Designer. In practice when writing code one goes back and forth between these views. Generally if one is in Designer mode double clicking on an object such as a button brings up a spot in the Code View to add some code or takes one to the piece of code that runs when the button is pressed. In this way the program flow becomes quite intuitive - the user clicks on things and bits of code run and change the screen and so on.

For our purposes though we are going to cheat and paste in a whole slab of working code.

The code view will have Public Class Form1 ...End Class - highlight this and delete it. Now take all of the code below and paste it in.

Imports System.IO
Imports Strings = Microsoft.VisualBasic ' so can use things like left( and right( for strings
Public Class Form1
Public Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Integer) ' for sleep statements
Dim WithEvents serialPort As New IO.Ports.SerialPort ' serial port declare
Dim PicaxeRegisters(0 To 13) As Byte ' registers b0 to b13
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Timer1.Enabled = True ' put this in code as defaults to false when created
Timer1.Interval = 5000 ' 5 seconds
PictureBox1.BackColor = Color.Red ' set to position 'red'
Array.Clear(PicaxeRegisters, 0, 13) ' probably not needed as array declared blank
End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
' timer ticks every 5 seconds
Call SerialTxRx() ' talk to picaxe
End Sub
Sub SerialTxRx()
Dim LabelString As String ' string to display byte values
Dim DataPacket(0 To 17) As Byte ' entire data packet "Data"+14 bytes
Dim i As Integer ' i is always useful for loops etc
Label1.Text = "" ' clear the text on the screen
For i = 0 To 3
DataPacket(i) = Asc(Mid("Data", i + 1, 1)) ' add the word "Data" to the packet
Next
For i = 0 To 13
DataPacket(i + 4) = PicaxeRegisters(i) ' add all the bytes to the packet
Next
If serialPort.IsOpen Then
serialPort.Close() ' just in case already opened
End If
Try
With serialPort
.PortName = "COM1" ' Most new computers default to com1 but any pre 1999 computer with a serial mouse will probably default to com2
.BaudRate = 2400 ' 2400 is the maxiumum speed for small picaxes
.Parity = IO.Ports.Parity.None ' no parity
.DataBits = 8 ' 8 bits
.StopBits = IO.Ports.StopBits.One ' one stop bit
.ReadTimeout = 1000 ' milliseconds so times out in 1 second if no response
.Open() ' open the serial port
.DiscardInBuffer() ' clear the input buffer
.Write(DataPacket, 0, 18) ' send the datapacket array
Call Sleep(300) ' 100 milliseconds minimum to wait for data to come back and more if data stream is longer
.Read(DataPacket, 0, 18) ' read back in the data packet array
.Close() ' close the serial port
End With
For i = 4 To 17
LabelString = LabelString + " " + Str(DataPacket(i)) ' turn into a text string
Next
Label1.Text = LabelString ' put the text string on the screen
Catch ex As Exception
'MsgBox(ex.ToString)' uncomment this if want to see the actual error message
Label1.Text = "Timeout" ' will display this if picaxe not connected etc
End Try
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
PictureBox1.BackColor = Color.Red ' change the box to red
PicaxeRegisters(0) = 120 ' an arbitrary value for the servo
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
PictureBox1.BackColor = Color.Green ' box to green
PicaxeRegisters(0) = 160 ' arbitrary value for the servo
End Sub
End Class