Virtual Thermometer

I've recently bought a book for learning Visual Basic (VB) since I've never learned them. I have not yet finished the book, but due to my hype towards microcontroller, I've already worked on a simple project which uses both VB programming and an Arduino.

The project is simple, it sense the surrounding temperature using a temperature sensor, Arduino reads it and sends it serially to a computer running a program written in VB. The program will then display the temperature continuously.

Although simple, the highlight of this project is the algorithm I wrote (which probably already thought of by some other people) to let the user to use the program right away without needing to select the baud rate or serial port for the serial communication with the Arduino. It will automatically be selected in the background.

The connection for the Arduino and temperature sensor (LM35) is as follow. The Arduino is then connected to a computer via the USB cable.

 

Connection between Arduino and LM35

The program written in VB (for now named Temp Sense) will display the temperature as follow. Inside the form TempSense, there' two label, one for displaying the temperature and another is the degree celcius symbol (°C). There's also a status bar displaying the serial port which is connected to the Arduino.

The program's interface

Below is the code for VB program.

float tempIn=0; Imports System.IO.Ports Public Class TempSense Dim port_name As String = "" 'Handles for as soon the form is loaded' Private Sub TempSense_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim timeout As Integer = 0 'Loop until port name is found' While port_name = "" Port_id() timeout += 1 'If ten loop is completed, the program will exit' If timeout = 10 Then Port_box.Text = "Device not found" Me.Close() End If End While Disp_temp() End Sub Sub Port_id() 'Function for finding the port' Dim code As String = "" Serial1.BaudRate = 9600 'The loop which check on every available serial port' For Each sp As String In My.Computer.Ports.SerialPortNames Serial1.PortName = sp Serial1.Open() Serial1.Write("$") 'Sends identification request from Arduino' code = Serial1.ReadLine 'Read a line from Arduino' 'Check whether the code sent by arduino is correct' If code = "65686577495254" + vbCr Then port_name = sp Port_box.Text = "Device on " + port_name End If Serial1.Close() Next End Sub Sub Disp_temp() Serial1.Open() 'Continuously read temperature from arduino and display' For i As Integer = 0 To 1 Step 0 Temp_box.Text = Serial1.ReadLine Next End Sub Private Sub TempSense_FormClosing(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles MyBase.FormClosing 'Close serial port upon exit' Serial1.Close() End Sub End Class


Below is the code for Arduino

float tempIn=0; char cmd=0; boolean state = false; void setup() { //Setting the baud rate for Arduino Serial.begin(9600); } void loop() { //Check if any character is sent if(Serial.available() > 0)cmd=Serial.read(); //Identification process if(cmd=='$') { Serial.println("65686577495254");cmd=0; state = true; } //Sends the temperature to the computer if(state==true) { tempIn=analogRead(0); tempIn= 5.0*tempIn*(100.0/1024.0); Serial.println(tempIn); } }

As confident as I wrote this post, the project is actually not going that well. I have not done enough research and learned everything that I should. The program does receive and display the temperature, but the problem is, the program is "locked". It cannot be closed when it reaches the looping state. I'm still finding ways to let the loop runs without disabling the controls of the program. Any help with this problem is very much appreciated. Leave a comment.

That is it for now. Looking forward for solution and probably other project.


Credit the first picture from:
http://hanez.org/2011/04/11/arduino-lm35-temperature-sensor/