Control Your Arduino From Your PC With the Qt Gui

The first step of this instructable is to get and install Qt.

You can get Qt sdk from this wedsite : http://qt.nokia.com/products/

Once downloaded, follow the instruction to install it.

The first part is over. Fairly easy, isn't it?
The next part is a bit more tricky.

Even if Qt is very huge and provides a lot of tools, there is one thing which is missing in our case :
the serial port functions.

So we have to install a library to be able to communicate with the port com.

To do this I use the qextserialport library (version 1.2alpha).

First you need to download the library on sourceforge :
http://sourceforge.net/projects/qextserialport/files/
or the last version here
http://code.google.com/p/qextserialport/

Then you extract the files.

Here comes the tricky part. The files you downloaded are not compiled.
So you must compiled them. To do so you must start the Qt prompt console.
You can find it on Windows in :
start menu,
Qt SDK,
Desktop,
Qt 4.7.3 for Desktop (MinGW)

Then send the command that are on picture 2.

Make sure that a new folder "build" was created during the compilation and the files
qextserialportd.dll and libqextserialportd.a are present.

Congratulation, you perfectly compiled the library!

Now everything is installed, we can start to program.

Open Qt Creator and create a new project.

I join an example of the program, there are a lot of comments which will help to understand.

The main things to know are :

- you have to include the library in your .pro file (see the example)

- to connect a port, you need to create a variable, to open the port and then to configure it (in this order).
(Don't forget to put the right number of your port)

- to send a message through, use the function write(char*).

- to receive data use the function read :
int numBytes =portcom.bytesAvailable();
char buff[256];
portcom.read(buff, numBytes);
(you can also use the signal readyRead() to launch function when a data arrives)

- if when compiling you have the error n°1073741515 (or maybe another) that mean that you need to put the qextserialportd.dll into your .exe folder.


You can find other examples in the library example folder. That will teach you how to scan the ports or receive data.

Attachments

• portcomsender.rar
  Download

The last part is very easy.

Plug a led with its resistance to the 9 pin.

Then you just have to load the program present in Examples => Communication => Drimmer.

Here is the relevant part of the program :

const int ledPin = 9; // the pin that the LED is attached to

void setup()
{
// initialize the serial communication:
Serial.begin(9600);
// initialize the ledPin as an output:
pinMode(ledPin, OUTPUT);
}

void loop() {
byte brightness;

// check if data has been sent from the computer:
if (Serial.available()) {
// read the most recent byte (which will be from 0 to 255):
brightness = Serial.read();
// set the brightness of the LED:
analogWrite(ledPin, brightness);
}
}

Start your Qt program and control the pin 9 voltage.

In this instructable, we have see how to use Qt to control your arduino.

I know that this example is very minimalist, but I'm sure that you will be able to start bigger project.

Next time I will show you how to plot graph on Qt, so you could also monitor temperature, pressure...

PS : As you probably notice it, I am not a native English speaker, I would be please if you can correct me.