Control Arduino With a Portable App

We are going to learn how to make an application to control arduino.

We will see how to:

• Easily make a windows application with python.
• Convert it as an executable to use it anywhere.
• Manage Serial ports (detection/reconnection) automatically with 1 line of code

We can even reuse the code to manage as many arduino as we want.

But before i tell you more about it, let's try utest first!
We will use it to control the internal led on an Arduino nano.

As always, all the documentation/code are available on github in english/french
http://github.com/pigetArduino/utest

Frist we need to upload the code on the arduino.

• Download the source code: http://utest.madnerd.org
• Download drivers for arduino nano : http://nano.madnerd.org

On the Arduino software ( http://arduino.madnerd.org/ )

• Copy utest folder into your sketch folder
• Upload utest.ino

(Tools: Arduino Nano / Processor : Atmega328)

You will need an Arduino nano clone (ch340g) as the application will only detected it.

You can use the serial monitor, to test your arduino:
No Line Ending / 115200

UTest : return OK
ON : Turn on internal led (pin13)
OFF: Turn off internal led (pin13)

utest is a portable application, you don't need to install anything to make it works.

• Download the application : http://utestapp.madnerd.org
• Click on utest.exe

utest will automatically find the arduino
You can try to unplugged it/plug it on another usb port, and it will reconnect.

utest might not work on Windows 7 due to missing .dll
This shouldn't happen if your computer is up to date
Source: http://stackoverflow.com/questions/34218333/pyins...

Let's see how to reuse this application, to make your own application.

First we need to install python 3 to modify it.

• Download python 3 (https://www.python.org/downloads/)
• During the installation, tick Add Python 3.5 to PATH

Then we need to install pySerial, to communicate with our arduino.

• Open a command prompt (Windows key + cmd)
• Type:

pip install serial

Finally, test the application, it is available in the source code ( http://utest.madnerd.org ) at apps/utest/

• Open a command prompt
• Go to the source code folder (apps/utest/)
• Type:

python utest.py

We have everything we need to modify our application.
Check out the source code : utest.py (github)

Let's see

• how to manage our arduino
• how to build a graphical interface with tkinter

In order to manage the arduino the easiest way possible, everything is handle by the module lib/usb.py

USB

As for now, this module has only two commands

usb = USB.Device(...)

• Connect to every serial ports which as CH340 in his name
• Send UTest to the serial port
• If it received "OK", it will connected to it

from lib import USB

device_name = "CH340" #Device name in Windows
device_type = "UTest" #Device type (in the arduino sketch)
device_return_string = "OK" #Answer when a response is correct
device_baudrate = 115200 #Baudrate
usb = USB.Device(device_name,device_type,device_return_string,device_baudrate,status)

Everything is inside a separate thread to avoid blocking the application.

usb.write(string)

• Send a string to the arduino
• If the serial port is not available, it will try to reconnect

GUI (TKinter)

utest use tkinter to manage the GUI (graphical interface)
You can find more information on tkinter here : http://www.tkdocs.com/tutorial/index.html

• To create a window:

from tkinter import *
root = Tk()

• To create a button ON

Button(text="on",command=on).pack()

• Create an action for the button ON

def on():
	print("on")

• Create a label

status = Label(text="Searching...")
status.pack() 

If you want to modify a widget , we need to save it into a variable, and use .pack() on a different line
We send the label to the USB Module to display the current state of the connection

usb = USB.Device(...,status)

Finally, we generate the GUI loop.

root.mainloop()

Our interface is ready,
but we need to teach our arduino to understand the commands we will send.
Check out the source code : utest.ino (Github)

Serial Functions

We use two functions to manage the serial communication.

serialManager()

Check the serial port and convert any messages to a string (inside readString)

serialCheck()

If UTest is received , answer OK

Device name

You can change the name of the usb device in the first line

const String usb_name = "UTest";

Add commands

We manage our commands inside void loop()

void loop() {
  serialManager();
  //If string received
     if (readString.length() > 0) {
      serialCheck();
     
      if (readString == "ON"){
        digitalWrite(13,1);
      }
      if (readString == "OFF"){
        digitalWrite(13,0);
      }
      
    }
  //We clean the serial buffer
  readString = "";
}

For each commands create a condition, for example to turn on the internal led when "ON" is sent

if (readString == "ON"){
   digitalWrite(13,1);
}

The arduino / Application is ready to be bundle into an .exe

• Install pyinstaller, we will use it to convert our application into an single executable file

pip install pyinstaller

• You can compile your application using the script compile.bat

pyinstaller --onefile --noconsole utest.py 

• If you want to display debug messages, use this command instead:

pyinstaller --onefile utest.py

You should now have a /dist/utest.exe file

You will probably have warning about api-ms...dll file.
This shouldn't be a problem as these DLL (Universal C Runtime) are preinstalled on Windows 10 and previous windows should also have them if they are up to date.

I hope this was useful, and that will inspired you to create Arduino application !
With some modification, this application should works on MacOS / Linux.

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Next time, we will learn how to improve our application and use it to control a led strip!