15. Interface and Application Programming¶

This is the assessment for this module:

Group assignment
- Compare as many tool options as possible.

Individual assignment
- Write an application that interfaces a user with an input and/or output device that you made.

Individual assignment¶

For this week I decided to make an Interface that could allow any user to blink a LED on the PCB I made during Input devices week.
I decided to use Python along with TKinter in order to create a basic Interface: two buttons that can turn the LED on or off. Before moving on with TKinter, I tried to do basic things with other libraries, such as:

The latter allowed me to create fancier interfaces:

Since I couldn’t find a proper way to make communicate my board with the PC, I kept looking on the web until I found useful material for connecting the board to my PC. This is when I decided to use TKinter.

Programming the Board¶

This is the code I flashed on the PCB through Arduino IDE:

#include <SoftwareSerial.h>

//defining which pins are going to be Receiver and Transmitter
SoftwareSerial mySerial (2, 1);

//creating a variable, a character that determines if the user selects on or off
char userInput;

void setup()

{

//setting pin3 as the output
pinMode(3, OUTPUT);

//setting the baudrate
mySerial.begin(9600);

}

void loop() {

delay (200);

//If the board receives an input from the serial
if (mySerial.available() > 0) {
//the board reads the input  
  userInput = mySerial.read();

//if the board receives a 1 message from the serial, the LED turns on
     if(userInput == '1'){
      digitalWrite(3, HIGH);
     }

//if the board receives a 0 message from the serial, the LED turns off
     if(userInput == '0'){
      digitalWrite(3, LOW);
     }
  }

}

Coding with Python: Interface¶

I am still less than a beginner with Python, I intend to learn how to work with it in the following months. This is the code I used for my basic blink LED interface:

import serial #importing the pySerial
from tkinter import *
import tkinter as tk

#specifying the communication through FTDI, setting the specific port, baudrate and timeout
commPort = "COM9"
ser = serial.Serial(commPort, baudrate = 9600, timeout = 1)

#setting the functions
#the code on arduino is waiting for "on" as a serial input to turn on the LED
#b stands for a byte of data, that's what I am sending
def turnOnLED():
    ser.write(b'1')

#the code on arduino is waiting for "off" as a serial input to turn off the LED
#also here b stands for a byte of data, that's what I am sending
def turnOffLED():
    ser.write(b'0')


#creating the window with tkinter
root = Tk()

#giving a title to the window
root.title("Week 15 - Interface - Blink LED")

#defining and placing the buttons. First I have to create a widget, then I place it within the window.
btn_On= tk.Button(root, text="Turn on the LED", command=turnOnLED)
btn_On.grid(row=1, column=0)

btn_Off= tk.Button(root, text="Turn off the LED", command=turnOffLED)
btn_Off.grid(row=1, column=2)

#defining window's size
root.geometry("320x320")

#making sure the GUI continuously runs
root.mainloop()

This is how it works:

Group Assignment¶

Here below you can find a comparison between two python libraries: QT and Tkinter, and javascript’s node.js.

Python¶

TKInter¶

Good

Comes already bundled with Python on Windows.
The learning curve is relatively easy for simple stuff.

Bad

Looks kind of ugly and obsolete.
Can be frustrating/limiting for complex applications.
Documentation could be better.

QT¶

Good

Good cross-platform support.
Looks good and native on any platform.
There is good documentation online through communities.
There is also a Graphical UI creator (QT Creator).

Bad

Heavy libraries. while compiling QT adds about 20Mb of .dll/.pyd files to the result.
Often there is the need to use the C++ documentation and to “translate” it into Python.
The learning curve is quite steep, mastering requires years.

Javascript¶

Good

Speed: the execution of the program is quick as it saves the time required to connect to the server.
Is easy to understand and learn. The structure is simple for the users as well as the developers.
Since all modern browsers support JavaScript, it is seen almost everywhere.
Provides various interfaces to developers for creating catchy webpages.
JavaScript is now capable of front-end as well as back-end development.

Bad

Not so safe: Since the code is accessible to the user, they may use it for malicious purposes.
The browser interprets JavaScript differently in different browsers.
A single code error can stop the rendering of the entire JavaScript code on the website.

Node.js¶

Good

Easy Scalability.
The learning curve is not so steep.
The community is huge and active.
Caching: no need to re-execute the codes as caching allows applications to load the web pages faster and responds more swiftly to the user.

Bad

Application Programming Interface (API) is Not Stable.
Does not have a Strong Library Support system.

Last update: June 25, 2021