XOR Simulation using Arduino

In this post, an experiment with Arduino to create a setup which simulates the XOR truth tables using two tactile buttons and an LED is explained.  The circuit setup is as below. The diagram is created using Fritzing – An EDA tool (Check it out!)


Setting up the Arduino IDE in GNU/Linux :

Dowload the latest version of the Arduino IDE.

After downloading, extract the archive and the execute the arduino script to open the IDE.

After opening the IDE, set the board and port used in the Tools menu. Goto Tools-> Board -> Arduino UNO (or any board which you use). Then again goto Tools -> Serial Port -> /dev/ttyACM0 (or any other port to which the arduino is connected.) To check which port the arduino is using, you can disconnect and reconnect the Arduino USB and check kernel logs using ‘dmesg’ command. For Arduino UNO (which is an ACM device) you will mostly see the following line in dmesg :

[ 1956.390390] cdc_acm 2-1.6:1.0: ttyACM0: USB ACM device (The port is mentioned in the dmesg line)

If you get such a line the port is, as mentioned above, /dev/ttyACM0.

After setting the IDE, you can start a new Sketch and use the below code to setup the Arduino.

 Xor Buttons

 Turns on and off a light emitting diode(LED) connected to digital
 pin 13, when pressing a pushbuttons attached to pin 2 and pin 4 based
 on the XOR truth table

 The circuit:
 * LED attached from pin 13 to ground
 * pushbutton attached to pin 2 from +5V
 * pushbutton attached to pin 4 from +5V
 * 10K resistor attached to pin 2 from ground
 * 10K resistor attached to pin 4 from ground

 * Note: on most Arduinos there is already an LED on the board
 attached to pin 13.

 created 2005
 by DojoDave
 modified 30 Aug 2011
 by Tom Igoe
 modified from original "Button" code on 30 Mar 2013
 By Rajgopal

 The original Button code is an example code is in the public domain.


// constants won't change. They're used here to
// set pin numbers:
const int buttonPin1 = 2;     // the number of the pushbutton1 pin
const int buttonPin2 = 4;    // the number of the pushbutton2 pin
const int ledPin =  13;      // the number of the LED pin

// variables will change:
int buttonState1 = 0;         // variables for reading the pushbutton status
int buttonState2 = 0;

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize the pushbuttons pin as an inputs:
  pinMode(buttonPin1, INPUT);
  pinMode(buttonPin2, INPUT);

void loop(){
  // read the state of the pushbuttons value:
  buttonState1 = digitalRead(buttonPin1);
  buttonState2 = digitalRead(buttonPin2);
  // check if the pushbuttons is pressed.
  // Based on the pushbutton status and truth table of XOR, turn on or off the LED at Pin 13
  if ((buttonState1 == HIGH && buttonState2 == LOW) || (buttonState1 == LOW && buttonState2 == HIGH)) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);

First you should “Verify and Compile” the code. Goto Sketch->Verify/Compile. If the compilation and verification is successful, then you can go ahead and upload your sketch’s binary to the Arduino micro-controller. Goto File -> Upload. If the upload is successful, then you can test the setup. Press either one of the tactile button and the LED should glow. If both tactile buttons are pressed together or if both are released together, then the LED shouldn’t glow, thus perfectly simulating XOR gate.

My Arduino UNO R3

Finally! The days of Arduino Hacking is here. I bought my own Arduino UNO from Simplelabs along with the Quick Start kit – the main attraction of which was the solder-less breadboard, the wire-stripper and the screwdriver.. (yeah..like I needed those desperately!).

My Ardiuno UNO

My Arduino UNO R3

Now that I got the Arduino, I wasted no time in pleasing the embedded gods by uploading the classical “hello world” program of the bit world..lovingly called the “Blink”.

The “Blink” is one of the pre-defined example in the Arduino IDE and you just have to verify and compile it and then connect your Arduino board and upload the compiled program image onto the microcontroller. (Yes. there are some pre-requisites before for setting up the IDE and its pretty straightforward. I will write about this setup in the next post.) On successful upload you can usually see the on-board LED named ‘L’ starting to blink. If you are still not convinced with the on-board LED,  you can check the same output by connecting an actual LED between the Port 13 and GND (with Anode[+], which is the longer leg of LED, connected to I/O port 13 and cathode connected to the GND port).

And it shall blink!

The LED in OFF State
LED Turned OFF – Arduino Blink Working
LED turned on
LED Turned ON – Arduino Blink Working

Presenting Non-linear presentations

A presentation aids a public speaker, a professional as well as an academician whenever they step into the limelight to project their idea or achievement to a larger audience. Now, this powerful tool can be made even more impressive by (carefully) adding some non-linearity to the presentation style.

Most of the presentation that we create today is a linear presentation, with a particular order. And although that is a great way of presenting things, sometimes they dull out and sometimes the audience is not immersed enough to understand the completeness of your idea.

If you face such challenges, where you need to get your audience involved in your talk, its a great idea to use a non-linear presentation.

Non-linear presentations are those presentations which uses a series of rotations, translations and zooming levels to emphasize and present the content. Few might consider that calling such type of presentations a Non-linear presentation is a misnomer. Rather it should be called a free canvas mode of presentation where there is a blank canvas where you can put in your entire idea and then emphasize areas where you need the audience attention in order to deliver the idea to them. I agree to that notion but don’t find any fault in calling it non-linear as well, cause it definitely uses rotations!

Now,enough theory..let’s make some presentations. There are many proprietary methods to create a non-linear presentation. Prezi is one among them and like they say.. “When you are creative.. Your ideas matter!”

Now we all can’t afford proprietary software and that is where Open Source steps in to save us. Welcome Sozi. Sozi is an extension of vector graphics tool called Inkscape and using Sozi extensions, you can create SVG files which can be played on most of the modern web browser (like Firefox and Chrome) as a presentation. And since its not flash dependent, iOS devices also shall support it.

So what are we waiting for..let’s jump in and make some non-linear presentations.

The instructions for installing Sozi is present in its website (link given above).

A quick tutorial to get you started is right here.

Enjoy the non-linear presentations! A simple creation from my end is downloadable here. Open it up in a browser!