Arduino is known as open source development board as it allows you to use this board to interact with real world thing by uploading programs on this board. There are many other microcontrollers like PIC microcontroller, ST microcontrollers, Texas microcontrollers but Arduino is used mostly as it is inexpensive and can be used in various forms. It can interact with anything that is controlled by electricity in any way. It can also interact with motors and electromagnets. In short we can make devices which react and respond to the world by using this board. In short we can say that Arduino is the brain of thousands of projects.Introduction to arduino UNO

Different types of ARDUINO UNO Boards

Arduino makes different board and each having different capabilities. Like Arduino Mega, Arduino UNO, Arduino Nano, Lily Pad Arduino, and much more because as advance our projects are , Arduino keeps on updating its development board to keep teachers, students and other interested people updated as these boards are being used in scientific research as well as many other advance field of robotics and may other fields. These boards are commonly used as they are inexpensive, cross platform (IDE software which is used to make a code for these development boards can run on Linux, OSX and windows operating system while some boards are limited only to windows) , extensible and open source hardware and software.


Arduino UNO is one of the famous microcontroller boards of Arduino family and is developed by Basically is an open source platform and is mainly based upon AVR microcontroller Atmega328. It is one of the most economical boards of Arduino family and is widely used because of its small number of input output pins and reduced size as compared to Arduino mega which is the big brother of Arduino UNO. In this article we are going to briefly discuss about Arduino UNO. We will discuss about its specifications, pin configuration, dimensions, shields compatibility, software for coding, applications and projects in which this board is used.


  • Digital pins: 14 (These pins have only 2 states i.e. high or low or in simple words either 5 V or 0 V no in between values. These pins are mostly used to sense the voltage presence when switch is open or close)
  • Analog pins: 6 (A0 to A5 and they come up with a resolution of 10 bits and they provide flexibility of connecting any external device via these pins. These pins are configured from 0 V to 5 V but they can be configured to high range by using AREF pin or analogReference () function. ADC (analog to digital convertor) is used to sample these pins. These pins take analog signal and by using ADC convertor they convert this analog signal to number between 0 – 1023)
  • 16 MHz crystal oscillator
  • Out of 14 digital pins, 6 can be used for PWM (pulse width modulation)
  • USB port
  • TX and RX pins (for serial communication)
  • SPI (serial peripheral interface)
  • External adaptor to deliver power to this board by external power supply up to 12 volts (board will make use of its voltage regulator and will make this voltage up to 5 V or 3.3 V as per our requirements)
  • Reset Pin: Used to reset our whole board and takes it to initial stage of running program. For instance our board gets hang in the middle of our running program then we can make use of this pin and this pin will clear everything up and starts program from beginning
  • ICSP connector (Used to bypass USB port and interfacing our board directly as serial device. This port is essential to reboot load our chip if it gets corrupted and we are not able to talk to our computer)Arduino Uno pinout


  • Flash Memory: 13KB (used to store number of instructions in code form)
  • SRAM of 2 KB
  • 1 KB EPROM


  • Operating voltage is 5 V and it can be achieved by using USB port or by using external adaptor.
  • External micro SD card is supported
  • This board comes with built-in feature of voltage regulation i.e. when device is connected to other external device it keeps voltage under control thus preventing board from damage.
  • Easy USB interface i.e. simply plug your external device with this port and your device is ready to use. This interface is also used to register your board as virtual serial port on your computer and advantage is that this type of serial communication setup is extremely easy and convenient.
  • 16 MHz clock makes it fast enough for most of the applications.
  • On board LED for easy and fast debugging of our code
  • Micro SD card can be used if functionality or nature of our project goes complex to make our board store more information.


  • Like other development boards of Arduino family this also uses Arduino IDE software to make sketches (Arduino programs are called sketches)
  • Sketches that are developed on IDE can be transferred directly by connecting our computer via USB port.
  • IDE is compatible with Linux , MAC or Windows operating system
  • Programming languages C and C++ are used
  • Thousands of preloaded sketches are easily available which we can use in order to get Arduino to do something according to our requirements.


Important things to remember when you are going to write code:

  • Sketch is an Arduino program
  • All code in Arduino sketch is going to process from top to bottom
  • These sketches are usually broken in 10 parts:
  • It starts with header that explains what we are going to do in our sketch
  • Global variables are defined
  • Constant names are assigned to different Arduino pins
  • Initial variables are set and configured
  • After initial variables setting , it begins with setup routine in which we set initial conditions of variables if needed
  • Run preliminary code that we want to run only once and at this point serial communication is initiated for running serial monitor
  • From setup function we jump to loop routine and keep in mind that it is the main routine of sketch
  • Loop routine will be executed over and over as long as our sketch continues to run.
  • After loop routine many user defined functions are listed and these functions work only when they are called in setup or loop function
  • Execution of these user defined functions depends on whether they are called in setup function or loop function. Whenever a user defined function is called it goes to that function execute it and then come back to the exactly next line of sketch from which that function was called.
  • Only 2 parts of sketch are mandatory i.e. loop and setup function


In order to make our Arduino UNO perform a special function we will use shields (an expensive adaptor plugged over top of board). Countless number of Arduino shields is available. Selection of shields depends on the requirement and functionality of our project. Before buying any shield , make sure that operating voltage of that shield don’t exceed the voltage of our board otherwise it will destroy our board. So after making sure of its operating voltage we can use any one of the shields available in market. Some of the important shields which are widely used are listed below:

  • Ethernet Shield
  • Wireless Shield
  • Motor Shield


As discussed earlier, the most economical and inexpensive board is Arduino UNO. So a wide number of applications are supported by this board. Some important applications that are developed using Arduino UNO are listed below

  • Embedded system
  • Robotics
  • Motion control rig
  • DC motor control ( using H-bridge )
  • Ardupilot ( drone hardware and software )
  • Defense and security defense
  • Parking lot counter
  • Home and industrial automation
  • Game Duino ( for creating retro 2D games )
  • Water quality testing
  • Data loggers ( used in scientific research )
  • Xoscillo ( open source oscilloscope )
  • Count down timer for traffic lights

That brings our today’s report to an end. If you have any questions regarding this then you can ask your queries in the comment section below.

Leave a Comment