Arduino UNO R3 Board Distribution: Each Pin Described

If you want to have hands on all the benefits of a micro-controller, then the Arduino UNO R3, development board is the best possible option.

It provides a simple, clear programming environment. An open source and extensible hardware which allows the student to innovate and make new projects.

You will find varieties of code available for your Arduino UNO R3 on the internet that you can use in your projects, most importantly many of the Arduino shields are built to work with Arduino UNO and this makes it the best board out there. 

In this post, I will briefly discuss Arduino UNO board distribution. Arduino UNO R3 has 20 pins more than the usual Arduino UNO board which opens more area to build one of its kind projects.

Arduino UNO (R3)

It will not be wrong if I say Arduino UNO is the most popular, and the easiest board to use among the Arduino family

It is an open-source hardware board using dual-inline-package (DIP) ATmega328p removable. The additional facility you get is if you inadvertently burn the microcontroller IC then you don’t need to change the whole board you can only change the ATmega328p microcontroller IC and reuse the board again.



It has 20 digital input and output pins (out of 20, 6 can be used as Pulse Width Modulation (PWM) output and 6 as analog inputs), a reset button, power jack, built-in LED, and USB port that is used to upload the program. 

Now moving ahead to board distribution in details:

Arduino UNO Board Distribution

Below are the list of board distribution:

  1. Reset Button – You might have seen a reset button in computers and in video game consoles. It helps the computer to restart forcibly. Same as computers, the reset button is used to restart an Arduino board and also clears all the previous memory.
  2. AREF – AREF means analog reference.
  3. Ground – Ground or GND is where the electrical level is at 0 volts.
  4. Digital input/output – Arduino UNO (R3) has 14 digital pins and 6 analog pins. Pin numbers 0 and 1 are used for transmitting and receiving serial data. Pin 3, 5,6,9,10,11 are PWM pins you could control voltage; adjust the brightness of LED, control the speed of motors, etc.
  5.  PWM – PWM stands for Pulse Width Modulation and it is used to convert the digital signal into an analog.
  6. USB connection – It needs a power source to start an Arduino and there are only two ways to start it. First, through the barrel jack (11) and the other is the USB connection (6). A USB port that is used to give power to the Arduino is also used to load programs onto it but if you do not want your Arduino to plug it into your computer all the time there is a barrel jack present next to the board. You can simply use it to power your Arduino.  
  7. TX RX LEDs – TX is short for transmitting and RX is short for receive. These led start blinking when receiving or transmitting the data. RX led starts blinking when you will be loading your program onto it and TX led starts blinking when your program starts running.
  8. ATmega328p Microcontroller – High performance, low power 8-bit microcontroller and you can also check its datasheet 
  9. Power LED Indicator – Power LED indicator is used to indicate that the Arduino has been powered.
  10. Voltage Regulator it converts the input to 5v
  11.  DC power barrel jackDC power barrel jack is used to power an Arduino, and it is a jack where you plug in your AC to DC adapter.
  12. 3.3V pin – it gives you 3.3V at the output.
  13. 5V pin – it gives you 5V at the output.
  14. Ground PinsGround pin is used to ground the circuit
  15. Analog pinsAnalog pins are used for reading the data which comes from the analog sensors.

Arduino UNO Power Supply

By this far, you must have understood the functions of pins. Let’s move on to powering up the board. There are multiple ways to power up the Arduino: firstly, you can use an AC-DC adaptor. Secondly, you can power up with a Micro USB cable and connect it to your laptop. Also, the same data cable could also be used to transfer your program to the board.



You will need software to sketch, so your Arduino can act accordingly. Luckily, it’s open-source software and you can download it from the Arduino website. If you don’t understand how to download it, then our guide to installing the software has come to your rescue.



Not only students, but professionals as well are taking advantage and playing with these boards. They are building unique projects using UNO, and some of the projects are listed below. 

  1. Robot car using Arduino 
  2. Arduino weather station 
  3. Autopilot for the sailing boat 
  4. Calculator using Arduino 
  5. How to Send and Receive SMS Using GSM Modem 
  6. Arduino alarm clock 


Arduino UNO R3 is going to fulfill all your demands and what you really need in your projects. 20 pins of digital input/output provide you a clear area to go off the limits.

This post here – Arduino boards will help you to find the best board for your electronics project. 

Let us know in the comment section box what Arduino UNO projects you have been working on or you have already made. 

Mataf Khan

An electronics enthusiasts from childhood became an electrical engineer, I've been playing with Arduino and other electronics gadgets like raspberry pi since when I was 14. and have a passion of troubleshooting Arduino problems.

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