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Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications

Hi Guys! Hope you are getting along with life pretty well. I always strive to keep you updated with most valuable information related to engineering and technology. Today, I’ll discuss the detailed Introduction to Arduino Leonardo. It is a microcontroller board based on the ATmega32U4 and comes with 23 digital input/output pins. It is developed by Arduino.cc, aiming to provide easy to use interface with the ability to perform a number of functions on a single chip.

It incorporates everything required to drive the automation in the relevant project. Simply connect this device with the USB cable or power it up using DC adapter and start playing with it

In this post, I’ll try to cover each and everything related to Arduino Leonardo, so you don’t need to wrestle your mind browsing the whole internet and find all the information in one place. Let’s dive right in and get down to the nitty-gritty of this tiny module.

Introduction to Arduino Leonardo

  • Arduino Leonardo is a microcontroller board developed by Arduino.cc. It is based on the ATmega32U4 and comes with 23 digital input/output pins that are enough to connect with external devices and turn your innovation into reality.
  • The Microcontroller on the board incorporates a built-in USB communication, setting you free from the use of a secondary processor. The USB communication helps Leonardo disguise the mouse or keyboard when it is connected to a computer.
  • The module supports the crystal oscillator with the frequency up to 16 MHz that is enough to generate clock pulses with decent pace required for the synchronization of all the internal operations.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications


In-circuit programming header is added in the device that gives you the flexibility to tweak the already written code after its installation in the relevant project.

  • This board supports common communication protocol like UART, SPI, and I2C. The UART is a serial communication protocol mainly used for transferring and receiving serial data using two pins called TX and RX.

While I2C is a two-wire interface that involves two main lines known as SDA and SCL where former is s serial data line that carries the data and later is serial clock line that is used to synchronize all data transfers over the I2C bus.

  • Serial Peripheral Interface (SPI) is a third communication protocol added on the board that is commonly used to send data between microcontrollers and small peripherals such as sensors, shift registers, and SD cards using separate clock and data lines, layered with a select line to pick the device for communication.

1. Arduino Leonardo Features

If you aim to work on your desired project, you must know the common features this device holds in order to avoid any hassle in future, getting you a clear idea if the ratings of the device are quite in line and stand fit for your project. Following table shows the main features of the Arduino Leonardo.

MicrocontrollerATmega32U4
CPU8-Bit
Digital I/O Pins23
PWM Output7
Analog Input12
Flash Memory (Program Memory)32 KB (Out of which 4 KB is used by bootloader)
SRAM2.5 KB
EEPROM1 KB
Input Voltage7-12 V
Operating Voltage5 V
Oscillatorup to 16 MHz
Software UsedArduino Software (IDE)
Reset ButtonYes
ICSP HeaderYes
USB Port1
UART (Serial Communication)Yes

2. Arduino Leonardo Pinout

Following figure shows the pinout of Arduino Leonardo.Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications




  • USB jack, Power Jack and Reset button are quite in line with each other and are surfaced on one side of the board. Nonetheless, all components and pins on the board are designed in a regular pattern, giving a compact and symmetrical interface.

3. Arduino Leonardo Pin Description

You have got a clear idea about some of the basic functions of this Arduino Module. In this section, we will break down pinout of the board with different images and describe them in terms of pin description of the board. Let’s get started.

Analog Pins

There are 12 analog pins added on the board. As per the nature of these pins, they can utilize any number of values, unlike digital signals that are designed to deal with only two values: HIGH and LOW. The following figure shows the placement of these analog pins on the board.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications

PWM Output

There are seven PWM pins available on the board. If you place the board with power jack pointing upward, these pins appear on the right side of the board. PWM is a process for getting analog results with digital means. You can see these pins in the figure below.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications

Communication Protocols

Three communication protocols including SPI, UART and I2C are incorporated on the board. You can see them on the figure below. It is important to note that SPI communication is not available on the digital I/O pins like other boards instead, it houses in the ICSP header as shown in the figure below.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications

Power Source

Difference power sources are available for a variety of purpose. Mainly, the board operates at 5V while 3.3V is the operating voltage of each pin. The Vin is the input voltage that ranges between +7 to +12 V. This voltage comes from the external power source. There are two ground pins on the board. The AREF is an Analogue reference voltage, mainly used for analog pins.

The IOREF is useful for powering and developing a compatibility between this board and Arduino Shields. As the shield is connected with this pin, it (shield) wears the I/O voltage provided by the Board. The Shield using IOREF pin will be compatible with both 3V3 and 5V.

You can see the power source in the figure below.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications

ICSP Header

ICPS stands for In-Circuit Serial Programming – A feature used for programming Arduino with another Arduino. ICSP header is added that helps in connecting the board with a computer for uploading a sketch in case USB port is not available.

Introduction to Arduino leonardo, Arduino leonardo features, Arduino leonardo pinout, Arduino leonardo pin description, applications



4. Programming

  • Arduino.cc has introduced its own official software, called Arduino IDE, for programming the Arduino module. This software supports common operating systems like Windows, Linux or MAC. Before you download this software, make sure the required software version is compatible with your system i.e. if you aim to download App version, you must have Windows 10 installed in your system as app version is not compatible with Windows 7 or 8.1.

You are ready to use the software as you install it. Some simple LED programs are already available on the software, giving you the flexibility to start working on the board in due course.

  • No external burner is required to burn the code inside the module as it comes with a built-in bootloader. Having said that, if you intend to insert a new controller on the module, you need to install the bootloader again using IDE software.

The Serial Monitor is added in Arduino Software, that helps you see the code working in real time as you verify and upload the code.

  • Arduino IDE comes with a compilation option that allows you to see the code compilation on the bottom of the screen as you upload the code. It generates hex file of the code which then is transferred into the board.

5. Difference between Arduino Leonardo and Arduino Uno

There is a slight difference between these two boards in terms of controller used, number of digital pins, PWM pins, and the pins reserved for SPI communication.

  • Arduino Uno incorporates ATmega328 while Arduino Leonardo comes with ATmega32U4.

Similarly, Uno has 20 digital I/O pins, out of them 6 are analog input pins and Leo has 23 digital I/O pins, out of which 12 are analog input pins.

  • There are 7 PWM output pins available on the Leonardo and 6 are added on the Uno board.

Uno comes with SPI protocol on the digital I/O pins while Leonardo contains SPI communication on the ICSP header pins.

6. Arduino Leonardo Projects and Applications

You can not write off the importance of Arduino Modules if you are working on a project that comes with a remote connection with automation. Arduino Leonardo comes with a wide range of applications and incorporates a number of peripherals, setting you free from the hassle of spending too much for buying external components.

Following are some major applications Arduino can be used for:

  • Industrial Automation
  • Health and Security Systems
  • Creating wireless keyboard
  • Automatic Pill Dispenser
  • Embedded Systems
  • Student Projects
  • USB Trackpad
  • Water Level Meter

That’s all for today. I hope you have got a lot of information regarding Arduino Leonardo. However, if you are unsure or have any question you can approach me in the comment section below. I’d love to help you the best way I can. You are most welcome to keep us updated with your valuable feedback and suggestions, they help us provide you quality work that resonates with your needs and requirements. Thanks for reading the article.

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