Arduino Leonardo Specifications/Functions

In this article, we will explain in detail the specifications and functions of Arduino Leonardo.

Compared to Arduino Uno, Arduino Leonardo does not require a USB-serial conversion chip, has more I/O ports, and the USB terminal has been changed to Micro-B.

Arduino Leonardo Specifications

Tech Specs	Arduino Leonardo
Board Size	74.9×53.3mm
Microcontroller/ Clock Speed	ATmega32U4/ 16MHz
SRAM (Main Memory)	2.5kB
Flash Memory	32kB
EEPROM	1kB
Operating Voltage	+5V
Input Voltage (recommended)	+7～+12V
Output Voltage	+5V, +3.3V
Digital I/O Pins	20
PWM Digital I/O Pins	7
Analog Input Pins	12
Analog Output Pins (DAC)	-
Rated Current per Pin	40mA/Pin
Program Writing Pins	Micro USB Type-B ICSP
Interface	UART I2C SPI

For the specifications of Arduino boards other than Arduino Leonardo, please refer to the following article.

Arduino Leonardo Functions

Arduino Leonardo Appearance

Socket Header Placement(Pin Header Placement)/LED Placement

↑Click to enlarge.

①Microcontroller(Microcomputer)

The microcontroller of the Arduino Leonardo uses “ATmega32U4” from Microchip Technology(USA).

A microcontroller is a very important component in controlling electronic devices that correspond to the human “brain”.

In addition, various memories such as SRAM, Flash memory, and EEPROM are also built into the microcontroller.

②USB Port

By connecting the Arduino Leonardo to the USB port of your PC with a USB cable, you can communicate between the Arduino Leonardo and your PC.

Programs (sketches) created on the PC can be written to the Arduino Leonardo, and the Arduino Leonardo can be controlled from the PC via serial communication.

The Arduino Leonardo can also be powered via USB instead of the power jack.

③Power Jack

You can connect an AC adapter(outer diameter 5.5mm, inner diameter 2.1mm) to power the Arduino Leonardo.

④Reset Button

You can restart the Arduino Leonardo by pressing the reset button. Use this when you want to restart the program from the beginning or when the Arduino Leonardo behaves strangely.

⑤I/O Port・Power

Digital I/O・PWM

Digital I/O・PWM	Explanation
D0-D13/D18-D23	Digital input/output(0-13, 18-23) HIGH(+5V)/LOW(0V)
PWM	0 to +5V analog output Analog output by switching between 0V and +5V at high speed

PWM and serial communication are shared with digital I/O. You can specify which one to use in the program.

Analog Input

Analog Input	Explanation
A0-A11	Analog input(0-11) 10-bit A/D converter(1step change every 4.8mV)

Communication

Communication		Explanation
UART (Serial communication)	TX	Serial data transmission
〃	RX	Serial data reception
I2C	SCL	Serial clock
〃	SDA	Serial data transmission/reception
SPI	SS	Select device to control
〃	SCK	Serial clock
〃	MOSI	Master ⇒ Slave data transfer
〃	MISO	Slave ⇒ Master data transfer

Power

Power	Explanation
Vin	The voltage of "③Power jack" is output, Power can be supplied from "Vin" without using the power jack.
GND	Ground/Reference point
+5V	+5V voltage output
+3.3V	+3.3V voltage output

Other

Other	Explanation
GND	Ground/Reference point
AREF	Analog input reference voltage (0 to +5V input), Not normally used
RESET	Reset (Same function as "④Reset Button")
IOREF	+5V voltage output

⑥LED

LED	Explanation
ON	Lights up when the Arduino Leonardo is powered
TX	Blinks when sending via serial communication
RX	Blinks when receiving via serial communication
L	Connect to digital I/O No.13

Arduino Leonardo has 4 LEDs(chip parts). The “L” of LED is connected to the 13th digital I/O, and can be lighted up by setting the 13th pin to HIGH (5V) in the program.

⑦ICSP(For ATmega32U4)

By connecting an ICSP-compatible writer(program writing device), you can write programs(sketches) directly to the “ATmega32U4”, which is an Arduino Leonardo microcontroller(microcomputer).

However, since you can usually write programs(sketches) via the USB port, I think that it is rarely used for writing purposes.

In addition, it can also be used as an SPI terminal.

How to get technical data for Arduino Leonardo

Various technical materials of Arduino Leonardo can be obtained from the official Arduino website.