Arduino Basic Knowledge

Arduino Uno R3 Specifications/Functions

In this article, we will explain in detail the specifications and functions of Arduino Uno R3(Arduino Uno).

Arduino Uno is the most representative and basic edition of the more than 20 editions.

Arduino Uno Specifications

Tech Specs Arduino Uno
Board Size 74.9×53.3mm
Microcontroller/
Clock Speed
ATmega328P/
16MHz
SRAM
(Main Memory)
2kB
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 6
Analog Input Pins 6
Analog Output Pins
(DAC)
Rated Current per Pin 40mA/Pin
Program Writing Pins USB Type-B
ICSP
Interface UART
I2C
SPI


For the specifications of Arduino boards other than Arduino Uno, see the following article.

Arduino Uno Functions

Arduino Uno Appearance

Socket Header Placement(Pin Header Placement)/LED Placement

Arduino Uno Pin Header LED Placement

↑Click to enlarge.

①Microcontroller(Microcomputer)

The Arduino Uno Microcontroller(Microcomputer) uses “ATmega328P” from Microchip Technology(USA).

A microcontroller(microcomputer) 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

You can communicate between Arduino Uno and PC by connecting it to the USB port of Arduino Uno and PC with a USB cable.

You can write a program(sketch) created on your PC to Arduino Uno, and control Arduino Uno from your PC by serial communication.

You can also power the Arduino Uno 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 Uno.

④Reset Button

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

⑤I/O Port・Power

Digital I/O・PWM

Digital I/O・PWM Explanation
D0-D19 Digital input/output(0-19)
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-A5 Analog input(0-5)
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 Uno 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 Uno 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

Arduino Uno has two ICSP terminals, for “ATmega328P” and “ATmega16U2”.

For ATmega328P

By connecting an ICSP-compatible writer(program writing device), you can write programs(sketches) directly to the “ATmega328P”, which is an Arduino Uno 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.

For ATmega16U2

By connecting an ICSP-compatible writer(program writing device), you can write sketches(programs) directly to the “ATmega16U2”, which is USB-serial conversion IC of Arduino Uno.

Therefore, you can create a device for USB, but it is rarely used because it cannot be written by the Arduino IDE.

How to get technical data for Arduino Uno

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

Arduino Uno Technical Data
  • EAGLE FILES
  • SCHEMATICS: PDF Format
  • BOARD SIZE Data: DXF Format
2

Arduino Uno DOCUMENTATION

Click “DOCUMENTATION”.

3

Arduino Uno EAGLE FILES SCHEMATICS BOARD SIZE Data Download

Click each icon to download the “EAGLE FILES”, “SCHEMATICS”, and “BOARD SIZE Data”.

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