Arduino Uno

The Arduino Uno is a popular microcontroller board based on the ATmega328P chip. It features 14 digital input/output pins, 6 analog inputs, a USB connection for programming, and a power jack. It's widely used for prototyping, robotics, and electronics projects. The board is compatible with the Arduino IDE, making it easy for beginners to write and upload code for a variety of applications.

Applications

Educational projects: Reading sensors, controlling motors, basic robotics, data logging
Home Automation: Controlling relays, light dimmers, smart thermostats
Prototyping of embedded control systems

Features/Specifications

Microcontroller	ATmega328P
Operating Voltage	5V
Input Voltage (recommended)	7-12V
Input Voltage (limits)	6-20V
Digital I/O Pins	14 (6 PWM outputs)
Analog Input Pins	6
DC Current per I/O Pin	40 mA
DC Current for 3.3V Pin	50 mA
Flash Memory	32 KB (0.5 KB used by bootloader)
SRAM	2 KB
EEPROM	1 KB
Clock Speed	16 MHz
LED_BUILTIN Pin	Pin 13
Dimensions	68.6 mm x 53.4 mm
Weight	25 g

📄 Arduino UNO datasheet (2584 kB)
📄 ATMega328P datasheet (8585 kB)

Connections

Pin Number	Pin Name	Type	Description
0	D0 / RX	Digital I/O	UART Receive
1	D1 / TX	Digital I/O	UART Transmit
2	D2	Digital I/O	Interrupt 0
3	D3	Digital I/O / PWM	Interrupt 1 / PWM
4	D4	Digital I/O	-
5	D5	Digital I/O / PWM	PWM Output
6	D6	Digital I/O / PWM	PWM Output
7	D7	Digital I/O	-
8	D8	Digital I/O	-
9	D9	Digital I/O / PWM	PWM Output
10	D10	Digital I/O / PWM	SPI SS / PWM
11	D11	Digital I/O / PWM	SPI MOSI / PWM
12	D12	Digital I/O	SPI MISO
13	D13	Digital I/O	Onboard LED / SPI SCK
A0	A0	Analog Input	ADC Input
A1	A1	Analog Input	ADC Input
A2	A2	Analog Input	ADC Input
A3	A3	Analog Input	ADC Input
A4	A4	Analog Input / I2C	SDA
A5	A5	Analog Input / I2C	SCL
-	Vin	Power	Input voltage to the Arduino (7-12V)
-	5V	Power	Regulated 5V output
-	3.3V	Power	3.3V output (max 50mA)
-	GND	Power	Ground
-	AREF	Power	Analog reference voltage
-	RESET	Control	Reset the microcontroller

Safety precautions for using the Arduino UNO

Never apply more than 12V to Vin.
Exceeding 5V on I/O pins may damage the microcontroller
Max current per I/O pin: 40mA (absolute max). Stay below 20mA for safety.
Total max current through 5V pin: ~500 mA (USB) or ~800 mA (with external power).
Do not bypass the onboard voltage regulator with unregulated power
Always use a proper DC adapter (center-positive, 7–12V) if not using USB
Accidental shorts between pins or to ground can damage the board
Don't power motors or high-current devices directly from the USB-powered 5V pin
When powering via Vin, ensure it’s at least 7V so the onboard regulator can supply stable 5V
When interfacing with 3.3V devices (e.g., some sensors or SD cards), use logic level converters

Used Components

Further information

Last edited by Christian Grieger on 2025-05-12

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Applications
Features/Specifications
Connections
Safety precautions for using the Arduino UNO
Used Components
Further information