Arduino Uno R3
Arduino
Microcontroller Development Board
8-bit AVR microcontroller development board based on ATmega328P with USB interface.
The Arduino Uno is a microcontroller board based on the ATmega328P. It has 14 digital input/output pins (6 with PWM output), 6 analog inputs, a 16 MHz crystal oscillator, USB connection, power jack, ICSP header, and reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.
Pin
Symbol
Type
Description
Pin
Symbol
Type
Description
1
D0
I/O
Digital I/O pin 0 (RX - Serial receive)
15
A0
Input
Analog input 0
2
D1
I/O
Digital I/O pin 1 (TX - Serial transmit)
16
A1
Input
Analog input 1
3
D2
I/O
Digital I/O pin 2 (External interrupt)
17
A2
Input
Analog input 2
4
D3
I/O
Digital I/O pin 3 (PWM, External interrupt)
18
A3
Input
Analog input 3
5
D4
I/O
Digital I/O pin 4
19
A4
Input
Analog input 4 (I2C SDA)
6
D5
I/O
Digital I/O pin 5 (PWM)
20
A5
Input
Analog input 5 (I2C SCL)
7
D6
I/O
Digital I/O pin 6 (PWM)
22
GND
Ground
Ground pin
8
D7
I/O
Digital I/O pin 7
23
3.3V
Power
3.3V power output (max 50mA)
9
D8
I/O
Digital I/O pin 8
24
5V
Power
5V regulated power output
10
D9
I/O
Digital I/O pin 9 (PWM)
25
VIN
Power
Voltage input (7-12V recommended)
11
D10
I/O
Digital I/O pin 10 (PWM)
26
RESET
Reset
Reset the microcontroller (active low)
12
D11
I/O
Digital I/O pin 11 (PWM)
27
AREF
Other
Analog reference voltage
13
D12
I/O
Digital I/O pin 12
28
IO REF
Other
IO reference voltage (3.3V)
14
D13
I/O
Digital I/O pin 13 (Built-in LED)
Supply Voltage:
7V - 12V
Package:
32-pin Microcontroller
Max Frequency:
16.0 MHz
Key Features
- ATmega328P microcontroller
- 16 MHz clock speed
- 32 KB Flash memory (0.5 KB used by bootloader)
- 2 KB SRAM
- 1 KB EEPROM
- 14 digital I/O pins (6 PWM outputs)
- 6 analog inputs (10-bit ADC)
- USB connection for programming and serial communication
- Built-in LED on pin 13
- Reset button
Applications
- Robotics projects
- Home automation
- IoT prototyping
- Sensor data acquisition
- Motor control
- Educational electronics projects
- Interactive art installations
- Wearable electronics
Notes
The Arduino Uno can be powered via USB or external power supply. When using external power, voltage range is 7-12V (6-20V limits). The board automatically selects the power source. USB provides 5V regulated, while VIN accepts unregulated voltage. Digital pins provide/sink max 40mA each. Analog inputs measure 0-5V range.