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This pinout is for the Arduino UNO R3. The board has 14 digital input/output pins, including six PWM-capable pins, and six analog inputs. Use the labels below to identify the connections; confirm your board is an UNO R3 before relying on this mapping, since “Uno” also names other models.
Arduino UNO R3 pinout diagram
DIGITAL HEADER D0/RX D1/TX D2 D3~ D4 D5~ D6~ D7 D8 D9~ D10/SS~ D11/MOSI~ D12/MISO D13/SCK AREF GND SDA SCL ANALOG / POWER HEADER NC IOREF RESET +3V3 +5V GND GND VIN A0 A1 A2 A3 A4/SDA A5/SCL
This text layout is a reference, not a physical-scale drawing. For exact connector orientation and board placement, consult the official UNO R3 datasheet.
Digital pins: D0 through D13
The UNO R3 has 14 digital input/output pins, numbered D0 to D13. Some have additional communication functions, and six also support PWM output.
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| Pin or pins | Label or function | What to recognize |
|---|---|---|
| D0 | RX | Digital I/O; labeled for serial receive. |
| D1 | TX | Digital I/O; labeled for serial transmit. |
| D2, D4, D7, D8 | Digital I/O | Standard digital pin labels in this pinout. |
| D3, D5, D6, D9, D10, D11 | PWM-capable | The six digital pins Arduino identifies as usable for PWM output. |
| D10 | SS | Also carries the SPI SS label. |
| D11 | MOSI | Also carries the SPI MOSI label. |
| D12 | MISO | Also carries the SPI MISO label. |
| D13 | SCK | Also carries the SPI SCK label. |
RX, TX, SS, MOSI, MISO, and SCK are alternate function labels associated with the numbered pins, not extra digital pins. Arduino’s UNO R3 documentation lists 14 digital I/O pins and six PWM-capable pins.
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ELEGOO UNO R3 Microcontroller Board ATmega328P+ATmega16U2 with USB Cable
- START CODING WITH THE ELEGOO UNO R3: Connect the included USB cable, upload your first sketch, and build sensor, motor, display, and automation projects, making it a practical controller for maker desks, classrooms, coding clubs, and robotics labs
- ATMEGA328P CORE FOR EVERYDAY PROJECTS: A 16 MHz clock, 32 KB flash, 14 digital I/O pins with 6 PWM outputs and 6 analog inputs provide a versatile foundation for LEDs, buttons, relays, servos, displays and sensors
- RELIABLE USB PROGRAMMING AND CLEAR WIRING: The ATmega16U2 USB interface supports sketch uploads and serial communication, while clearly labeled headers help simplify connections to jumper wires, shields and modules
- POWER AND EXPAND YOUR WAY: Run the board from USB or a recommended 7-12 V external supply, then add compatible shields and modules for data logging, automation, robotics, test fixtures and custom electronics projects
- BOARD AND USB CABLE INCLUDED: Comes with 1 ELEGOO UNO R3 development board and 1 USB-A to USB-B data cable; breadboard, sensors, shields and power adapter are not included, and younger learners should work with an experienced adult
Analog inputs and I2C
A0 through A5 are the six analog input labels. A4 and A5 also have I2C functions: A4 is SDA and A5 is SCL. They remain the same physical header connections; SDA and SCL do not indicate two additional pins.
The datasheet also prints SDA and SCL labels near AREF on the digital-header side. These correspond to the same I2C lines as A4/SDA and A5/SCL.
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![Arduino Uno REV3 [A000066] - ATmega328P Microcontroller, 16MHz, 14 Digital I/O Pins, 6 Analog Inputs, 32KB Flash, USB Connectivity, Compatible with Arduino IDE for DIY Projects and Prototyping](https://m.media-amazon.com/images/I/515P6aYSP4L._SL160_.jpg)
Arduino Uno REV3 [A000066] - ATmega328P Microcontroller, 16MHz, 14 Digital I/O Pins, 6 Analog Inputs, 32KB Flash, USB Connectivity, Compatible with Arduino IDE for DIY Projects and Prototyping
- ATmega328P Microcontroller: Powered by the reliable ATmega328P, running at 16 MHz with 32KB of flash memory, 2KB SRAM, and 1KB EEPROM, offering ample resources for a wide range of basic to advanced electronics projects.
- 14 Digital I/O Pins & 6 Analog Inputs: Features 14 digital I/O pins (6 of which support PWM output) and 6 analog inputs (10-bit resolution), providing flexible options for sensors, motors, and other external components.
- USB Connectivity for Easy Programming: The built-in USB port allows for direct programming and serial communication, enabling a simple connection to your computer for sketch uploading and debugging through the Arduino IDE.
- Compatible with Arduino IDE: Full compatibility with the Arduino IDE ensures easy access to a vast array of libraries, code examples, and community-driven projects, making the Uno a great choice for both beginners and experienced makers.
- Widely Used in Education & Prototyping: The Arduino Uno is a standard in educational environments, widely used for learning and teaching electronics and programming. It's perfect for prototyping, robotics, IoT projects, and more.
Power, ground, reset, and reference labels
The analog/power header includes NC, IOREF, RESET, +3V3, +5V, two GND positions, and VIN. The digital header includes AREF and another GND position. These are pin identifiers, not a complete wiring or electrical-safety guide; do not infer voltage tolerances or power limits from the labels alone.
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- GND: Ground connection labels; the board shows multiple positions.
- +5V and +3V3: Supply labels shown on the header.
- VIN: Input supply label.
- IOREF: The board’s reference-voltage label.
- RESET: Reset connection label.
- AREF: Analog reference label.
- NC: Marked not connected in the pinout.
Check the board model before using this pinout
This mapping is specifically for the Arduino UNO R3, based on the ATmega328P. Arduino’s product documentation identifies its pin counts and board identity, while the datasheet supplies the connector labels. Because other boards also use “Uno” in their names, compare the exact model and revision printed on your board with the UNO R3 documentation before selecting a connection.
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UNO R3 Board ATmega328P with USB Cable(Arduino-Compatible) for Arduino, Input Voltage 7-12V, 16MHZ,14 Digital 1/0 pins Support PWM, SRAW 2KB, Compatible with RPi 4B/3B+/3B/2B/B+/Zero/Zero W
- Unlock your creativity with the versatile UNO R3 Board ATmega328P! Explore endless possibilities in electronics projects with its user-friendly Arduino development environment, extensive digital and analog I/O pins, and compatibility with various sensors and modules. Let your imagination soar!
- Experience the power of UNO R3 Board ATmega328P! This feature-packed development board boasts a high-performance ATmega328P microcontroller, 32KB of flash memory, and 2KB of SRAM. It's perfect for both beginners and advanced users seeking to build innovative applications in robotics, home automation, and more.
- Ignite your passion for electronics with the UNO R3 Board ATmega328P! Its open-source design allows for customization, while its 14 digital I/O pins and 6 analog input pins provide ample connectivity options. Get ready to bring your ideas to life and create interactive projects like never before.
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- Discover the endless potential of the UNO R3 Board ATmega328P! With its robust communication interfaces, including UART, SPI, and I2C, you can connect and communicate with a wide range of devices. Whether you're a hobbyist or a professional, this powerful development board is a must-have for creating innovative and interactive electronic systems.
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ELEGOO UNO R3 Project Super Starter Kit with PDF Tutorial for Beginners
- TURN CODE INTO REAL-WORLD RESULTS — Follow 22+ guided lessons to make LEDs blink, read temperature and distance, move servo and stepper motors, control an LCD and respond to joystick or IR input; ideal for a family weekend build, homeschool unit, coding club or STEM classroom
- MORE PROJECT VARIETY IN ONE ORGANIZED KIT — Includes the UNO R3 controller, LCD1602 with pre-soldered header, breadboard power module, ultrasonic and DHT11 sensors, joystick, IR receiver and remote, SG90 servo, stepper motor, relay, DC motor, fan blade, displays, LEDs, buttons, resistors and jumper wires
- START WITHOUT SOLDERING — Plug-in modules, a solderless breadboard and the pre-soldered LCD help beginners focus on wiring, code and testing; the illustrated component list makes it easier to find each part and move from one lesson to the next
- LEARN THE LOGIC, THEN CREATE YOUR OWN — Use Arduino IDE and the included example code to understand digital input and output, analog sensing, timing, motor control and display functions, then change thresholds, speeds and sequences for alarms, environmental monitors, reaction games and motion projects
- CLEAR SETUP SUPPORT FOR FIRST-TIME BUILDERS — Download the latest tutorial and code, select the UNO board and correct computer port, check component polarity and breadboard rows, and keep power-module input at 9V or below; younger learners should work with an experienced adult
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ELEGOO UNO R3 Controller Board ATmega328P, Compatible with Arduino
- START CODING WITH A FLEXIBLE UNO R3 BOARD: Connect the included USB cable, upload sketches with Arduino IDE and build sensor, motor, display and automation projects for maker desks, classrooms, coding labs and electronics prototyping
- ATMEGA328P CORE FOR EVERYDAY PROJECTS: A 16 MHz clock, 32 KB flash, 2 KB SRAM, 1 KB EEPROM, 14 digital I/O pins with 6 PWM outputs and 6 analog inputs support LEDs, buttons, relays, servos, displays and sensors
- CH340C USB-TO-SERIAL INTERFACE: The onboard CH340C handles USB communication for sketch uploads and serial monitoring, while clearly labeled digital, analog and power headers help simplify wiring to modules and shields
- USB OR EXTERNAL POWER: Run the board from the included USB cable or a recommended 7-12 V external DC supply, then expand with compatible shields and modules for robotics, data logging, automation and custom embedded projects
- BOARD AND USB CABLE INCLUDED: Comes with 1 ELEGOO UNO R3 controller board and 1 USB-A to USB-B data cable; breadboard, jumper wires, sensors, shields and power adapter are not included
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