# Arduino Uno Rev3 > The original Arduino UNO — the world's most popular development board with ATmega328P at 16MHz, 32KB flash, 2KB SRAM, 14 digital I/O (6 PWM), 6 analog inputs, USB-B, and 5V operation. The gateway to electronics and programming for millions. ## Quick Facts - **Brand:** Arduino - **Board Type:** dev-board - **Price:** ~$26.5 - **Product Readiness:** consumer - **CPU:** ATmega328P @ 16MHz, 8-bit AVR - **CPU Architecture:** AVR - **CPU Cores:** 1 - **RAM:** 2KB SRAM - **Flash:** 32KB - **USB:** USB-B - **Power:** 5V via USB-B or 7-12V via barrel jack - **Operating Voltage:** 5V - **Operating Temp:** -40°C to 85°C - **Dimensions:** 68.6 × 53.4mm - **Weight:** 25g - **Antenna:** No - **SD Card:** No ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware arduino ## Use Cases - educational-platform - iot ## Components - **ATmega328P** (mcu): Microchip ATmega328P 8-bit AVR at 16MHz with 32KB flash, 2KB SRAM, 1KB EEPROM, 6 ADC channels, and 6 PWM outputs in removable DIP-28 package. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FAtmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) ## Protocols - **SPI**: MOSI: D11, MISO: D12, SCK: D13, SS: D10 - **I2C**: SDA: A4, SCL: A5 - **UART**: TX: D1, RX: D0 ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D0 | UART RX | UART | digital-input, digital-output | | D1 | UART TX | UART | digital-input, digital-output | | D2 | Digital I/O / INT0 | | digital-input, digital-output | | D3 | PWM / INT1 | PWM | digital-input, digital-output, pwm | | D4 | Digital I/O | | digital-input, digital-output | | D5 | PWM | PWM | digital-input, digital-output, pwm | | D6 | PWM | PWM | digital-input, digital-output, pwm | | D7 | Digital I/O | | digital-input, digital-output | | D8 | Digital I/O | | digital-input, digital-output | | D9 | PWM | PWM | digital-input, digital-output, pwm | | D10 | PWM / SPI SS | SPI | digital-input, digital-output, pwm | | D11 | PWM / SPI MOSI | SPI | digital-input, digital-output, pwm | | D12 | SPI MISO | SPI | digital-input, digital-output | | D13 | SPI SCK / LED | SPI | digital-input, digital-output | | A0 | Analog Input | ADC | digital-input, digital-output, adc | | A1 | Analog Input | ADC | digital-input, digital-output, adc | | A2 | Analog Input | ADC | digital-input, digital-output, adc | | A3 | Analog Input | ADC | digital-input, digital-output, adc | | A4 | I2C SDA / Analog | I2C | digital-input, digital-output, adc | | A5 | I2C SCL / Analog | I2C | digital-input, digital-output, adc | ## Description ## Overview The Arduino Uno Rev3 is the quintessential microcontroller board that introduced millions to electronics and programming. Based on the ATmega328P running at 16MHz with 32KB flash and 2KB SRAM, it defined the Arduino form factor, pinout, and shield ecosystem that remains the standard today. With 14 digital I/O pins (6 PWM-capable), 6 analog inputs, a 16MHz crystal oscillator, USB-B connection, power jack (7-12V), ICSP header, and reset button, the UNO provides everything needed to get started. Its DIP-package ATmega328P can be removed and replaced, making it forgiving for beginners who might damage the chip. Despite being superseded by the R4 series, the Uno Rev3 remains in active production and is the most documented, most supported, and most widely-used Arduino board ever made. Virtually every Arduino tutorial, library, and shield was designed for or tested on the UNO, making it the safest choice for learning and maximum compatibility. ## Where to Buy - [Arduino Store (US)](https://openhardware.directory/r?to=https%3A%2F%2Fstore-usa.arduino.cc%2Fproducts%2Farduino-uno-rev3&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $26.50 - [Arduino Store (EU)](https://openhardware.directory/r?to=https%3A%2F%2Fstore.arduino.cc%2Fproducts%2Farduino-uno-rev3&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — €29.30 - [DigiKey](https://openhardware.directory/r?to=https%3A%2F%2Fwww.digikey.com%2Fen%2Fproducts%2Fdetail%2Farduino%2FA000066%2F2784006&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $27.60 - [Mouser](https://openhardware.directory/r?to=https%3A%2F%2Fwww.mouser.com%2FProductDetail%2FArduino%2FA000066&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $27.60 - [Amazon US](https://openhardware.directory/r?to=https%3A%2F%2Fwww.amazon.com%2Fdp%2FB008GRTSV6&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $27.60 - [SparkFun](https://openhardware.directory/r?to=https%3A%2F%2Fwww.sparkfun.com%2Farduino-uno-r3.html&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $27.95 - [The Pi Hut (UK)](https://openhardware.directory/r?to=https%3A%2F%2Fthepihut.com%2Fproducts%2Farduino-uno-rev3&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — £20.00 - [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F50&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) — $27.95 ## Resources - [product](https://openhardware.directory/r?to=https%3A%2F%2Fstore.arduino.cc%2Fproducts%2Farduino-uno-rev3&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) - [wiki](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.arduino.cc%2Fhardware%2Funo-rev3%2F&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) - [datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.arduino.cc%2Fresources%2Fdatasheets%2FA000066-datasheet.pdf&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) - [schematics](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.arduino.cc%2Fresources%2Fschematics%2FA000066-schematics.pdf&ref=openhardware.directory&product=arduino-uno-rev3&source=md-export) ## Tags `arduino`, `uno`, `atmega328p`, `classic`, `beginner`, `5v` ## Images ![Arduino Uno Rev3](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-uno-rev3/8ab6e1e71862.jpg) ![Arduino Uno Rev3](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-uno-rev3/1e46303ded3e.jpg) --- [View full device page](https://openhardware.directory/devices/arduino-uno-rev3)