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Description
UNO-R3 Development Board Product Overview
The UNO-R3 is the most classic official development board, featuring the ATmega328P main MCU, fully compatible with Arduino IDE. Available with or without USB cable, it is ideal for beginners, makers, competitions, and rapid prototyping.
UNO-R3 Development Board Core Features
ATmega328P MCU： 16MHz, 32KB Flash, 2KB SRAM, 1KB EEPROM
Standard R3 Pin Layout： 14 digital I/O (6 PWM), 6 analog inputs, I2C, SPI, UART, compatible with thousands of Shields
Flexible Power： USB 5V or DC 7-12V with auto-switching
Two Options： Board only or board with USB cable
UNO-R3 Development Board Applications
Learning, robotics competitions, maker projects, smart hardware prototyping, sensor data acquisition
UNO-R3 Development Board Key Advantages
World's Largest Open Source Community： Millions of developers, extensive libraries and tutorials
Low Development Barrier： Arduino IDE works out of the box, beginners can light an LED in one hour
Perfect Shield Compatibility： Plug-and-play modular development with thousands of shields
Two Configurations： Cable-included ready to use, board-only suitable for users who already have a USB cable
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FAQ:
What is the UNO R3 development board and its key specifications?
The UNO R3 is the official Arduino‑compatible board built around the ATmega328P microcontroller. It operates at 16 MHz, provides 32 KB of Flash memory (with 0.5 KB used by the bootloader), 2 KB of SRAM, and 1 KB of EEPROM. The board offers 14 digital input/output pins (of which 6 support PWM), 6 analog inputs, and a USB‑B connector for programming and power. It can be powered via USB or an external 7–12 V DC supply (limit 6–20 V). The UNO R3 is the most popular entry‑level board for learning electronics and prototyping.
What is the difference between the UNO R3 and the earlier UNO versions?
The UNO R3 (Revision 3) introduced several improvements over the previous UNO R1/R2. It replaced the ATmega8U2 USB‑to‑serial chip with a more capable ATmega16U2, added dedicated SCL and SDA pins next to AREF, and included two new pins near the reset button (IOREF and a spare). The reset circuit was also made more robust. All existing shields and code are fully compatible with the R3, and the R3 is backwards compatible with the R1/R2.
How do I power the UNO R3, and what voltage should I use?
You can power the board through the USB‑B port (5 V) or via the DC barrel jack (center‑positive). The recommended external voltage is 7 V to 12 V. The on‑board 5 V and 3.3 V regulators supply the microcontroller and can provide a small amount of current (up to about 500 mA on 5 V and 50 mA on 3.3 V) for external sensors. The absolute input limits are 6 V to 20 V, but voltages above 12 V may cause the voltage regulator to overheat without a heatsink.
How do I program the UNO R3 with the Arduino IDE?
Programming is done via the USB cable. Install the Arduino IDE, connect the board, and the operating system will detect it as a virtual COM port. In the IDE, select “Arduino Uno” from the Board menu, choose the correct port, and click Upload. The on‑board ATmega16U2 handles the USB‑to‑serial conversion. No external programmer is needed. The board can be programmed in C/C++ using the Arduino framework.
How much memory does the ATmega328P have, and what can I fit in it?
The ATmega328P provides 32 KB of Flash for program storage (about 31.5 KB usable after the bootloader), 2 KB of SRAM for variables, and 1 KB of EEPROM for non‑volatile data. This is enough for moderately complex sketches: you can run multiple libraries (e.g., a small display, sensors, and communication) but must watch SRAM usage if you use large strings or arrays. For projects that need more memory, the Arduino Mega 2560 is a common upgrade.
What is the ATmega16U2 chip and what does it do?
The ATmega16U2 acts as a USB‑to‑serial bridge between the computer and the main ATmega328P. It replaces the older FTDI or 8U2 chips used in earlier Arduino versions. With the 16U2, you can also reprogram it to behave as an HID device (keyboard, mouse, joystick) or a MIDI controller, making the UNO more versatile. It appears as a standard COM port when connected, and its firmware can be updated via the DFU (Device Firmware Upgrade) mode.
Can I use Arduino shields with the UNO R3?
Yes, the UNO R3 has the standard shield‑compatible header footprint that is widely adopted. Most shields that are designed for the Arduino Uno form factor (including the Arduino Uno R1‑R3) will fit and work electrically. The R3 introduced additional pins (SDA, SCL, IOREF) that some shields utilise for I2C and voltage reference, but traditional shields that use only the original headers remain fully compatible.
How many PWM pins does the UNO R3 have, and what are they used for?
It has 6 PWM‑capable pins: 3, 5, 6, 9, 10, 11. These pins output a pulse‑width modulated (PWM) signal with 8‑bit resolution, which can be used to simulate analog output for dimming LEDs, controlling motor speed, generating audio tones, and more. The analogWrite() function sets the duty cycle from 0 (off) to 255 (full on). The PWM frequency is approximately 490 Hz on most pins, and 980 Hz on pins 5 and 6.
What are the analog input capabilities of the UNO R3?
The board provides 6 analog input pins (A0–A5), each connected to a 10‑bit successive‑approximation ADC. This gives a resolution of 0–1023 for voltages between 0 V and 5 V (the reference voltage can be changed using the AREF pin or internal references). Analog pins can also be used as digital I/O when extra pins are needed. The ADC has a maximum sampling rate of about 15 ksps.
What are the most typical applications for the UNO R3?
It is the standard platform for learning electronics and programming, rapid prototyping, IoT sensor nodes (with an add‑on WiFi/Ethernet shield), home automation, robotics, interactive art installations, and educational projects. Its huge community, countless libraries, and plug‑and‑play nature make it the go‑to board for beginners and a reliable workhorse for professionals testing concepts.