he Arduino Uno Rev3 SMD is a versatile microcontroller board based on the ATmega328P, designed for easy prototyping and development of electronic projects. Unlike the standard Uno, it uses the surface-mount (SMD) version of the ATmega328P, making the board slightly more compact while maintaining the same functionality and pin layout. It features 14 digital input/output pins (6 of which can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, USB connection, power jack, ICSP header, and a reset button.

The board can be powered via USB or an external power supply, supporting a wide range of voltages for flexibility. Known for its reliability and ease of use, the Arduino Uno Rev3 SMD is widely used by beginners, students, hobbyists, and professionals for building interactive electronics projects, from simple sensor applications to complex automation systems.

Features

• ATmega328 processor running at 16MHz
• CH340 Serial to USB converter
• 32KB Flash memory
• 14 Digital I/O
• 6 PWM shared with the digital I/O
• 6 Analog inputs that can also be used as digital I/O for a total of up to 20 digital I/O
• 1 Hardware serial port
• 5V Operation

The Uno R3 SMD operates at 5V which can be supplied via an external power supply or through the USB port connection. The power source is selected automatically if both are available. If an external supply is used, it is recommended to use a supply between 7-12V. Higher input voltages will cause the on-board regulator to work harder and may cause it to overheat.

A great feature on this version of the board is that besides the standard female headers for bringing out I/O, each female header also has a row of holes next to it which can be soldered male headers, a second row of female headers, or even wires. These can be soldered to either the top or bottom side of the board.

The board comes with a strip of male headers which are normally soldered to the top side of the board as shown in one of the pictures. If the male headers are soldered to the bottom of the board, the board can’t be mounted directly into a breadboard since the separate sections of headers on one side are not spaced apart on 0.1″ centers and the holes are offset somewhat side-to-side.

The board also has an array of solder points which gives another place to access I2C (SCL/SDA), Serial (TX/RC), 3.3V, 5V, and GND which can come in handy.
Like all Arduino-compatible boards, it can be programmed using the Arduino IDE via the USB port.
The original Uno design which we also sell uses a DIP processor placed in a socket. The benefit to that design is that it is easy to replace the processor should the chip become damaged. The downside is that the DIP part is becoming harder to find and the assemblies cost more than the SMD version.

Our Evaluation Results

These are nice clone assemblies with good build quality. The ability to add a 2nd row of male or female headers can be very handy. If going old school, you can wire wrap to the male headers which I have found handy at times when embedding these boards into a project where you can’t or don’t want to use a shield and you want more reliable connections than the normal jumpers provide.

The board uses the CH340 chip for USB communications. If you have any issues with connecting to the board, you may need to download a driver. Just search for Arduino CH340 driver and you will find a number of sources for drivers depending on what Windows or Mac operating system you are using.

Specifications