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SparkFun

· MPN: DEV-18158

$58.15 |
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This Arduino-compatible development board keeps the familiar Uno-style layout while adding a few genuinely handy upgrades for modern projects. Built around t...

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This Arduino-compatible development board keeps the familiar Uno-style layout while adding a few genuinely handy upgrades for modern projects. Built around the ATmega328P, it works with the Arduino IDE and fits the Uno R3 footprint, so it is a straightforward choice if you want broad compatibility with shields, libraries and existing example sketches.

One of the biggest improvements is the built-in Qwiic connector, which makes it easy to add compatible I2C sensors, actuators and other boards without soldering or extra shields. The board also breaks out SDA, SCL and IOREF for better R3 shield compatibility, and includes the extra analogue pins A6 and A7 for a bit more flexibility than a standard Uno-style board.

USB-to-serial is handled by a CH340G over a reversible USB-C connector, and power can come from USB-C or the barrel jack. For mixed-voltage projects, SparkFun has added a switch to select 3.3V or 5V GPIO logic levels. There are also A4/A5 jumpers for disconnecting the logic level converters from the I2C pins, clearly labelled plated through-hole pads for more permanent wiring, and bottom-side D+/D- pads if you want to embed the board into a finished build.

To get started, connect a USB-C cable, open the Arduino IDE, select Arduino UNO from the board menu, and upload your sketch. It is a solid option for prototyping, education, and projects that want classic Arduino compatibility with easier Qwiic expansion.

Features:

  • Arduino IDE support: Program over USB-C by selecting Arduino UNO from the board menu
  • Qwiic connectivity: Connect compatible I2C-based Qwiic products without soldering or shields
  • USB-C connector: Reversible USB-C connector with through hole anchoring
  • Selectable GPIO voltage: Easily select the GPIO voltage between 3.3V or 5V
  • Uno R3 compatibility: SDA, SCL and IOREF are broken out on the Arduino Uno R3 footprint for future shield compatibility
  • A4/A5 jumpers: Can be used to disconnect the logic level converters from the pins tied directly to the I2C bus
  • Prototyping-friendly layout: Clearly labeled PTH holes alongside the standard female headers
  • Embedded USB access: Solder pads on the bottom of the board for USB data pins D+/D- allow an external USB connection

Specifications:

  • Microcontroller: ATmega328P microcontroller with Optiboot (UNO) Bootloader
  • Input voltage: 7V to 15V via barrel jack
  • Input voltage: 5V via USB-C
  • Voltage regulators: LM1117 adjusted to 5V
  • Voltage regulators: AP2112 for 3.3V
  • PTC fuse: Built-in Resettable PTC Fuse 5V/2A
  • USB converter: CH340G Serial-to-USB Converter
  • Logic level switch: 3.3V to 5V Logic Level Switch
  • Digital I/O: 22x Digital I/O Pins (6x PWM Outputs, 8x Analog Inputs, 1x UART, 1x I2C, 1x SPI)
  • Qwiic connector: 1x Qwiic Connector
  • Jumpers: A4/A5 Jumpers
  • ISP header: 2x3 ISP Header
  • Flash memory: 32kB Flash Memory
  • Clock speed: 16MHz Clock Speed
  • Construction: All SMD Construction
  • Shield compatibility: R3 Shield Compatible
  • Reset button: Improved Reset Button

If you are already using the Qwiic ecosystem, this board makes a neat bridge between classic Arduino development and fast, solder-free I2C expansion.

Jargon buster

Plain-language definitions for the technical terms used above.

ATmega328P
An 8-bit microcontroller chip used on many Arduino Uno-compatible boards. Knowing the controller uses an ATmega328P helps you understand its memory, speed, pin compatibility, and the Arduino sketches it can run.
Bootloader
Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
Flash memory
Flash memory is non-volatile memory that retains stored data even when power is removed, and can be erased and rewritten in blocks. It lets data such as firmware, settings or saved records persist across power cycles.
GPIO
General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
Headers
Rows of connector contacts on a fixed pitch (commonly 2.54 mm) used to link a board to a breadboard, jumper wires, or another board. They come as male pin headers and female socket headers; when a module ships with pre-soldered headers it can be used straight away, whereas bare pads require soldering the pins yourself.
I2C
I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
IDE
Short for Integrated Development Environment, a program used to write, run and manage code. It matters because some learners prefer a traditional coding workspace instead of a guided notebook-style lesson.
ISP
In electronics, ISP usually means In-System Programming, a way to load firmware onto a microcontroller while it stays on the board (often via an ICSP header), or an Image Signal Processor, hardware that turns raw camera sensor data into usable images and offloads the main CPU. The surrounding context shows which meaning applies.
microcontroller
A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
PTC fuse
A resettable fuse that increases its resistance when too much current flows, helping protect the board from short circuits or overloads. It matters because it can recover after a fault instead of needing replacement like a traditional fuse.
PTH
Plated through-hole means the pin holes are metal-lined so solder connects the pad on both sides of the board. It is useful for connectors and headers that need a strong mechanical and electrical connection.
PWM
Pulse Width Modulation is a way for a digital pin to simulate variable output power by switching on and off very quickly. It matters for controlling things like LED brightness, motor speed, or servo-style signals from a microcontroller pin.
Qwiic
Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
Shield
An add-on board that plugs into a main controller board to give it extra features such as sensing, motor control or communication. Knowing a product supports shields helps you judge whether it can connect neatly into an existing maker-board setup.
SMD
SMD means surface-mount device, a component style designed to be soldered directly onto the surface of a circuit board rather than through holes. SMD parts are compact and mounted flat on the board, which suits smaller and mass-produced designs.
SPI
A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
through-hole
A mounting style where the component leads pass through holes in a circuit board and are soldered on the other side. Through-hole parts are often easier to handle and solder by hand, which is useful for classroom and hobby projects.
UART
UART is a simple asynchronous serial interface that sends data over separate transmit and receive wires, usually labelled TX and RX, with both ends set to the same baud rate. It is a common way for microcontrollers and other serial devices to exchange data.
USB-C
USB-C is a small, reversible USB connector that can carry power, data and, on some devices, video over a single cable. The same connector can range from charging only to high-speed data, so the functions a given port actually supports vary.

RedBoard Plus Schematic

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RedBoard Plus Graphical Datasheet

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Supplier page — sparkfun.com

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Source Code

Open-source libraries, firmware & example projects for this product

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