Unveiling the Arduino UNO R4: A Comprehensive Review & Compatibility Guide

Welcome to the innovative realm of Arduino, a place where possibilities and practicality intertwine. Today, we will take you on a deep dive into the Arduino UNO R4, an exceptional development board that has garnered widespread attention in the global electronics community. The UNO R4 not only inherits the excellent features of its predecessor, the UNO R3, but also makes significant upgrades and improvements on that basis. So, compared to the UNO R3, what unique upgrade highlights does the upgraded UNO R4 possess that enable it to stand out among numerous development boards, becoming the top choice for both beginners and experienced makers? Is it the more powerful ARM Cortex-M4 chip, the newly added Wi-Fi and Bluetooth connectivity features, or the optimized module compatibility and convenient development experience? Let's delve into the Arduino UNO R4 together, exploring its unique charm and upgrade highlights, and revealing the innovative technology and design wisdom behind it.

The New Chapter of Arduino: UNO R4 Unveiled

Thirteen years ago, Arduino introduced the UNO R3, a development board that won the hearts of makers worldwide due to its stability and ease of use. Time flies, and now, Arduino has finally launched the latest upgraded version of this series - the Arduino UNO R4. Compared to the previous model, the new version has significantly improved in terms of computing power, memory, and network connectivity, offering more possibilities for innovators.

 Figure: Arduino UNO R4

UNO R4 VS UNO R3

The Arduino UNO R4 inherits the classic design and appearance of the UNO R3, but has undergone significant internal upgrades. It no longer uses the ATmega328P chip, but instead adopts the more powerful ARM Cortex-M4. This processor operates at a frequency of up to 48 MHz and is equipped with 32KB of RAM and 256KB of flash memory. Such configuration almost redefines the performance category of Arduino. The Cortex M4 microcontroller onboard the Arduino UNO R4 provides higher performance, faster clock speeds, and a more advanced instruction set. Compared to the Uno R3, it can execute code more efficiently and faster, not only handling more complex projects with ease but also providing faster operating speeds.

Compared to the Uno R3, the processing power of the Cortex M4 microcontroller has increased dramatically, from 3 to 16 times. Compared with smaller microcontroller boards like the Raspberry Pi Pico, which uses the Cortex M0+, the performance of the Cortex-M4 has improved by about six times.

With faster clock speeds and expanded memory, you'll say goodbye to those common confusing moments. You'll no longer wonder why your code isn't working, only to find out it's because your Serial.print() statement is too long and too heavy for a slow-running microcontroller or because a massive array has consumed all available memory.

In addition, the UNO R4 can be powered by a 5V supply, making it more convenient and practical.

It's worth mentioning that the UNO R4 has finally adopted the USB-C interface, which is a significant upgrade from the previous USB-B interface. This new interface not only provides faster data transfer speeds but is also more universal, capable of connecting to almost all modern devices. Additionally, the Uno R4 supports a Vin input voltage of 24V, making it compatible with a wider range of power supplies.

Figure: Arduino UNO R4 Upgraded to a Type-C Interface

New Highlighted Features:

DAC:

The analog output of the Arduino UNO R3 could only output a waveform through PWM, and it couldn't achieve true analog output. In industrial scenarios, a large number of devices, such as PLCs can only receive voltage signals. The newly added DAC in UNO R4 can directly output analog voltage through the API, enabling Arduino UNO to adapt more quickly in industrial scenarios.

CAN Bus:

As a commonly used communication bus in embedded systems, the Controller Area Network (CAN) bus can minimize wiring and execute multiple tasks in parallel by connecting multiple expansion boards. It has excellent stability and a long transmission distance. The UNO R3 did not have a built-in CAN communication interface, and thus could not natively drive some servo control systems. The appearance of the Arduino UNO R4 solves this pain point.

Minima Version VS Wi-Fi Version

 Figure Caption: Arduino UNO R4 WiFi & Arduino UNO R4 Minima

The upgraded Arduino UNO R4 is actually divided into two versions: the Minima version and the Wi-Fi version. Both use the high-performance ARM Cortex-M4 chip, but they differ in other features.

• Wireless Connectivity: The Arduino UNO R4 Wi-Fi integrates an ESP32-S3 module, which supports Wi-Fi and Bluetooth connections, providing your projects with wireless communication capabilities. The Arduino UNO R4 Minima, on the other hand, does not have wireless connectivity, but it can be connected to other wireless modules via a Qwiic connector, providing greater flexibility. The cloud connectivity on the UNO R4 Wi-Fi means you can upload data and synchronize certain variables and data between different Arduinos. For example, you can have one Arduino with a button and another Arduino wirelessly connected to an LED. Pressing the button can turn on the LED without any additional single-line code to handle communication. Everything is handled behind the scenes.
• LED Matrix: The Arduino UNO R4 Wi-Fi has a built-in 12x8 LED matrix that can be used to display graphics or text, adding visual effects to your projects. The Arduino UNO R4 Minima does not have an LED matrix. This matrix uses Charlieplexing to connect 96 LEDs to only 11 GPIO ports (D28 to D38 in Arduino terminology). This means that only a few LEDs can be active at any one time, as pixels are made up of two LEDs connected in reverse parallel, and pixels share ports. However, due to the slow speed of the human eye, rapid time multiplexing can trick the brain into seeing a complete image.
• VRTC and OFF Pins: The Arduino UNO R4 Wi-Fi has a VRTC pin, which can be used to power the ESP32-S3 module, allowing it to maintain a Wi-Fi connection in low power mode. It also has an OFF pin, which can be used to turn off the ESP32-S3 module to save power. The Arduino UNO R4 Minima does not have these two pins.

 Figure: Features of Arduino UNO R4 WiFi & Arduino UNO R4 Minima

Compatibility Assessment

From the above parameter table, we find that the Arduino UNO R4 has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog input pins, and a set of serial communication interfaces (including UART, I2C, and SPI interfaces). This means that in addition to chip upgrades, the Arduino UNO R4 has also been fully optimized in terms of module compatibility, providing users with a wealth of interfaces and a more convenient development experience.

To help readers better understand its compatibility, we tested it according to the commonly used modules of various interfaces on the DFRobot platform, including digital signal devices, analog signal devices, and I2C interface devices, UART interface devices, and expansion boards.

Figure: Arduino UNO R4 Compatibility Assessment

Digital Signal Devices

In terms of digital signal devices, the Arduino UNO R4 has been tested and is compatible with many common digital signal devices, including buttons, lights, servos, temperature sensors, etc. By connecting with the digital input/output pins of the Arduino UNO R4, you can easily read and control these devices, realizing interactive control, status indication, and precise motion control functions.

Analog Signal Devices

The Arduino UNO R4 is also compatible with a variety of analog signal devices, such as knobs and analog electrical conductivity sensors. By connecting to the analog input pins of the Arduino UNO R4, you can obtain data from analog sensors, which can be used for parameter adjustment, environmental monitoring, and other applications.

I2C Interface Devices

Through the I2C interface of Arduino UNO R4, you can connect a variety of I2C devices, such as Huskylens vision sensors, speech synthesis modules, voice recognition modules, NFC modules, LCD screens, etc. These devices communicate with the Arduino UNO R4 via the I2C bus, realizing functions such as image recognition, voice output, and data interaction.

During the testing of Arduino UNO R4, it was found that the OLED screen (product number DFR0486) is temporarily incompatible due to the lack of the wiring_private.h in the official library. We believe that the Arduino team will solve this problem in future updates.

UART Interface Devices

The UART interface of the Arduino UNO R4 can be used for communication with serial devices. You can connect devices such as Huskylens vision sensors, serial data loggers, USB TTL adapters, etc., and perform data transmission and communication via serial ports.

Expansion Boards

The design of the Arduino UNO R4 also takes into account compatibility with various expansion boards, which can further expand the functional range of the Arduino UNO R4. For example, by connecting a motor driver board, the Arduino UNO R4 can perform more complex mechanical control; by connecting expansion modules, the Arduino UNO R4 can achieve access to more types of sensors and actuators.

In summary, the Arduino UNO R4 has ensured good compatibility with common module devices through compatibility testing, providing users with a wider range of choices and a more convenient development experience. Whether it's digital signal devices, analog signal devices, I2C interface, UART interface, or expansion board devices, the Arduino UNO R4 can meet your needs and let you enjoy the fun of creation.

Please note that the above compatibility test results only cover common module devices. In fact, the Arduino UNO R4 is compatible with many more module devices, and you can try and explore according to your specific needs.

Conclusion

In conclusion, the Arduino UNO R4, with its advanced ARM Cortex-M4 chip, enhanced compatibility, and additional Wi-Fi and Bluetooth connectivity, is a game-changer in the world of electronics. Its upgraded features, coupled with its user-friendly design, make it an ideal choice for both beginners and experienced makers looking to push the boundaries of their creativity.

The UNO R4 is not just about offering more power or connectivity options, it's about providing a platform that adapts to your needs, whether you're developing a complex industrial project or exploring the basics of electronics. With the UNO R4, you're not just buying a development board, you're investing in a world of possibilities.

We hope this exploration of the Arduino UNO R4 has been informative and inspiring. As always, we encourage you to experiment, explore, and innovate. After all, the future of electronics is in your hands. Happy making!