Is Arduino Uno R4 better than R3? Why Arduino Uno R3 is still relevant and what should you chose for your next project.
In this video I also mentioned advanced 16-bit PWM technique for R3, more on it here: [ Ссылка ]
In June 2023 we had a huge update of the Arduino UNO platform, as version R4 was released. This is a really large jump forward, as the previous version R3 was released in 2012 and was on the market for 11 years without any modifications.
Many users are now inclined to buy R4 as it is the latest version, however this may not always be the best option. In this video we will see why Arduino UNO R3 is still relevant and in which cases you still may want to choose it for your next project.
But first let’s quickly go over R4 specifications and compare them to R3, just to be on the same page.
Arduino UNO R4 comes in two flavors: Minima and WiFi and based on their names you may think that WiFi connectivity is the only difference between them, but there’s actually more. I have a WiFi board here, this is the official Arduino R4 WiFi board and today I’ll be using it as an example. The Minima board looks like you can see on this picture, and by just visual comparison we immediately can see that the WiFi board also features this LED matrix, which could be great for beginner projects.
Another visual difference is the presence of a second chip here, which is ESP32-S3 used for WiFi connectivity.
And one more thing which makes me like this new board - USB C connector! I’m so glad! I hate this USB B in R3 - it is large, relatively rarely used and only makes things more complicated.
VRTC and OFF pins. Real Time Clock is included on both boards, but only the WiFi board has connections for a battery backup. This is a VRTC pin which is used to keep the onboard Real Time Clock running even when the board's main power supply is turned off, and the OFF pin is used to turn off the board completely by cutting off the power.
But of course all major specifications are still the same for these two boards:
Main microcontroller is a 32 bit RA4M1 running on 48MHz, which has an ARM core and compared to R3 this is a big step forward because R3 has an 8 bit ATmega328 chip running on 16Mhz.
Also R4 features 8 times more memory than R3: 256kb flash, 32kb SRAM and 8kb EEPROM, compared to 32/2/1kb for R3.
R4 also has a CAN controller, so in addition to UART, SPI and I2C protocols available in R3 you also have CAN support in R4. CAN is mainly used in the automotive industry.
So, in other words R4 is better than R3 in almost everything with only one notable exception: pin current limitation. The Arduino Uno R4 has a maximum source current of 8 milliamperes (mA) per I/O pin. This is about 40% of the current handling capacity of the older Arduino Uno R3, which has a maximum current of 20 mA.
Which means that some projects or shields designed for R3 may not work for R4! In other words R3 and R4 boards are not completely compatible, and pin current is not the only thing that contributes to this incompatibility - remember that R3 and R4 use completely different CPUs, so your code can only run on both boards if it is written strictly with the use of Arduino API. If you used any code specific to the ATmega chip of R3 - you will have to rewrite it, it will simply not run on R4.
And this incompatibility is the main reason why Arduino UNO R3 still is and will be relevant - because R4 is not the replacement for R3, despite what Arduino may think. It is more like another more powerful board, which you may want to use, or you may want to stick to R3.
So the first reason why Arduino Uno R3 is still relevant is: Widespread Adoption and Ecosystem
The Arduino Uno R3 has been around for years and is one of the most widely adopted development boards in the world.
Due to its popularity, there is a vast ecosystem of shields, libraries, and tutorials specifically designed for the R3.
Most projects, guides, and online resources are still built around the R3, making it a highly accessible platform, especially for beginners.
And this leads us to the second point of why Arduino UNO R3 is still current:
Large Amount of Learning Resources
For beginners, the large volume of educational content (videos, blogs, tutorials) dedicated to the R3 is unmatched.
This makes it easier for new makers to troubleshoot issues or find solutions for common problems, thanks to the large community support.
A large number of existing Arduino projects were built specifically for the Uno R3. If a project doesn’t require the additional power or features of the R4, there’s no need to switch.
Lower Cost
The price point of the R3 is typically lower than the new R4 models, especially the WiFi version.
