Arduino Uno R3 vs R4

What are the similarities, differences, and compatibilities between Arduino Uno R3 and Arduino Uno R4?

Answer

TL;DR:

The Arduino UNO R4 is the new version of the Arduino UNO R3. The Arduino UNO R4 has a number of improvements over the previous UNO R3, including a faster processor, more memory, and a number of new peripherals. The Arduino UNO R4 is not fully compatible with Arduino UNO R3 because it uses the diffrent microcontroller.

For details, In the next parts, we will explore the following in order:

The overview of differences between UNO R4 and R3
The compatibilities between UNO R4 and R3 in terms of hardware, AID, Shield, Libraries ...
The detailed differences between UNO R4 and R3

Hardware Features

Arduino IDE Compatibility

Arduino UNO R3 works with Arduino IDE (1.x and 2.x) WITHOUT additional configuration
Arduino UNO R4 works with Arduino IDE (1.x and 2.x) WITH additional configuration. You will need to install the UNO R4 board package. See more details inHow to get started with Arduino UNO R4

Arduino Shield Compatibility

The Arduino UNO R4 boards maintain both mechanical and electrical compatibility with previous versions, allowing for a seamless transition and utilization of existing shields and hardware. Most shields that are stackable on Arduino UNO R3 will also work with the Arduino UNO R4. However, it's important to note that not all shields compatible with Arduino UNO R3 will be compatible with the UNO R4. Here are a few scenarios to consider:

Shields that do not require a library, such as the Proto screw shield, breadboard shield, or Relay Shield, are generally compatible with the Arduino UNO R4.
For shields that do require a library:

If the library is compatible with the Arduino UNO R4, the shield will be compatible as well.
If the library is incompatible with the Arduino UNO R4, the shield will be incompatible. In such cases, you may need to modify the library or update the firmware for the shield to ensure compatibility with the Arduino UNO R4.

It's essential to verify the compatibility of specific shields and libraries when transitioning from Arduino UNO R3 to Arduino UNO R4. This will help ensure that your shields and hardware function correctly with the new board.

The below are list of compatible shields:

Shield Name	Compatible	Libraries
Breadboard Shield	Yes	NOT required
Screw Expansion Shield	Yes	NOT required
Arduino 4 Relays Shield	Yes	NOT required
Arduino Motor Shield Rev3	Yes	NOT required
Arduino Ethernet Shield Rev2	Yes	Ethernet.h

Please note that this is not an exhaustive list, and there are many more shields compatible with arduino uno r4. it's always recommended to check the specific shield documentation and compatibility with your arduino board to ensure proper usage.

Arduino Library Compatibility

This section answers the question: Are libraries for UNO R3 also compatible with the UNO R4 boards?

Libraries based on Arduino API are compatible without any modifications on UNO R4 boards.
Libraries that rely on AVR-specific instructions are not compatible with the architecture of UNO R4 boards. Nonetheless, some libraries have been successfully ported through our early adopters program to ensure compatibility.

To determine whether a library is compatible with Arduino UNO R4, you can follow these steps:

Locate the source code of the library either on GitHub or on your computer where the code is installed.
Look for the library.properties file within the library.
Open the library.properties file and search for the architectures property.
If the architectures property is set to *, or renesas_uno, it means that the library is compatible with Arduino UNO R4.

Other ways to check the library compatibilities:

Contact the creator of the library and ask them directly about its compatibility with Arduino UNO R4.
Inspect the source code of the library line by line to see if it includes any architecture-specific code. If the code does not contain any architecture-specific instructions, it is likely compatible with Arduino UNO R4.

By following these steps and considering the suggested methods, you can determine the compatibility of a library with Arduino UNO R4.

The following is a list of libraries that are compatible with Arduino UNO R4:

please note that this is not an exhaustive list, and there are many more libraries available for arduino uno r4. it's always recommended to check the specific library documentation and compatibility with your arduino board version to ensure proper usage.

User Code (schetch) Compatibility

This section answers the question: Is it possible to use a code (sketch) created for Arduino UNO R3 on an Arduino UNO R4 board?

Yes, if your code uses the Arduino API, it will work without modifications.
If your code includes AVR-specific instructions, some adjustments may be necessary for compatibility.

Advanced Differences

Arduino UNO R4 Minima/WiFi uses 32-bit MCU (RA4M1 series from Renesas), whereas Arduino UNO R3 uses 8-bit MCU (ATmega328P)
Arduino UNO R4 Minima/WiFi uses a USB Type-C connector, whereas Arduino UNO R3 uses a USB Type-B connector.
Arduino UNO R4 Minima/WiFi uses a 256kB flash memory, whereas Arduino UNO R3 uses a 32kB flash memory.
Arduino UNO R4 Minima/WiFi uses a 32kB SRAM, whereas Arduino UNO R3 uses a 2kB SRAM.
Arduino UNO R4 Minima/WiFi runs at 48MHz, which provides a 3x increase over the UNO R3.
Analog-to-Digital Converter (ADC):

Default is 10-bit resolution ⇒ compatible with ADC of Arduino UNO R3.
Options to change the resolution to 12-bit or 14-bit

Arduino UNO R4 Minima/WiFi has power voltage voltage between 6-24V, while Arduino UNO R3 has 7-12V range.
Arduino UNO R4 Minima/WiFi has the Real-Time Clock, which UNO R3 does not have.
Arduino UNO R4 Minima/WiFi has the CAN Bus, which UNO R3 does not have.
Arduino UNO R4 WiFi has the LED Matrix, which UNO R3 does not have.

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	1 × Arduino UNO R3Buy on Amazon
	1 × Arduino UNO R4 WifiBuy on Amazon
	1 × Arduino UNO R4 MinimaBuy on Amazon
	1 × DIYables Sensor KitBuy on Amazon

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