Please add official support for Arduino Nano R4 in the Arduino_CAN library

[ohoriyoshi]

I’m currently working with the Arduino Nano R4 (MCU: Renesas R7FA4M1) and trying to use its built-in CAN interface.

However, the current Arduino_CAN library included in ArduinoCore-renesas v1.5.0 does not appear to support the Nano R4 board. The CAN object and related types like CanMsg are not defined when compiling for arduino:renesas_uno:nanor4, which leads to compilation errors.

The following preprocessor conditionals are present in the Arduino_CAN library code:

ArduinoCore-renesas/libraries/Arduino_CAN/src/R7FA4M1_CAN.cpp

Line 17 in f781844

#if defined(ARDUINO_MINIMA) || defined(ARDUINO_UNOWIFIR4)

ArduinoCore-renesas/libraries/Arduino_CAN/src/R7FA4M1_CAN.h

Line 20 in f781844

#if defined(ARDUINO_MINIMA) || defined(ARDUINO_UNOWIFIR4)

As you can see, the ARDUINO_NANO_R4 macro is not included, so the CAN object is not available for Nano R4 despite it using the exact same RA4M1 MCU as the UNO R4 Minima/WiFi.

By locally modifying the condition as follows, I was able to compile and run CAN sketches successfully on the Nano R4:

#if defined(ARDUINO_UNOR4_MINIMA) || defined(ARDUINO_UNOR4_WIFI) || defined(ARDUINO_NANO_R4)

Since the hardware (pin mapping, CAN peripheral, etc.) is virtually identical, it would be highly beneficial to officially support the Nano R4 in the Arduino_CAN library. This would allow developers to take full advantage of CAN communication on a smaller form factor board.

I kindly request that you consider officially enabling support for Arduino Nano R4 in this library.

Thank you very much for your consideration.

Environment details (optional)
Board: Arduino Nano R4

FQBN: arduino:renesas_uno:nanor4

Arduino IDE: 2.3.6

Core Version: arduino/renesas_uno@1.5.0

Arduino_CAN Library Version: 1.0

CAN operation tested successfully using loopback mode

[facchinm]

Hi @ohoriyoshi ,
thanks for spotting this! Would you mind providing a PR with the fix so we can give proper attribution? Thanks!

[ohoriyoshi]

Description:
Problem:
The Arduino_CAN library does not recognize the ARDUINO_NANO_R4 macro in R7FA4M1_CAN.h and R7FA4M1_CAN.cpp, which results in compilation errors such as:

kotlin
'CAN' was not declared in this scope
'CanMsg' was not declared in this scope
Cause:
The preprocessor conditions only include:

cpp
#if defined(ARDUINO_UNOWIFIR4) || defined(ARDUINO_MINIMA)
This excludes ARDUINO_NANO_R4, even though it uses the same RA4M1 microcontroller.

Solution:
Added defined(ARDUINO_NANO_R4) to the preprocessor condition:

cpp
#if defined(ARDUINO_UNOWIFIR4) || defined(ARDUINO_MINIMA) || defined(ARDUINO_NANO_R4)
Modified Files:

R7FA4M1_CAN.h

R7FA4M1_CAN.cpp

Compatibility:
Confirmed working with the following environment:

Arduino IDE 2.3.6

Core: arduino:renesas_uno@1.5.0

Board: Arduino Nano R4 (RA4M1)

Library: Arduino_CAN@1.0

✅ Compatibility with Arduino Nano R4 has been successfully verified.

[per1234]

@ohoriyoshi it seems you may have misunderstood what @facchinm meant. @facchinm is asking you to submit a pull request that makes the necessary changes to the code hosted in this repository.

You can learn about contributing code changes through pull requests from the documentation here:

https://docs.github.com/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request

If you have any problems while making the pull request, or questions about it, you are welcome to post over on Arduino Forum. I'm sure we'll be able to assist you:

https://forum.arduino.cc/c/community/general-discussion/17

If you decide you don't want to submit a pull request, you can comment here to let us know. Another contributor will take responsibility for the task.