The repository contains the Arduino APIs and IDE integration files targeting a generic mbed-enabled board

mkdir -p $sketchbook/hardware/arduino-git
cd $sketchbook/hardware/arduino-git
git clone git@github.com:arduino/ArduinoCore-mbed mbed

git clone git@github.com:arduino/ArduinoCore-API

Create a symlink to ArduinoCore-API/api in $sketchbook/hardware/arduino-git/mbed/cores/arduino.

Open the Arduino IDE.

You should now see three new targets under the MBED boards label.

This procedure does not automatically install the required ARM compiler toolchain.

If the toolchain is missing, you'll see errors like this when you try to build for an mbed-os enabled board.:

fork/exec /bin/arm-none-eabi-g++: no such file or directory

To install ARM build tools, use the Boards Manager option in the Arduino IDE to add the Arduino mbed-enabled Boards package.

The backbone of the packaging process is https://github.com/arduino/ArduinoCore-mbed/blob/master/mbed-os-to-arduino script. It basically compiles a blank mbed-os project for any supported target board, recovering the files that will be needed at compile time and copying them to the right location.

It can be used for a variety of tasks including:

Recompiling libmbed with source level debug support

cd $sketchbook/hardware/arduino-git/mbed
./mbed-os-to-arduino -a -g PORTENTA_H7_M7:PORTENTA_H7_M7

In this case -a applies all the patches from patches folder into a mainline mbed-os tree, and -g restores the debug info.

Selecting a different optimization profile

cd $sketchbook/hardware/arduino-git/mbed
PROFILE=release ./mbed-os-to-arduino -a NANO_RP2040_CONNECT:NANO_RP2040_CONNECT

The PROFILE environment variable tunes the compilation profiles (defaults to DEVELOP). Other available profiles are DEBUG and RELEASE.

Selecting a different mbed-os tree

cd $sketchbook/hardware/arduino-git/mbed
./mbed-os-to-arduino -r /path/to/my/mbed-os-fork NICLA_VISION:NICLA_VISION

-r flag allows using a custom mbed-os fork in place of the mainline one; useful during new target development.

Adding a new target (variant)

Adding a target is a mostly automatic procedure.

For boards already supported by mbed-os , the bare minimum is

cd $sketchbook/hardware/arduino-git/mbed
mkdir -p variants/$ALREADY_SUPPORTED_BOARD_NAME/{libs,conf}
./mbed-os-to-arduino $ALREADY_SUPPORTED_BOARD_NAME:$ALREADY_SUPPORTED_BOARD_NAME
# for example, to create a core for LPC546XX
# mkdir -p variants/LPC546XX/{libs,conf}
# ./mbed-os-to-arduino LPC546XX:LPC546XX

This will produce almost all the files needed. To complete the port, add the board specifications to boards.txt (giving it an unique name) and provide pins_arduino.h and variants.cpp in variants/$ALREADY_SUPPORTED_BOARD_NAME folder. Feel free to take inspirations from the existing variants :)

For boards not supported by mainline mbed-os, the same applies but you should provide the path of your mbed-os fork

cd $sketchbook/hardware/arduino-git/mbed
mkdir -p variants/$BRAND_NEW_BOARD_NAME/{libs,conf}
./mbed-os-to-arduino -r /path/to/mbed-os/fork/that/supports/new/board $BRAND_NEW_BOARD_NAME:$BRAND_NEW_BOARD_NAME

You can use this core as a standard mbed library; all APIs are under arduino namespace (so they must be called like arduino::digitalWrite() )

The opposite is working as well; from any sketch you can call mbed APIs by prepending mbed:: namespace.