Overview

To run Lingua Franca on an Arduino-compatible microcontroller, you can use the C target with the platform target property set to arduino. The Lingua Franca compiler will then not output ordinary C code in a CMake project, but generate a .ino sketch that can be compiled and deployed using arduino-cli. To flash the compiled sketch onto a board, you need specify a Fully Qualified Board Name (FQBN) as well as the port to which your board is connected. On this page, we explain exactly how to do this.

Prerequisites

• You need a development system that runs on macOS or Linux (there is currently no Windows support).
• Arduino CLI must be installed on your development system. Confirm that your installation works by running:

arduino-cli version

Writing a simple Arduino Program

The most basic Arduino program (Blink) can be defined in LF like so:

target C { platform: "Arduino" } main reactor Blink { timer t1(0, 1 sec) timer t2(500 msec, 1 sec) reaction(startup) {= pinMode(LED_BUILTIN, OUTPUT); =} reaction (t1) {= digitalWrite(LED_BUILTIN, HIGH); =} reaction (t2) {= digitalWrite(LED_BUILTIN, LOW); =} }

The key difference between writing ordinary Arduino code and writing LF code is that there is no setup() and loop() function. In LF, execution is event-driven, with reactive code being triggered by events, such as the expiration of a timer. Those pieces of reactive code, specified as reactions, can invoke Arduino library functions, just like one would do in the definition of an Arduino loop(). For any setup that might be needed at the beginning of execution, a reaction triggered by the built-in startup trigger can be used.

Platform Options

The platform property can also be used so specify more details. Along with name: "arduino", you can specify which board, port, and baud-rate you are using. If you want the program to be flashed onto the board automatically after compilation, specify flash: true. Here a target declaration that specifies all of these options:

target C { platform: { name: "arduino", board: "arduino:avr:uno", port: "/dev/ttyd2", baud-rate: 115200, flash: true } }

The board is necessary for building and the port is necessary for flashing.

Baud rate of the serial port

All Arduino boards have at least one serial port (also known as a UART or USART), and some have several. By default, Lingua Franca will assume a default baud rate of 9600. This parameter is tunable by adjusting the baud-rate parameter in platform options.

Building

In order to have arduino-cli compile the generated sketch file, a board must be specified. If no board is set, lfc will run in no-compile mode, meaning it will not invoke the target compiler. Whether specified as a target property or given directly to arduino-cli, you need an FQBN. You can find the FQBN of the board that you have plugged in using the following command:

arduino-cli board list

To see the list of all FQBN's installed on your device (all FQBNs supported by the libraries you have installed), run the following command:

arduino-cli board listall

You likely need to install support for your board first, which you can do using the following command:

arduino-cli core install arduino:[BOARD_FAMILY]

The common board families include avr, megaAVR, sam, samd, and mbed.

If you specify your FQBN under board in the platform target property, lfc will automatically invoke arduino-cli on the generated sketch. To invoke arduino-cli manually

• for unthreaded programs (most arduino flavors), run: arduino-cli compile -b [FQBN] --build-property compiler.c.extra_flags="-DLF_SINGLE_THREADED=1 -DPLATFORM_ARDUINO -DINITIAL_EVENT_QUEUE_SIZE=10 -DINITIAL_REACT_QUEUE_SIZE=10" --build-property compiler.cpp.extra_flags="-DLF_SINGLE_THREADED=1 -DPLATFORM_ARDUINO -DINITIAL_EVENT_QUEUE_SIZE=10 -DINITIAL_REACT_QUEUE_SIZE=10"

• for threaded programs (arduino:mbed boards), run: arduino-cli compile -b [FQBN] --build-property compiler.c.extra_flags="-DPLATFORM_ARDUINO -DINITIAL_EVENT_QUEUE_SIZE=10 -DINITIAL_REACT_QUEUE_SIZE=10" --build-property compiler.cpp.extra_flags="-DPLATFORM_ARDUINO -DINITIAL_EVENT_QUEUE_SIZE=10 -DINITIAL_REACT_QUEUE_SIZE=10"

Flashing

Arduino's can be flashed via USB. To find the port oto which your device is connected, run the following command:

arduino-cli board list

You can either use arduino-cli to flash the code onto your device after the sketch file has been built, or you can set flash:true and provide a port in your Lingua Franca file. To flash manually using arduino-cli, enter the subdirectory of src-gen in which the generated sketch file is located and run:

arduino-cli upload -p PORT -b FQBN .