This target supports building Pigweed on a few Arduino cores.

See also

There are a few caveats when running Pigweed on top of the Arduino API. See pw_arduino_build for details.

Supported Boards#

Currently only Teensy 4.x and 3.x boards are supported.


You must first install an Arduino core or let Pigweed know where you have cores installed using the pw_arduino_build_CORE_PATH build arg.

Installing Arduino Cores#

The arduino_builder utility can install Arduino cores automatically. It’s recommended to install them to into third_party/arduino/cores/.

# Setup pigweed environment.
. ./
# Install an arduino core, only teensy is supported
pw package install teensy


To build for this Pigweed target, simply build the top-level “arduino” Ninja target. You can set Arduino build options using gn args out or by running:

gn gen out --args='
  pw_arduino_build_CORE_PATH = "//environment/packages"
  pw_arduino_build_CORE_NAME = "teensy"
  pw_arduino_build_PACKAGE_NAME = "avr/1.58.1"
  pw_arduino_build_BOARD = "teensy40"
  pw_arduino_build_MENU_OPTIONS=["menu.usb.serial", "menu.keys.en-us"]'

On a Windows machine it’s easier to run:

gn args out

That will open a text file where you can paste the args in:

pw_arduino_build_CORE_PATH = "//environment/packages"
pw_arduino_build_CORE_NAME = "teensy"
pw_arduino_build_PACKAGE_NAME = "avr/1.58.1"
pw_arduino_build_BOARD = "teensy40"
pw_arduino_build_MENU_OPTIONS = ["menu.usb.serial", "menu.keys.en-us"]

Save the file and close the text editor.

Then build with:

ninja -C out arduino

To see supported boards and Arduino menu options for a given core:

arduino_builder --arduino-package-path ./environment/packages/teensy \
                --arduino-package-name avr/1.58.1 \
Board Name  Description
teensy41    Teensy 4.1
teensy40    Teensy 4.0
teensy36    Teensy 3.6
teensy35    Teensy 3.5
teensy31    Teensy 3.2 / 3.1

You may wish to set different arduino build options in pw_arduino_build_MENU_OPTIONS. Run this to see what’s available for your core:

arduino_builder --arduino-package-path ./environment/packages/teensy \
                --arduino-package-name avr/1.58.1 \
                list-menu-options \
                --board teensy40

That will show all menu options that can be added to gn args out.

All Options
menu.usb.serial             Serial
menu.usb.serial2            Dual Serial
menu.usb.serial3            Triple Serial
menu.usb.keyboard           Keyboard
menu.usb.touch              Keyboard + Touch Screen
menu.usb.hidtouch           Keyboard + Mouse + Touch Screen
menu.usb.hid                Keyboard + Mouse + Joystick
menu.usb.serialhid          Serial + Keyboard + Mouse + Joystick
menu.usb.midi               MIDI

Default Options
menu.usb.serial             Serial
menu.speed.600              600 MHz
menu.opt.o2std              Faster
menu.keys.en-us             US English


When working in upstream Pigweed, building this target will build all Pigweed modules’ unit tests. These tests can be run on-device in a few different ways.

Run a unit test#

If using out as a build directory, tests will be located in out/arduino_debug/obj/[module name]/[test_name].elf.

Tests can be flashed and run using the arduino_unit_test_runner tool. Here is a sample bash script to run all tests on a Linux machine.

gn gen out --export-compile-commands \
            pw_arduino_build_MENU_OPTIONS=["menu.usb.serial", "menu.keys.en-us"]' && \
  ninja -C out arduino

for f in $(find out/arduino_debug/obj/ -iname "*.elf"); do
    arduino_unit_test_runner --verbose \
        --config-file ./out/arduino_debug/gen/arduino_builder_config.json \
        --upload-tool teensyloader \

Using the test server#

Tests may also be run using the pw_arduino_use_test_server = true GN arg. The server must be run with an arduino_builder config file so it can locate the correct Arduino core, compiler path, and Arduino board used.

arduino_test_server --verbose \
    --config-file ./out/arduino_debug/gen/arduino_builder_config.json

Flashing Known Issues#

Teensy Boards#

By default Teensyduino uses the Teensy Loader Application which has a couple limitations:

  • Requires a GUI (or X11 on Linux).

  • Can only flash one board at a time.

GN Target Example#

Here is an example pw_executable gn rule that includes some Teensyduino libraries.


_library_args = [
  rebase_path(arduino_core_library_path, root_build_dir),

pw_executable("my_app") {
  # All Library Sources
  _library_c_files = exec_script(
          arduino_show_command_args + _library_args + [
          "list lines")
  _library_cpp_files = exec_script(
          arduino_show_command_args + _library_args + [
          "list lines")

  sources = [ "" ] + _library_c_files + _library_cpp_files

  deps = [

  include_dirs = exec_script(arduino_builder_script,
                             arduino_show_command_args + _library_args +
                                 [ "--library-include-dirs" ],
                             "list lines")

  # Required for using Arduino.h and any Arduino API functions
  remove_configs = [ "$dir_pw_build:strict_warnings" ]
  deps += [ "$dir_pw_third_party/arduino:arduino_core_sources" ]