arduino-mk-vars.md

Documentation of variables

The following are the different variables that can be overwritten in the user makefiles.

• Global variables
• Installation/Directory variables
• Arduino IDE variables
• Sketch related variables
• ISP programming variables
• Compiler/Executable variables
• Avrdude setting variables
• Bootloader variables
• ChipKIT variables

Global variables

ARDUINO_QUIET

Description:

Suppress printing of Arduino-Makefile configuration.

Defaults to 0 (unset/disabled).

Example:

ARDUINO_QUIET = 1

Requirement: Optional

---

Installation/Directory variables

ARDMK_DIR

Description:

Directory where the *.mk files are stored.

Usually can be auto-detected as parent of Arduino.mk.

Example:

ARDMK_DIR = /usr/share/arduino

Requirement: Optional

---

AVR_TOOLS_DIR

Description:

Directory where tools such as avrdude, avr-g++, avr-gcc, etc. are stored in the bin/ subdirectory.

Usually can be auto-detected from $PATH as SYSTEMPATH_AVR_TOOLS_DIR or as BUNDLED_AVR_TOOLS_DIR within the Arduino distribution.

Example:

AVR_TOOLS_DIR = /usr
# or
AVR_TOOLS_DIR = /usr/share/arduino/hardware/tools/avr

Requirement: Optional

---

RESET_CMD

Description:

Command to reset the MCU.

Defaults to ard-reset-arduino with the extra --caterina flag for atmega32u4 boards.

Example:

RESET_CMD = ~/gertduino/reset

Requirement: Optional

---

Arduino IDE variables

ARDUINO_DIR

Description:

Directory where the Arduino IDE and/or core files are stored. Usually can be auto-detected as AUTO_ARDUINO_DIR.

Example:

# Linux
ARDUINO_DIR = /usr/share/arduino
# Mac OS X
ARDUINO_DIR = /Applications/Arduino.app/Contents/Resources/Java
# Mac OSX with IDE 1.5+
ARDUINO_DIR = /Applications/Arduino.app/Contents/Java

Requirement: Optional

---

ARDUINO_PLATFORM_LIB_PATH

Description:

Directory where the Arduino platform dependent libraries are stored. (Used only for Arduino 1.5+)

Example:

ARDUINO_PLATFORM_LIB_PATH = /usr/share/arduino/hardware/arduino/avr/libraries

Requirement: Optional

---

ARDUINO_VERSION

Description:

Version string for Arduino IDE and/or core.

Usually can be auto-detected as AUTO_ARDUINO_VERSION from /usr/share/arduino/lib/version.txt

Example:

ARDUINO_VERSION = 105

Requirement: Optional

---

ARCHITECTURE

Description:

Architecture for Arduino 1.5+

Defaults to unset for 1.0 or avr for 1.5+

Example:

ARCHITECTURE = sam

Requirement: Optional

---

ARDMK_VENDOR

Description:

Board vendor/maintainer.

Defaults to arduino

Example:

ARDMK_VENDOR = sparkfun

Requirement: Optional

---

ARDUINO_SKETCHBOOK

Description:

Path to sketchbook directory.

Usually can be auto-detected from the Arduino preferences.txt file or the default ~/sketchbook

Example:

ARDUINO_SKETCHBOOK = ~/sketches

Requirement: Optional

---

ARDUINO_PREFERENCES_PATH

Description:

Path to Arduino preferences.txt file.

Usually can be auto-detected as AUTO_ARDUINO_PREFERENCES from the defaults:

• on Linux (1.0): ~/.arduino/preferences.txt
• on Linux (1.5+): ~/.arduino15/preferences.txt
• on Mac OS X (1.0): ~/Library/Arduino/preferences.txt
• on Mac OS X (1.5+): ~/Library/Arduino15/preferences.txt

Example:

ARDUINO_PREFERENCES_PATH = ~/sketches/preferences.txt

Requirement: Optional

---

ARDUINO_CORE_PATH

Description:

Path to standard Arduino core files.

Example:

ARDUINO_CORE_PATH = /usr/share/arduino/hardware/arduino/cores/arduino

Requirement: Optional

---

Sketch related variables

ARDUINO_LIBS

Description:

Any libraries you intend to include.

Usually can be auto-detected from the sketch. Separated by spaces. If the library has a /utility folder (like SD or Wire library), then the utility folder should also be specified.

Example:

ARDUINO_LIBS = SD SD/utility Wire Wire/utility

Requirement: Optional

---

BOARD_TAG

Description:

Device type as listed in boards.txt or make show_boards.

Example:

BOARD_TAG = uno or mega2560

Requirement: Mandatory

---

BOARD_SUB

Description:

1.5+ submenu as listed in boards.txt

Example:

# diecimila.name=Arduino Duemilanove or Diecimila
BOARD_TAG=diecimila

# diecimila.menu.cpu.atmega168=ATmega168
BOARD_SUB=atmega168

Requirement: Mandatory for 1.5+ if using a submenu CPU

---

MONITOR_PORT

Description:

Path to serial (USB) device used for uploading/serial comms.

Example:

# Linux
MONITOR_PORT = /dev/ttyUSB0
# or
MONITOR_PORT = /dev/ttyACM0
# Mac OS X
MONITOR_PORT = /dev/cu.usb*
# Windows
MONITOR_PORT = com3

Requirement: Mandatory

---

FORCE_MONITOR_PORT

Description:

Skip the MONITOR_PORT existance check.

Example:

# Enable
FORCE_MONITOR_PORT = true
# Disable (default)
undefine FORCE_MONITOR_PORT

Requirement: Optional

---

USER_LIB_PATH

Description:

Directory where additional libraries are stored.

Defaults to libraries directory within user's sketchbook.

Example:

# Linux
USER_LIB_PATH = ~/sketchbook/libraries
# For a random project on *nix
USER_LIB_PATH = /path/to/my/project

Requirement: Optional

---

OBJDIR

Description:

Directory where binaries and compiled files are put.

Defaults to build-$(BOARD_TAG) in your Makefile directory.

Example:

OBJDIR = /path/to/my/project-directory/bin

Requirement: Optional

---

TARGET

Description:

What name you would like for generated target files.

Defaults to the name of your current working directory, but with underscores (_) instead of spaces.

Example:

TARGET = my-project

Will generate targets like my-project.hex and my-project.elf.

Requirement: Optional

---

ALTERNATE_CORE

Description:

Non-standard core for Arduino-unsupported chips like the ATtiny.

Example:

# HLT core
ALTERNATE_CORE = attiny-master
# tiny core
ALTERNATE_CORE = arduino-tiny
# tiny core 2
ALTERNATE_CORE = tiny2

Requirement: Optional

---

ARDUINO_VAR_PATH

Description:

Path to non-standard core's variant files.

Example:

ARDUINO_VAR_PATH = ~/sketchbook/hardware/arduino-tiny/cores/tiny

Requirement: Optional

---

CORE

Description:

Name of the core inside the ALTERNATE_CORE or the standard core.

Usually can be auto-detected as build.core from boards.txt.

Example:

# standard Arduino core (undefine ALTERNATE_CORE)
CORE = arduino
# or
CORE = robot
# tiny core (ALTERNATE_CORE = arduino-tiny)
CORE = tiny

Requirement: Optional

---

VARIANT

Description:

Variant of a standard board design.

Usually can be auto-detected as build.variant from boards.txt.

Example:

VARIANT = leonardo

Requirement: Optional

---

USB_TYPE

Description:

Define Teensy 3.1 usb device type. Default is USB_SERIAL

Example:

USB_TYPE = USB_SERIAL
# or
USB_TYPE = USB_HID
# or
USB_TYPE = USB_SERIAL_HID
# or
USB_TYPE = USB_MIDI
# or
USB_TYPE = USB_RAWHID
# or
USB_TYPE = USB_FLIGHTSIM

Requirement: Optional

---

USB_VID

Description:

Override USB VID for atmega32u4 boards.

Usually can be auto-detected as build.vid from boards.txt

Example:

USB_VID = 0x2341

Requirement: Optional

---

USB_PID

Description:

Override USB PID for atmega32u4 boards.

Usually can be auto-detected as build.pid from boards.txt

Example:

USB_PID = 0x8039

Requirement: Optional

---

F_CPU

Description:

CPU speed in Hz

Usually can be auto-detected as build.f_cpu from boards.txt, except in some 1.5+ cores like attiny where there is a clock submenu.

Example:

F_CPU = 8000000L

Requirement: Optional

---

HEX_MAXIMUM_SIZE

Description:

Maximum hex file size

Usually can be auto-detected as upload.maximum_size from boards.txt

Example:

HEX_MAXIMUM_SIZE = 14336

Requirement: Optional

---

MCU

Description:

Microcontroller model.

Usually can be auto-detected as build.mcu from boards.txt

Example:

MCU = atmega32u4

Requirement: Optional

---

MCU_FLAG_NAME

Description:

Override default MCU flags.

Defaults to mmcu

Example:

MCU_FLAG_NAME = mprocessor

Requirement: Optional

---

MONITOR_BAUDRATE

Description:

Baudrate of the serial monitor.

Defaults to 9600 if it can't find it in the sketch Serial.begin()

Example:

MONITOR_BAUDRATE = 57600

Requirement: Optional

---

ISP programming variables

ISP_PROG

Description:

Type of ISP. Either a USB device or ArduinoISP protocol.

Example:

ISP_PROG = usbasp
# or
ISP_PROG = usbtiny
# or
ISP_PROG = stk500v2
# or
ISP_PROG = stk500v1

Requirement: Optional

---

ISP_PORT

Description:

Device path to ArduinoISP. Not needed for hardware ISP's.

Example:

# Linux
ISP_PORT = /dev/ttyACM0

Requirement: Optional

---

ISP_LOCK_FUSE_PRE

Description:

Bootloader unlock bits.

Usually can be auto-detected from boards.txt

Example:

ISP_LOCK_FUSE_PRE = 0x3f

Requirement: Optional

---

ISP_LOCK_FUSE_POST

Description:

Bootloader lock bits.

Usually can be auto-detected from boards.txt

Example:

ISP_LOCK_FUSE_POST = 0xcf

Requirement: Optional

---

ISP_HIGH_FUSE

Description:

ISP_LOW_FUSE/ISP_EXT_FUSE - high/low/extended fuse bits.

Usually can be auto-detected from boards.txt

Example:

ISP_HIGH_FUSE = 0xdf # or 0xff or 0x01

Requirement: Optional

---

ISP_EEPROM

Description:

Whether to upload the EEPROM file or not.

Defaults to 0

Example:

ISP_EEPROM = 1

Requirement: Optional

---

Compiler/Executable variables

CC_NAME

Description:

C compiler.

Defaults to avr-gcc

Example:

CC_NAME = pic32-gcc

Requirement: Optional

---

CXX_NAME

Description:

C++ compiler.

Defaults to avr-g++

Example:

CXX_NAME = pic32-g++

Requirement: Optional

---

OBJCOPY_NAME

Description:

Objcopy utility.

Defaults to avr-objcopy

Example:

OBJCOPY_NAME = pic32-objcopy

Requirement: Optional

---

OBJDUMP_NAME

Description:

Objdump utility.

Defaults to avr-objdump

Example:

OBJDUMP_NAME = pic32-objdump

Requirement: Optional

---

AR_NAME

Description:

Archive utility.

Defaults to avr-ar

Example:

AR_NAME = pic32-ar

Requirement: Optional

---

SIZE_NAME

Description:

Size utility.

Defaults to avr-size

Example:

SIZE_NAME = pic32-size

Requirement: Optional

---

NM_NAME

Description:

Nm utility.

Defaults to avr-nm

Example:

NM_NAME = pic32-nm

Requirement: Optional

---

OPTIMIZATION_LEVEL

Description:

Linker's -O flag

Defaults to s, which shouldn't really be changed as it breaks SoftwareSerial and usually results in bigger hex files.

Example:

OPTIMIZATION_LEVEL = 3

Requirement: Optional

---

CFLAGS_STD

Description:

Controls, exclusively, which C standard is to be used for compilation.

Defaults to undefined

Possible values:

• With avr-gcc 4.3, shipped with the Arduino IDE:
  • undefined
  • -std=c99
  • -std=gnu89 - This is the default for C code
  • -std=gnu99
• With avr-gcc 4.7, 4.8 or 4.9, installed by you
  • undefined
  • -std=c99
  • -std=c11
  • -std=gnu89 - This is the default for C code
  • -std=gnu99
  • -std=gnu11

For more information, please refer to the Options Controlling C Dialect

Example:

CFLAGS_STD = = -std=gnu89

Requirement: Optional

---

CXXFLAGS_STD

Description:

Controls, exclusively, which C++ standard is to be used for compilation.

Defaults to undefined

Possible values:

• With avr-gcc 4.3, shipped with the Arduino IDE:
  • undefined
  • -std=c++98
  • -std=c++0x
  • -std=gnu++98 - This is the default for C code
  • -std=gnu++0x
• With avr-gcc 4.7, 4.8 or 4.9, installed by you
  • undefined
  • -std=c++98
  • -std=c++11
  • -std=c++1y
  • -std=c++14
  • -std=gnu++98 - This is the default for C++ code
  • -std=gnu++11
  • -std=gnu++1y
  • -std=gnu++14

For more information, please refer to the Options Controlling C Dialect

Example:

CXXFLAGS_STD = = -std=gnu++98

Requirement: Optional

---

CFLAGS

Description:

Flags passed to compiler for files compiled as C. Add more flags to this variable using +=.

Defaults to all flags required for a typical build.

Example:

CFLAGS += -my-c-only-flag

Requirement: Optional

---

CXXFLAGS

Description:

Flags passed to the compiler for files compiled as C++. Add more flags to this variable using +=.

Defaults to all flags required for a typical build.

Example:

CXXFLAGS += -my-c++-onlyflag

Requirement: Optional

---

ASFLAGS

Description:

Flags passed to compiler for files compiled as assembly (e.g. .S files). Add more flags to this variable using +=.

Defaults to all flags required for a typical build.

Example:

ASFLAGS += -my-as-only-flag

Requirement: Optional

---

CPPFLAGS

Description:

Flags passed to the C pre-processor (for C, C++ and assembly source flies). Add more flags to this variable using +=.

Defaults to all flags required for a typical build.

Example:

CPPFLAGS += -DMY_DEFINE_FOR_ALL_SOURCE_TYPES

Requirement: Optional

---

OVERRIDE_EXECUTABLES

Description:

Override the default build tools.

If set to 1, each tool (CC, CXX, AS, OBJCOPY, OBJDUMP, AR, SIZE, NM) must have its path explicitly defined. See chipKIT.mk.

Example:

OVERRIDE_EXECUTABLES = 1

Requirement: Optional

---

MONITOR_CMD

Description:

Command to run the serial monitor.

Defaults to screen

Example:

MONITOR_CMD = minicom

Requirement: Optional

---

PRE_BUILD_HOOK

Description:

Path to shell script to be executed before build. Could be used to automatically bump revision number for example.

Defaults to pre-build-hook.sh

Example:

PRE_BUILD_HOOK = ~/bin/bump-revision.sh

Requirement: Optional

---

Avrdude setting variables

AVRDUDE

Description:

Path to avrdude utility

Usually can be auto-detected within the parent of AVR_TOOLS_DIR or in the $PATH

Example:

AVRDUDE = /usr/bin/avrdude

Requirement: Optional

---

AVRDUDE_CONF

Description:

Path to avrdude.conf file

Usually can be auto-detected within the parent of AVR_TOOLS_DIR

Example:

AVRDUDE_CONF = /etc/avrdude.conf
# or
AVRDUDE_CONF = /usr/share/arduino/hardware/tools/avrdude.conf

Requirement: Optional

---

AVR_TOOLS_PATH

Description:

Directory where tools such as avrdude, avr-g++, avr-gcc etc. are stored.

Usually can be auto-detected from AVR_TOOLS_DIR/bin

Example:

AVR_TOOLS_PATH = /usr/bin
# or
AVR_TOOLS_PATH = /usr/share/arduino/hardware/tools/avr/bin

Requirement: Optional

---

ARDUINO_LIB_PATH

Description:

Directory where the standard Arduino libraries are stored.

Defaults to ARDUINO_DIR/libraries

Example:

# Linux
ARDUINO_LIB_PATH = /usr/share/arduino/libraries

Requirement: Optional

---

ARDUINO_CORE_PATH

Description:

Directory where the standard Arduino cores are stored.

Defaults to ARDUINO_DIR/hardware/arduino/cores/arduino

Example:

ARDUINO_CORE_PATH = /usr/share/arduino/hardware/arduino/cores/robot

Requirement: Optional

---

ALTERNATE_CORE_PATH

Description:

Path to non-standard cores.

Defaults to ARDUINO_SKETCHBOOK/hardware/ALTERNATE_CORE

Example:

ALTERNATE_CORE_PATH = ~/sketchbook/hardware/arduino-tiny/cores/tiny

Requirement: Optional

---

BOARDS_TXT

Description:

Path to boards.txt

Defaults to ARDUINO_DIR/hardware/arduino/boards.txt

Example:

BOARD_TXT = ~/sketchbook/hardware/boards.txt
# or
BOARD_TXT = /usr/share/arduino/hardware/arduino/boards.txt

Requirement: Optional

---

AVRDUDE_ARD_BAUDRATE

Description:

Upload speed

Usually can be auto-detected as upload.speed from boards.txt

Example:

AVRDUDE_ARD_BAUDRATE = 19200

Requirement: Optional

---

AVRDUDE_ARD_PROGRAMMER

Description:

Upload protocol

Usually can be auto-detected as upload.protocol from boards.txt

Example:

AVRDUDE_ARD_PROGRAMMER = stk500v1

Requirement: Optional

---

AVRDUDE_ISP_BAUDRATE

Description:

ISP speed if different to upload.speed

Defaults to same as AVRDUDE_ARD_BAUDRATE or 19200

Example:

AVRDUDE_ISP_BAUDRATE = 19200

Requirement: Optional

---

AVRDUDE_OPTS

Description:

Options to pass to avrdude.

Defaults to -q -V (quiet, don't verify). User values are not ANDed to the defaults, you have to set each option you require.

Example:

AVRDUDE_OPTS = -v

Requirement: Optional

---

Bootloader variables

BOOTLOADER_FILE

Description:

File for bootloader.

Usually can be auto-detected as bootloader.file from boards.txt

Example:

BOOTLOADER_FILE = optiboot_atmega328.hex

Requirement: Optional

---

BOOTLOADER_PATH

Description:

Relative path to bootloader directory.

Usually can be auto-detected as a relative bootloader.path from boards.txt

Deprecated in 1.5, now part of bootloader.file

Example:

BOOTLOADER_PATH = optiboot
# or
BOOTLOADER_PATH = arduino:atmega

Requirement: Optional

---

BOOTLOADER_PARENT

Description:

Absolute path to bootloader file's parent directory.

Defaults to /usr/share/arduino/hardware/arduino/bootloaders (Linux)

Example:

BOOTLOADER_PARENT = ~/sketchbook/hardware/promicro/bootloaders
BOOTLOADER_PATH  = caterina
BOOTLOADER_FILE  = Caterina-promicro16.hex

Would result in an absolute path to the bootloader hex file of ~/sketchbook/hardware/promicro/bootloaders/caterina/Caterina-promicro16.hex

Requirement: Optional, unless BOOTLOADER_FILE and/or BOOTLOADER_PATH are user-defined

---

ChipKIT variables

MPIDE_DIR

Description:

Path to chipKIT MP IDE

Usually can be auto-detected as AUTO_MPIDE_DIR from the defaults /usr/share/mpide (Linux) or /Applications/Mpide.app/Contents/Resources/Java (OSX)

Example:

MPIDE_DIR = ~/mpide

Requirement: Optional

---

MPIDE_PREFERENCES_PATH

Description:

Path to chipKIT preferences.txt file.

Usually can be auto-detected as AUTO_MPIDE_PREFERENCES_PATH from the defaults ~/.mpide/preferences.txt (Linux) or ~/Library/Mpide/preferences.txt (OSX)

Example:

MPIDE_PREFERENCES_PATH = ~/chipkit/preferences.txt

Requirement: Optional