Reference   Language (extended) | Libraries | Comparison

Libraries

To use an existing library in a sketch, go to the Sketch menu, choose "Import Library", and pick from the libraries available. This will insert one or more #include statements at the top of the sketch and allow it to use the library.

Because libraries are uploaded to the board with your sketch, they increase the amount of space it takes up. If a sketch no longer needs a library, simply delete its #include statements from the top of your code.

Official Libraries

These are the "official" libraries that are included in the Arduino distribution.

  • SoftwareSerial - for serial communication on any digital pins
  • Stepper - for controlling stepper motors
  • EEPROM - reading and writing to "permanent" storage

These libraries are compatible Wiring versions, and the links below point to the (excellent) Wiring documentation.

  • Matrix - Basic LED Matrix display manipulation library
  • Sprite - Basic image sprite manipulation library for use in animations with an LED matrix
  • Wire - Two Wire Interface (TWI/I2C) for sending and receiving data over a net of devices or sensors. On the Arduino, SDA is on analog input pin 4, and SCL on analog input pin 5.

Unofficial Libraries

These are not (yet) included with the Arduino distribution and may change.

  • Simple Message System - send messages between Arduino and the computer
  • OneWire - control devices (from Dallas Semiconductor) that use the One Wire protocol.
  • LCD - control LCDs (using 8 data lines)
  • LCD 4 Bit - control LCDs (using 4 data lines)
  • LedControl - for controlling LED matrices or seven-segment displays with a MAX7221 or MAX7219.
  • TextString - handle strings
  • Metro - help you time actions at regular intervals
  • Servo - provides software support for Servo motors on any pins.
  • Servotimer1 - provides hardware support for Servo motors on pins 9 and 10
  • X10 - Sending X10 signals over AC power lines
  • LedControl - an alternative to the Matrix library for driving multiple LEDs with Maxim chips.

To install, unzip the library to a sub-directory of the hardware/libraries sub-directory of the Arduino application directory. Then launch the Arduino environment; you should see the library in the Import Library menu.

For a guide to writing your own libraries, see this tutorial.

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Corrections, suggestions, and new documentation should be posted to the Forum.

The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.