IRremote Arduino Library

Available as Arduino library "IRremote"

Version 2.8.0 - work in progress

License: MIT
Commits since latest
Installation instructions
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This library enables you to send and receive using infra-red signals on an Arduino.

Tutorials and more information will be made available on the official homepage.


Click on the LibraryManager badge above to see the instructions.


  • IR does not work right when I use Neopixels (aka WS2811/WS2812/WS2812B)
    Whether you use the Adafruit Neopixel lib, or FastLED, interrupts get disabled on many lower end CPUs like the basic arduinos for longer than 50 us. In turn, this stops the IR interrupt handler from running when it needs to. There are some solutions to this on some processors, see this page from Marc MERLIN
  • The default IR timer on AVR's is timer 2. Since the Arduino Tone library as well as analogWrite() for pin 3 and pin 11 requires timer 2, this functionality cannot be used simultaneously.
  • You can use multiple IR receiver by just connecting the output pins of several IR receivers together. The IR receivers use an NPN transistor as output device with just a 30k resistor to VCC. This is almost "open collector" and allows connecting of several output pins to one Arduino input pin.

Supported IR Protocols

Aiwa, BoseWave, Denon, Dish, JVC, Lego, LG, MagiQuest, NEC, Panasonic, RC5, RC6, Samsung, Sanyo, Sharp, Sony, Whynter, (Pronto).

Protocols can be switched off and on by changing the lines in IRremote.h:

#define SEND_<PROTOCOL_NAME>    1


This is a quite old but maybe useful wiki for this library.

Compile options / macros for this library

To customize the library to different requirements, there are some compile options / makros available.

Modify it by commenting them out or in, or change the values if applicable. Or define the macro with the -D compiler option for gobal compile (the latter is not possible with the Arduino IDE, so consider to use Sloeber.

Name File Default value Description
DEBUG IRremote.h disabled Enables lots of lovely debug output.
USE_NEC_STANDARD IRremote.h disabled Use LSB first, address/code schema for encoding.
USE_NO_SEND_PWM IRremote.h disabled Use no carrier PWM, just simulate an active low receiver signal.
USE_SOFT_SEND_PWM IRremote.h disabled Use carrier PWM generation in software, instead of hardware PWM.
PULSE_CORRECTION_MICROS IRremote.h 3 If USE_SOFT_SEND_PWM, this amount is subtracted from the on-time of the pulses.
USE_SPIN_WAIT IRremote.h disabled If USE_SOFT_SEND_PWM, use spin wait instead of delayMicros().
RAW_BUFFER_LENGTH IRremoteint.h 101 Buffer size of raw input buffer. Must be odd!
IR_SEND_DUTY_CYCLE IRremoteBoardDefs.h 30 Duty cycle of IR send signal.
MICROS_PER_TICK IRremoteBoardDefs.h 50 Resolution of the raw input buffer data.

Modifying library properties with Arduino IDE

First use Sketch/Show Sketch Folder (Ctrl+K).

If you did not yet stored the example as your own sketch, then you are instantly in the right library folder.

Otherwise you have to navigate to the parallel libraries folder and select the library you want to access.

In both cases the library files itself are located in the src directory.

Modifying library properties with Sloeber IDE

If you are using Sloeber as your IDE, you can easily define global symbols with Properties/Arduino/CompileOptions.

Sloeber settings

Handling unknown Protocols


This library was never designed to handle long codes like the ones used by air conditioners. See Recording long Infrared Remote control signals with Arduino.

The main reason is, that it was designed to fit inside MCUs with relatively low levels of resources and was intended to work as a library together with other applications which also require some resources of the MCU to operate.


If you do not know which protocol your IR transmitter uses, you have several choices.

Other IR libraries

Here you find a short comparison matrix of 4 popular Arduino IR libraries.

Here you find an ESP8266/ESP32 version of IRremote with an impressive list of supported protocols.

Supported Boards

  • Arduino Uno / Mega / Leonardo / Duemilanove / Diecimila / LilyPad / Mini / Fio / Nano etc.
  • Teensy 1.0 / 1.0++ / 2.0 / 2++ / 3.0 / 3.1 / Teensy-LC; Credits: @PaulStoffregen (Teensy Team)
  • Sanguino
  • ATmega8, 48, 88, 168, 328
  • ATmega8535, 16, 32, 164, 324, 644, 1284,
  • ATmega64, 128
  • ATmega4809 (Nano every)
  • ATtiny84, 85
  • SAMD21 (receive only)
  • ESP32
  • ESP8266 is supported in a fork based on an old codebase that isn't as recent, but it works reasonably well given that perfectly timed sub millisecond interrupts are different on that chip. See
  • Sparkfun Pro Micro

We are open to suggestions for adding support to new boards, however we highly recommend you contact your supplier first and ask them to provide support from their side.

Hardware specifications

The timer and the pin usage can be adjusted in IRremoteBoardDefs.h

Board/CPU IR-Send (PWM) Pin Timers
ATtiny84 6 1
ATtiny85 > 1 MHz 1, 4 0, 1
ATmega8 9 1
ATmega48, ATmega88, ATmega168, ATmega328 3, 9 1, 2
ATmega1284 13, 14, 6 1, 2, 3
ATmega164, ATmega324, ATmega644 13, 14 1, 2
ATmega8535 ATmega16, ATmega32 13 1
ATmega64, ATmega128, ATmega1281, ATmega2561 13 1
ATmega8515, ATmega162 13 1
ATmega1280, ATmega2560 5, 6, 9, 11, 46 1, 2, 3, 4, 5
ATmega4809 5, 6, 9, 11, 46 TCB0
Leonardo (Atmega32u4) 5, 9, 13 1, 3, 4_HS
Zero (SAMD) *, 9 TC3
ESP32 4, all pins 1
Sparkfun Pro Micro 5, 9 1, 3
Teensy 1.0 17 1
Teensy 2.0 9, 10, 14 1, 3, 4_HS
Teensy++ 1.0 / 2.0 1, 16, 25 1, 2, 3
Teensy 3.0 / 3.1 5 CMT
Teensy-LC 16 TPM1

Revision History

Please see

API documentation

See API reference in wiki.

To generate the API documentation,
Doxygen, as well as Graphviz should be installed.
(Note that on Windows, it may be necessary to add the Graphviz binary directory
(something like C:\Program Files\Graphviz2.38\bin)
to the PATH variable manually.)
With Doxygen and Graphviz installed, issue the command
doxygen from the command line in the main project directory, which will
generate the API documentation in HTML format.
The just generated api-doc/index.html can now be opened in a browser.


If you want to contribute to this project:

  • Report bugs and errors
  • Ask for enhancements
  • Create issues and pull requests
  • Tell other people about this library
  • Contribute new protocols

Check here for some guidelines.


Please only email me if it is more appropriate than creating an Issue / PR. I will not respond to requests for adding support for particular boards, unless of course you are the creator of the board and would like to cooperate on the project. I will also ignore any emails asking me to tell you how to implement your ideas. However, if you have a private inquiry that you would only apply to you and you would prefer it to be via email, by all means.


Check here


Up to the version 2.7.0 the License is GPLv2.
From the version 2.8.0 the license is the MIT license.


Initially coded 2009 Ken Shirriff
Copyright (c) 2016 Rafi Khan