IRremote Arduino Library

Available as Arduino library "IRremote"

Version 3.0.2 - work in progress

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.

Installation

Click on the LibraryManager badge above to see the instructions.

Supported IR Protocols

Denon, JVC, LG, NEC / Apple, Panasonic / Kaseikyo, RC5, RC6, Samsung, Sharp, Sony, (Pronto), BoseWave, Lego, Whynter, MagiQuest.
Protocols can be switched off and on by changing the lines in IRremote.h:

#define DECODE_<PROTOCOL_NAME>  1
#define SEND_<PROTOCOL_NAME>    1

Wiki

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

Converting your 2.x program to the 3.x version

• Now there is an IRreceiver and IRsender object like the well known Arduino Serial object.
• Just remove the line IRrecv IrReceiver(IR_RECEIVE_PIN); and/or IRsend IrSender; in your program, and replace all occurrences of IRrecv. or irrecv. with IrReceiver.
• Since the decoded values are now in IrReceiver.decodedIRData and not in results any more, remove the line decode_results results or similar.
• Like for the Serial object, call IrReceiver.begin(IR_RECEIVE_PIN, ENABLE_LED_FEEDBACK); or IrReceiver.begin(IR_RECEIVE_PIN, DISABLE_LED_FEEDBACK); instead of the IrReceiver.enableIRIn(); or irrecv.enableIRIn(); in setup().
• Old decode(decode_results *aResults) function is replaced by simple decode(). So if you have a statement if(irrecv.decode(&results)) replace it with if (IrReceiver.decode()).
• The decoded result is now in in IrReceiver.decodedIRData and not in results any more, therefore replace any occurrences of results.value and / or results.decode_type (and similar) to IrReceiver.decodedIRData.decodedRawData and / or IrReceiver.decodedIRData.decodedRawData.
• Overflow, Repeat and other flags are now in IrReceiver.receivedIRData.flags.
• Seldom used: results.rawbuf and results.rawlen must be replaced by IrReceiver.decodedIRData.rawDataPtr->rawbuf and IrReceiver.decodedIRData.rawDataPtr->rawlen.
• The old functions sendNEC() and sendJVC() are deprecated and renamed to sendNECMSB() and sendJVCMSB() to make it clearer that they send data with MSB first, which is not the standard for NEC and JVC. Use them to send your old 32 bit IR data codes. In the new version you will send NEC commands not by 32 bit codes but by a (constant) 8 bit address and an 8 bit command.

FAQ

• 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 <20>s. 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 tone() but after the tone has stopped, you must call IrReceiver.enableIRIn() to restore the timer settings for receive.
  If you can live with the NEC protocol, you can try the MinimalReceiver example, it requires no timer.
• 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.

Minimal version

For applications only requiring NEC protocol, there is a receiver which has very small codesize of 500 bytes and does NOT require any timer. See the MinimalReceiver and IRDispatcherDemo example how to use it.

Handling unknown Protocols

Disclaimer

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.

Hints

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

• Use the IRreceiveDump example to dump out the IR timing. You can then reproduce/send this timing with the IRsendRawDemo example. For long codes with more than 48 bits like from air conditioners, you can change the length of the input buffer in IRremote.h.
• The IRMP AllProtocol example prints the protocol and data for one of the 40 supported protocols. The same library can be used to send this codes.
• If you have a bigger Arduino board at hand (> 100 kByte program space) you can try the IRremoteDecode example of the Arduino library DecodeIR.
• Use IrScrutinizer. It can automatically generate a send sketch for your protocol by exporting as "Arduino Raw". It supports IRremote, the old IRLib and Infrared4Arduino.
• To increase strength of sent output signal you can increase the current through the send diode, or use 2 diodes in series, since one IR diode requires only 1.5 volt. Changing IR_SEND_DUTY_CYCLE to 50 increases the signal current by 40%.

Compile options / macros for this library

To customize the library to different requirements, there are some compile options / macros 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 global compile (the latter is not possible with the Arduino IDE, so consider using Sloeber.

Name	File	Default value	Description
USE_OLD_DECODE	IRremoteInt.h	disabled	Enables the old decoder in order to be version 2.x compatible, where all protocols were MSB first.
EXCLUDE_EXOTIC_PROTOCOLS	Before #include <IRremote.h>	disabled	If activated, BOSEWAVE, MAGIQUEST,WHYNTER and LEGO_PF are excluded in decode() and in sending with IrSender.write(). Saves up to 900 bytes program space.
MARK_EXCESS_MICROS	Before #include <IRremote.h>	20	MARK_EXCESS_MICROS is subtracted from all marks and added to all spaces before decoding, to compensate for the signal forming of different IR receiver modules.
IR_INPUT_IS_ACTIVE_HIGH	IRremoteInt.h	disabled	Enable it if you use a RF receiver, which has an active HIGH output signal.
DEBUG	IRremoteInt.h	disabled	Enables lots of lovely debug output.
USE_NO_SEND_PWM	IRremoteInt.h	disabled	Use no carrier PWM, just simulate an active low receiver signal.
USE_SOFT_SEND_PWM	IRremoteInt.h	disabled	Use carrier PWM generation in software, instead of hardware PWM.
PULSE_CORRECTION_MICROS	IRremoteInt.h	3	If USE_SOFT_SEND_PWM, this amount is subtracted from the on-time of the pulses.
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.
USE_CUSTOM_DELAY	irSend.cpp	disabled	Use old custom_delay_usec() function for mark and space delays.
-	-	-	-
IR_INPUT_PIN	TinyIRReceiver.h	2	The pin number for TinyIRReceiver IR input, which gets compiled in.
IR_FEEDBACK_LED_PIN	TinyIRReceiver.h	LED_BUILTIN	The pin number for TinyIRReceiver feedback LED, which gets compiled in.
DO_NOT_USE_FEEDBACK_LED	TinyIRReceiver.h	disabled	Enable it to disable the feedback LED function.

Modifying compile options 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 compile options with Sloeber IDE

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

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. It works well given that perfectly timed sub millisecond interrupts are different on that chip.
• Sparkfun Pro Micro
• Nano Every, Uno WiFi Rev2, nRF5 BBC MicroBit, Nano33_BLE

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 receiver sample interval is generated by a timer. On many boards this must be a hardware timer, on some a software timer is available and used.
The send PWM signal is generated by a hardware timer. The same timer as for the receiver is used. Since each hardware timer has its dedicated output pins, you must change timer to change PWN output.
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

Adding new protocols

To add a new protocol is quite straightforward. Best is too look at the existing protocols to find a similar one and modify it.
As a rule of thumb, it is easier to work with a description of the protocol rather than trying to entirely reverse-engineer the protocol. Please include a link to the description in the header, if you found one.
The durations you receive are likely to be longer for marks and shorter for spaces than the protocol suggests, but this depends on the receiver circuit in use. Most protocols use multiples of one time-unit for marks and spaces like e.g. NEC. It's easy to be off-by-one with the last bit, since the last space is not recorded by IRremote.

Try to make use of the template functions decodePulseDistanceData() and sendPulseDistanceData(). If your protocol supports address and code fields, try to reflect this in your api like it is done in sendNEC(uint16_t aAddress, uint8_t aCommand, uint_fast8_t aNumberOfRepeats, bool aIsRepeat) and decodeNEC().

Integration

To integrate your protocol, you need to extend the two functions decode() and getProtocolString() in IRreceice.cpp, add macros and function declarations for sending and receiving and extend the enum decode_type_t in IRremote.h.
And at least it would be wonderful if you can provide an example how to use the new protocol. A detailed description can be found in the ir_Template.cpp file.

Revision History

Please see changelog.md.

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.

Why do we use 33% duty cycle

We do it according to the statement in the Vishay datasheet:

• Carrier duty cycle 50 %, peak current of emitter IF = 200 mA, the resulting transmission distance is 25 m.
• Carrier duty cycle 10 %, peak current of emitter IF = 800 mA, the resulting transmission distance is 29 m. - Factor 1.16 The reason is, that it is not the pure energy of the fundamental which is responsible for the receiver to detect a signal. Due to automatic gain control and other bias effects high intensity and lower energy (duty cycle) of the 38 kHz pulse counts more than high low intensity and higher energy.

BTW, the best way to increase the IR power is to use 2 or 3 IR diodes in series. One diode requires 1.1 to 1.5 volt so you can supply 3 diodes with a 5 volt output.
To keep the current, you must reduce the resistor by (5 - 1.3) / (5 - 2.6) = 1.5 e.g. from 150 ohm to 100 ohm for 25 mA and 2 diodes with 1.3 volt and a 5 volt supply.
For 3 diodes it requires factor 2.5 e.g. from 150 ohm to 60 ohm.

Quick comparison of 4 Arduino IR receiving libraries

This is a short comparison and may not be complete or correct

I created this comparison matrix for myself in order to choose a small IR lib for my project and to have a quick overview, when to choose which library.
It is dated from 03.02.2021. If you have complains about the data or request for extensions, please send a PM or open a discussion.

Subject	IRMP	IRLremote	IRLib2 mostly unmaintained	IRremote	Minimal NEC
Number of protocols	50	Nec + Panasonic + Hash *	12 + Hash *	17 + Hash *	NEC
3.Party libs needed	%	PinChangeInterrupt if not pin 2 or 3	%	%	%
Timing method receive	Timer2 or interrupt for pin 2 or 3	Interrupt	Timer2 or interrupt for pin 2 or 3	Timer2 or interrupt for NEC	Interrupt
Timing method send	PWM and timing with Timer2 interrupts	Timer2 interrupts	Timer2 and blocking wait	PWM with Timer2 and blocking wait with delayMicroseconds()	%
Send pins	All	All	All ?	Timer dependent	%
Decode method	OnTheFly	OnTheFly	RAM	RAM	OnTheFly
Encode method	OnTheFly	OnTheFly	OnTheFly	OnTheFly or RAM	%
Callback suppport	x	%	%	%	x
Repeat handling	Receive + Send (partially)	%	?	Receive + Send	x
LED feedback	x	%	x	x	x
FLASH usage (simple NEC example with 5 prints)	1820 (4300 for 15 main / 8000 for all 40 protocols) (+200 for callback) (+80 for interrupt at pin 2+3)	1270 (1400 for pin 2+3)	4830	1770	900
RAM usage	52 (73 / 100 for 15 (main) / 40 protocols)	62	334	227	19
Supported platforms	avr, megaAVR, attiny, Digispark (Pro), esp8266, ESP32, STM32, SAMD 21, Apollo3 (plus arm and pic for non Arduino IDE)	avr, esp8266	avr, SAMD 21, SAMD 51	avr, attiny, esp8266, esp32, SAM, SAMD	All platforms with attachInterrupt()
Last library update	2/2021	4/2018	9/2019	2/2021	2/2021
Remarks	Decodes 40 protocols concurrently. 39 Protocols to send. Work in progress.	Only one protocol at a time.	Consists of 5 libraries. Project containing bugs - 45 issues, no reaction for at least one year.	Decoding and sending are easy to extend. Supports Pronto codes.	Requires no timer.

* The Hash protocol gives you a hash as code, which may be sufficient to distinguish your keys on the remote, but may not work with some protocols like Mitsubishi

Contributing

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.

Contributors

Check here

Contact

Email: zetoslab@gmail.com 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.

License

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

Copyright

Initially coded 2009 Ken Shirriff http://www.righto.com Copyright (c) 2016 Rafi Khan Copyright (c) 2020-2021 Armin Joachimsmeyer