[](https://github.com/z3t0/Arduino-IRremote/commits/master)
[](https://gitter.im/z3t0/Arduino-IRremote?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
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](http://marc.merlins.org/perso/arduino/post_2017-04-03_Arduino-328P-Uno-Teensy3_1-ESP8266-ESP32-IR-and-Neopixels.html)
- 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.
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](https://www.analysir.com/blog/2014/03/19/air-conditioners-problems-recording-long-infrared-remote-control-signals-arduino).<br/>
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 [IRreceiveDumpV2 example](examples/IRreceiveDumpV2) to dump out the IR timing.
You can then reproduce/send this timing with the [IRsendRawDemo example](examples/IRsendRawDemo).
For **long codes** with more than 48 bits like from air conditioners, you can **change the length of the input buffer** in [IRremoteInt.h](src/private/IRremoteInt.h#L31).
- The [IRMP AllProtocol example](https://github.com/ukw100/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](https://github.com/bengtmartensson/Arduino-DecodeIR/blob/master/examples/IRremoteDecode/IRremoteDecode.ino) of the Arduino library [DecodeIR](https://github.com/bengtmartensson/Arduino-DecodeIR).
- Use [IrScrutinizer](http://www.harctoolbox.org/IrScrutinizer.html).
It can automatically generate a send sketch for your protocol by exporting as "Arduino Raw". It supports IRremote,
the old [IRLib](https://github.com/cyborg5/IRLib) and [Infrared4Arduino](https://github.com/bengtmartensson/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%.
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](https://eclipse.baeyens.it).
[Here](https://github.com/ukw100/IRMP#quick-comparison-of-4-arduino-ir-receiving-libraries) you find a **short comparison matrix** of 4 popular Arduino IR libraries.<br/>
[Here](https://github.com/crankyoldgit/IRremoteESP8266) you find an **ESP8266/ESP32** version of IRremote with an **[impressive list of supported protocols](https://github.com/crankyoldgit/IRremoteESP8266/blob/master/SupportedProtocols.md)**.
- [ESP8266 is supported in a fork](https://github.com/crankyoldgit/IRremoteESP8266) based on an old codebase. It works well given that perfectly timed sub millisecond interrupts are different on that chip.
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.
To add a new protocol is quite straightforward. Best is too look at the existing protocols to find a similar one and modify it.<br/>
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.<br/>
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. It's easy to be off-by-one with the last bit; the last space may be implicit.
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 [`sendNECStandard(uint16_t aAddress, uint8_t aCommand, uint8_t aNumberOfRepeats)`](https://github.com/z3t0/Arduino-IRremote/src/ir_NEC.cpp#L76) and [`decodeNECStandard()`](https://github.com/z3t0/Arduino-IRremote/src/ir_NEC.cpp#L165).<br/>
### 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*.<br/>
And at least it would be wonderful if you can provide an example how to use the new protocol.
We do it according to the statement in the [Vishay datasheet](https://www.vishay.com/docs/80069/circuit.pdf):
- 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.<br/>
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.<br/>
For 3 diodes it requires factor 2.5 e.g. from 150 ohm to 60 ohm.
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.
