This is yet another infrared library for the Arduino. (Although its name does not start with YA...)
It is a major rewrite of Chris Young's IRLib, (GitHub repo), which itself is a major rewrite of a library called IRremote, published by Ken Shirriff in his blog, now maintained on GitHub. It uses Michael Dreher's IrWidget (article in German), see also this forum contribution.
IrWidgetAggregating are based on Michael's code.
IrSenderPwm, and in particular the file
are adapted from Kevin's and Chris' work. The remaining files are almost completely written
from scratch, although the influence of Kevin and Chris is gratefully acknowledged.
This work is a low-level library (like IRremote and IRLib) that can be used in other projects,
like AGirs, which is an high-level program taking commands interactively
from a user or a program through a bi-directional
The goal has been to provide a sound, object oriented basis for the fundamental basis, not
to provide maximal functionality, the maximal number of protocols supported, or the most complete support of
different hardware. A clean design and high readability, without being "too" inefficient,
has been the highest priority. Dynamic memory allocation with
delete is used extensively.
The user who is afraid of this can create his required objects at the start of the run, and keep
them. Most classes are immutable. The classes are
There are some project specific data typedefs in
For durations in microseconds, the data type
microseconds_t is to be
used. If desired/necessary, this can be either
uint32_t. For durations in milliseconds, use the type
millisecons_t. Likewise, use
frequency_t for modulation frequency in
Hz (not kHz as in the IRremote/IRLib).
size_t, the standard C type, is used.
Implementation dependent types like
int are used if and only if it is OK for the
compiler to select any implementation allowed by the C++ language.
unsigned int is used for quantities that can "impossibly" be larger than 65535.
IrSequences and IrSignals
IrSequence is a vector of durations, i.e. sequence of interleaving gaps and spaces. It does not
contain the modulation frequence. As opposed to IRremote and IRLib, our sequences always start with
a space and end with a gap. It is claimed to be a more relevant representation than the one of IRremote and IRLib.
IrSignal consists of a modulation frequency and three
IrSequences: intro-, repeat-, and ending sequence. All of these, but not all, can be
empty. If repeat is empty, intro has to be non-empty and ending empty. The intro sequence is always sent first,
then comes a zero or more repeat sequences, and finally the ending sequence. To send a signal n > 0 times shall mean
the following: If the intro is non-empty, send intro, n - 1 repeats, and then the ending. If the intro is empty,
send n repeats, and then then ending.
For some receiving and transmitting classes, multiple instantiations are not sensible,
for other it may be. In this library, the classes that should only be instantiated
once are implemented as singleton classes, i.e. with no public constructor, but instead
a static "factory" method (
newThing()) that delivers a pointer to a newly constructed instance
Thing has not been instantiated before. The classes, where multiple instances
is sensible, come with public constructors. (However, the user still has to take responsibility
for avoiding pin- and timer-conflicts.)
For hardware support, the file
IRremoteInt.h from the IRremote project is used. This means that
all hardware that project supports is also supported here (for
(Actually, a small fix, borrowed from IRLib, was used
to support Arduinos with ATMega32U4 (Leonardo, Micro).)
However, IrWidgetAggregating is currently supported on the boards Uno/Nano (ATmega328P), Leonardo/Micro (ATmega32U4),
and Mega2560 (ATmega2560).
Several of the sending and receiving classes take a GPIO pin as argument to the constructor.
However, the sending pin of
IrSenderPwm and the capture pin of
are not configurable, but (due to hardware limitations) have to be taken from the following table:
Sender Pin Capture Pin Uno/Nano (ATmega328P) 3 8 Leonardo/Micro (ATmega32U4) 9 4 Mega2560 (ATmega2560) 9 49
All the receiving classes adhere to the following conventions: When initialized, it waits
up to the time
beginningTimeout for the first on-period. If not received within that period,
it returns with a timeout. Otherwise, is starts collecting data. It will collect data until one of the
- A silence of length
endingTimeouthas been detected. This is the normal ending. The detected last gap is returned with the data.
- The buffer gets full. Reception stops.
As opposed to other infrared libraries, there are no user changeable parameters as CPP symbols.
However, the timer
configuration is compiled in, depending on the CPP processors given to the compiler, see
As opposed to the predecessor projects, this project has a header (
*.h) file and an implementation file
*.cpp, sometimes missing) for each public class.
Simple answer: there is none. If a function is sent erroneous data, it just silently ignores the request, or does something else instead. This (unfortunately) seems to be the standard procedure in Arduino programming.
I am used to exception based error handling, for some reason this is not used by the Arduino community.
Constructive suggestions are welcome.
Comparing with the predecessor works, this project may look meager, currently supporting only two protocols (NEC1 and RC5). It is planned to generate the corresponding C++ code automatically from the IRP notation. (For this reason, contributed implementations of more protocols are not solicited.)
Sending non-modulated signals.
RF signals (433 MHz and other carrier frequencies) do not use the IR
typical modulation. Also there are a few IR protocols (like Revox, Barco,
not using modulation. These signals can be sent by the class
after connecting suitable hardware capable of sending non-modulated (IR- or RF-) signals
to the GPIO pin given as argument to the constructor.
This library does not depend on any other libraries; only the standard Arduino environment.
Questions and answers
- What is the difference between the
They are intended for two different use cases, receiving and capturing. Differently put, "receive" uses a demodulating receiver (TSOPxxx, etc.), "capture" a non-demodulating decoder (TSMPxxx, OPLxxx QSExxx, etc.). Note that this terminology is not universally accepted (yet!).
My goal is to write excellent code, even though I do not always succeed :-). "Everything as simple as possible, but not simpler." Cleanliness, logical structure, readability and maintainability are the most important requirements. Efficiency (runtime and/or space) is also important, although it normally comes on second place. The Arduino Style Guide has different goals (essentially optimizing for novice programmers, "Some of these run counter to professional programming practice"). It is therefore not given priority in this project.
The main documentation for the classes is found in the source files themselves. It can be
extracted to a browse-able documentation using the program Doxygen.
After installing the program, fire up the program in the source directory. It will generate documentation in
html. To browse, open
html/index.html in a browser.
The documentation is written for the user of the library, not the developer.
For this reason, the file
Arduino.h has been deliberately excluded from the documentation,
to keep it centered on the main issues for the programming on the target system.
Multi platform coding
For someone used to, e.g., Netbeans or Eclipse, the Arduino IDE
feels "somewhat" primitive and limited. In particular, it does not support debugging. Mainly
for this reason, the code in the present library is designed to compile, and at least
to some extent, run in a normal C++ environment on the host compiler. For this,
some code modifications, in particular, a customized
Arduino.h was needed.
If the preprocessor symbol
ARDUINO is defined,
just includes the standard Arduino
Arduino.h is included, otherwise (i.e. for compiling for the host),
some more-or-less dummy stuff are defined, allowing compiling for, and execution/debugging
on the host.
This way, certain types of problems can be solved much faster. The drawback is that the code
is "polluted" with ugly
#ifdef ARDUINO statements, which decreases readability and
makes maintenance harder.
tests contains test(s) that run on the host. The supplied
is intended for compiling for the host as target. It creates a library in the
standard sense (
*.a), and can be used to build and run tests in subdirectory
With the provided
Doxyfile, Doxygen will document only the (strict) Arduino parts,
not the "portable C++".
The entire work is licensed under the GPL2 "or later" license. Chris' as well as Ken's code is licensed under the LGPL 2.1-license. Michael's code carries the GPL2-license, although he is willing to agree to "or later versions".