Consumer IRconsumer infraredor CIRis a class of devices employing the infrared portion of the electromagnetic spectrum for wireless communications. The functionality of CIR is as broad as the consumer electronics that carry it. For instance, a television remote control can convey a "channel up" command to the television, while a computer might be able to surf the internet solely via CIR. The type, speed, bandwidthand power of the transmitted information depends on the particular CIR protocol employed.
CIR is the most common type of free-space optical communication. Since the consumer IR protocols are for the most part not standardized, computers and universal remotes often memorize a bit stream, possibly with compression and possibly without determining the actual bit rate, and play it back. Manufacturers of consumer appliances often reuse the same protocol on many similar devices, though for each manufacturer and device type there are usually multiple protocols in use. The code listings inform about for any universal remote.
With the ready availability of inexpensive microcontroller chips, many remotes may be based on such chips today rather than dedicated remote control encoder chips.
This makes it easier to keep the same codes when moving the buttons on the remote. Also, the decoder functionality will often be integrated into a more complicated microcontroller that controls the AV device, eliminating the need for the separate chip. These offer keyboard wake, low power standby modes, and sample controller code though similar features are present on more general PIC microcontrollers or Atmel AVRs.
Some infrared wireless laptop keyboards and mice use protocols similar to consumer IR devices. Some PC remote controls used for controlling computer media players, controlling presentation software, or other applications also use consumer IR style protocols. Some computer remotes, keyboards, and mice may also use IrDA protocol though IrDA was designed for very short range use.
Sony manufactured a number of consumer devices of different types that share a common proprietary protocolcalled S-link. A jack on each device allowed the remote control signals to be interconnected between devices. The protocol included the useful but unusual feature of supporting more than one of the same type of device such as multiple CD changers.
Some AV components could generate informational status codes that could be used to do things like automatically stop your tape deck when the CD you were recording stopped playing. Software running on a PC with a suitable interface could also control the AV components and monitor their activity; for example, your computer could tell what disk and track were playing in your CD changer and look up the titles in one of the internet CD databases.
After 12 bits have been received, the receiver waits to see if there are more falling edges to know if the SIRC protocol is 15 bit or 20 bit coded.
Although it appears that they were proprietary protocols developed by Philipsthey were also adopted by various other manufacturers, specifically European- and US-based ones. This allowed interoperability between the remote handsets and equipment of various brands.
Unfortunately, documentation of the standard commands were not widely distributed. Therefore, there are some brands of equipment that use non-standard commands, causing interference with other equipment also using the RC-5 protocol. The RC-5 command set was defined in the late s and expanded to increase the number of commands in the early s sometimes called RC-5x.
However, the rapidly expanding requirements for newer categories of electronics products since that time e.There are 3 basic types of data transmission formats, which are illustrated in the following diagram.
Protocols can be based on these transmission formats, but need not necessarily conform to them. So how do you know what your remote control uses?
And how do you capture the sequence so that you can re-transmit it from an IR diode? To capture these infrared signals, we use an IR receiver module. This is typically a 3-pin device, which consists of an IR detector as well as built-in circuitry to demodulate the 36 — 38kHz signal, producing a digital output corresponding to the transmitted data.
If we had used an IR photodiode or phototransistor instead, we would have to demodulate the signal ourselves. If you have a logic analyzer or an oscilloscope, you could simply hook up the IR receiver module and see its output on your screen.
However, I do not have either of these, so I am going to rely on my trusty Arduino. You should also verify the pinout of your receiver by reading its datasheet.
Infrared Remote Control Protocols: Part 1
I started off with this sketch from the Arduino Playground, which uses pin 2 as its input. The output, formatted into rows of 4, looks something like this:. This output was captured from an Apple Remote, whose format is well-documented. Looking at the Apple Remote page on Wikipediathe IR signal protocol can be summarized by the following table:.NEC protocol IR remote control decoder with PIC12F1822
The oscillator that provides the signal timing is probably an on-chip RC oscillator, which is not a very accurate time source. Another possible reason could be lag in the IR receiver module. Therefore when designing an IR receiver, this must be taken into account. What should you do if the protocol that you captured is not documented? Well, you should capture it a couple of times to get a good idea of what values are used, as well as acceptable. When you plot the histogram for all the durations, you should see a few clusters, representing the regions of interest.
For the Apple remote, there will be 4 such regions, each of which will correspond to a value in the above table. These regions are shown in detail below:. The and values appear less often because they only occur at the start of the IR signal, whereas the values and are used to represent the data and therefore occur many times with each button press, depending on how many bits are transmitted.
If you have no idea what protocol this is, you could browse through the different IR protocols, looking for a match. The IR protocol is unlikely to use many different durations, due to previously stated reasons. It is probably safe to take the middle of the seen values since any one of those are considered valid by the receiver.
You could workaround this problem by pressing the remote twice, but that would be an inelegant solution. I have also cleaned up the code considerably. If you take the greatest common divisor of, andyou will have your answer: The values went from 1ms to 10ms — the error is quite large and it happens often. Since this protocol has been documented, understanding it will be much easier. The protocol starts off with two values for the header: and The first two bytes sent are the Apple custom code ID 0xEE followed by 0x87which are followed by … making a total of 32 bits of data.
All bytes are sent least significant bit first. The first 8 decoded bits are but since the LSB is sent first, the bits should read instead, which is 0xEE in hexadecimal. The subsequent decoded byte should therefore be 0x In the next posta case study of an unknown remote control protocol will be presented, as well as how we can use this information to make our own remote control that emulates the protocol.
The last piece of the puzzle was to capture packets produced by each unique change of the control […].Here's a contribution from one of my visitors, Pablot from Sweden. He generously composed the information on this page. I also had help from looking at the lirc remote archive. I then concluded my best guess nothing confirmed. It is actually quite similar to the NEC protocol. The RCA protocol uses pulse distance encoding of the bits.
A logical "1" takes 2. The picture above shows a typical pulse train of the RCA protocol. With this protocol the MSB is transmitted first. Address and Command are transmitted twice. The second time all bits are inverted and can be used for verification of the received message. The total transmission time is constant because every bit is repeated with its inverted length. If you're not interested in this reliability you can ignore the inverted values.
Commands are repeated every 64ms measured from start to start for as long as the key on the remote control is held down. Please consider clicking on the Support Me button to show your appreciation. Last updated: 02 June Features bit protocol.
Pulse distance modulation. Carrier frequency of 56kHz. Bit time of 1. Complement of code sent out after real code for reliability.
Modulation The RCA protocol uses pulse distance encoding of the bits. Protocol The picture above shows a typical pulse train of the RCA protocol. Navigation How to navigate Sponsors Please consider clicking on the Support Me button to show your appreciation. My way of keeping this site alive.Follow technoblogy. The IR Remote Control Detective decodes the signal from several common types of infrared remote control, such as audio, TV, and hobbyist remote controls.
To use it you point a remote control at the receiver and press a key; it will then identify the protocol, and display the address and command corresponding to the key:. I originally built it to help design a project based on an IR remote control. It will be useful if you're trying to automate the control of an existing domestic device using its infrared remote control codes, or you want to make a device you can control with an existing remote control.
Once you've used the IR Remote Control Detective to find out what codes your remote control generates you could use it to control your own project using the receive routine in this program. It is used by many Japanese and Chinese manufacturers, and by the remote controls available from Adafruit  and SparkFun . A variant of it is also used by Samsung. The data is encoded using pulse distance encoding.
Each bit starts with A zero has a total width of 1. The carrier pulse consists of 21 cycles at 38kHz. Each code sequence starts with a long pulse, known as the AGC pulse, followed by a gap. In the NEC protocol the pulse is 9ms long and the gap 4. The data then consists of 32 bits, a bit address followed by a bit command, shown in the order in which they are transmitted left to right :.
The Address identifies the piece of equipment being controlled, and the Command indicates which key was pressed. In the original version of the NEC protocol the high-order 8 bits of the address was just an inverted version of the low-order 8 bits, and likewise for the command as in the above example. The remote controls I've tested from Adafruit and SparkFun follow this convention, so for these you could ignore the high-order bytes of the command.
The Sony SIRC protocol uses a 12, 15, or 20 bit code consisting of a 7-bit command followed by 5, 8, or 13 address bits. The data is encoded using pulse width encoding.Application processes IR signal from a remote control and compares it with its own database of known protocols.
When a match is found, packet is decoded and its characteristic is displayed to user including protocol name, description, decoded data and graph with timing. Protocol definitions are stored in separate XML file. This XML file can be easily modified and new protocol definitions can be added by user. When an unknown packet is captured, user may still display its graph with timing details. Then, on the basis of the graph and timing, he may create new protocol description.
All captured data can be saved to a file and restored later. Moreover, packet graph can be exported to a bitmap image. Did you use this instructable in your classroom?
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Useful Tool for IR Remote Control Protocol Analysis
Reply 6 years ago on Introduction. Sorrywhy your emitter pin of phototransistor is not connected the ground. Reply 5 years ago on Introduction. This is old, but for people like me drifting in here through google, he's essentially using it as a photodiode rather than a phototransistor.
If one of the edges is left floating such as connecting to just the first or last P and N of a PNP transistoryou're instead looking at a diode with an extra doped layer sitting beside it doing nothing.
Hi, I'm always getting unknown protocol. What is wrong? I'm trying to use AC IR remote control. Please advice. Specially i want to use 89c51 for it, but i also familier to work with PIC.
More by the author:.Great, i will like to build this project, am a beginner in MCUs and i think this realy straightforward pls where is the circuit diagram, can't see it. Dear Sir. Can i use pic12f or pic12f instead of 12f with same HEX code R. Murugan murugabi07 yahoo. Dear Gaurav, I found a mistake in the schematics for your infrared encoder. As a result, there will be a very high current flowing through the LED. The current through the LED must be limited to about mA. Thanks for your good work, i will build it!
Now i'm requesting you to give me a C source code with hex file so that the receiver can be run by a Sony remote control unit. And obviously please mention your explanation of the code on comment section. Hello, please, I would like to use pic12f75 on the transmitter but they are not in possession of the compiler. Could you do it and send, or publish only. Hex file? Send to rinosannino tin.
Thank you and good job. The source code is for both the PIC's in the transmitter and receiver,am i right?. And one thing more No Sir, I make both are remote and receiver. I check all connection properly, all are correct but the circuit is not working. I have a doubt in this micro controller,This micro controller with programmed or without program. Please clarify this problem. Sir, I check my remote circuit that all connection is correct but when I pressed any switch the IR led is not emitting check in mobile phone camera what is the problem i cant understand.
One of the three programs in source code can i use in pic12f or no? My id is armangml gmail. Dear Gaurav Chaudhary I tried this circuit and I achive my goals, and the range of this remote about 1. Sincerely, Wassim Khalife wassim. Dear Mr. Gaurav, Thanks for this nice project and it is absolutely working fine. If possible kindly show me, if not I like to have your advice.
Regrds, D. Please suggest Me. Sir how to extend 4 channel into 8 channel can u please help me Mr. For nec protocol detection which ir receiver i should use? TSOP will do? I am implementing similar proejct using FPGA? Also can you please tell me the algorithm of the program? How did you detect each bit and after detecting how you proceded further for detecting command bits? Pls rply ASAP!!
Thanks in advance!The advantage of the lack of a visible signature is unclear in non-military applications.
There are no legal restrictions for the use of IR beams to transmit any kind of data. Modulation at a definite frequency is just necessary to distinguish the signal from other sources of near infrared, from daylight to fluorescent lighting. Data is encoded by turning this modulated carrier on and off. Standard parts for this modulation band are becoming difficult to locate.
This is probably the simplest possible type of remote control; only one button and one type of action. It stands to reason that the observed intervals are nominally a whole number of carrier cycles:. The sequence for the ML-L3 seems to be: Leader pulse of 80 cycles. Pause for cycles. Burst of 16 cycles. Pause for 64 cycles. Repeat the above after a long pause of cycles.
Because of the noisy infrared environments caused by modern fluorescent lighting, current IC detectors are no longer able to handle a continuous modulated IR beam. The best commercially available detectors discussed below can handle up to such pulses per second, if they last at least 6 carrier cycles and are separated by a recovery time of at least 10 cycles.
Those short bursts can encode bits in several different ways. The most popular are:. When the width of bursts is constant, as is usually the case in modern IR protocols, the last two encoding methods are equivalent. The first one has many advantages over them. However, in the world of remote control keypads, a frame is often sent just to indicate that a certain key is still being pressed. Each time a key is released, the state of the so-called "toggle" bit is changed. IR commands are one-way only, with no feedback.
Typically, the "power" button on a TV remote turns the set on if it's off but will turn it off if it's on If you want to make sure your TV is on as part of a complex sequence of control commands that will enable you to watch a movie from a particular source, say, you need a function which is not available on an ordinary remote.
This "make sure the TV is on" command is an example of what has become known as a "discrete" command code. Such codes cannot be obtained by decoding the ouput of ordinary remote units. They are typically compiled in specialized databases for use by programmable "universal remotes" which control several units of different brands for maximal flexibility.
Information about discrete codes was either provided by friendly manufacturers or discovered by trial and error The 0. However, it is rather curious and I don't have an explanation for it at this time I have also been unable to find what IR wavelength the Rohm receivers are designed for!
We may guess that their receivers would spectrally match that, but it's unfortunately just a guess. It's unclear to me what commercial products, if any, made use of the system before it was superseeded by RC The modulation frequency was obtained by dividing by 12 the frequency of that master resonnator and could therefore be between Presumably, the emitter and the receiver were supposed to be tuned to the same frequency, though.
The specs for the M are clear on that point. In that scheme, bursts were speparated either by two units of time to encode a "0" bit or three units to encode a "1".