Consumer IR
Encyclopedia
Consumer IR, consumer infrared, or CIR, refers to a wide variety of devices employing the infrared
electromagnetic spectrum
for wireless communications. Most commonly found in television
remote controls, infrared ports are equally ubiquitous in consumer electronics
, such as PDAs
, laptop
s, and computers. 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, bandwidth
, and power of the transmitted information depends on the particular CIR protocol employed.
Also, the decoder functionality will often be integrated into a more complicated micro-controller that controls the A/V device, eliminating the need for the separate chip. In the absence of a viable standard, the microcontrollers can be used to emulate the ambiguous protocols used by the old dedicated encoder/decoder chips and it appears that this is often the case. There are even stripped down 4 bit mask programmable microcontrollers designed only for remote control use (such as NEC uPD6124A (discontinued), uPD6125A (discontinued), uPD6126A (discontinued), uPD6132, uPD6133, uPD6134, µPD1724x, uPD67AMC, uPD68AMC, uPD68AMC, uPD6P9M1MC (OTP), upd6PLM3MC (OTP), and µPD17932x (8-bit)). These offer keyboard wake, low power standby modes, and sample controller code though similar features are present on more general PIC microcontroller
s or Atmel AVR
s.
manufactured a number of consumer devices of different types that share a common protocol, called 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 A/V 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 A/V 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. Sony charges 5000 USD
for access to the S-Link documentation.
Sony
use the SIRC protocol for remote controls.
SIRC is developed in three different versions: 12 bit, 15 bit and 20 bit.
After 12 bits have been received, the receiver is waiting if there're coming more falling edges to know if the SIRC protocol is 15 bit or 20 bit coded.
Some infrared wireless PC 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.
and RECS-80 codes developed by Philips have been casually referred to as international standards . However, the RECS-80 protocol was prone to interference and was quickly replaced by the RC-5 protocol. Although it appears that they were proprietary protocols developed by Philips
, they 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. The RC-5 code was, and still is, used by many US- and European-based manufacturers of specialty audio/video equipment. 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 1980s and expanded to increase the number of commands in the early 1990s (sometimes called RC-5x). However, the rapidly expanding requirements for newer categories of electronics products since that time (e.g., DVD players, cable boxes, DVR's, et cetera) has led Philips to replace the RC-5 protocol with the newer RC-6 protocol that has both an expanded set of devices (256 versus 32) and commands per device (256 versus 64 in RC-5 and 128 in RC-5x). Again, information on the RC-6 protocol is not readily available from Philips.
In contrast, the major Japanese consumer electronics manufacturers almost universally adopted a protocol that was developed and administered by NEC
. In the NEC protocol, each manufacturer is assigned a unique code that is contained in the transmitted command, avoiding the possibility of false triggering by other remote handsets.
RECS-80 uses pulse position modulation and RC-5 uses bi-phase. Early dedicated-purpose chips were offered by Philips Semiconductors to allow for the easy use of RECS-80 and RC-5 protocols. The SAA3004, SAA3007, and SAA3008 encoder chips used RECS-80, and the SAA3006 and SAA3010 encoder chips used RC-5. The SAA3049A decoder chip decoded either type. (Note that the Philips Semiconductors division is now NXP). All of these chips have been discontinued. However, these transmission protocols are easily created and/or decoded with general-purpose 8-bit microcontrollers, such as those offered by Microchip Technology
and Atmel
.
Transmission of the IR commands requires only a microcontroller and an infrared
LED
, available from a wide variety of sources. Reception of the modulated commands for RC-5, RC-6, and the NEC protocols is easily accomplished with specialized IR receivers, most readily available from Sharp Corporation
and Vishay Intertechnology
. These receivers include a photo-diode, an automatic gain control
(AGC) circuit, and a demodulator. The demodulated signal is then decoded with a microcontroller.
CEA-931-B defines a method for encapsulating remote control codes over IP
and CEA-931-A defines a method for encapsulating remote control codes over IEEE-1394 http://www.ce.org/print/Press/CurrentNews/press_release_detail.asp?id=10321. These documents are not free even though free standards are the norm for Internet Protocols and contributed significantly to their widespread adoption.
A well designed Consumer IR standard would have fields for device type (CD player, DVD player, TV, VCR, Cable Box, Receiver, Tape Deck, DVR, home automation
, etc.), unit number (settable via dip switches on remote and A/V component or other means), and function code and would standardize the values in each field. It would address the semantic differences between different similar operations (separate play and pause vs. play/pause, stop and eject vs stop/eject, etc.) and would recommend that devices accept all of the semantic variations, not just the ones present on the original remote. This would allow consistent behavior across devices with a universal remote (or other control device) and would allow enhanced remotes with features like jog/shuttle. It would also allow devices to talk together, even across brands. Even if such a standard were created today, however, it would be years before consumers saw the full benefits due to legacy devices.
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
for wireless communications. Most commonly found in television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
remote controls, infrared ports are equally ubiquitous in consumer electronics
Consumer electronics
Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver...
, such as PDAs
Personal digital assistant
A personal digital assistant , also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. Current PDAs often have the ability to connect to the Internet...
, laptop
Laptop
A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
s, and computers. 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
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
solely via CIR. The type, speed, bandwidth
Bandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
, and power of the transmitted information depends on the particular CIR protocol employed.
Protocol description
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. Similarities between remotes are often largely the accidental result of the finite selection of infrared encoder/decoder chips (though now microcontrollers are also used) and IR receiver modules or imitation of the older chips rather than by design. 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.CIR and Protocol Implementation
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 micro-controller that controls the A/V device, eliminating the need for the separate chip. In the absence of a viable standard, the microcontrollers can be used to emulate the ambiguous protocols used by the old dedicated encoder/decoder chips and it appears that this is often the case. There are even stripped down 4 bit mask programmable microcontrollers designed only for remote control use (such as NEC uPD6124A (discontinued), uPD6125A (discontinued), uPD6126A (discontinued), uPD6132, uPD6133, uPD6134, µPD1724x, uPD67AMC, uPD68AMC, uPD68AMC, uPD6P9M1MC (OTP), upd6PLM3MC (OTP), and µPD17932x (8-bit)). These offer keyboard wake, low power standby modes, and sample controller code though similar features are present on more general PIC microcontroller
PIC microcontroller
PIC is a family of Harvard architecture microcontrollers made by Microchip Technology, derived from the PIC1650 originally developed by General Instrument's Microelectronics Division...
s or Atmel AVR
Atmel AVR
The AVR is a modified Harvard architecture 8-bit RISC single chip microcontroller which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other...
s.
CIR-equipped Consumer Electronics
SonySony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
manufactured a number of consumer devices of different types that share a common protocol, called S-link. A jack
Jack (connector)
In electronics and electrical assemblies, the term jack commonly refers to a surface-mounted connector, often, but not always, with the female electrical contact or socket, and is the "more fixed" connector of a connector pair...
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 A/V 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 A/V 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. Sony charges 5000 USD
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
for access to the S-Link documentation.
Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
use the SIRC protocol for remote controls.
SIRC is developed in three different versions: 12 bit, 15 bit and 20 bit.
After 12 bits have been received, the receiver is waiting if there're coming more falling edges to know if the SIRC protocol is 15 bit or 20 bit coded.
Some infrared wireless PC 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
Infrared Data Association
The Infrared Data Association defines physical specifications communications protocol standards for the short-range exchange of data over infrared light, for uses such as personal area networks ....
was designed for very short range use.
Standards
The RC-5RC-5
The RC-5 protocol was developed by Philips in the late 1980s as a semi-proprietary consumer IR remote control communication protocol for consumer electronics. However, it was also adopted by most European manufacturers, as well as many US manufacturers of specialty audio and video equipment...
and RECS-80 codes developed by Philips have been casually referred to as international standards . However, the RECS-80 protocol was prone to interference and was quickly replaced by the RC-5 protocol. Although it appears that they were proprietary protocols developed by Philips
Philips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
, they 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. The RC-5 code was, and still is, used by many US- and European-based manufacturers of specialty audio/video equipment. 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 1980s and expanded to increase the number of commands in the early 1990s (sometimes called RC-5x). However, the rapidly expanding requirements for newer categories of electronics products since that time (e.g., DVD players, cable boxes, DVR's, et cetera) has led Philips to replace the RC-5 protocol with the newer RC-6 protocol that has both an expanded set of devices (256 versus 32) and commands per device (256 versus 64 in RC-5 and 128 in RC-5x). Again, information on the RC-6 protocol is not readily available from Philips.
In contrast, the major Japanese consumer electronics manufacturers almost universally adopted a protocol that was developed and administered by NEC
NEC
, a Japanese multinational IT company, has its headquarters in Minato, Tokyo, Japan. NEC, part of the Sumitomo Group, provides information technology and network solutions to business enterprises, communications services providers and government....
. In the NEC protocol, each manufacturer is assigned a unique code that is contained in the transmitted command, avoiding the possibility of false triggering by other remote handsets.
RECS-80 uses pulse position modulation and RC-5 uses bi-phase. Early dedicated-purpose chips were offered by Philips Semiconductors to allow for the easy use of RECS-80 and RC-5 protocols. The SAA3004, SAA3007, and SAA3008 encoder chips used RECS-80, and the SAA3006 and SAA3010 encoder chips used RC-5. The SAA3049A decoder chip decoded either type. (Note that the Philips Semiconductors division is now NXP). All of these chips have been discontinued. However, these transmission protocols are easily created and/or decoded with general-purpose 8-bit microcontrollers, such as those offered by Microchip Technology
Microchip Technology
Microchip Technology is an American manufacturer of microcontroller, memory and analog semiconductors. Its products include microcontrollers , Serial EEPROM devices, Serial SRAM devices, KEELOQ devices, radio frequency devices, thermal, power and battery management analog devices, as well as...
and Atmel
Atmel
Atmel Corporation is a manufacturer of semiconductors, founded in 1984. Its focus is on system-level solutions built around flash microcontrollers...
.
Transmission of the IR commands requires only a microcontroller and an infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
, available from a wide variety of sources. Reception of the modulated commands for RC-5, RC-6, and the NEC protocols is easily accomplished with specialized IR receivers, most readily available from Sharp Corporation
Sharp Corporation
is a Japanese multinational corporation that designs and manufactures electronic products. Headquartered in Abeno-ku, Osaka, Japan, Sharp employs more than 55,580 people worldwide as of June 2011. The company was founded in September 1912 and takes its name from one of its founder's first...
and Vishay Intertechnology
Vishay Intertechnology
Vishay Intertechnology, Inc. , is one of the world's largest manufacturers of discrete semiconductors and passive electronic components. Vishay has manufacturing plants in Israel, Asia, Europe, and the Americas where it produces rectifiers, diodes, MOSFETs, optoelectronics, selected integrated...
. These receivers include a photo-diode, an automatic gain control
Automatic gain control
Automatic gain control is an adaptive system found in many electronic devices. The average output signal level is fed back to adjust the gain to an appropriate level for a range of input signal levels...
(AGC) circuit, and a demodulator. The demodulated signal is then decoded with a microcontroller.
CEA-931-B defines a method for encapsulating remote control codes over IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
and CEA-931-A defines a method for encapsulating remote control codes over IEEE-1394 http://www.ce.org/print/Press/CurrentNews/press_release_detail.asp?id=10321. These documents are not free even though free standards are the norm for Internet Protocols and contributed significantly to their widespread adoption.
Protocol limitations
The lack of standardization creates a lot of problems for consumers. The need to purchase universal remotes because the original can't control related functions on interconnected devices and upgrade them when you buy a new device, universal remotes that don't adequately control the devices, inability to control more than one of the same type unit, most consumer setups can't stop tape recording when CD ends, VCRs are often unable to control cable channels, etc.A well designed Consumer IR standard would have fields for device type (CD player, DVD player, TV, VCR, Cable Box, Receiver, Tape Deck, DVR, home automation
Home automation
Home automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC , appliances, and other systems, to provide improved convenience, comfort, energy efficiency and...
, etc.), unit number (settable via dip switches on remote and A/V component or other means), and function code and would standardize the values in each field. It would address the semantic differences between different similar operations (separate play and pause vs. play/pause, stop and eject vs stop/eject, etc.) and would recommend that devices accept all of the semantic variations, not just the ones present on the original remote. This would allow consistent behavior across devices with a universal remote (or other control device) and would allow enhanced remotes with features like jog/shuttle. It would also allow devices to talk together, even across brands. Even if such a standard were created today, however, it would be years before consumers saw the full benefits due to legacy devices.
Technical information
- Infrared Wavelength: around 930 nm, 870 nm and 950 nm.
- Carrier Frequency: Usually fixed carrier frequency, typically somewhere between 33 to 40 kHz or 50 to 60 kHz. The most commonly used protocol is the NEC protocol, which specifies a carrier frequency of 38 kHz. The NEC protocol is used by the vast majority of Japanese-manufactured consumer electronics. The Philips RC-5 and RC-6 protocols both specify a carrier frequency of 36 kHz. However, the early RC-5 encoding chips divided the master frequency of the 4-bit microcontroller by 12. This required a ceramic resonator of 432 kHz to achieve a 36 kHz carrier, which was not widely available. Many companies therefore used a 455 kHz ceramic resonator, which is commonplace due to that frequency being used in the intermediate frequencyIntermediate frequencyIn communications and electronic engineering, an intermediate frequency is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called...
stages of AM broadcastingAM broadcastingAM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
radios, resulting in a carrier frequency of 37.92 kHz (essentially 38 kHz). Even documentation for Philips' own controller chips recommended an easier-to-obtain 429 kHz ceramic resonator, yielding a carrier frequency of 35.75 kHz. Modern IR transmitters typically use 8-bit microcontrollers with a 4 MHz master clock frequency, allowing a nearly arbitrary selection of the carrier frequency. Examination of LIRCLIRCLIRC is an open source package that allows users to receive and send infrared signals with a Linux-based computer system.There is a Microsoft Windows equivalent of LIRC called WinLIRC....
datafiles shows the vast majority of remote handsets use 38 kHz. A few protocols such as ITT's protocol do not use a carrier frequency. Electronics component distributor Digi-Key carries Panasonic infrared receivers with 36.7, 38, 40, and 56.8 kHz carrier frequencies and Mouser carries Vishay receiver with carrier frequencies of 36, 38, 56, 455, and 33.0 to 57 kHz with maximum data rates of 800 and 4000 bit/s (20k for the 455 kHz carrier). - Modulation Schemes: typically 100% amplitude-shift keyingAmplitude-shift keyingAmplitude-shift keying is a form of modulation that represents digital data as variations in the amplitude of a carrier wave.Any digital modulation scheme uses a finite number of distinct signals to represent digital data. ASK uses a finite number of amplitudes, each assigned a unique pattern of...
(ASK). May also involve pulse-position modulationPulse-position modulationPulse-position modulation is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of 2^M possible time-shifts. This is repeated every T seconds, such that the transmitted bit rate is M/T bits per second...
, biphase/manchesterManchester codeIn telecommunication and data storage, Manchester code is a line code in which the encoding of each data bit has at least one transition and occupies the same time...
encoding, etc. of the transmitted pulses (as opposed to the carrier itself). Most remotes use the length of the space between pulses to encode data. - Data Rate: usually significantly lower than the carrier frequency. Most protocols seem to range between 120 bits/second and 4 bits/second. Data rate may be variable as some common bit encoding schemes vary the timing between pulses to distinguish between a 1 and 0.
- Encoding: varies based on encoder/decoder chips used. Usually includes some redundancy for error detection or correction. For example, some NEC chips send the same code four times (inverted the second and fourth time).
- Key to code mapping: varies from remote control to remote control. In many cases, the codes sent may have more to do with the row and column positions on the remote than any unified plan.
- An analysis of remote control definition files from the LIRC project yielded the following statistics on carrier frequency:
- 112x 38000 Hz
- 40x 40000 Hz
- 40x 36000 Hz
- 20x 56000 Hz
- 13x 39200 Hz
- 8x 32000 Hz
- 3x 40244 Hz
- 3x 37037 Hz
- 2x 37916 Hz
- 1x 57600 Hz
- 1x 56800 Hz
- 1x 44000 Hz
- 1x 42000 Hz
- 1x 38380 Hz
- 1x 14000 Hz
Note that the default frequency is 38000 Hz and frequency was not specified on about 90% of the remotes so it appears that the overwhelming majority use 38 kHz. Considerable additional statistical information could be gleaned from elaborate parsing of the LIRC files.