Infrared Data Association
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The Infrared Data Association (IrDA) is an industry-driven interest group that was founded in 1994 by around 50 companies. IrDA provides specifications for a complete set of protocols for wireless infrared communications, and the name "IrDA" also refers to that set of protocols. The main reason for using the IrDA protocols had been wireless data transfer over the "last one meter" using point-and-shoot principles. Thus, it has been implemented in portable devices such as mobile telephones, laptops, cameras, printers, and medical devices. The main characteristics of this kind of wireless optical communication are physically secure data transfer, line-of-sight (LOS) and very low
bit error rate In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise (telecommunications), noise, interference (communication), interference, distortion ...
(BER) that makes it very efficient.


Specifications


IrPHY

The mandatory IrPHY (Infrared Physical Layer Specification) is the physical layer of the IrDA specifications. It comprises optical link definitions, modulation, coding,
cyclic redundancy check A cyclic redundancy check (CRC) is an Error correcting code, error-detecting code commonly used in digital Telecommunications network, networks and storage devices to detect accidental changes to digital data. Blocks of data entering these syste ...
(CRC) and the framer. Different data rates use different modulation/coding schemes: * SIR: 9.6–115.2 kbit/s, asynchronous, RZI, UART-like, 3/16 pulse. To save energy, the pulse width is often minimized to 3/16 of a 115.2KBAUD pulse width. * MIR: 0.576–1.152 Mbit/s, RZI, 1/4 pulse, HDLC bit stuffing * FIR: 4 Mbit/s, 4 PPM * VFIR: 16 Mbit/s, NRZ, HHH(1,13) * UFIR: 96 Mbit/s, NRZI, 8b/10b * GigaIR: 512 Mbit/s – 1 Gbit/s, NRZI, 2-ASK, 4-ASK, 8b/10b Further characteristics are: * Range: ** standard: 2 m; ** low-power to low-power: 0.2 m; ** standard to low-power: 0.3 m. ** The 10 GigaIR also define new usage models that supports higher link distances up to several meters. * Angle: minimum cone ±15° * Speed: 2.4 kbit/s to 1 Gbit/s * Modulation:
baseband In telecommunications and signal processing, baseband is the range of frequencies occupied by a Signal (electrical engineering), signal that has not been modulation, modulated to higher frequencies. Baseband signals typically originate from trans ...
, no carrier * Infrared window (part of the device body transparent to infrared light beam) * Wavelength: 850–900 nm The frame size depends on the data rate mostly and varies between 64  B and 64 kB. Additionally, bigger blocks of data can be transferred by sending multiple frames consecutively. This can be adjusted with a parameter called "window size" (1–127). Finally, data blocks up to 8 MB can be sent at once. Combined with a low bit error rate of generally <, that communication could be very efficient compared to other wireless solutions. IrDA transceivers communicate with infrared pulses (samples) in a cone that extends at least 15 degrees half angle off center. The IrDA physical specifications require the lower and upper limits of irradiance such that a signal is visible up to one meter away, but a receiver is not overwhelmed with brightness when a device comes close. In practice, there are some devices on the market that do not reach one meter, while other devices may reach up to several meters. There are also devices that do not tolerate extreme closeness. The typical sweet spot for IrDA communications is from away from a transceiver, in the center of the cone. IrDA data communications operate in
half-duplex A duplex communication system is a Point-to-point (telecommunications), point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many commu ...
mode because while transmitting, a device’s receiver is blinded by the light of its own transmitter, and thus
full-duplex A duplex communication system is a Point-to-point (telecommunications), point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many commu ...
communication is not feasible. The two devices that communicate simulate full-duplex communication by quickly turning the link around. The primary device controls the timing of the link, but both sides are bound to certain hard constraints and are encouraged to turn the link around as fast as possible.


IrLAP

The mandatory IrLAP (Infrared Link Access Protocol) is the second layer of the IrDA specifications. It lies on top of the IrPHY layer and below the IrLMP layer. It represents the
data link layer The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link laye ...
of the
OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communicatio ...
. The most important specifications are: * Access control * Discovery of potential communication partners * Establishing of a reliable bidirectional connection * Distribution of the primary/secondary device roles * Negotiation of QoS parameters On the IrLAP layer the communicating devices are divided into a "primary device" and one or more "secondary devices". The primary device controls the secondary devices. Only if the primary device requests a secondary device to send, is it allowed to do so.


IrLMP

The mandatory IrLMP (Infrared Link Management Protocol) is the third layer of the IrDA specifications. It can be broken down into two parts. First, the LM-MUX (Link Management Multiplexer), which lies on top of the IrLAP layer. Its most important achievements are: * Provides multiple logical channels * Allows change of primary/secondary devices Second, the LM-IAS (Link Management Information Access Service), which provides a list, where service providers can register their services so other devices can access these services by querying the LM-IAS.


Tiny TP

The optional Tiny TP (Tiny Transport Protocol) lies on top of the IrLMP layer. It provides: * Transportation of large messages by SAR (Segmentation and Reassembly) * Flow control by giving credits to every logical channel


IrCOMM

The optional IrCOMM (Infrared Communications Protocol) lets the infrared device act like either a serial or
parallel port In computing, a parallel port is a type of Hardware interface, interface found on early computers (personal computer, personal and otherwise) for connecting peripherals. The name refers to the way the data is sent; parallel ports send mu ...
. It lies on top of the IrLMP layer.


OBEX

The optional OBEX (Object Exchange) provides the exchange of arbitrary data objects (e.g., vCard, vCalendar or even applications) between infrared devices. It lies on top of the Tiny TP protocol, so Tiny TP is mandatory for OBEX to work.


IrLAN

The optional IrLAN (Infrared Local Area Network) provides the possibility to connect an infrared device to a local area network. There are three possible methods: * Access point *
Peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a peer-to-peer ...
* Hosted As IrLAN lies on top of the Tiny TP protocol, the Tiny TP protocol must be implemented for IrLAN to work.


IrSimple

IrSimple achieves at least 4 to 10 times faster data transmission speeds by improving the efficiency of the infrared IrDA protocol. A 500 KB normal picture from a cell phone can be transferred within 1 second.


IrSimpleShot

One of the primary targets of IrSimpleShot (IrSS) is to allow the millions of IrDA-enabled camera phones to wirelessly transfer pictures to printers, printer kiosks and flat-panel TVs.


Infrared Financial Messaging

Infrared Financial Messaging (IrFM) is a wireless payment standard developed by the Infrared Data Association. It was thought to be logical because of the excellent privacy of IrDA, which does not pass through walls.


Power meters

Many modern (2021) implementations are used for semi-automated reading of power meters. This high-volume application is keeping IrDA transceivers in production. Lacking specialized electronics, many power meter implementations utilize a bit-banged SIR phy, running at 9600 BAUD using a minimum-width pulse (i.e. 3/16 of a 115.2KBAUD pulse) to save energy. To drive the LED, a computer-controlled pin is turned on and off at the right time. Cross-talk from the LED to the receiving
PIN diode A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutc ...
is extreme, so the protocol is
half-duplex A duplex communication system is a Point-to-point (telecommunications), point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many commu ...
. To receive, an external interrupt bit is started by the start bit, then polled a half-bit time after following bits. A timer interrupt is often used to free the CPU between pulses. Power meters' higher protocol levels abandon IrDA standards, typically using DLMS/COSEM instead. With IrDA transceivers (a package combining an IR LED and PIN diode), even this crude IrDA SIR is extremely resistant to external optical noise from incandescents, sunlight, etc.


Reception

IrDA was popular on PDAs, laptops and some desktops from the late 1990s through the early 2000s. However, it has been displaced by other wireless technologies such as
Wi-Fi Wi-Fi () is a family of wireless network Communication protocol, protocols, based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital d ...
and
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limit ...
, favored because they don't need a direct line of sight and can therefore support hardware like mice and keyboards. It is still used in some environments where interference makes
radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device ...
-based wireless technologies unusable. An attempt was made to revive IrDA around 2005 with IrSimple protocols by providing sub-1-second transfers of pictures between cell phones, printers, and display devices. IrDA hardware was still less expensive and didn't share the same security problems encountered with wireless technologies such as Bluetooth. For example, some Pentax DSLRs (K-x, K-r) incorporated IrSimple for image transfer and gaming.http://www.pentaximaging.com/about-us.aspx?p=press&pid=PENTAXANNOUNCESK-rDIGITALSLRANDNEW35MMLENS20100908174223 Pentax K-r


See also

* Consumer IR * Li-Fi * List of device bandwidths * RZI


References


Further reading

* ''IrDA Principles and Protocols''; Knutson and Brown; MCL Press; 214 pages; 2004; .


External links

Official
List of official specifications
physical layer specification is US$100 Other
Linux Infrared HOWTO

Linux Infrared Remote Control


* ttps://web.archive.org/web/20110902095151/http://wiki.linuxencaja.net/wiki/Academico/Embebidos/IrDA_SIE IrDA project of Universidad Nacional de Colombia SIE board {{authority control Standards organizations in the United States Organizations based in California