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11.1 IrDA’s New Full Range of Digital Information Exchange via Cordless Infrared
Connections
Regarding present publications on IrDA features for PC99, IrDA Data is recommended for high
speed short range, line of sight, point-to-point cordless data transfer - suitable for HPCs, digital
cameras, handheld data collection devices, etc. If IrDA is supported, it must be targeted at the 4
Mb/s components. IrDA Control is recommended for in-room cordless peripherals to hostPC.
PC99 for lower speed, full cross range, point-to-point or to-multipoint cordless controller -
suitable for keyboards (1way), joysticks (2 way & low latency) etc. IrDA Data and IrDA Control
require designer attention to ensure spatial or time sharing techniques (Appendix E) so as to avoid
interference.
Since 1994"IrDA DATA" has defined a standard for an interoperable universal two way cordless
infrared light transmission data port and now appears in approximately 50 million electronic
devices including desktop, notebook and palm PCs, printers, digital cameras, public
phones/kiosks, cellular phones, pagers and other mobile devices. Adaptors now include the
traditional upgrades to serial and parallel ports, plus Universal Serial Bus (USB) and
Ethernet/Token Ring LAN point to point access.
IrDA Data Protocols consist of a mandatory set of protocols and a set of optional protocols.
The mandatory protocols are listed below.
• PHY (Physical Signaling Layer)
• IrLAP (Link Access Protocol)
• IrLMP (Link Management Protocol and Information Access Service (IAS))
Characteristics of Physical IrDA Data Signalling
• Range: Continuous operation from contact to at least 1 metre (typically 2 metres can be
reached). A low power version relaxes the range objective for operation from contact through
at least 20 cm between low power devices and 30 cm between low power and standard power
devices. This implementation affords 10 times less power consumption. These parameters are
termed the required maximum ranges by certain classes of IrDA featured devices and sets the
end user expectation for discovery, recognition and performance.
• Bi-directional communication is the bases of all specifications
• Data transmission from 9600 b/s with primary speed/cost steps of 115 kb/s and maximum
speed up to 4 Mb/s
• Data packets are protected using a CRC (CRC-16 for speeds up to 1.152Mb/s and CRC-32 at
4 Mb/s).
Characteristics of IrDA Link Access Protocol (IrLAP)
• Provides a device-to-device connection for the reliable, ordered transfer of data.
• Device discover procedures.
• Handles hidden nodes.
Characteristics of IrDA Link Management Protocol (IrLMP)
• Provides multiplexing of the IrLAP layer. Multiple channels above an IrLAP connection.
• Provides protocol and service discovery via the Information Access Service (IAS).
Optional IrDA Data Protocols
• Tiny TP - provides flow control on IrLMP connections with an optional Segmentation and
Reassembly service.
• IrCOMM - provides COM (serial and parallel) port emulation for legacy COM applications,
printing and modem devices.
• IrOBEX - provides object exchange services similar to HTTP.
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