Data Acquisition Web

The IrDA protocols are organized in a layered architecture. Some are required for a device to carry the IrDA logo. In addition, optional layers apply to specific use models. Current protocols provide connectivity up to one meter, and up to 4 Mbps. IrDA is currently working on extending specifications in both cases.

Use models extend to devices of all types,including digital cameras, LAN access devices, pagers, cell phones, laptops, PDAs, printers, scanners, medical devices, etc.

In the basic IrDA use model, there are two devices. One is the primary and the other is the secondary. The primary device is responsible for selecting a device within its visual space, establishing a connection, and maintaining the virtual wire or link. The secondary responds when spoken to. At the beginning of a typical IrDA operation, the primary initiates a process known as “discovery”, in which it explores its visible space for devices. From those devices that respond the primary selects a device and attempts to connect to it. During connection establishment, the two devices negotiate to understand each other’s capabilities. In this way a connection can be optimized despite the unpredictable differences between two disparate devices.

Once they have negotiated, they will jump to their highest common transmission speed, and attempt to communicate in ways that optimize the throughput and reliability of their connection.

Having established a connection, the devices may now search the services of the other device. If the other device supports a desired service, a connection can be made to the service. At this point, applications on either side of the connection can transfer data.

There are considerably more details, and the IrDA specifications are the definitive source.