MCP2140-ISO datasheet(48/58 Pages) MICROCHIP

48 / 58 page

MCP2140

DS21790A-page 48

Preliminary

 2003 Microchip Technology Inc.

B.1.3

IrLMP

The IrLMP protocol provides:

• Multiplexing of the IrLAP layer. This allows

multiple channels above an IrLAP connection.

• Protocol and service discovery. This is

accomplished via the Information Access Service

(IAS).

When two devices that contain the IrDA standard fea-

ture are connected, there is generally one device that

has something to do and the other device that has the

resource to do it. For example, a laptop may have a job

to print and an IrDA standard compatible printer has the

resources to print it. In IrDA standard terminology, the

laptop is a Primary device and the printer is the Sec-

ondary device. When these two devices connect, the

Primary device must determine the capabilities of the

Secondary device to determine if the Secondary device

is capable of doing the job. This determination is made

by the Primary device asking the Secondary device a

series of questions. Depending on the answers to

these questions, the Primary device may or may not

elect to connect to the Secondary device.

The queries from the Primary device are carried to the

Secondary device using IrLMP. The responses to these

queries can be found in the Information Access Service

(IAS) of the Secondary device. The IAS is a list of the

resources of the Secondary device. The Primary

device compares the IAS responses with its require-

ments and then makes the decision if a connection

should be made.

B.1.4

LINK MANAGEMENT -

INFORMATION ACCESS SERVICE

(LM-IAS)

Each LM-IAS entity maintains an information database

to provide:

• Information on services for other devices that

contain the IrDA standard feature (Discovery)

• Information on services for the device itself

• Remote accessing of another device’s information

base

This is required so that clients on a remote device can

find configuration information needed to access a

service.

B.1.5

TINY TP

Tiny TP provides the flow control on IrLMP connec-

tions. An optional service of Segmentation and

Reassembly can be handled.

B.1.6

IRCOMM

IrCOMM provides the method to support serial and par-

allel port emulation. This is useful for legacy COM

applications, such as printers and modem devices.

The IrCOMM standard is a syntax that allows the Pri-

mary device to consider the Secondary device a serial

device. IrCOMM allows for emulation of serial or

parallel (printer) connections of various capabilities.

FIGURE B-5:

IRCOMM SERVICE CLASSES

Note:

The

MCP2140

supports

the

9-wire

“cooked” service class of IrCOMM. Other

service classes supported by IrCOMM are

shown in Figure B-5.

IrCOMM Services

Uncooked Services

Cooked Services

Parallel

Serial

IrLPT

3-wire Raw

Parallel

Centronics

IEEE 1284

Serial

3-wire Cooked

9-wire Cooked

Supported by MCP2140

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