MCP2140AT-ISLASHSS datasheet(54/60 Pages) MICROCHIP

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MCP2140A

DS22050A-page 54

C.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

feature 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 Secondary 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

series

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

requirements and then makes the decision if a

connection should be made.

C.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.

C.1.5

TINY TP

Tiny

provides

the

flow

control

IrLMP

connections. An optional service of Segmentation and

Reassembly can be handled.

C.1.6

IRCOMM

IrCOMM provides the method to support serial and

parallel port emulation. This is useful for legacy COM

applications, such as printers and modem devices.

The IrCOMM standard is a syntax that allows the

Primary Device to consider the Secondary Device a

serial device. IrCOMM allows for emulation of serial or

parallel (printer) connections of various capabilities.

FIGURE C-5:

IRCOMM SERVICE CLASSES

Note:

The

MCP2140A

supports

the 9-wire

“cooked” service class of IrCOMM. Other

service classes supported by IrCOMM are

shown in Figure C-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 MCP2140A

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