MCP2155_13 datasheet(13/52 Pages) MICROCHIP

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Preliminary

DS21690B-page 13

MCP2155

2.9.1.3

IrLMP

The MCP2155 implements the IrLMP protocol. The

IrLMP protocol provides:

• Multiplexing of the IrLAP layer. This allows multi-

ple channels above an IrLAP connection

• Protocol and service discovery. This is 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 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 capablities 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.

The MCP2155 identifies itself to the Primary device as

a modem.

2.9.1.4

Link Management - Information

Access Service (LM-IAS)

The MCP2155 implements the LM-IAS. Each LM-IAS

entity maintains an information data base to provide:

• Information on services for other devices that con-

tain 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 ser-

vice.

2.9.1.5

Tiny TP

Tiny TP provides the flow control on IrLMP connec-

tions. An optional service of Segmentation and Reas-

sembly can be handled.

2.9.1.6

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 simply a syntax that allows

the Primary device to consider the Secondary device

as a serial device. IrCOMM allows for emulation of

serial or parallel (printer) connections of various capa-

bilities. The MCP2155 supports the 9-wire “cooked”

service class of IrCOMM. Other service classes sup-

ported by IrCOMM are shown in Figure 2-9.

FIGURE 2-9:

IRCOMM SERVICE CLASSES

Note:

The MCP2155 identifies itself as a modem

to ensure that it is identified as a serial

device with a limited amount of memory.

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 MCP2155

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