MCP2140_13 Datasheet, PDF (48/58 Pages) Microchip Technology – IrDA® Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate

MCP2140
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.
Note:
The MCP2140 supports the 9-wire
“cooked” service class of IrCOMM. Other
service classes supported by IrCOMM are
shown in Figure B-5.
FIGURE B-5: IRCOMM SERVICE CLASSES
IrCOMM Services
Uncooked Services
Cooked Services
Parallel
IrLPT
Serial
3-wire Raw
Supported by MCP2140
Parallel
Centronics
IEEE 1284
Serial
3-wire Cooked
9-wire Cooked
DS21790B-page 48
Preliminary
 2003-2012 Microchip Technology Inc.