MCP2140A Microchip Technology, MCP2140A Datasheet - Page 47

• Manufacturer Part Number: MCP2140A
• Description: IrDA Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate
• Manufacturer: Microchip Technology

APPENDIX A:
Revision A (June 2007)
• Original release of this document
© 2007 Microchip Technology Inc.
REVISION HISTORY
APPENDIX B:
When two devices implementing the IrDA standard
feature establish a connection using the IrCOMM
protocol, the process is analogous to connecting two
devices with serial ports using a cable. This is referred
to as a “point-to-point” connection. This connection is
limited to half-duplex operation because the IR
transceiver cannot transmit and receive at the same
time. The purpose of the IrDA protocols is to allow this
half-duplex link to emulate, as much as possible, a full-
duplex connection. In general, this is done by dividing
the data into “packets”, or groups of data. These
packets can then be sent back and forth, when needed,
without risk of collision. The rules of how and when
these packets are sent constitute the IrDA protocol.
The MCP2140A supports elements of this IrDA
standard protocol to communicate with other IrDA
standard compatible devices.
When a wired connection is used, the assumption is
made that both sides have the same communications
parameters and features. A wired connection has no
need to identify the other connector because it is
assumed that the connectors are properly connected.
In the IrDA standard, a connection process has been
defined to identify other IrDA compatible devices and
establish a communication link. There are three steps
that these two devices go through to make this
connection. They are:
• Normal Disconnect Mode (NDM)
• Discovery Mode
• Normal Connect Mode (NCM)
Figure B-1
shows the connection sequence.
HOW DEVICES
CONNECT
MCP2140A
DS22050A-page 47