MCP2150-I/SS Microchip Technology Inc., MCP2150-I/SS Datasheet - Page 16

• Manufacturer Part Number: MCP2150-I/SS
• Description: IRDA PROTOCOL HANDLER PLUS ENDEC FOR DTE APPS
• Manufacturer: Microchip Technology Inc.

Specifications of MCP2150-I/SS

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

MCP2150
2.9.3.2
Discovery mode allows the Primary device to deter-
mine the capabilities of the MCP2150 (Secondary
device). Discovery mode is entered once the MCP2150
(Secondary device) has sent an XID response to the
Primary device and the Primary device has completed
sending the XIDs and then sends a Broadcast ID. If this
sequence is not completed, then a Primary and
Secondary device can stay in NDM indefinitely.
When the Primary device has something to do, it
initiates Discovery. Discovery has two parts. They are:
• Link initialization
• Resource determination
The first step is for the Primary and Secondary devices
to determine, and then adjust to, each other’s hardware
capabilities. These capabilities are parameters like:
• Data rate
• Turn around time
• Number of packets without a response
• How long to wait before disconnecting
Both the Primary and Secondary device begin commu-
nications at 9600 baud, which is the default baud rate.
The Primary device sends its parameters, then the
Secondary device responds with its parameters. For
example, if the Primary supports all data rates up to
115.2 kbaud and the Secondary device only supports
19.2 kbaud, the link will be established at 19.2 kbaud.
Once the hardware parameters are established, the
Primary device must determine if the Secondary device
has the resources it requires. If the Primary device has
a job to print, then it must know if it’s talking to a printer,
not a modem or other device. This determination is
made using the Information Access Service (IAS). The
job of the Secondary device is to respond to IAS que-
ries made by the Primary device. The Primary device
must ask a series of questions like:
• What is the name of your service?
• What is the address of this service?
• What are the capabilities of this device?
When all the Primary device’s questions are answered,
the Primary device can access the service provided by
the Secondary device.
During Discovery mode, the MCP2150 handles all
responses to the Primary device (see
without any communication with the Host Controller.
The Host Controller is inhibited by the CTS signal of the
MCP2150 from sending data to the MCP2150.
DS21655B-page 16
Note:
The MCP2150 is limited to a data rate of
115.2 kbaud.
Discovery Mode
Figure
2-10)
Preliminary
2.9.3.3
Once discovery has been completed, the Primary
device and MCP2150 (Secondary device) can freely
exchange data.
The MCP2150 can receive IR data or serial data, but
not both simultaneously. The MCP2150 uses a hard-
ware handshake to stop the local serial port from
sending data while the MCP2150 is receiving IR data.
Both the Primary device and the MCP2150 (Secondary
device) check to make sure that data packets are
received by the other without errors. Even when data is
required to be sent, the Primary and Secondary
devices will still exchange packets to ensure that the
connection hasn’t, unexpectedly, been dropped. When
the Primary device has finished, it then transmits the
close link command to the MCP2150 (Secondary
device). The MCP2150 will confirm the close link com-
mand and both the Primary device and the MCP2150
(Secondary device) will revert to the NDM state.
It is the responsability of the Host Controller program to
understand the meaning of the data received and how
the program should respond to it. It’s just as if the data
were being received by the Host Controller from a
UART.
Note:
Note:
Data loss will result if this hardware
handshake is not observed.
If the NCM mode is unexpectedly termi-
nated for any reason (including the Primary
device not issuing a close link command),
the MCP2150 will revert to the NDM state
10 seconds after the last frame has been
received.
Normal Connect Mode (NCM)
2002 Microchip Technology Inc.