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PDA Robotics
the microcontroller or the microprocessor is unable to drive the sup-
ply current required by the transceiver, a low-cost SOT23 pnp transis-
tor can be used to switch voltage on and off from the regulated power
supply. The additional component cost is minimal, and saves the sys-
tem designer additional power supply costs.
The 5-V regulator on the main board powers the transceiver in PDA
Robot.

The Microchip MCP2150 Plug and Play IrDA

The MCP2150 is a cost-effective, low pin-count (18-pin), easy to use
device for implementing IrDA standard wireless connectivity. The
MCP2150 provides support for the IrDA standard protocol “stack,”
plus bit encoding/decoding.
The serial interface baud rates are user selectable to one of four IrDA
standard baud rates between 9600 baud and 115.2 kbaud (9600, 19200,
57600, 115200). The IR baud rates are user selectable to one of five
IrDA standard baud rates between 9600 baud and 115.2 kbaud (9600,
19200, 37400, 57600, 115200). The serial interface baud rate will be
specified by the BAUD1:BAUD0 pins, while the IR baud rate is speci-
fied by the primary device (during Discover phase). This means that
the baud rates do not need to be the same.
The MCP2150 operates in data terminal equipment (DTE) applications
and sits between a UART and an IR optical transceiver. The MCP2150
encodes an asynchronous serial data stream, converting each data bit
to the corresponding IR formatted pulse. IR pulses received are decod-
ed and then handled by the protocol handler state machine. The pro-
tocol handler sends the appropriate data bytes to the host controller in
UART formatted serial data.

The MCP2150 supports point-to-point applications, that is, one pri-
mary device and one secondary device. The MCP2150 operates as a
secondary device. It does not support multipoint applications. Sending
data using IR light requires some hardware and the use of specialized
communication protocols. These protocol and hardware requirements
are described, in detail, by the IrDA standard specifications.

The chapters dealing with the software for the PDAs explain, in detail,
how to implement the specialized communication protocols.

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