User`s manual

User’s Manual 33
C.2 Serial Communication
The RabbitLink uses two serial ports of the Rabbit 2000 microprocessor.
C.2.1 Serial Programming Ports
The RabbitLink board has two 10-pin programming headers labeled J8 and J9. The
PROG
IN
(J8) header uses the Rabbit 2000’s serial port A for communication, and PROG OUT (J9)
uses serial port B. The Rabbit 2000 startup-mode pins (SMODE0, SMODE1) are pre-
sented to PROG IN so that an externally connected device can force a start-up in an external
bootstrap mode when the PROG connector on the programming cable is used.
NOTE: Refer to the Rabbit 2000 Microprocessor User’s Manual for more information on
the bootstrap mode.
The PROG IN header is used with the DIAG connector on the programming cable to config-
ure network addresses for the RabbitLink. This connection transmits information to and
from a PC running a terminal emulation program. The PROG IN header is also used with
the PROG connector on the programming cable. With this connection, you can download
firmware to the RabbitLink and also reset default network addresses.
The PROG OUT header is connected with the program download cable to the programming
port of the Rabbit-based target. This connection allows the RabbitLink to transmit infor-
mation to and from the Rabbit-based target. A network-enabled PC running Dynamic C or
the RFU communicates with the RabbitLink using the RabbitLink’s Ethernet connection.
These 2 connections give you the power to remotely download and/or debug an applica-
tion on a Rabbit-based target.
C.2.2 Ethernet Port
The 10 Mbps twisted-pair Ethernet system allows segment lengths of approximately 100 m
for voice-grade twisted-pair telephone wiring. The maximum segment length may be
shorter or longer than this, depending on the quality of the twisted-pair cabling in your
system. While the 10Base-T system is designed to use voice-grade telephone cable, higher
quality Category 5 cables, connectors, and wire terminating devices provide the best pos-
sible signal carrying system for 100 Mbps Ethernet media systems.
The 10Base-T media system uses two pairs of wires. They are terminated in an 8-pin (RJ-
45 style) connector. Four pins of the 8-pin connector are used as shown in Figure C-2. The
transmit and receive data signals on each pair of a 10Base-T segment are polarized, with
one wire of each signal pair carrying the positive (+) signal, and the other carrying the
negative (-) signal.