Rabbit BL2020, User Manual

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User’s Manual 25
The transformer/connector assembly ground is connected to the BL2000 printed circuit
board digital ground via a 0
Ω
resistor “jumper,” R1, as shown in Figure 15.
Figure 15. Isolation Resistor R1
The factory default is for the 0
Ω
resistor “jumper” at R1 to be installed. In high-noise
environments, it may be useful to ground the transformer/connector assembly directly
through the chassis ground. This will be especially helpful to minimize ESD and/or EMI
problems. Once you have removed the 0
Ω
resistor “jumper,” R1, use a ring lug to attach
the BL2000 to the chassis ground, thereby grounding the transformer/connector assembly.
A convenient position for the ring lug has been provided at the top-left mounting screw
hole near the RJ-45 jack as shown in Figure 16.
Figure 16. Recommended Location for Ring Lug
3.4.4 Programming Port
The BL2000 has a 10-pin programming header labeled J5. The programming port uses the
Rabbit 2000’s Serial Port A for communication. Dynamic C uses the programming port to
download and debug programs.
The programming port is also used for the following operations.
•
Cold-boot the Rabbit 2000 after a reset.
•
Remotely download and debug a program over an Ethernet connection using the
RabbitLink EG2110.
•
Fast copy designated portions of flash memory from one Rabbit-based board (the
master) to another (the slave) using the Rabbit Cloning Board.
RJ-45 Ethernet Plug
R1
Chassis
Ground
Board
Ground
R1
C23
C17
J6
C20
D1
U4
Y3
Q2
C24
R151
R4
C16
R20
R6
R12
C10
J5
R19
C80
R16
R130
C19
R153
R154
R9
R13
R15
C1
Y2
R27
C22
C27
R28
U5
J2
J1
GND RST- IN1 IN0 485- 485+ RXD2 TXD2 RXD1 TXD1 +RAW +K
GND GND GND GND GND GN D
Remove R1
Add solder lug to
connect ground
wire to chassis