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RabbitCore RCM3750
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B.2.5 Serial Communication
As shipped, the RCM3720 Prototyping Board has no RS-232 chip installed, and so no
RS-232 communication is possible. An optional through-hole RS-232 chip may be
installed at U1
or
a surface-mount RS-232 chip may be installed at U3. Five correspond-
ing through-hole or surface-mount 0.1 µF capacitors must also be installed. Figure B-16
shows where to install the RS-232 chip and its associated capacitors for the two options.
Figure B-16. Locations Where to Install RS-232 Chip and Capacitors
NOTE:
Only one RS-232 circuit needs to be stuffed.
Rabbit Semiconuctor offers the through-hole RS-232 chip and 0.1 µF capacitors for sale in
a subassembly with some other parts (part number 151-0082). Contact your Rabbit Semi-
conuctor sales representative or authorized distributor for more information.
RS-232 serial communication on the RCM3720 Prototyping Board is supported by the
RS-232 transceiver you installed at U1 or U3. This transceiver provides the voltage out-
put, slew rate, and input voltage immunity required to meet the RS-232 serial communica-
tion protocol. Basically, the chip translates the Rabbit 3000’s signals to RS-232 signal
levels. Note that the polarity is reversed in an RS-232 circuit so that a +5 V output
becomes approximately -10 V and 0 V is output as +10 V. The RS-232 transceiver also
provides the proper line loading for reliable communication.
+5V
VBA
T
PD5
/IORD
PG6
PE0
PE4
PE7
PC2
PB3
PB0
PF1
PA
1
PA
3
PA
5
PA
7
PC0
PF6
PF4
PB5
GND
GND
/RES
PD4
/IOWR
PG7
PE1
PE5
PC3/PG3
PC1/PG2
PF7
PF5
PB7
PB4
PB2
PF0
PA
0
PA
2
PA
4
PA
6
GND
GND
/RES
PD4
/I
OWR
PG7
PE1
PE5
PC3/PG3
PC1/PG2
PF1
PF5
PB7
PB4
PB2
PF0
PA
0
PA
2
PA
4
PA
6
+5V
VBA
T
PD5
/IO
RD
PG6
PE0
PE4
PE7
PC2
PC0
PF6
PF4
PB5
PB3
PB0
PF1
PA
1
PA
3
PA
5
PA
7
J4
PF4
PB7
PF6
PF7
SW1
SW2
DS1
DS2
J3
J1
J6
U2
C7
C2
C9 D1
C1
C14
U3
C1
1
C12
C13 C10
R6
J2
BT1
RCM3720 PROTOTYPING BOARD
CX1
CX2
RX7
RX8
RX9
RX10
RX11
RX12
RX13
RX14
RX15
RX16
RX5
CX14
CX13
RX6
UX9
CX12
CX10
CX5
CX3
CX6
UX7
CX4
RX1
CX9
RX2
UX8
RX4
CX11
RX3
UX3
UX2
UX1
CX8
CX7
J5
+5V
GND
PF7
R3
D2
R2
U1
C8
C5
C4
C6
C3
R4
R1
S3
PF4
R5
PB7
S2
S1
RESE
T
POWER
PF6
DS2
DS1
DS3
1
3
4
2
1
3
2
4
1
2
4
3
U1
C8
C4
C6
C3
C5
Header J3
Surface-Mount Option
SP232ECT/EET chip
(Z-World part no. 660-0188)
five 0.1 µF capacitors
(Z-World part no. 321-0004)
C14
U3
C1
1
C12
C13 C10
232ECP
SP232ECP chip
(Z-World part no. 660-0006)
five 0.1 µF capacitors
(Z-World part no. 300-0005)
Through-Hole Option
DO NOT INSTALL
BOTH OPTIONS!
Summary of Contents for RabbitCore
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