Hardware Reference
In-Depth Information
+5 V
6.3 V
-
+
1.0
μ
F
C4
16
V
CC
1
C1+
2
V+
C1
1.0
μ
F
3
C1-
4
6
C2+
V-
1.0
μ
F
C3
C2
1.0
μ
F
DC-to-DC Converter
5
C2-
+5 V
T1
IN
T1
OUT
14
11
TTL/CMOS
inputs
D1
+5 V
EIA-232E
outputs
10
T2
IN
T2
OUT
7
TTL/CMOS
inputs
D2
12
R1
OUT
R1
IN
13
TTL/CMOS
outputs
R1
5 k
Ω
EIA-232E
inputs
R2
OUT
9
R2
IN
8
TTL/CMOS
outputs
R2
5 k
Ω
GND
15
Figure 9.17
■
Pin assignments and connections of the DS14C232
Adding a TIA-232 transceiver chip allows the HCS12 to use the SCI interface to com-
municate with the TIA-232 interface circuit. An example of such a circuit is shown in
Figure 9.18. A null-modem wiring is followed in this circuit.
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