P
P
P
S
S
S
-
-
-
3
3
3
0
0
0
1
1
1
S
S
S
e
e
e
r
r
r
i
i
i
e
e
e
s
s
s
19
5.7 I/O Ports
5.7.1 RS232
The RS232 Pin functions are described as below:
Pin No.
Abbreviation
Description
1
N/u
Null
2
TXD
Send
3
RXD
Receive
4
N/u
Null
5
GND
Ground
6
N/u
Null
7
N/u
Null
8
N/u
Null
9
N/u
Null
Figure 5-8a RS232 Pin Function
Figure 5-8b RS232 Pin Function