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6.4 Electrical Characteristics(1) RS-232C I/O signals (RD/TD/DTR)
•Input (RD)
Mark = (−8 V): Stop bit
Space = (+8 V): Start bit
•Output (TD, DTR)
Mark = (−8 V): For Busy
Space = (+8 V): For Ready
(2) TTL circuit
Input (RESET)
2:TD
SP232ENC
20:DTR
3:RD
25:RESET
12
9
R1 in
R2 in
R1 out
R2 out
13
8
14
7
T1 in
T2 in
T1 out
T2 out
11
10
C1+
C1−
1
3
16
VCC
VCC
00
104
104
104
104
GND
104
GND
15
C2+
C2−
4
5
V+
V−
2
6
23:RESET(L)
7:GND
1:FG
(HC04 or equivalent)
RESET23 :
VCC
104
3.3k
Set to LOW when reset.