8051 ISP by COM Port
©2010 Nuvoton Technology Corporation. All Rights Reserved.
< Revision 5.02 > 6
2.2 Without an RS232 Transceiver in the Target System
To save an RS232 transceiver (e.g. MAX232) built in each target system, the user may use the
RS232 Cable
Adaptor
with an RS232 transceiver inside, as shown below.
R5
100
RI
VCC
COM Port
DCD
(PL)
RD
Note 1:
The I/O pins used for booting from LDROM may be P2.6&P2.7, P4.3, P3.6&P3.7, P4.0 or none.
(See the above table.)
U2
MAX232
1
3
4
5
11
10
12
9
2
6
14
7
13
8
15
16
C1+
C1-
C2+
C2-
T1_IN
T2_IN
R1_OUT
R2_OUT
V+
V-
T1_OUT
T2_OUT
R1_IN
R2_IN
GN
D
VC
C
C6
1u/16V
DSR
C4
1u/16V
CTS
(without RS232 Transceiver)
R1
47K
RXD
GND
R2
10K
UA RT
In te rfa ce
Pulled low
PC
RST
R3
4.7K
GND
To b oo t fro m LDRO M.
(S e e No te 1 )
P2.7
C5
1u/16V
DTR
8051 MCU
C2
10p
P3.0
VCC
GND
GND
RST
RTS
Q1
2N3906
RS232
Connector
RST
P3.0(RXD)
C7
1u/16V
P2.6
C3
10p
P2.6
TD
TXD
XTAL2
Target System
U1
VCC
/EA
General
Connector
RST
TXD
VCC
P1
Male DB9
5
9
4
8
3
7
2
6
1
RST
P3.1
X1
Fosc
Fo r re se t co n tro l .
(S ee No te 2)
RS232 Cable Adaptor
Note 2:
For "With Reset Control" configuration, Q1, R3 and R4 are needed.
For "Without Reset Control" configuration, Q1, R3 and R4 are not needed.
C1
2u
R4
10K
RS232
Transceiver
P2.6
P2.7
RS232 Cable
XTAL1
VCC
VCC
P3.1(TXD)
P2.7
RXD
VCC
