6
Keypad connector
8 pins of AT89C51ED2 are connected to the Keypad Connector. Matrix keypads such 3 by 5 or 4 by 4
can be connected directly to the connector. 5 Volt and Ground power lines are also available on the
connector.
The keypad connector can also be used as a general purpose 8-pin input/output port.
Table 1 shows the pin assignments for the Keypad connector.
Keypad Connector (J1)
Name
Signal
Pin
VCC
+5V
10
GND
Ground
9
P2.7
In/Out
8
P2.6
In/Out
7
P2.5
In/Out
6
P2.4
In/Out
5
P2.3
In/Out
4
P2.2
In/Out
3
P2.1
In/Out
2
P2.0
In/Out
1
Table 1
Asynchronous Serial Port
One asynchronous RS232 serial port is available on a 9-pin male D connector J2. RS232 port can be
used by both a PC for In-circuit Programming of the T89C51ED2 through PIC16F818 microcontroller
and by T89C51ED2 for data communications.
RTS line is used by an external host such as a PC to put MINI-MAX/51-C2 in program or run mode.
Therefore, user applications must not use RTS.
Many users try to use HyperTerminal to send some data bytes to a Mini-Max/51-C2 board.
HyperTerminal forces a board to PROGRAM MODE by RTS line. AT89C51ED2 program can not be
executed if HyperTerminal occupies RS-232 port. We advise to use Micro-IDE terminal window instead
of HyperTerminal.
Table 2 shows the pin assignments for RS232 serial port connector
Serial Port Connector (J2)
Name
Signal
Pin
-
Not Connected (NC)
1
TXD
MM51C2 Input
2
RXD
MM51C2 Output
3
DTR
NC or Vcc from MM51C2
4
GND
GND
5
-
NC
6
CTS
CTS
(MM51C2 Output)
7
RTS
RTS
(MM51C2 Input)
8
-
NC
9
Table 2
Summary of Contents for MINI-MAX/51-C2
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