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9
RS232 Serial Ports
Two RS232 serial ports are available on the MINI-MAX/ARM. IC4 converts micro-controller’s RXD and TXD
pins to/from RS232 levels. IC4 has an internal circuit that gen/- 10 Volts for RS232 logic levels. First
RS232 port is wired to a 10-pin header (J4). Second RS232 port is wired to a 6-pin header (J5).
There are two options. First option is two RS232 ports, each port has TXD and RXD lines only. Second option
is a single RS232 interface with TXD, RXD, CTS and RTS signals on J4. For this purpose, 2 jumpers must be
set between pins 5, 6 and 1, 2 of J5.
Figure 4
First serial port also serves downloading procedure to the MINI-MAX/ARM board. DSR is used by an external
host to switch between BOOT and RUN modes.
1st RS232 Serial Port (J4)
Signal
Pin
Pin
Signal
NC (Not Connected)
1
2
DSR_0 (BOOT)
RXD_0 (RX0 input)
3
4
RTS_0* (RTS0 output)
TXD_0 (TX0 output)
5
6
CTS_0* (CTS0 input)
NC (Not Connected)
7
8
NC (Not Connected)
Ground (GND)
9
10
NC (Not Connected)
Table 3
Note. RTS_0 /CTS_0 lines can be provided only installing 2 jumpers to J5.
2nd RS232 Serial Port (J5)
Signal
Pin
Pin
Signal
RXD_1 (RX input)
1
2
CTS_0* (CTS0 input)
Ground (GND)
3
4
NC (Not Connected)
TXD_1 (TX output)
5
6
RTS_0* (RTS0 output)
Table 4