easyAVR128™ Development Board Users Manual
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14
Figure 2.11:
DS1302 pin assignment
Num
Name
Function
1
VCC2
Power Supply Pins
2
X1,
32.768 kHz Crystal Pins
3
X2
32.768 kHz Crystal Pins
4
GND
Ground
5
RST
Reset
6
I/O
Data Input/Output
7
SCLK
Serial Clock
8
VCC1
Power Supply Pins
UART via RS.232
The UART (universal asynchronous receiver/transmitter) is one of the most common ways of exchanging data
between the MCU and peripheral components. It is a serial protocol with separate transmit and receive lines, and
can be used for full5duplex communication. Both sides must be initialized with the same baud rate, otherwise the
data will not be received correctly. RS5232 serial communication is performed through a 95pin SUB5D connector
and the microcontroller UART module. In order to enable this communication, it is necessary to establish a
connection between RX and TX lines on SUB5D connector and the same pins on the target microcontroller using
SW2
. Since
RS.232
communication voltage levels are different than microcontroller logic levels, it is
necessary to use a
RS.232
Transceiver circuit, such as
SP232
as shown on
Figure 2.12
.
Figure 2.12:
RS232 Module
In order to connect RS232 Module to the microcontroller you must turn SW1 “OFF” and turn the relevant Bit of
