CP480 Wireless Communication and Networks lab
Serial Bluetooth module (UART)
This week's laboratory investigates
(or EIA 232) communication.
One of the limitations of the Arduino is that if two devices need
serial communication, there is a problem. Fortunately, there is a
SoftwareSerial library that allows a UART to be simulated on other
pins. You'll use this for the Bluetooth module since you
still need to connect to the console.
Note: The Bluetooth module is designed for
"TTL serial" operation, which means its pins
will be at TTL levels, not at acceptable RS-232 levels.
Since the UART pins on
the Arduino are also at
TTL levels, this makes the interfacing simpler than it would be
- Become familiar with real serial communication using the
SoftwareSerial library emulating a
UART with an external device.
- Arduino Uno board, with LCD display
- Bluetooth module
Demonstrate and explain your results to the
- Look at one of the SoftwareSerial examples and figure out how
to set up pins to use for this purpose.
The comments at the beginning of the sketch should indicate
pins that can be used. Choose two
for the software UART and connect them together as in the previous
Modify your previous sketch to
send characters out the TX and in the RX
echo the received
characters to the LCD
display. This should be a pretty minor modification to the
- Answer these questions before you start connecting the
Bluetooth module. (Consult the data sheet.)
- What supply voltage does the Bluetooth module use? Which
Arduino pin provides that?
- What Arduino pins will you use for the software serial port?
- What baud rate does the Bluetooth module use? How many data
and stop bits?
- What pin has data coming out of the Bluetooth module? Does
need to go into the TxD or RxD pin on the Arduino? In other
words, when connecting to serial devices, do TxD and RxD of
both match, or do they reverse?
- Connect the Arduino to the Bluetooth module.
- Once you have it working, create a sketch that incorporates
the LCD software as well so you can display the Bluetooth module
to the LCD display instead of to the hardware UART.
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