Pages created and updated by Terry Sturtevant Date Posted: September 19, 2017

CP480 Wireless Communication and Networks lab

Serial Bluetooth module (UART)


This week's laboratory investigates RS-232 (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 otherwise.


  1. Become familiar with real serial communication using the SoftwareSerial library emulating a UART with an external device.



  1. 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 exercise. Modify your previous sketch to send characters out the TX and in the RX pins and echo the received characters to the LCD display. This should be a pretty minor modification to the previous sketch.
  2. Answer these questions before you start connecting the Bluetooth module. (Consult the data sheet.)
    1. What supply voltage does the Bluetooth module use? Which Arduino pin provides that?
    2. What Arduino pins will you use for the software serial port?
    3. What baud rate does the Bluetooth module use? How many data and stop bits?
    4. What pin has data coming out of the Bluetooth module? Does that 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?
  3. Connect the Arduino to the Bluetooth module.
  4. Once you have it working, create a sketch that incorporates the LCD software as well so you can display the Bluetooth module information to the LCD display instead of to the hardware UART.
Demonstrate and explain your results to the lab instructor


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