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

CP480 Wireless Communication and Networks lab

Universal Asynchronous Receiver Transmitter (UART)


This week's laboratory investigates RS-232 (or EIA 232) communication.


The RS-232 protocol has been around since 1962. Originally designed to basically connect a single "smart" device to a single "dumb" device, it is now still very commonly used to connect sensors to microprocessors or microcontrollers, and so will remain relevant for the forseable future. It's also one of the simplest serial protocols, and so it's easy to study. The Arduino board has a UART built-in, so it can be used to study RS-232 communications. Note: The UART pins on the Arduino will be at TTL levels, not at acceptable RS-232 levels.


  1. Become familiar with the hardware layer of a UART.



  1. Look at a very simple Arduino serial communication example.
  2. Note: The Arduino uses the serial port internally, so while you are programming you can't have the pins tied to each other or some other device. Only make those connections after you have finished uploading. (A later exercise will show you how to solve this problem.)
    Connect the Tx and Rx pins of your Arduino so it communicates with itself. Write a sketch to send a character every second and display received characters on the LCD.
    Hint: Start with the simple example and modify it to repeatedly send a character out from the UART.
  3. Show your pin assignments on the diagram.
Demonstrate and explain your results to the lab instructor


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Wilfrid Laurier University