Using a VEX Controller for Electronic Experiments
By Daniel Ramirez
This project does require that some firmware be downloaded to the microcontroller using the Innovations First, Inc. (IFI), Bootloader. I will provide the firmware as a hex file so that readers who only
want to build and run the project can do so without having
to do any C programming. However, I will also provide C
source code for those who do wish to know how the
embedded firmware works and want to modify it.
What the VEX?
It is not generally known that a VEX Construction Set can be used as a platform to
carry out various educational electronic experiments. Performing the experiments
that will be described in this series of articles will help you understand the basic
electronics that are used to read digital and analog inputs, and to control digital
and analog devices connected to a standard VEX microcontroller. A VEX
microcontroller will be the primary component used to carry out these experiments
utilizing its versatile I/O ports as will be demonstrated here. The VEX
microcontroller is well designed and very robust, and can stand up to harsh
environments using internal protection circuitry which makes it perfect for the first
experiment described here.
Why would you want to interface non-VEX components
to the VEX microcontroller? Especially since sensors and
motors sold by IFI conveniently plug into the digital and
analog I/O ports. There are some sensors that IFI currently
does not sell, like temperature and humidity sensors, and
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GPS sensors. These units might require a high speed serial
protocol such as SPI or I2C that is currently not supported
by the standard VEX chip since it is already using the SPI
I have found other instances where I needed to drive a
stepper motor and high speed DC motor. A solution to this
dilemma is to build your own circuits that read the needed
sensors and drive the external motors. I will be showing you
simple experiments that allow you to interface other kinds
of non-VEX electronic components including numeric LED
displays, LCD displays, keypads, temperature sensors, DC
motors, and stepper motors.
The experience gained by understanding just what
controllers can do and what their limitations are is a big
advantage both for learning and in contest environments.
Remember, modifications to the VEX Microcontroller and