Using the VEX IQ Touch LED

Description

This sensor can detect capacitive touch, such as the touch of a finger. It can also be set to display many colors.

The following article will cover:

  • How the Touch LED Works
  • Common Uses of the Touch LED
  • Uses of the Touch LED on a Competition Robot

The VEX IQ Touch LED Sensor is included in the VEX IQ Super Kit but it can also be purchased here.


How the Touch LED Works: Detecting Touches

The Touch LED uses technology that detects small changes in the physical properties of its surroundings. It does this by measuring capacitance.

Capacitance is a physical property of any object. It can be affected by what a thing is made of, or what it's shaped like. The air around us has a certain capacitance, an electrical circuit has a certain capacitance, and your body has a certain capacitance.

The Touch LED can detect this capacitance by sending an electrical signal and noting what comes back. In the image you can see that when the button is pressed, the purple response signal changes compared to the blue input signal. If the response signal is just right, it means there is a finger present, and the Touch LED sends a message back to the Robot Brain which means that it's being touched.

One advantage of checking for touch in this way is that a change in capacitance does not require that you touch the circuit directly, only that you get very close. As a result, the electronics in the Touch LED can be shielded with plastic and packaged along with more electronics, like the multi-color LEDs inside the device.


Common Uses of the Touch LED:

  • This sensor can be used to start or pause a program at the touch of a finger.

  • This sensor can be used to display different colors at different parts of a program.


Uses of the Touch LED on a Competition Robot:

  • The Touch LED can be used to start a running program with a finger press.
  • Team members can see when different sections of an autonomous program are running by programming the Touch LED to display a unique color for each section.
  • Using the Touch LED can also be used to help troubleshoot programming problems if issues occur.