How to use evive's Capacitive Touch Inputs

About This Tutorial
This tutorial discusses what are capacitive touch sensors, evive's capacitive touch input, and how to control the touch sensors in evive, with the help of an Arduino IDE sketch.
Tutorial Info
Programming Platform:
Difficulty:
Estimated Time (hrs):
2.5

Components Required

Introduction

Touch sensors, as the name suggests, sense, or detect a touch, i.e. a physical contact made by something, typically a human. Unlike a button or switch, touch sensors are more sensitive, and are often able to respond differently to different kinds of touch, such as tapping, and swiping.

Working Principle

A touch sensor works in a way similar to a tactile (momentary) switch. When someone or something touches the sensor, there is a contact between the touch surface and the lower surface of the sensor and the circuit is complete. As a result current flows through the circuit. When there is no contact between the two surfaces the circuit is open and no current flows.

Capacitive Touch Sensor

Capacitive touch sensors are one of the most commonly used type of touch sensors. They are widely used in portable electronic devices such as Smartphones and MP3 players. The capacitive touch sensors are designed keeping in mind the fact that human beings have a certain amount of free charge. The sensor, when not touched has a certain amount of charge that is the reference. Whenever you touch the surface of the sensor, the amount of charge at the surface goes beyond the set reference and the sensor is activated.

evive has 12 touch inputs, which are interfaced via the MPR121 chip using SPI interface.

These touch inputs can be attached to any fruit or metal surface and can be used as inputs.  These inputs, otherwise complicated to interface, but can easily be interfaced  with Arduino IDE using the Adafruit MPR121 library.evive Capacitive Touch Input Pinouts

Example

In this example we will connect a banana or any other fruit  to channel 1 and detect if someone has touched the banana or not and display the result accordingly on the TFT Screen.

Below is the Arduino IDE sketch:

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