Learn about the working principle of capacitive touch sensors and how they detect touch or proximity without physical contact. Explore their applications in various electronic devices.
The capacitive touch sensor (TTP223B) is a tiny gadget that can sense when you touch it or get close to it without actually making contact. It’s like magic! Do you know how some fancy phones and tablets can tell when you touch the screen? Well, this little sensor can do something similar, but on a smaller scale.
It’s really easy to use. You just connect it to your electronic project using a few wires, and it’s ready to go. When you touch the sensor or even just hover your finger near it, it sends a signal to your project, letting it know that something’s touching or getting close to it.
One cool thing about this sensor is that it doesn’t need a lot of power to work, so you can use it in projects that run on batteries without draining them too quickly. You can adjust how sensitive the sensor is, meaning you can decide how close or how hard you need to touch it for it to respond. This makes it versatile for different types of projects.
People use these sensors in all sorts of things, like making touch-sensitive buttons for gadgets, creating interactive art installations, or even building smart home devices that respond to your touch. It’s a neat little gadget that adds a touch of magic to your projects!
In this article, I will use a basic peace of code to explain how it works with Arduino Uno. I will try to control the built-in LED of the Arduino uno board using the capacitive touch sensor TTP223B. This basic example will help you to use this sensor in any other project to operate something based on the Input of the touch sensor.
How does a capacitive touch sensor work?
Every object has a property called capacitance, which is its ability to store electrical charge. When you bring an object close to another object, the capacitance between them changes. The TTP223B sensor has two electrodes, one acting as a transmitter and the other as a receiver. These electrodes are usually made of conductive material. Between these electrodes, there’s a dielectric medium (usually air or some non-conductive material).
When you touch the sensor or come close to it, your finger (or any conductive object) changes the capacitance between the electrodes and the dielectric medium. As your finger gets closer, the capacitance increases. This change in capacitance is detected by the circuitry. The TTP223B sensor has a built-in circuit that continuously monitors the capacitance. When the capacitance crosses a certain threshold, indicating a touch or proximity event, the sensor sends a signal (usually a digital HIGH or LOW) to the microcontroller or circuit connected to its output pin.
This output signal indicates to your electronic project that a touch or proximity event has occurred. You can then program your project to perform certain actions based on this signal, such as turning on a light, playing a sound, or displaying a message.
Pin description of Capacitive touch sensor
The TTP223B touch sensor typically has three pins. Here’s a breakdown of each pin:
- VCC (Power Supply): This pin is used to connect the sensor to the positive supply voltage, usually 3.3V or 5V, depending on the module’s specifications. It provides the necessary power for the sensor to operate.
- GND (Ground): This pin is connected to the ground (0V) of the power supply. It completes the circuit and provides the reference voltage for the sensor’s operation.
- OUT (Output): This pin is the output of the sensor module. When a touch or proximity event is detected, the OUT pin provides a digital signal indicating the event. The signal could be either HIGH or LOW, depending on the sensor’s configuration and the presence of a touch/proximity event.
To use the TTP223B capacitive touch sensor module, you’ll typically connect the VCC pin to a power source, the GND pin to ground, and the OUT pin to a digital input pin on a microcontroller (such as an Arduino). Always refer to the datasheet or documentation provided with your specific module for accurate pin descriptions and usage guidelines.
Required components
Circuit connection
As I mentioned earlier the capacitive touch sensor has three pins. The VCC pin of the touch sensor should be connected to the 5-volt power supply of the Arduino uno Board. The GND pin should be connected to the the GND pin of the Arduino uno board. The last pin OUT should be connected to the pin digital pin 2 of the Arduino uno board. This was all about the circuit connection, now let’s check the coding part.
Code
//Copyright (C) 2007 Free Software Foundation, Inc. <[email protected]>
//For more projects please visit://www.arduinounomagic.com
//How to use capacitive touch sensor with Arduino Uno
const int Touch_pin=2; //Connect the sensor at pin 2
void setup()
{
Serial.begin(9600);
pinMode(Touch_pin, INPUT); //Set sensor pin as input pin
pinMode(LED_BUILTIN, OUTPUT); //Set builtin LED pin as output pin
}
void loop() {
int state=digitalRead(Touch_pin); //Read the input at touch sensor
digitalWrite(LED_BUILTIN,state); //Operate the LED according to the input
Serial.print("State of builtin LED is:");//Print the state on LED, 1 as ON OR 0 as OFF
Serial.println(state);//Print 0 OR 1 state of LED
delay(1000);//Wait for 1 second
}Application
Touch-Sensitive Controls: TTP223B sensors are used in various electronic devices to create touch-sensitive controls, such as buttons and sliders. These sensors make buttons that you can touch instead of pressing. You find these in things like microwave ovens and TV remotes.
Proximity Detection: They are utilized for proximity detection in applications where physical contact is not desired, such as automatic faucets, hand dryers, and proximity switches.
Interactive Displays: These sensors are integrated into interactive displays and kiosks to provide user-friendly interfaces. Users can interact with the display by touching or hovering their fingers over specific areas.
Human-Machine Interfaces (HMIs): They play a crucial role in HMIs, allowing users to control and interact with machines and devices through touch-based inputs. Examples include touch panels in automotive dashboards, vending machines, and control panels.
Security Systems: These sensors are employed in security systems for touch-based authentication and access control. They can be used in keypad locks, security alarms, and biometric scanners.
Educational Projects: They are popular components in educational projects and experiments to teach concepts related to capacitive sensing, microcontroller programming, and sensor interfacing.
Gesture Recognition: These sensors can be used for simple gesture recognition applications, such as detecting swipes or taps. They are employed in devices like smartwatches and motion-activated lighting systems.
Art Installations: Artists use them to make interactive art installations where you can touch or wave your hand to change colors or sounds.
This was all about the capacitive touch sensor and its usage with Arduino uno.
Hope you learn something new from it.
Tell me in the comments what will you make using it to make life easier.
