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2.1.3 Touch Switch Module

Introduction

In this project, you will learn about touch switch module. It can replace the traditional kinds of switch with these advantages: convenient operation, fine touch sense, precise control and least mechanical wear.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Raphael Kit	337	Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
GPIO Extension Board	BUY
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
LED	BUY
Touch Switch Module	BUY

Schematic Diagram

Experimental Procedures

Step 1: Build the circuit.

Step 2: Change directory.

cd ~/raphael-kit/python-pi5

Step 3: Run.

sudo python3 2.1.3_TouchSwitch_zero.py

While the code is running, the red LED lights up; when you tap on the touch switch module, the yellow LED turns on.

Warning

If there is an error prompt RuntimeError: Cannot determine SOC peripheral base address, please refer to If gpiozero doesn’t work.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like raphael-kit/python-pi5. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from gpiozero import LED, Button  # Import LED and Button classes from gpiozero
from time import sleep  # Import sleep for delay

# Initialize touch sensor (Button) on GPIO pin 17, pull-up resistor disabled
touch_sensor = Button(17, pull_up=False)  # Suitable for sensors that pull the pin low when pressed

# Initialize LED1 and LED2 connected to GPIO pins 22 and 27 respectively
led1 = LED(22)  # LED1 connected to GPIO pin 22
led2 = LED(27)  # LED2 connected to GPIO pin 27

try:
    # Continuously monitor the state of the touch sensor and control LEDs accordingly
    while True:
        if touch_sensor.is_pressed:  # Check if the touch sensor is pressed
            print('You touch it!')  # Output message indicating sensor activation
            led1.off()  # Turn off LED1
            led2.on()   # Turn on LED2
        else:  # If the sensor is not pressed
            led1.on()   # Turn on LED1
            led2.off()  # Turn off LED2

        sleep(0.5)  # Pause for 0.5 seconds before rechecking the sensor state

except KeyboardInterrupt:
    # Handle a keyboard interrupt (Ctrl+C) for a clean exit from the loop
    pass

Code Explanation

1. This line sets the script to run with Python 3. It imports LED and Button from gpiozero for controlling GPIO devices, and sleep from time for delays.

   #!/usr/bin/env python3
   from gpiozero import LED, Button  # Import LED and Button classes from gpiozero
   from time import sleep  # Import sleep for delay
   

2. Initializes a touch sensor (as a Button) on GPIO pin 17 with pull-up disabled, and two LEDs on GPIO pins 22 and 27.

   # Initialize touch sensor (Button) on GPIO pin 17, pull-up resistor disabled
   touch_sensor = Button(17, pull_up=False)  # Suitable for sensors that pull the pin low when pressed
   
   # Initialize LED1 and LED2 connected to GPIO pins 22 and 27 respectively
   led1 = LED(22)  # LED1 connected to GPIO pin 22
   led2 = LED(27)  # LED2 connected to GPIO pin 27
   

3. The main loop checks the state of the touch sensor. When touched, LED2 turns on and LED1 off; when not touched, LED1 is on and LED2 off. The loop repeats every 0.5 seconds. Catches a KeyboardInterrupt (like Ctrl+C) to allow for graceful script termination.

   try:
       # Continuously monitor the state of the touch sensor and control LEDs accordingly
       while True:
           if touch_sensor.is_pressed:  # Check if the touch sensor is pressed
               print('You touch it!')  # Output message indicating sensor activation
               led1.off()  # Turn off LED1
               led2.on()   # Turn on LED2
           else:  # If the sensor is not pressed
               led1.on()   # Turn on LED1
               led2.off()  # Turn off LED2
   
           sleep(0.5)  # Pause for 0.5 seconds before rechecking the sensor state
   
   except KeyboardInterrupt:
       # Handle a keyboard interrupt (Ctrl+C) for a clean exit from the loop
       pass