Raspberry Pi - Touch Sensor - LED
This tutorial instructs you how to use the Raspberry Pi and touch sensor to control the LED. We will learn two different applications:
Application 1 - The LED state is synchronized with the touch sensor state. In detail:
- Raspberry Pi turns on the LED when the touch sensor is being touched.
- Raspberry Pi turns off the LED when the touch sensor is NOT being touched.
Application 2 - The LED state is toggled each time the touch sensor is touched. More specifically:
- If Raspberry Pi detects that the touch sensor has been touched (changing from LOW to HIGH), it will turn ON the LED if it's currently OFF, or turn OFF the LED if it's currently ON.
- Releasing the touch sensor does not affect to the LED state.
Hardware Preparation
| 1 | × | Raspberry Pi 4 Model B | |
| 1 | × | Touch Sensor | |
| 1 | × | LED | |
| 1 | × | 220 ohm resistor | |
| 1 | × | Breadboard | |
| 1 | × | Jumper Wires | |
| 1 | × | (Optional) Screw Terminal Adapter for Raspberry Pi |
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Overview of LED and Touch Sensor
If you are unfamiliar with LED and touch sensor (including pinout, operation, and programming), the following tutorials can help:
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Application 1 - The LED state is in sync with the touch sensor state
Detailed Instructions
- Make sure you have Raspbian or any other Raspberry Pi compatible operating system installed on your Pi.
- Make sure your Raspberry Pi is connected to the same local network as your PC.
- Make sure your Raspberry Pi is connected to the internet if you need to install some libraries.
- If this is the first time you use Raspberry Pi, See how to set up the Raspberry Pi
- Connect your PC to the Raspberry Pi via SSH using the built-in SSH client on Linux and macOS or PuTTY on Windows. See to how connect your PC to Raspberry Pi via SSH.
- Make sure you have the RPi.GPIO library installed. If not, install it using the following command:
sudo apt-get update
sudo apt-get install python3-rpi.gpio
- Create a Python script file touch_sensor_led.py and add the following code:
# This Raspberry Pi code was developed by newbiely.com
# This Raspberry Pi code is made available for public use without any restriction
# For comprehensive instructions and wiring diagrams, please visit:
# https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-touch-sensor-led
import RPi.GPIO as GPIO
import time
# Set the GPIO mode to BCM (Broadcom SOC channel numbering)
GPIO.setmode(GPIO.BCM)
# Set the pin number connected to the touch sensor
TOUCH_PIN = 15
# Set the pin number connected to the LED
LED_PIN = 16
# Set the GPIO pin as an input
GPIO.setup(TOUCH_PIN, GPIO.IN)
# Set the GPIO pin as an output for the LED
GPIO.setup(LED_PIN, GPIO.OUT)
try:
while True:
# Read the state from the touch sensor
touch_state = GPIO.input(TOUCH_PIN)
if touch_state == GPIO.HIGH:
# Sensor touched, turn on the LED
GPIO.output(LED_PIN, GPIO.HIGH)
else:
# Sensor not touched, turn off the LED
GPIO.output(LED_PIN, GPIO.LOW)
time.sleep(0.1) # A small delay to debounce the input
except KeyboardInterrupt:
# Clean up the GPIO settings on program exit
GPIO.cleanup()
- Save the file and run the Python script by executing the following command in the terminal:
python3 touch_sensor_led.py
- Touch the touch sensor and hold it for a few seconds.
- Check out the change in the LED's condition. You will see that the LED state is in sync with the touch sensor state.
The script runs in an infinite loop continuously until you press Ctrl + C in the terminal.
Code Explanation
Check out the line-by-line explanation contained in the comments of the source code!
Application 2 - Touch Sensor toggles LED
Detailed Instructions
- Create a Python script file touch_sensor_toggle_led.py and add the following code:
# This Raspberry Pi code was developed by newbiely.com
# This Raspberry Pi code is made available for public use without any restriction
# For comprehensive instructions and wiring diagrams, please visit:
# https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-touch-sensor-led
import RPi.GPIO as GPIO
import time
# Set the pin number connected to the touch sensor
TOUCH_PIN = 15
# Set the pin number connected to the LED
LED_PIN = 16
# Set GPIO mode and initial LED state
GPIO.setmode(GPIO.BCM)
GPIO.setup(TOUCH_PIN, GPIO.IN) # Touch sensor input
GPIO.setup(LED_PIN, GPIO.OUT) # LED output
led_state = False # LED is initially OFF
try:
prev_touch_state = GPIO.input(TOUCH_PIN)
while True:
touch_state = GPIO.input(TOUCH_PIN)
if touch_state != prev_touch_state:
if touch_state == GPIO.HIGH: # Check if touch sensor is being touched
led_state = not led_state # Toggle the LED state. If it was ON, it becomes OFF, and vice versa.
GPIO.output(LED_PIN, led_state) # Apply the updated LED state
# Debounce by adding a small delay
time.sleep(0.2)
prev_touch_state = touch_state
except KeyboardInterrupt:
GPIO.cleanup()
- Save the file and run the Python script by executing the following command in the terminal:
python3 touch_sensor_toggle_led.py
- Touch and release the touch sensor several times.
- Check out the change in the LED's state.
You will see that the LED state is toggled once each time the touch sensor is touched.