SENSORS/ACTUATORS

Raspberry Pi - Touch Sensor - Piezo Buzzer

This tutorial instructs you how to use Raspberry Pi and touch sensor to control piezo buzzer. In detail:

Raspberry Pi produces a sound when the touch sensor is touched.
Raspberry Pi ceases making noise when the touch sensor is not engaged.
Raspberry Pi plays a melody when the touch sensor is touched.

Hardware Preparation

1	×	Raspberry Pi 4 Model B
1	×	Touch Sensor
1	×	Piezo Buzzer
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)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Overview of Piezo Buzzer and Touch Sensor

If you are unfamiliar with piezo buzzer and touch sensor (including pinout, functionality, and programming), the following tutorials can help:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Raspberry Pi Code - Simple Sound

In this section, we'll program Raspberry Pi to trigger a piezo buzzer to generate a simple sound whenever you touch your finger on the touch sensor.

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_buzzer.py and add the following code:

Save the file and run the Python script by executing the following command in the terminal:

python3 touch_sensor_buzzer.py

Place your finger on the touch sensor and hold it there for several seconds.
Listen to the sound coming from the piezo buzzer.

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!

Raspberry Pi plays the melody of the song

In this section, we'll program Raspberry Pi to trigger a piezo buzzer to play the song "Jingle Bells" when you place your finger on the touch sensor.

Detailed Instructions

Create a Python script file touch_sensor_buzzer_Jingle_Bells.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-piezo-buzzer import RPi.GPIO as GPIO import time # Set the GPIO mode (BCM or BOARD) GPIO.setmode(GPIO.BCM) # Define the GPIO pin number to which the buzzer is connected BUZZER_PIN = 18 # Define the GPIO pin number to which the touch sensor is connected TOUCH_SENSOR_PIN = 16 # Set up the GPIO pins GPIO.setup(BUZZER_PIN, GPIO.OUT) GPIO.setup(TOUCH_SENSOR_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP) # Constants for note names and their corresponding frequencies C4 = 261 D4 = 293 E4 = 329 F4 = 349 G4 = 392 A4 = 440 B4 = 493 # Dictionary to map numeric values to note names note_names = { C4: "C4", D4: "D4", E4: "E4", F4: "F4", G4: "G4", A4: "A4", B4: "B4", } # List of notes in the "Jingle Bells" melody melody = [ E4, E4, E4, E4, E4, E4, E4, G4, C4, D4, E4, F4, F4, F4, F4, F4, E4, E4, E4, E4, E4, D4, D4, E4, D4, G4 ] # List of note durations (in milliseconds) note_durations = [ 200, 200, 400, 200, 200, 400, 200, 200, 200, 200, 200, 200, 200, 400, 200, 200, 200, 200, 200, 200, 200, 200, 200, 400, 200, 200 ] # Pause duration between notes (in milliseconds) pause_duration = 300 def play_tone(pin, frequency, duration): # Calculate the period based on the frequency period = 1.0 / frequency # Calculate the time for half of the period half_period = period / 2.0 # Calculate the number of cycles for the given duration cycles = int(duration / period) for _ in range(cycles): # Set the GPIO pin to HIGH GPIO.output(pin, GPIO.HIGH) # Wait for half of the period time.sleep(half_period) # Set the GPIO pin to LOW GPIO.output(pin, GPIO.LOW) # Wait for the other half of the period time.sleep(half_period) def play_jingle_bells(): for i in range(len(melody)): note_duration = note_durations[i] / 1000.0 note_freq = melody[i] note_name = note_names.get(note_freq, "Pause") print(f"Playing {note_name} (Frequency: {note_freq} Hz) for {note_duration} seconds") play_tone(BUZZER_PIN, note_freq, note_duration) time.sleep(pause_duration / 1000.0) GPIO.output(BUZZER_PIN, GPIO.LOW) try: while True: touch_state = GPIO.input(TOUCH_SENSOR_PIN) if touch_state == GPIO.HIGH: play_jingle_bells() # Allow the user to stop the buzzer by pressing Ctrl+C except KeyboardInterrupt: GPIO.output(BUZZER_PIN, GPIO.LOW) GPIO.cleanup()

Save the file and run the Python script by executing the following command in the terminal:

python3 touch_sensor_buzzer_Jingle_Bells.py

Touch your finger on the touch sensor.
Hear the tune from the piezo buzzer.

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial

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