Raspberry Pi - Ultrasonic Sensor - Piezo Buzzer
This tutorial instructs you how to use Raspberry Pi and ultrasonic sensor to control piezo buzzer. In detail:
- Raspberry Pi produces sound when the object is near the ultrasonic sensor.
- Raspberry Pi halts the sound when the object is away from the ultrasonic sensor.
- Raspberry Pi plays a melody when the object is close to the ultrasonic sensor.
Hardware Preparation
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.
Additionally, some of these links are for products from our own brand, DIYables.
Additionally, some of these links are for products from our own brand, DIYables.
Overview of Piezo Buzzer and Ultrasonic Sensor
If you are unfamiliar with piezo buzzer and ultrasonic sensor (including pinout, how it works, and how to program), the following tutorials can provide you with more information:
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 make a piezo buzzer to generate a simple sound whenever the distance measured by ultrasonic sensor is below a threshold.
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 ultrasonic_sensor_buzzer.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-ultrasonic-sensor-piezo-buzzer
"""
import RPi.GPIO as GPIO
import time
# GPIO pin numbers for the ultrasonic sensor
TRIG_PIN = 14
ECHO_PIN = 15
# GPIO pin number for the piezo buzzer
BUZZER_PIN = 16
# Threshold distance in centimeters
THRESHOLD_DISTANCE_CM = 20
def get_distance():
GPIO.output(TRIG_PIN, GPIO.HIGH)
time.sleep(0.00001)
GPIO.output(TRIG_PIN, GPIO.LOW)
while GPIO.input(ECHO_PIN) == 0:
pulse_start = time.time()
while GPIO.input(ECHO_PIN) == 1:
pulse_end = time.time()
pulse_duration = pulse_end - pulse_start
speed_of_sound = 34300 # Speed of sound in cm/s
distance = (pulse_duration * speed_of_sound) / 2
return distance
GPIO.setmode(GPIO.BCM)
GPIO.setup(TRIG_PIN, GPIO.OUT)
GPIO.setup(ECHO_PIN, GPIO.IN)
GPIO.setup(BUZZER_PIN, GPIO.OUT)
GPIO.output(TRIG_PIN, GPIO.LOW)
GPIO.output(BUZZER_PIN, GPIO.LOW)
try:
while True:
distance = get_distance()
print(f"Distance: {distance:.2f} cm")
if distance < THRESHOLD_DISTANCE_CM:
GPIO.output(BUZZER_PIN, GPIO.HIGH) # Turn the buzzer on
else:
GPIO.output(BUZZER_PIN, GPIO.LOW) # Turn the buzzer off
except KeyboardInterrupt:
GPIO.cleanup()
- Save the file and run the Python script by executing the following command in the terminal:
python3 ultrasonic_sensor_buzzer.py
- Wave your hand in front of the sensor.
- Listen to the sound of 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 the distance is below a threshold.
Detailed Instructions
- Create a Python script file ultrasonic_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-ultrasonic-sensor-piezo-buzzer
"""
import RPi.GPIO as GPIO
import time
# GPIO pin numbers for the ultrasonic sensor
TRIG_PIN = 14
ECHO_PIN = 15
# GPIO pin number for the piezo buzzer
BUZZER_PIN = 16
# Threshold distance in centimeters
THRESHOLD_DISTANCE_CM = 20
# 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)
def get_distance():
GPIO.output(TRIG_PIN, GPIO.HIGH)
time.sleep(0.00001)
GPIO.output(TRIG_PIN, GPIO.LOW)
while GPIO.input(ECHO_PIN) == 0:
pulse_start = time.time()
while GPIO.input(ECHO_PIN) == 1:
pulse_end = time.time()
pulse_duration = pulse_end - pulse_start
speed_of_sound = 34300 # Speed of sound in cm/s
distance = (pulse_duration * speed_of_sound) / 2
return distance
GPIO.setmode(GPIO.BCM)
GPIO.setup(TRIG_PIN, GPIO.OUT)
GPIO.setup(ECHO_PIN, GPIO.IN)
GPIO.setup(BUZZER_PIN, GPIO.OUT)
GPIO.output(TRIG_PIN, GPIO.LOW)
GPIO.output(BUZZER_PIN, GPIO.LOW)
try:
while True:
distance = get_distance()
print(f"Distance: {distance:.2f} cm")
if distance < THRESHOLD_DISTANCE_CM:
play_jingle_bells()
except KeyboardInterrupt:
GPIO.cleanup()
- Save the file and run the Python script by executing the following command in the terminal:
python3 ultrasonic_sensor_buzzer_Jingle_Bells.py
- Move your hand in front of the sensor.
- Hear the tune played by the piezo buzzer.
Code Explanation
Check out the line-by-line explanation contained in the comments of the source code!