Raspberry Pi - Ultrasonic Sensor - LED
This tutorial instructs you how to use Raspberry Pi and ultrasonic sensor to control LED. In detail:
- Raspberry Pi turns on the LED when detecting the object near the ultrasonic sensor
- Raspberry Pi turns off the LED when detecting the object far from 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 LED and Ultrasonic Sensor
If you are unfamiliar with LED and ultrasonic 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
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_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-ultrasonic-sensor-led
"""
import RPi.GPIO as GPIO
import time
# Set the GPIO mode to BCM
GPIO.setmode(GPIO.BCM)
# Define the GPIO pins for the ultrasonic sensor
TRIG_PIN = 14
ECHO_PIN = 15
# Define the GPIO pin for the LED
LED_PIN = 16
# Set up the ultrasonic sensor pins
GPIO.setup(TRIG_PIN, GPIO.OUT)
GPIO.setup(ECHO_PIN, GPIO.IN)
# Set up the LED pin as an output
GPIO.setup(LED_PIN, GPIO.OUT)
# Define the distance threshold in cm (adjust as needed)
DISTANCE_THRESHOLD = 20 # 20 cm
def get_distance():
# Send a trigger signal
GPIO.output(TRIG_PIN, GPIO.HIGH)
time.sleep(0.00001)
GPIO.output(TRIG_PIN, GPIO.LOW)
# Wait for the echo response
pulse_start = time.time()
pulse_end = time.time()
while GPIO.input(ECHO_PIN) == GPIO.LOW:
pulse_start = time.time()
while GPIO.input(ECHO_PIN) == GPIO.HIGH:
pulse_end = time.time()
# Calculate the distance in centimeters
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
try:
while True:
# Get the distance from the ultrasonic sensor
distance = get_distance()
print("Distance:", distance, "cm")
# If the distance is below the threshold, turn on the LED
if distance < DISTANCE_THRESHOLD:
print("Distance below threshold. Turning on the LED.")
GPIO.output(LED_PIN, GPIO.HIGH)
else:
print("Distance above threshold. Turning off the LED.")
GPIO.output(LED_PIN, GPIO.LOW)
# Add a small delay to avoid excessive readings
time.sleep(0.1)
except KeyboardInterrupt:
# Clean up the GPIO on exiting the script
GPIO.cleanup()
- Save the file and run the Python script by executing the following command in the terminal:
python3 ultrasonic_sensor_led.py
- Move your hand or an object slowly from a far distance towards the ultrasonic sensor. Observe the terminal output, which will display the distance measured by the ultrasonic sensor. * Check out the LED state:
- As you get closer to the sensor and the distance falls below the defined threshold, the LED should turn on.
- When you move away from the sensor and the distance goes above the threshold, the LED should turn off.
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!
※ NOTE THAT:
The code above is for educational purposes. The ultrasonic sensor is highly sensitive to noise. If you intend to use the ultrasonic sensor in a real-world application, it is necessary to filter out noise for the ultrasonic sensor. For more information on how to filter noise from distance measurements of an ultrasonic sensor, please refer to this tutorial.