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4.5 Welcome

Introduction

Have you ever noticed the automatic doors in convenience stores that open with a welcoming chime when someone approaches? This project replicates that functionality on a smaller scale. Using a PIR sensor, servo motor, LED, and buzzer, you’ll create a miniature “automatic door” system. When motion is detected, the system lights an LED, “opens” the door using a servo, and plays a welcoming chime with a buzzer.

What You’ll Need

Below are the components required for this project:

COMPONENT INTRODUCTION	PURCHASE LINK
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
PIR Motion Sensor Module	BUY
Servo	BUY
Buzzer	BUY
Transistor	BUY
Fusion HAT+	-
Raspberry Pi	-

Circuit Diagram

Below is the circuit diagram for this project:

Wiring Diagram

Follow the wiring diagram to assemble the circuit:

Note

Adjust the potentiometers on the PIR sensor module for optimal sensitivity and detection range. Rotate both potentiometers fully counterclockwise for best performance.

Running the Example

All example code used in this tutorial is available in the ai-lab-kit directory. Follow these steps to run the example:

cd ~/ai-lab-kit/python/
sudo python3 4.5_Welcome.py

Code

Below is the Python script for the project:

from fusion_hat.pin import Pin, Mode, Pull
from fusion_hat.servo import Servo
from fusion_hat.modules import Buzzer
from fusion_hat.pwm import PWM
import time

# GPIO pin setup
ledPin = Pin(17, Pin.OUT)

# Initialize a PIR Module object on GPIO pin 17
pirPin = Pin(22, mode=Mode.IN, pull=Pull.DOWN)

buzPin = Buzzer(PWM('P0'))

# Initialize servo with custom pulse widths
servoPin = Servo('P4')

# Musical tune for buzzer, with notes and durations
tune = [('C#4', 0.2), ('D4', 0.2), (None, 0.2),
      ('Eb4', 0.2), ('E4', 0.2), (None, 0.6),
      ('F#4', 0.2), ('G4', 0.2), (None, 0.6),
      ('Eb4', 0.2), ('E4', 0.2), (None, 0.2),
      ('F#4', 0.2), ('G4', 0.2), (None, 0.2),
      ('C4', 0.2), ('B4', 0.2), (None, 0.2),
      ('F#4', 0.2), ('G4', 0.2), (None, 0.2),
      ('B4', 0.2), ('Bb4', 0.5), (None, 0.6),
      ('A4', 0.2), ('G4', 0.2), ('E4', 0.2),
      ('D4', 0.2), ('E4', 0.2)]

def setAngle(angle):
   """
   Move the servo to a specified angle.
   :param angle: Angle in degrees (0-180).
   """
   servoPin.angle(angle)       # Set servo position
   time.sleep(0.001)           # Short delay for servo movement

def doorbell():
   """
   Play a musical tune using the buzzer.
   """
   for note, duration in tune:
      buzPin.play(note,float(duration))       # Play the note
   buzPin.off()               # Stop buzzer after playing the tune

def closedoor():
   # Turn off LED and move servo to close door
   ledPin.off()
   for i in range(180, -1, -1):
      setAngle(i)             # Move servo from 180 to 0 degrees
      time.sleep(0.001)       # Short delay for smooth movement
   time.sleep(1)               # Wait after closing door

def opendoor():
   # Turn on LED, open door (move servo), play tune, close door
   ledPin.on()
   for i in range(0, 181):
      setAngle(i)             # Move servo from 0 to 180 degrees
      time.sleep(0.001)       # Short delay for smooth movement
   time.sleep(1)               # Wait before playing the tune
   doorbell()                  # Play the doorbell tune
   closedoor()                 # Close the door after the tune

def loop():
   # Main loop to check for motion and operate door
   while True:
      if pirPin.value()==1:
            opendoor()               # Open door if motion detected
      time.sleep(0.1)              # Short delay in loop

try:
   loop()
except KeyboardInterrupt:
   # Clean up GPIO on user interrupt (e.g., Ctrl+C)
   buzPin.off()
   ledPin.off()

This Python script integrates a PIR motion sensor, servo motor, LED, and buzzer to create an automated welcoming system. When executed:

Motion Detection: A PIR motion sensor connected to GPIO pin 22 detects motion.
Door Automation: When motion is detected:
- The servo motor (on PWM 4) opens a door by moving from 0° to 180°.
- The LED (on GPIO pin 17) turns on.
- A welcoming chime is played through the buzzer (on PWM 0).
- The servo motor closes the door by moving back from 180° to 0°.
- The LED turns off.
Continuous Monitoring: The system continuously monitors for motion and triggers the above sequence whenever motion is detected.
Graceful Exit: On Ctrl+C, the buzzer and LED are turned off, and the script exits cleanly.

Understanding the Code

Motion Detection: The PIR sensor detects motion and triggers the system.
Servo Control: The servo motor opens and closes the door using angles from 0° to 180°.
Buzzer Melody: A welcoming tune is played using the Buzzer.
Reset: After the chime, the system closes the door and turns off the LED, ready for the next event.

Troubleshooting

Motion Not Detected:
- Cause: PIR sensor not wired correctly or environmental interference.
- Solution:
  - Ensure the PIR sensor is connected to GPIO pin 22, power, and ground.
  - Adjust the sensor’s sensitivity and delay potentiometers if available.
Servo Not Moving:
- Cause: Incorrect servo configuration or power supply issues.
- Solution:
  - Verify the servo is connected to P4 and powered correctly.
Chime Not Playing:
- Cause: Buzzer misconfiguration or incorrect tune format.
- Solution:
  - Ensure the buzzer is connected to P0.
  - Verify the tune list contains valid note and duration pairs.
LED Not Turning On:
- Cause: LED wiring or GPIO configuration issues.
- Solution: Verify the LED is connected to GPIO pin 17 with an appropriate resistor.

Extendable Ideas

Adjustable Chime: Add more melodies or allow the user to select different chimes for different events.

Time-Based Operation: Disable the system during specific hours (e.g., at night):

from datetime import datetime
if 8 <= datetime.now().hour < 22:  # Operate only between 8 AM and 10 PM
    opendoor()

Data Logging: Log motion detection events and timestamps to a file for analysis:

with open("motion_log.txt", "a") as log_file:
    log_file.write(f"{time.strftime('%Y-%m-%d %H:%M:%S')} - Motion detected\n")

Voice Greetings: Replace the buzzer chime with pre-recorded voice messages using a speaker.

Conclusion

This project replicates the functionality of automatic doors in a fun and educational way. It introduces concepts like motion detection, servo control, and sound generation, making it a great entry point for IoT and automation projects. Try expanding it by adding features like remote notifications or cloud integration for real-time monitoring.