PIR Motion Detection with the PIR Class

The PIR class in the RpiL library is designed to interface with a Passive Infrared (PIR) motion sensor using the GPIO pins of a Raspberry Pi. It allows you to detect motion in a specific area and take action when motion is detected.

Class Overview

The PIR class requires the following parameter for initialization:

  • pin - The GPIO pin connected to the PIR sensor’s output.

The sensor can be monitored continuously using a background thread that checks for motion, and it provides methods for detecting motion and waiting for motion events.

Methods

  • motion_detected()

    • Returns True if motion is detected, otherwise returns False. This method checks the most recent motion status.

  • wait_for_motion()

    • Blocks and waits until motion is detected, returning True when motion is detected. This is useful for event-driven applications where an action is triggered once motion is detected.

Example Usage

Here’s how you can use the PIR class to detect motion with a PIR sensor:

from RpiL import PIR

# Initialize PIR motion sensor with the GPIO pin number
pir_sensor = PIR(pin=17)

# Wait for motion detection
if pir_sensor.wait_for_motion():
    print("Motion detected!")

# Check if motion is detected
if pir_sensor.motion_detected():
    print("Motion detected in the last check!")

Notes

  • The PIR sensor works by detecting infrared radiation, which typically comes from moving objects such as humans or animals.

  • The motion_detected method returns a boolean indicating if motion has been detected at the last check, while the wait_for_motion method is a blocking call that waits until motion is detected before proceeding.

  • The motion detection is continuously monitored in a separate background thread, ensuring non-blocking operation in your main program.

  • The PIR class automatically handles GPIO cleanup when the object is deleted.

Cleanup

The PIR class automatically cleans up the GPIO pin when the object is deleted, ensuring proper release of resources and preventing conflicts with other GPIO tasks.