MotionSensor (PIR) in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does a PIR Motion Sensor detect?

A PIR (Passive Infrared) Motion Sensor detects changes in infrared radiation, which usually means it senses movement of warm objects like people or animals.

beginner

How do you connect a PIR sensor to a Raspberry Pi?

You connect the PIR sensor's power pin to 5V or 3.3V, ground pin to GND, and the output pin to a GPIO pin on the Raspberry Pi to read motion signals.

beginner

What Python library is commonly used to read GPIO pins on a Raspberry Pi?

The RPi.GPIO library is commonly used to control and read GPIO pins on a Raspberry Pi in Python programs.

intermediate

What is the basic Python code structure to detect motion using a PIR sensor?

Set up the GPIO pin as input, then use a loop to check if the pin reads HIGH (motion detected) or LOW (no motion), and respond accordingly.

intermediate

Why is it important to add a delay or debounce when reading PIR sensor signals?

Adding a delay helps avoid false triggers caused by sensor noise or rapid changes, ensuring the program reacts only to real motion events.

What type of signal does a PIR sensor output when motion is detected?

A Digital HIGH signal

B Analog voltage

C PWM signal

D No signal

A PIR sensor outputs a digital HIGH signal on its output pin when it detects motion.

Which Raspberry Pi pin type should you use to read a PIR sensor output?

A GPIO output pin

B GPIO input pin

C Power pin

D Ground pin

The PIR sensor output connects to a GPIO input pin to read motion signals.

What Python command sets a GPIO pin as input using RPi.GPIO?

A GPIO.output(pin, True)

B GPIO.setup(pin, GPIO.OUT)

C GPIO.input(pin)

D GPIO.setup(pin, GPIO.IN)

GPIO.setup(pin, GPIO.IN) configures the pin as an input to read signals.

Why should you use a try-except or cleanup in a PIR sensor Python script?

A To safely release GPIO resources on exit

B To speed up the sensor

C To increase sensor sensitivity

D To change sensor voltage

Using try-except or GPIO.cleanup() ensures GPIO pins are properly reset when the program ends.

What does a PIR sensor NOT detect?

A Motion of warm objects

B Changes in infrared radiation

C Sound waves

D Presence of people

PIR sensors do not detect sound waves; they detect infrared radiation changes.

Explain how a PIR sensor works with a Raspberry Pi to detect motion.

Think about how the sensor senses heat changes and how the Pi reads that signal.

Describe the steps to write a Python program that alerts you when motion is detected by a PIR sensor.

Start from setting up the pin to cleaning up after the program ends.