Raspberry Pi PIR motion sensor for Home Assistant lighting

Also available in French.

Light the hall or utility room when someone walks in—without flipping a switch. A PIR (HC-SR501) on a Raspberry Pi does not switch mains: it reports occupancy to Home Assistant, which controls your existing smart bulbs or relays. Safer and flexible.

Goal

Motion on GPIO4 (default).
MQTT occupancy sensor in HA.
Turn light on on motion; off after 2 minutes still.

Time, level, parts

Time	Level
~45 min	Beginner

HC-SR501: UK · US

Module runs on 5 V; OUT is 3.3 V—safe on Pi GPIO.

Wiring

PIR	Pi (physical)
VCC	2 (5V)
OUT	7 (GPIO4)
GND	6 (GND)

Jumper H (repeat trigger); time dial minimum—HA handles timeout. Adjust sensitivity pot as needed.

Script

Download presence_pir_mqtt.py. Uses gpiozero MotionSensor—works on Pi 5 with lgpio, not legacy RPi.GPIO.

Automation (restart mode)

alias: Hall light on motion
mode: restart
triggers:
  - trigger: state
    entity_id: binary_sensor.raspberry_pi_pir_hall_occupancy
    to: "on"
actions:
  - action: light.turn_on
    target:
      entity_id: light.hall
  - wait_for_trigger:
      - trigger: state
        entity_id: binary_sensor.raspberry_pi_pir_hall_occupancy
        to: "off"
        for: "00:02:00"
  - action: light.turn_off
    target:
      entity_id: light.hall

Replace entity ids. Use a dimmable bulb if you add night dimming:

data:
  brightness_pct: "{{ 15 if now().hour >= 23 or now().hour < 6 else 100 }}"

systemd

presence-pir.service with MQTT env vars—same pattern as door sensor.

Troubleshooting

False triggers at boot: wait ~60 s after power-up for PIR warmup.
Heat sources: avoid aiming at radiators or sunny windows.
Pi 5 GPIO errors: install python3-lgpio, venv with --system-site-packages.
GPIO busy: change PIR_GPIO if GPIO4 used by 1-Wire etc.

Sources: Adafruit PIR guide · gpiozero MotionSensor.

Also: door notifications · getting started.

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