PIR sensor wiring (HC-SR501)

Pin map (typical)

PIR pin	Connect to Pi
VCC	5V (pin 2 or 4) or 3.3V if module is 3.3V-safe — check your board
GND	GND (pin 6)
OUT	GPIO input (example GPIO17, physical pin 11)

⚠️ Warning: Many HC-SR501 boards output 3.3V logic on OUT when powered at 5V, but not all. Verify with a multimeter or datasheet — never feed 5V into a 3.3V-only GPIO.

Adjustments (on-board pots)

Sensitivity — lower to reduce false triggers from HVAC / pets.
Time delay — how long OUT stays HIGH after motion; tune so screen does not flicker.

Software binding

Note BCM GPIO number (example 17).
In M2C2 open Settings → Sensors → PIR and enter the BCM pin.
Map motion → wake display and no motion timeout → screensaver.

ASCII diagram


   HC-SR501                Raspberry Pi 40-pin header (simplified)
  +---------+
  | VCC  o  |------------ 5V  (Pin 2 or 4)
  | OUT  o  |------------ GPIO17 (Pin 11)
  | GND  o  |------------ GND  (Pin 6)
  +---------+

Troubleshooting

Always HIGH
Bad jumper (retrigger mode); loose ground; sensor facing heat source.

No response
Wrong GPIO in software; Wi‑Fi USB dongle RF interference — move sensor cable away from transmitter.