Pinout
PIR motion sensor (HC-SR501, 3-pin) pinout
Pins
- GND
- OUT (digital — HIGH while motion is detected, 3.3V-level even on a 5V supply, so it is safe straight into a 3.3V input)
- VCC (5V typical — 4.5–20V in; the onboard regulator makes the 3.3V the sensor runs on)
Specifications
| Supply voltage | 4.5–20 V DC (5 V typical, onboard 3.3 V regulator) |
|---|---|
| Quiescent current | < 50 µA |
| Output level | 3.3 V HIGH / 0 V LOW |
| Detection range | ≈3–7 m (sensitivity trimmer) |
| Detection angle | < 100° cone |
| Hold time | Adjustable, roughly 3 s – 5 min (time trimmer) |
| Block time | ≈2.5 s after OUT goes LOW |
| Trigger modes | H: repeatable; L: single |
| Warm-up | ≈1 min after power-up |
| Operating temperature | −15–70 °C |
| Board size | 32 × 24 mm |
Notes
- Seen from the lens side the pins read GND, OUT, VCC left to right — the opposite of the VCC-first order most 3-pin modules use. Powering it backwards is the classic first-use mistake; the silkscreen that says so is on the back, under the edge of the lens.
- The two orange trimmers on the back set sensitivity (detection range, roughly 3–7 m) and the hold time (how long OUT stays HIGH after a trigger, about 3 s to 5 min). The H/L jumper picks repeatable (H: OUT stays HIGH while motion continues) or single trigger (L: one fixed pulse per detection).
- Allow about a minute of warm-up after power-up — OUT may pulse a few times before the pyro element settles.
