rcwl0516

Overview

The rcwl0516 node detects motion using the RCWL-0516 microwave Doppler radar sensor. Unlike PIR sensors that detect infrared radiation, this sensor uses 3.18 GHz microwave signals to detect movement through walls, glass, and thin enclosures. It provides a digital HIGH/LOW output when motion is detected, making it ideal for concealed installations and through-wall presence sensing.

Properties

Output

{
  "motion": true,
  "pin": 17,
  "holdTime": 2000,
  "timestamp": 1640000000000
}

Wiring

  RCWL-0516        Raspberry Pi
  ---------        ------------
  VIN  ─────────── 5V   (Pin 2)
  GND  ─────────── GND  (Pin 6)
  OUT  ─────────── GPIO17 (Pin 11)

  Optional pads on sensor PCB:
  CDS  ── LDR ── for light-dependent enable
  R-GN ── Resistor ── adjust sensitivity

Example: Hidden Security Sensor

Use the through-wall detection capability for a concealed security system that detects motion behind walls or inside enclosures.

// Function node: Security alert with cooldown
var motion = msg.motion;
var lastAlert = flow.get('lastAlert') || 0;
var cooldown = 30000; // 30 second cooldown
var now = Date.now();
var armed = global.get('securityArmed') || false;

if (motion && armed && (now - lastAlert) > cooldown) {
    flow.set('lastAlert', now);

    msg.payload = {
        alert: true,
        zone: "Zone A - Living Room",
        sensor: "rcwl0516",
        type: "microwave_radar",
        timestamp: msg.timestamp,
        message: "Motion detected in Zone A"
    };

    return msg;
}

return null;

Example: Room Occupancy with Auto-Lighting

Combine with a hold timer for occupancy-based lighting control that works even when the sensor is hidden behind a panel.

// Function node: Occupancy state machine
var motion = msg.motion;
var state = flow.get('roomState') || { occupied: false, lastMotion: 0 };
var timeout = 300000; // 5 minutes
var now = Date.now();

if (motion) {
    state.lastMotion = now;
    if (!state.occupied) {
        state.occupied = true;
        flow.set('roomState', state);
        msg.payload = { occupied: true, action: "lights_on" };
        return msg;
    }
} else if (state.occupied && (now - state.lastMotion) > timeout) {
    state.occupied = false;
    flow.set('roomState', state);
    msg.payload = { occupied: false, action: "lights_off" };
    return msg;
}

flow.set('roomState', state);
return null;

Common Use Cases