void motionISR() motionDetected = true;
// Turn off LED after hold time (simulates retrigger management) if (millis() - lastMotionTime > MOTION_HOLD_MS) digitalWrite(LED_PIN, LOW); hw416b pir sensor datasheet better
The HW416B is a popular passive infrared (PIR) motion sensor module, often compared to the HC-SR501. However, finding a can be frustrating. Many available documents miss critical details like retriggering timing, lens specifications, or voltage ripple sensitivity. void motionISR() motionDetected = true; // Turn off
HW416B OUT → 1kΩ resistor → Base of BC547 Emitter of BC547 → GND Collector → Relay coil negative terminal Relay coil positive → VCC (with flyback diode) The stock fresnel lens is cheap plastic. You can upgrade the lens with a universal PIR lens (e.g., from a KC7783R) to achieve the claimed 7 meters. Also, the sensor is less sensitive to motion moving directly toward it versus moving across its field of view. HW416B OUT → 1kΩ resistor → Base of