// Turn off LED after hold time (simulates retrigger management) if (millis() - lastMotionTime > MOTION_HOLD_MS) digitalWrite(LED_PIN, LOW);
void loop() if (motionDetected) digitalWrite(LED_PIN, HIGH); Serial.println("Motion detected!"); motionDetected = false; lastMotionTime = millis();
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 pir sensor datasheet better
This article serves as your : a comprehensive guide covering every technical parameter, common pitfalls, circuit improvements, and practical tweaks to make the HW416B outperform its generic copy-paste documentation. Part 1: What Exactly is the HW416B? (And Why Most Datasheets Fail) The HW416B is a motion detector module based on the passive infrared principle. It senses changes in infrared radiation—specifically, the heat signature of a moving human or animal. Unlike its cousin the HC-SR501, the HW416B is often marketed as a miniature or low-voltage variant , though specifications vary wildly between sellers. Typical (But Often Unreliable) Datasheet Claims | Parameter | Common Value | Problem | |-----------|--------------|---------| | Operating Voltage | 3.3V – 5V DC | Many fail below 4.5V | | Quiescent Current | <50 µA | Often 80–100 µA in reality | | Detection Range | Up to 7 meters | Drops to 3-4 meters without proper lens | | Output High | VCC – 0.3V | Can be as low as 2.8V at 3.3V input | | Trigger Mode | Single / Repeatable (Jumper) | Jumper labeling often wrong |
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. // Turn off LED after hold time (simulates
attachInterrupt(digitalPinToInterrupt(PIR_PIN), motionISR, RISING);
The HW416B can be better for low-power, 3.3V systems (ESP32, Raspberry Pi Pico) if you follow the power filtering advice above. Otherwise, the HC-SR501 is more forgiving. Part 5: Real-World Example Code (Better Than Datasheet Snippets) Most sample code is lazy delay() -based nonsense. Here is a robust Arduino example that handles warm-up, debouncing, and low-power mode using the HW416B parameters. This article serves as your : a comprehensive
For ESP32 deep sleep applications, connect HW416B OUT to a wake-up pin and use esp_sleep_enable_ext0_wakeup() . Use this better troubleshooting table when your HW416B misbehaves.