PIR & Motion Sensor
PIR & Motion Sensor
Introduction A PIR sensor that stays triggered (output HIGH) indefinitely can be annoying and render your project useless. Let’s troubleshoot why it won’t turn off. 1. Hold Time Too Long If the hold time (delay) potentiometer is turned to maximum,…
Introduction The PIR sensor is one of the most successful electronic sensors ever invented. Billions are in use worldwide. But where did it come from? Let’s trace its history from冷战-era military research to today’s smart homes. The Physics Foundation: Pyroelectricity…
Introduction The ESP32 is a popular microcontroller for IoT projects, but its 3.3V logic and deep sleep capabilities require special consideration when interfacing with PIR sensors. Here are common issues and solutions. 1. Voltage Level Compatibility Issue: Many PIR sensors…
Introduction You power up your PIR sensor, and immediately it starts triggering like crazy. Wait—this is normal. Most PIR sensors require a warm-up period of 30-60 seconds before they operate correctly. What Happens During Warm-Up? Inside the sensor, the pyroelectric…
Introduction The Fresnel lens is often overlooked, but it’s crucial to PIR sensor performance. Different lenses create different detection patterns. Choosing the right lens can make or break your project. What Does a Fresnel Lens Do? The lens focuses infrared…
Introduction PIR sensors seem simple, but there are common pitfalls that lead to frustration. Learn from others’ mistakes. Mistake 1: Not Allowing Warm-Up Time The problem: You power up the sensor and immediately test, but it doesn’t work or triggers…
Introduction Before connecting a PIR sensor to your microcontroller, it’s wise to test it independently. A multimeter is all you need to verify power, output, and basic functionality. What You’ll Need Digital multimeter (any basic model) PIR sensor (e.g., HC-SR501)…
Introduction Before connecting a PIR sensor to your microcontroller, or if you suspect a sensor is faulty, testing it with a multimeter is quick and definitive. Here’s how. What You’ll Need Digital multimeter (with voltage measurement) Power supply (e.g., 5V…
Introduction You’ve connected a PIR sensor to your Arduino, uploaded a sketch, but nothing happens when you wave your hand. Let’s systematically debug the issue. 1. Verify Hardware Connections The most common mistake is incorrect wiring. For HC-SR501: VCC →…
The Short Answer No, a standard PIR sensor will not work reliably behind glass. Glass is opaque to the mid-infrared wavelengths (8-14 μm) that PIR sensors detect. Why Glass Blocks Infrared Ordinary glass (soda-lime glass) is transparent to visible light…