Raspberry Pi GPIO Sensing: Motion DetectionFeb 19, 2014
In previous tutorials, we outlined the basics behind physical computing and the Raspberry Pi by activating LEDs and scripts using a simple one button circuit. I..
Audible Sensor ReadingsDec 09, 2014
This tutorial will show you how to make the reading of a sensor audible. In this example, we will be using the HC-SR04 Ultrasonic sensor, but it can be applied ..
Motion Triggered Video RecordingApr 29, 2015
So you’ve got your camera setup with your Raspberry Pi, and you’ve got a PIR Infrared Motion Sensor and you’re thinking to yourself “The..
PIR sensors, often referred to as, "Passive Infrared" or "IR motion" sensors, enable you to sense motion. Everything emits a small amount of infrared radiation (IR), and the hotter something is, the more radiation it emits. PIR sensors are able to detect a change in average IR levels of their detection zone (e.g. when a human enters a room, that room will increase in temperature slightly) and hence sense motion.
This one's great, as it can be powered via the Raspberry Pi's 5V output, and be read directly from the Raspberry Pi's GPIO input (as the sensor has a digital 3.3V output!)
This PIR includes an adjustable delay before firing (approx 0.5 - 200 seconds), has adjustable sensitivity and two M2 mounting holes! It runs on 4.5V-20V power (or 3V by bypassing the regulator with a bit of soldering) and has a digital signal output (3.3V) high, 0V low. Its sensing range is up to 7 meters in a 100 degree cone.
Protocol that enables multiple PIR sensors to use single set of GPIO pins?
I'm building a security camera system that will use multiple PIR sensors with my Raspberry Pi. Having previously used the DS18B20 thermometer on a different project, I've been impressed with the 1-wire protocol's ability to enable connectivity of multiple sensors using only 1 GPIO pin for data (and thus use only one cable to my Raspberry, not counting the +3v and GND). My question is, if I want to use multiple PIR sensors, would I have to use a separate GPIO pin for each sensor? Or can multiple PIR sensors be connected to just one "data" GPIO pin and they identify themselves when a detection occurs. Thus I can save having to run many different runs of cable. Effectively I'd like to daisy-chain these sensors to save having separate cables for each one also using-up GPIO pins that I'd like to use for something else... This is the way I've been able to use the DS18B20 thermometers. If this PIR sensor doesn't support this, does anyone know of one that does perhaps? Cheers for any info