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
Raspberry Pi Zero
Hi, I want to use this with Zero W, but see you say it's not compatible. Is that because the Zero W has no headers, or another reason?
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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.
The HC-SR501 Infrared Motion Sensor Features:
- Input Voltage: 4.5V - 20V
- Current Draw: <50µA
- Digital Output: 3.3V (High)
- Digital Output: 0V (Low)
- Working Temperature: -15°C to 70°C
- Delay Time: 0.5 - 200 Seconds
- Sensing Angle: 100° Cone
- Range 5m - 7m
- Sensor Lens Diameter: 23mm
- Length: 24.03mm
- Width: 32.34mm
- Height (with lens): 24.66mm
- Centre screw hole distance: 28mm
- Screw hole diameter: 2mm (M2)