PIR Motion Sensor Output Voltage

LightAce

What is the PIR Motion Sensor Output Voltage. I read in a few places that it was 3.3V and others 3V but wasn't 100% sure. Also is the output constant or vary upon the input voltage?

Franklin

Seems like the output is the input switched between ground and vcc.

Humanoido

Franklin is right as it uses an Propeller input pin with a 2K resistor to detect on off conditions. You are welcome to use my code. It is in a state of continual recycling detection.

Here are some related posts with schematics and code. I'm using a PIR as an in flight, launch and landing sensor for the Big Brain's Airport and the Micro Space Program.

Propeller PIR Motion Sensor for Flight Recorder
http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain&p=1029568&viewfull=1#post1029568


Big Brain Propeller Airport PIR Build
Aircraft Motion Detector Machine for launch, flight, recovery
http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain&p=1032658&viewfull=1#post1032658


pir_air_LED.spin‎
http://forums.parallax.com/attachment.php?attachmentid=84773&d=1314945455


PIR Materials Transparency Test
For the Robotic Micro Space Airport
http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain&p=1034028&viewfull=1#post1034028


Brain Senses - Focus on Vision Part 3
Human Detection
http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain&p=977870&viewfull=1#post977870

Humanoido

LightAce wrote: »

Also is the output constant or vary upon the input voltage?

You will want to run the sensor at the recommended specs voltage (which is normally held constant and regulated) which will enable the PIR device to stay constant (not vary its voltage). The design is to output a high low state which the Propeller can read across a pin. The link is to the manual which has code for review.

http://www.parallax.com/tabid/768/ProductID/83/Default.aspx
http://www.parallax.com/dl/docs/prod/audiovis/pirsensor-v1.2.pdf



The PIR (Passive Infra-Red) Sensor is a pyroelectric device that detects motion by measuring changes in the infrared (heat) levels emitted by surrounding objects. When motion is detected the PIR Sensor outputs a high signal on its output pin. This logic signal can be read by a microcontroller or used to drive an external load.

LightAce

Humanoido wrote: »

You will want to run the sensor at the recommended specs voltage (which is normally held constant and regulated) which will enable the PIR device to stay constant (not vary its voltage). The design is to output a high low state which the Propeller can read across a pin. The link is to the manual which has code for review.

What I meant by varying voltages is that if I gave an input of a constant 3V would the output be 3V and if I gave an input of a constant 6V would the output be 6V?

Franklin

and if I gave an input of a constant 6V would the output be 6V?

You would want to be careful where you put that 6v as some parts may not be able to handle over 5 (or 3.3) volts without damage.

Jessica Uelmen

LightAce,

The output voltage depends on which version of the PIR you are using. If using Revision B, the voltage on the OUT pin is within 5% of the supply voltage.

With Revision A, however, the output voltage drops significantly and can vary between production runs. If you have Revision A, your best bet would be to measure the voltage on the OUT pin and see what it is.

You can determine which version you have using the product documentation.

Cheers,
Jessica

Humanoido

Good point. The project and code I posted is for PIR revision A.

schelled

Does anyone have a very simple project for the PIR sensor revision B on a Basic stamp board. I can get it to do the 1 and 0 thing but I would like it to at least turn a LED on and off