Build a motion detector using the EKMC1601112

This EKMC1601112 is a passive infra red (PIR) motion sensor.  It detects variations in IR energy in its field of view. You can learn about PIR sensors at “http://en.wikipedia.org/wiki/Passive_infrared_sensor#MOTION” and “http://steveslockandsafe.com/venice-locksmith-home-security-technicians-notebook/“.

We have bought a bunch of these sensors. We interfaced one to a WiSense sensor node.  We wrote a simple app which sends out an alarm messages to an app outside the WiSense network whenever the sensor detects motion. The sensor worked as expected.

pir_pic

This sensor can be interfaced to a micro through an interrupt capable GPIO pin. The sensor’s output stays low as long as it does not detect any motion in it’s field of view.  When the sensor detects motion, the output pin goes high. The output goes back to low when the sensor adjusts to the new IR energy level in it’s field of view.  The GPIO pin should be configured to raise an interrupt on a positive edge (GPIO pin goes from low to high).  On a reduced function device (running on battery), any motion will wake up the micro. The application entity on the sensor node can then take appropriate action.

pir_ckt

We have written a simple driver which interfaces with this sensor. The software implementation is divided between a driver and an application level entity (app). The driver initializes the GPIO pin allocated to this device, handles interrupts and informs the “app” whenever motion is detected. The app can then take appropriate action. Typically it will send out an alarm message to interested application entities within and outside the WiSense sensor network. It will then request the system layer to put the node back into deep sleep only waking up the next time motion is detected.

This sensor costs between $8 and $10 from different distributors.

The current consumption of this sensor (~ 200 microamperes)  is not trivial. There is another WL series (from Panasonic) with average current consumption of less than 1 microamps but it is twice as expensive. Look up EKMB1101111.

Details

  • Manufacturer: Panasonic
  • Part Number:  EKMC1601112 (VZ series)
  • Pins: Vcc, Gnd and Vout
  • Interface: Digital out (Simply connect Vout pin to one of Micro’s interrupt capable GPIO pins)
  • Range:  Distance (5 meters), Field of view (94 Deg x 82 Deg)
  • Power supply: 3.0 Volts to 6.0 Volts
  • Current consumption:  170  micro-amperes
  • Datasheet: http://www1.futureelectronics.com/doc/PANASONIC%20ELECTRIC%20WORKS/EKMC1601112.pdf

Posted on December 3, 2013, in Uncategorized. Bookmark the permalink. Leave a comment.

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