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Sensors, Actuators, and Robotics » PIR motion sensor and Camera trigger problem

March 23, 2012
by victor
victor's Avatar

I'm developing a small home security project using Nerdkits, so far using it as 5v power DC supply but later will put more logics into the MCU.

I tried to use a PIR motion sensor to trigger my home wireless camera, thru the camera "Armed Input", their models are: PIR http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176

wireless cam http://www.scribd.com/doc/29523918/Foscam-us-FI8908W-manual

"Alarm Input Armed Input Pins: The input pins can be used for 1-way external sensor input. For example, you mayconnect a Person Infrared Sensor (PIR) to it for motion detection. When external sensor triggered,IPCAM can be programmed to send an email with picture or control the internal relay output.If you link a external alarm with Pin3 and Pin4,when enable alarm input armed,external alarm is enabled."

According to this, I connected PIR and camera like this:

PIR CAMERA GND -- GND VCC -- the PIR DC power OUT -- INPUT

1), PIR has been tested separately and works perfectly, say, when idle, out and gnd is 0v; when motion, out and gnd is 5v.

2), but the weird thing is: when i measure the camera input and gnd, it is always 5V ?! Be more precisely, when PIR idle, it's 4.8v, when PIR motion triggered, it's 4.2v...

3) next, i used a 1k ohm resister to short the camera input and gnd. once it's shorted, the camera is triggered. (i can get an email)

i guess it's something wrong with the TTL voltage etc, but without knowing the camera circuit design, i've no clue how to fix it....

thanks!

March 24, 2012
by lukel
lukel's Avatar

The PIR sensor has a jumper wire under it. You probably have it on low trigger mode. See if you can change it.

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