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Topic: Presence detection. (Read 1 time) previous topic - next topic

mellink

Hi all,

I'm wanting to detect if I moves near to the arduino that it turns on some lights.
However, I dont want to turn on lights if just someone walks up to it.

For example Im hoping to apply this tech to my project car so as i walk up to the car the door handles light up on the inside. (I can imagine having a small piece on my key ring that will have the transimtter in)

Could someone tell me what senor type I need? as i dont want a general PIR and am i right in saying RFID will have to short a range? Or is there a obveous way of doing it that im missing? Think cheap and cheerful because i'll probably protype it all first and then make a higher quality version when I've compelted the PCB designs for the rest of the car.

Thanks for the advice
Rob

pwillard

#1
Jan 29, 2011, 05:27 pm Last Edit: Jan 29, 2011, 05:30 pm by pwillard Reason: 1
So you dont want them to touch it... You could use a PING sensor and only activate when the response is like "within 5 cm".  Other than RFID, you are eliminating most options.

mellink

Thats right I dont want to touch it just as im walking up to the car the lights to come on. So I was hoping for about 5+ meters. Between 5-20 would be idea. for it to activate.

mellink

WEll is RFID long range enough I though that is basically you have to be very close to the system for it to work.
Im looking for a range of 5-20 meters like I said, but it should only come on when i walk up to the car not when something moves around the car.

jameseyb

Second vote for RIFD.

You could get one of the short range reader kits and hook it up into the car, then find the corresponding RFID token (the sort that look like fuses) and put it on your keychain. Failing that, if you have soe sort of RFID in your wallet already, you might be able to use that instead. The range might be too short for the HiD type readers/cards though.

I've often thought of using something similar as a sort of central locking for my house...

mellink

#5
Jan 29, 2011, 07:29 pm Last Edit: Jan 29, 2011, 07:31 pm by mellink Reason: 1
So is HiD a longer range version of RFID?
Sorry I thought RDIF was only a short range thing were it gathers it power via induction in its loops.

How do car manufactures do it then? for example keyless go etc?

mellink

Hi again,
should have said it dosen't really matter if I get some false positives. So may radio trasmitter but i have no idea how to do this. Hnecy why im asking.

mellink


Cintax

There are kits that provide a key FOB that can be interfaced with a micro controller. You would still need to hit a button on the key FOB though.

Sparkfun also sells a few items which you could use. Look up 'nordic key fob'.

Info: http://blog.diyembedded.com/



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