RFID

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goujam
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Posted by goujam: Mon. Apr 7, 2008 - 09:56 AM
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Can anyone recommend a RFID reader chip to run on a battery operated device. I have a 3V supply from batteries, I can use a DC/DC converter for higher voltages.

Also I am looking for it to run using passive Tags the card style ones. I think this means I am looking for 125 khz frequency only.

thanks

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Learning and Information, General Electronics
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valusoft
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Posted by valusoft: Mon. Apr 7, 2008 - 11:51 AM
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Hi Goujam,

You might like to investigate ID-12 from Innovations.

http://www.id-innovations.com/Mo...(non%20write).htm

Not sure that they are really suitable for battery operations because they have to continue to keep the RF field energised and that is a power hungry task compared to an AVR in sleepy-byes mode. The ID-12 runs on +5 volts. I can measure the current if you need me to do so.

This is a read only system you realise. No writing.

Cheers,

Ross McKenzie ValuSoft Melbourne Australia

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goujam
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Posted by goujam: Mon. Apr 7, 2008 - 12:11 PM
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Thanks Valusoft i will check that out, i was thinking of shutting down the reader and checking every second if there is a card near or maybe 0.5 of a second.

I hope this should increase battery life, i will have to check it out.

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TrevorWhite
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Posted by TrevorWhite: Mon. Apr 7, 2008 - 12:48 PM
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Hi, Elektor Electronics did some articles on RFID last year. Probabaly more like 18months ago. They went through all the technologies and also had some circuitry designs. www.elektor-electronics.co.uk is the site.

I am sure you can purchase the old articles or even order the back issue. There also might be some chat about them in their forum pages as well.

Trev

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DocJC
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Posted by DocJC: Mon. Apr 7, 2008 - 01:21 PM
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I haven't played with RFID, but here is another source for comparison. Parallax . Parallax sells the RFID reader, and several cards.

JC

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icarus1
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Posted by icarus1: Mon. Apr 7, 2008 - 04:56 PM
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There is no RFID reader working at lower than 4.2V (EM4095) in the market. There are ways to do it by yourself.
What type of tags would you like to use Read Only or Read/Write. Also in which frequency?

Michael

Michael.

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icarus1
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Posted by icarus1: Mon. Apr 7, 2008 - 05:00 PM
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Oooops sorry,

I didn't see that you almost said about 125KHz.

Yes, using a step up converter you could also use the HTRC110 ic.

Personally I suggest you to use the EM4095. Easy to use and few and cheap outside components.

Michael

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icarus1
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Posted by icarus1: Mon. Apr 7, 2008 - 05:45 PM
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Oh,

Something else, I have to tell you this because I had this problem in the past. Be carefull if you have a step up converter, because it uses a coil. Remember the rfid antenna is also a coil.
Just think the idea of a simple voltage doubler (2 caps and two switches).

Michael

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goujam
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Posted by goujam: Mon. Apr 7, 2008 - 06:45 PM
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Thanks Icarus, I have downloaded the EM4095 data sheet today it seems popular and runs at a low voltage. I maybe being stupid but i could not see any comunication data in the data sheet i.e how to read the data out of the EM4095.

Oh yeah i am ordering a dev kit later so i hope this should get me started.

thanks

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