RFID

Log in or register to post comments
Go To Last Post
9 posts / 0 new
Author
Message
goujam
goujam's picture
Level: Wannabe
Joined: Thu. Mar 22, 2007
Posts: 58 View posts
#1
Posted by goujam: Mon. Apr 7, 2008 - 09:56 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Tags:

Learning and Information, General Electronics
Top
valusoft
valusoft's picture
Level: Moderator
Joined: Sat. Jul 2, 2005
Posts: 15632 View posts
Location: Melbourne, Australia
Posted by valusoft: Mon. Apr 7, 2008 - 11:51 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
goujam
goujam's picture
Level: Wannabe
Joined: Thu. Mar 22, 2007
Posts: 58 View posts
Posted by goujam: Mon. Apr 7, 2008 - 12:11 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

Top
TrevorWhite
TrevorWhite's picture
Level: Hangaround
Joined: Mon. Jan 20, 2003
Posts: 451 View posts
Location: Birmingham, England
Posted by TrevorWhite: Mon. Apr 7, 2008 - 12:48 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
DocJC
DocJC's picture
Level: 10k+ Postman
Joined: Tue. Dec 11, 2007
Posts: 13281 View posts
Location: Cleveland, OH
Posted by DocJC: Mon. Apr 7, 2008 - 01:21 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I haven't played with RFID, but here is another source for comparison. Parallax . Parallax sells the RFID reader, and several cards.

JC

Top
icarus1
icarus1's picture
Level: Posting Freak
Joined: Wed. May 26, 2004
Posts: 1460 View posts
Location: Thessaloniki, Hellas
Posted by icarus1: Mon. Apr 7, 2008 - 04:56 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

Top
icarus1
icarus1's picture
Level: Posting Freak
Joined: Wed. May 26, 2004
Posts: 1460 View posts
Location: Thessaloniki, Hellas
Posted by icarus1: Mon. Apr 7, 2008 - 05:00 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Michael.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

Top
icarus1
icarus1's picture
Level: Posting Freak
Joined: Wed. May 26, 2004
Posts: 1460 View posts
Location: Thessaloniki, Hellas
Posted by icarus1: Mon. Apr 7, 2008 - 05:45 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Michael.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

Top
goujam
goujam's picture
Level: Wannabe
Joined: Thu. Mar 22, 2007
Posts: 58 View posts
Posted by goujam: Mon. Apr 7, 2008 - 06:45 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top