Dynamic RFID tag chip ???

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For a specific project I am looking for a RFID active tag chip, but with
both contactless and wired connectivity.

Basically I want to design a RFID tag, but with an on-board microcontroller
which should be able to change the content of the RFID tag based on external
events, through a I2C link or similar. Do you know products or chips that
could implement this functionnality ?

Frequency range probably in the 13MHz or 860MHz bands.

Many thanks,
Robert Lacoste
email : rlacoste and the same domain name...

Re: Dynamic RFID tag chip ???
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Absolutely brilliant idea.
But it misses the point of RFID tags.
The RFID tags were developped for being selfpowered
from the RF field, at least most of them.
the clock is the RF or an integer fraction of it.
And the RF response is the sidebands being created by
on-off modulation, eg shorting single bits which in
turn are integer divisions of the clock
Having an additional cpu means an external powersupply.
It also means shielding of your cpu from the RF.

Since the selfpowering requirement falls with your
application, you can replace the the RFID statemachine
with some own hardware. Just modulate the antenna
impedance with the bitpattern synchroneous to the RF.

Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Re: Dynamic RFID tag chip ???
I think philips do some 'smart card' style RFID stuff. Maybe they would do
the trick. Personally I think for you application you would be better off
with a micro and a transmitter module, like a car alarm remote.

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Re: Dynamic RFID tag chip ???
On Wed, 8 Oct 2003 18:27:38 +0200, "Robert Lacoste"

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I do not know of a commercial product which meets your needs but we
recently completed a project for a customer that is along the line of
your search.  The ASIC used in an automotive 'Toll Tag" went
end-of-life and we did a redesign using a low-cost low-power micro.
It uses a battery to power the circuit for about 10 years but as an
RFID tag, does not have an active transmitter.  It communicates by
'back-scattering' (modulating) the received RF carrier in the 902-928
MHz band.  The tag ID and other parameters can be programmed into
internal flash via the RF link and of course, the information can be
interrogated by the proper readers.  The design could be easily
extended to monitor and log external events.  We also had completed
projects for both Part 90 (licensed) and Part 15 (unlicensed) RFID
readers capably of communicating with the tag.
If you wish to discuss this more off-line, please contact me via

-Bill Knight
R O SoftWare
billk AT rosw DOT com

Re: Dynamic RFID tag chip ???
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Tagsys have a variety of 13.56MHz tags, and sell a kit with some tag samples,
along with a reader.



David Milne

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