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The 'rub'
Want to detect the presence of RFID readers? Want to control when a RFID tag is active or readable? We describe how to do both using bits of copper and card, and some readily available electronics hardware.
Longer preamble
Radio frequency identification ( RFID) is rapidly growing in popularity. RFID tags are found everywhere. They're attached to container freight, in those funny-looking white labels you find in newly purchased books, embedded in many corporate ID cards and passports, etc. The tags have a few common properties: they transmit a unique ID number, are optimized to be 'read' from predefined distances, and are usually small so they can remain unobtrusive or hidden.
RFID readers are used to track nearby tags by wirelessly reading a tag's unique ID (see Figure 4); a tag simply has to be brought into physical proximity with a reader to be read. Readers are mostly used for industrial or commercial purposes, e.g. asset tracking or electronic payment. Wal-mart use RFID tags and readers in their supply chain. The technology is also used in mass transit systems in cities like London and Hong Kong. In Japan, many mobile phones incorporate readers to enable e-money payments in shops and vending machines.
For those of us who want to experiment with RFID, the problem is that the technology is almost always black boxed. That is, the inner workings of a tag and its interaction with a reader is hidden from view, and thus difficult to have much control over.
In the two exercises that follow (building a RFID reader detector and a tilt-sensitive RFID tag), we offer an example of how you can start revealing some of the workings of RFID and thus gain some control over the technology. The two exercises also hopefully show that the technology is relatively simple and how it can be extended to support some interesting interactions. We offer some other possibilities that build on our examples at the end.
Want to detect the presence of RFID readers? Want to control when a RFID tag is active or readable? We describe how to do both using bits of copper and card, and some readily available electronics hardware.
Longer preamble
Radio frequency identification ( RFID) is rapidly growing in popularity. RFID tags are found everywhere. They're attached to container freight, in those funny-looking white labels you find in newly purchased books, embedded in many corporate ID cards and passports, etc. The tags have a few common properties: they transmit a unique ID number, are optimized to be 'read' from predefined distances, and are usually small so they can remain unobtrusive or hidden.
RFID readers are used to track nearby tags by wirelessly reading a tag's unique ID (see Figure 4); a tag simply has to be brought into physical proximity with a reader to be read. Readers are mostly used for industrial or commercial purposes, e.g. asset tracking or electronic payment. Wal-mart use RFID tags and readers in their supply chain. The technology is also used in mass transit systems in cities like London and Hong Kong. In Japan, many mobile phones incorporate readers to enable e-money payments in shops and vending machines.
For those of us who want to experiment with RFID, the problem is that the technology is almost always black boxed. That is, the inner workings of a tag and its interaction with a reader is hidden from view, and thus difficult to have much control over.
In the two exercises that follow (building a RFID reader detector and a tilt-sensitive RFID tag), we offer an example of how you can start revealing some of the workings of RFID and thus gain some control over the technology. The two exercises also hopefully show that the technology is relatively simple and how it can be extended to support some interesting interactions. We offer some other possibilities that build on our examples at the end.
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Signing UpStep 1Material and Tools
This section provides an overview of the necessary materials and tools.
Materials (see Figure 1):
We need the following material to built the basic RFID reader detector.
- Cardboard (around 100x70 mm)
- Conductive copper tape (e.g., order number 1218478 at www.farnell.com)
- Capacitor 82 pF (picofarad) (e.g., order number 1138852 at www.farnell.com)
- Low current LED (light-emitting diode) (e.g., order number 1003207at www.farnell.com)
Tools (see Figure 2 and 3):
- Craft knife and scissors
- Insulating tape (e.g., order number 1373979 at www.farnell.com)
- Soldering iron and solder
RFID reader for testing (see Figure 4):
To test our RFID tags we need an RFID reader that can operate at a frequency of 13.56 MHz.
There many readers for this widely used RFID standard, for instance the Sonmicro MIFARE USB reader (http://www.sonmicro.com/).
Note: The Phidget RFID reader does not work with the tags created in this project, as it uses a different frequency for communication with the tags (125 kHz).
Advanced material (see Figure 5):
The following material is necessary to build the second part of the project: the tilt-sensitive RFID tag.
- Micro tilt switches (e.g., www.digikey.com)
- RFID ICs (e.g., MIFARE Standard 1k, part no. 568-2219-1-ND at www.digikey.com)
Materials (see Figure 1):
We need the following material to built the basic RFID reader detector.
- Cardboard (around 100x70 mm)
- Conductive copper tape (e.g., order number 1218478 at www.farnell.com)
- Capacitor 82 pF (picofarad) (e.g., order number 1138852 at www.farnell.com)
- Low current LED (light-emitting diode) (e.g., order number 1003207at www.farnell.com)
Tools (see Figure 2 and 3):
- Craft knife and scissors
- Insulating tape (e.g., order number 1373979 at www.farnell.com)
- Soldering iron and solder
RFID reader for testing (see Figure 4):
To test our RFID tags we need an RFID reader that can operate at a frequency of 13.56 MHz.
There many readers for this widely used RFID standard, for instance the Sonmicro MIFARE USB reader (http://www.sonmicro.com/).
Note: The Phidget RFID reader does not work with the tags created in this project, as it uses a different frequency for communication with the tags (125 kHz).
Advanced material (see Figure 5):
The following material is necessary to build the second part of the project: the tilt-sensitive RFID tag.
- Micro tilt switches (e.g., www.digikey.com)
- RFID ICs (e.g., MIFARE Standard 1k, part no. 568-2219-1-ND at www.digikey.com)
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Thanks!
Also, would it b epossible to use a "zig-zag" or "back and forth" pattern instead? This way it would be to possible prevent the crossings in the first place.
In the middle of step 4 under sub topic tilt-sensitive tag stated that:
"We add the three tilt switches to the tag as shown in Figure 3. The tilt switches are soldered to the copper tape, and it is important to connect them in a slight angle (around 5-10 degrees) as shown in Figure 4. This makes sure that the silt switches are in a closed state while the RFID tag is in a horizontal position, and in a open state while the tag is in a vertical position."
I not understand about the concept behind, why we need to connect the tilt switch to be slight angle (around 5-10 degrees) and how the orientation of the tag affect the state of tilt switches (open/close).
Can anyone here please explain to me or send me any link to the related page will do. Your help will be appreciate.
they sell them for £1 here what's more,
its available in 5mm so you only have to halve it...
Hey there, nice instructable! I have a few questions about it though...
1. How would one go about making the detector actively powered?
2. Could you make the antenna on a PCB? Or would the copper be to thin?
3. Is there possibly a way to make an Über charged, directional RFIDcard/gun?
Q1 is to try and make it have a further range, Q2 is to see if I can make it in school with minimal materials, Q3 is just to make a replacement for my ID card (needeed to get into buildings)
.
Any help, from anyone, is much appreciated. Thanks!
first of all, I would like to say that I know absolutely nothing about electronics, and, of course, RFID... So it seemed impossible to me, at first glance, that it would work !
Then I decided to have a try. I went down to my local electronic stuff supplier, bought all the required components and built a sample...
What was my surprise to find out that it actually works !
So I would like to thank you for your GREAT Instructable. Very well explained and documented.
Now, here are some questions...
How are "stored" the informations into the tag and how is it possible to modify (interact with) them ? You say that The technology is also used in mass transit systems in cities like London and Hong Kong. In Japan, many mobile phones incorporate readers to enable e-money payments in shops and vending machines.
Do they need a distinct "writer" and a distinct "reader" ? How come the reader can not also write ?
If a Faraday cage would "shield" the tag from the reader, why shoplifters don't simply coat the tags with some metal (aluminium foil) ?
What if I put two (or several) tags close to each others ? Will the reader get confused ?
Finally, are you some kind of electronic engineer/teacher ?
I am looking forward for more Instructables from you !
Thanks again.
This one of the Achilles Heels of RFID
There is a mechanism for the cards to wait for a time period for a second or further transmission, when the reader polls them. The software in the reader simply ignores multiple hits in a given timeframe.
There is a jammer that you can make, that jams the RFID system by *always* responding to every request, and responding constantly. This defeats the random time waiting that the cards use to get a clear transmission.
(If you are thinking that simply waiting a [pseudo-random] moment before trying again seems a bit inefficient, well, it is, but since even a crowded place would have only a few dozen tags within range (about 10 metres is the maximum, and normally it's 1 metre) and the tags are talking at over 1 million bits per second, each card takes well under a millisecond to do it's thing. So there is plenty of time for anything human scale to work, with perhaps 5 cards a second tops going through a scanner.)
As to how to "program them, this is usually done with an RFID reader.
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