RFID enabled drawer

Hello.

I have a little idea and would like to explore possibilities of making it true. I'm looking forward to advice and remarks. Thanks!

IDEA

I want to make a RFID enabled drawer. Drawer contains 3 objects marked with RFID (HF?) tags, those tags fit into 3 spaces with RFID antennas. So it works like up2date inventory. When you take things out it notices, when you have things in it notices. Something along those lines.

QUESTIONS

Is it doable (not extremely hard)?

What arduino platform would be best suited for something like this?

Is there any RFID HF shield for arduino platform? Or something similar?

If there is RFID shield (x freq), how many antennas can it support?

Yes it's doable. You could have hundreds of tags, with no problem.

By coincidence, I just bought one of these kits based on this module today.

I'll report back over the weekend....

@KenF

What arduino platform would be best suited for the job? Are there any HF RFID (13,56 MHz) arduino shields or something similar?

If I could read hundreds of tags over a small interval, how can I multiplex or otherwise wire pcb antennas?

@JimboZA

How is your project going? Any ideas on how to wire multiple antennas together?

Trdi:
What arduino platform would be best suited for the job? Are there any HF RFID (13,56 MHz) arduino shields or something similar?

Just about any of the standard arduinos will run an rfid shield. The UNO is usually the entry level board and I'm sure it would cope easily. There are a few shields out there, hit google.

If I could read hundreds of tags over a small interval, how can I multiplex or otherwise wire pcb antennas?

You don't, you just have one antenna on one shield. The protocol used is such that it can find multiple tags within it's range without any conflicts. This explains it quite well

The protocol used is such that it can find multiple tags within it's range without any conflicts.

That protocol is only used in a tiny number of systems. The vast majority of systems have no collision avoidance and can only read when there is only one tag in the field.

Grumpy_Mike:
That protocol is only used in a tiny number of systems. The vast majority of systems have no collision avoidance and can only read when there is only one tag in the field.

Mike, thank you for your insight. I was (probably mistakenly) under the impression that this was standard practice.

Does the interface exposed by the, run of mill, shield allow the development of such a scheme or is it too hardwired?

I think I don't want to use LF reader (125 kHz), because antennas are too big, read rates are poor and it has some other unwanted properties (interference). UHF frequencies and protocols means it's going to be expensive and so not suited for me. Maybe HF is the best option.

Don't get me wrong, I would love to have one antenna and do all the reading with great accuracy, but it seems to me I better have an antenna for each tag (ratio n:n). So n objects in drawer relate to n PCB antennas. It is the case now, that I want to have 3 antennas connected to one (HF?) reader. How do I connect 3 PCB antennas to that RFID shield? Multiplexing (how?) or having 3 parallel connections (possible?)?

Does the interface exposed by the, run of mill, shield allow the development of such a scheme or is it too hardwired?

Not only is it the reader but the RFID tag has to know about this so it has to be a special chip set. There is nothing you can do with a normal reader.

I want to have 3 antennas connected to one (HF?) reader.

Trying to multiplex antennas is tricky, first the frequency is very high for normal multiplexers but the big problem is the voltage. RFID antenna work with resonant circuits so the voltage on the coil can be anything from 50 to 300V.

KenF:
Just about any of the standard Arduinos will run an RFID shield. The UNO is usually the entry level board and I'm sure it would cope easily. There are a few shields out there, hit google.

Suggest dropping the term "shield" - this implies something made to mount on a UNO.

RFID modules use a (type of) serial interface and generally connect by a few flying leads. The smaller Arduino forms such as the Nano or Pro Mini (if you do not require to connect it to a PC) are more convenient. If you have a number of compartments in a drawer, you would have one RFID module per compartment, spaced or shielded from each other - or simply activate them one at a time in sequence which would be a good way to multiplex a single serial port for all.

@Paul

I would like a connection to some sort of terminal and maybe it would be the most convenient (at first) to connect it to laptop - option of having some sort of application as to if anything is missing.

In reality I'm hoping to have about 10 rfid tagged pieces to be accounted for in the drawer. Your idea - 1 rfid module per piece - is analogous with 1 pcb antenna per piece. However, I appreciate the simplicity of gathering each read with time sequencing you proposed.

Some important issues are cost-efficiency, size of pcb antenna or rfid module, wiring difficulty and scalability.

Any ideas, suggestions?

Maybe this is not quite what you are looking for but this is what I did to read multiple tags in close proximity.
http://www.thebox.myzen.co.uk/Hardware/RFID_Sequencer.html