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RFID tag

PostPosted: Sat Feb 28, 2009 12:00 pm
by tmntmn
Hello everyone

If this is the wrong place to post this please feel free to edit or delete it.

What I’m looking for is an inexpensive ID tag that with a reading range of 5 to 10 meters. I’ve been looking at dozens of professional RFID tags, but these are expensive, you must buy thousands, the readers are expensive and SDK kits for programming are even more expensive.

So is it possibly to build a very simple ID tag based on the nRF24LU chip.

What I’m imagining is that the TAG ID number could be flashed into a register on the chip, and with a simple board with additional components, ceramic antenna and small battery for power, the ID of the tag could be read from an ordinary mobile device with bluetooth running win CE or windows mobile.

If anyone has some suggestions or brilliant ideas on how to pull this off, I would be very thankful.

Best regards

Thomas Mathiasen

Re: RFID tag

PostPosted: Sat Feb 28, 2009 4:12 pm
by brennen
That shouldn't be too difficult to build. The RFID would just have a 24LU1 that chirped every so often (maybe once every second or two) and then went to sleep. Keep in mind the tag would have to have a battery on-board, so that's going to increase your form-factor quite a bit. The receiver could be interfaced to a PC via the USB or UART.

Re: RFID tag

PostPosted: Sun Mar 01, 2009 8:26 am
by tmntmn
Thanks very much for your reply.

I might not have been precise in my decription. I need to use a very small handheld device, running quite a lot of other software for recieving the tag ID's. So to avoid building a reciever and interfacing it(USB or UART), I wonder if it is possibly to use the allready build in bluetooth reciver hardware of the handheld device?

It's OK with the battery, as a formfactor like a creditcard would be OK, as long as it s not to thick.

How many digits can the ID be(register size of the chip)?

I'm normally writing C#, not building hardware, so I might be asking foolish questions.

best regards


Re: RFID tag

PostPosted: Sun Mar 01, 2009 3:27 pm
by brennen
The 24LU1 doesn't support Bluetooth, so you'd have to build your own driver for the PC side of the application. You could make the ID pretty much as long as you wanted, and you're right that you could program the ID into the flash program memory somewhere. The processor is 8-bit, but using C will allow you to have a 32-bit ID by using the C type unsigned long. The 24LU1 can transmit up to 32 bytes at once, and I can't imagine you would make the ID that long, so you should be able to get the full ID in one packet.