View Full Version : Using a stamp to detect/monitor proximity or RFID tags?

11-21-2006, 10:23 AM
I am trying to determine if a BS2 or other stamp could be made to receive input (identifying IDs) from either Weigand-type proximity sensors or RFID-type tags, and produce output signals based on particular rules.

My application is loss-prevention in a small supermarket (mostly fresh meat items). What I am thinking is, could I put a low-cost proximity tag in each package, and connect short-range prox sensors at various key locations, and have the Stamp repeatedly poll the IDs off the tags (i.e. get pre-programmed tags) at each senor location, and respond accordingly.

Say for example, I had a prox sensor behind the case shelf where the meat is displayed for sale. As product (each with its own tag) is placed on the shelf, the Stamp reads each ID and adds it to a register (say it polls that reader each 15 seconds).

I would have additional sensors at the checkstands, and enterance and exit doors. Program rules could be if a particular ID value is read at shelf sensor (1), and then is absent from sensor (1), but detected first at say checkstand sensor (2), and then exit sensor (3), that ID would be discarded from the system. However, if a particular ID value is read at (1), and then at (3), without being read by (2), the Stamp would generate an output at a particular pin.

Is this feasible, from the point of view of Stamp control, and also, can passive (Weigand or other) tags be read at distance (say 5 or 6 feet) without the bulkly antennas you often see with so-called 'security gate' type systems? Could a Stamp receive Weigand ID information, and handle real-time control/monitoring of say, 20 IDs? I would like to build a reliable, low-cost simple system. I know there very sophisticated (and expensive) RFID tracking systems out there---but can something simpler be done with a stamp?

Any input or direction would be VERY much appreciated. Thanks!

11-21-2006, 11:38 AM
Take a look at this recent thread in the projects section http://forums.parallax.com/showthread.php?p=616134

Also look at the RFID reader from parallax. It appears that the range is a few inches at best, and the card must be oriented perfectly with the reader to transfer data. Just going off the parallax one and reading its manual, it doesn't look like passive RFID could go that far.