hey HNers, this is sorta related to an idea I have, using a Pi plus an RF transceiver for reading RFID tags. Commercial ones with Bluetooth seem to run $1,000 or more.
I'm helping out with a food distribution org (lfrad.org). One of their gleaners, Steve, would like an easy way to estimate the weight of the food they've collected from a supermarket. The idea we like is to attach an RFID tag to each box of food (not each item), and segregate the types of food, e.g. a bread box, a produce box, a milk box. Steve already does the repacking, in boxes in his SUV. He knows the average weight of a box of each type of food.
The tags will just say what kind of food it is. They can be reused once they're counted.
Note that the boxes don't come pre-packed from the store, and he doesn't lay them all out on the ground before putting them in his car.
SO: the goal is, he just points his homebrew RFID reader at the car full of boxes, and it counts the boxes of each type of food.
Has anyone ever done anything like this?
He's a former circuit designer, so hardware hacking is not beyond him. I also have other friends who could help. I think a funky-looking homebrew product is actually preferable to a commercial one, since who's going to steal it?
EDIT: thanks for the answers so far. I think some commercial units do work with passive tags at that distance (say, 5 meters), but I'll have to recheck.
The trunk can be open; that's not a problem.