Long Range UHF RFID Item Tracking System

Maker spaces typically have hundreds of valuable tools available for use by their members. These tools can navigate from room to room and project to project. There is no real good way of knowing the whereabouts of a particular tool at a given time. Paper sign-out systems are often forgotten in the adrenaline rush of finishing an exciting project, and you can't always count on people putting things away properly (though they really should!). It is easy for items to become misplaced and lost, sometimes for weeks on-end!

The hardware and software projects contained within this article aim to provide an affordable method of tracking these tools and other valuable items. This solution uses Long Range Ultra High Frequency RFID technology to tag and monitor items. This solution may also be implemented in homes: workspaces, dens and garages if need be (and definitely on that elusive Phillip's head screwdriver!!).

In order to keep the solution affordable, most of the cost is up-front when deploying the actual monitors and antennas. Any number of individual items can be tagged with inexpensive EPC Gen 2 passive RFID stickers, cards, or fobs. This means the solution can scale cost effectively.

In a nutshell, multiple RFID readers are deployed to various rooms throughout the building, and, depending on the room size, you can even deploy multiple readers to the same room. These readers (which are also called Monitors in this article) will collect time stamped readings of specific tags with the monitor IP address and feed this data to a cloud Web Api service hosted on Azure. There is also a ASP.NET MVC web application UI provided that will allow the consumer to register their RFID readers (Monitors) and Tags. The web application also has an inventory screen where they can view the last known location of an item (based on the location of the monitor providing the latest reading) as well as the time stamp of the latest reading for that item.

Hardware Required

–  Raspberry Pi 2 with Windows IoT Core (1 for each monitor)

– CP2102 USB to UART TTL conversion module (1 for each monitor)

– Cottonwood UART Long Range UHF RFID reader board (1 for each monitor)

– Mid to Long Range UHF RFID antenna (commercial grade circular antennas are best, in my case I had to stay on a personal budget, so this proof of concept uses an 8dbi directional antenna) (1 for each monitor)

– Antenna adapter cable (1 for each monitor)

– 5VDC 2A Power Supply with center-positive 5.5×2.1mm barrel connector (1 for each monitor – the Cottonwood board requires it's own power supply)

– A series of UHF RFID tags (stickers, cards, fobs)

Hardware Setup

Hardware setup is pretty simple. First grab your CP2102 USB to UART TTL conversion module and connect 3 wires: Ground (GND), TX and RX.

Connect the following wires:

– CP2102 GND to Cottonwood GND

– CP2102 TX to Cottonwood RX

– CP2102 RX to Cottonwood TX

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