The RFI2D system is a modular, grid-based positioning and identification system for RFID tags. It is designed for token identification and positioning in tabletop game applications, but it can also be used for any object tracking and positioning application that requires high speed contactless identification.
The RFI2D system is comprised by one or more of modules that are interconnected, creating an RFID-aware surface. Each module uses a dedicated 8-bit microcontroller in order to control and monitor an A4 sized area, divided in a 4x6 grid. A dedicated antenna, implemented as a PCB microstrip, is located at each grid position. RFID tags placed on the module will be detected by the corresponding antenna and the system will report both their X/Y coordinates on the grid, as well as their unique identifier (UID).
The system implements the popular ISO/IEC 14443A standard for radio frequency proximity identification, making use of the 13.56 MHz, 106 kbit/s communication mode. RFID tags with 4 byte, 7 byte and 10 byte UIDs are fully supported. Furthermore, the system implements the ISO14443A anti-collision protocol, in order to detect multiple tags per grid position.
An external computer equipped with one or more I2C master interfaces reads the system's data, with each I2C master interface handling up to 127 modules. This way, the system can be scaled up indefinitely, covering a surface of any size, provided there are enough I2C master interfaces.
The system prototype was tested on a 42.0 x 59.4 cm (A2) surface with 16 tags spread randomly, achieving a resolution of 2.5 cm with a response time of 14 ms. While the system vastly outperformed the project's requirements, its performance is expected to increase further in next iterations.
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