Design of a Passively-Powered, Programmable Sensing Platform for UHF RFID Systems

TLDR

The paper introduces a battery‑free, UHF‑RFID powered sensing and computing platform. The WISP platform incorporates a 16‑bit microcontroller with ADC, firmware that implements the EPC‑C1G1 protocol, and dynamically encodes sensor data into an EPC tag ID, enabling the RFID reader to retrieve the data from the tag ID. The platform’s programmability and PCB implementation allow flexible integration of low‑power sensors that are powered solely by the RFID reader, achieving an operating range of up to 4.5 m; to the authors’ knowledge, it is the first fully programmable computing platform that operates using power from a long‑range UHF RFID reader and transmits arbitrary multi‑bit data in a single response packet.

Abstract

This paper presents a wireless, battery-free, platform for sensing and computation that is powered and read by a standards compliant ultra-high frequency (UHF) radio frequency identification (RFID) reader. The WISP (wireless identification and sensing platform) includes a fully-programmable 16 bit microcontroller with analog-to-digital converter. The microcontroller firmware implements portions of the electronic product code (EPC) class 1 generation 1 protocol. When queried, the platform communicates arbitrary sensor data by emulating an EPC tag whose ID encodes the desired sensor data; the required 16-bit CRC is computed dynamically by the microcontroller. The RFID reader reports the received tag ID to application software which can interpret the information contained in the tag ID. The programmability of the WISP along with its implementation as a PCB allows for flexible integration of arbitrary low-power sensors. Furthermore, sensors are also exclusively powered from the RFID reader resulting in a completely battery free device. Sensors integrated into the WISP platform so far include light, temperature, and rectified voltage, and are shown experimentally to have an operating range of up to 4.5m. To the authors' knowledge, WISP is the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary, multi-bit data in a single response packet.