Active wireless sensor with radio frequency identification chip

In this article, a proof of concept is made for the wireless sensor based on the of the shelf radio frequency identification (RFID) chip. The component used is the NXP Semiconductors G2iL+. This novel chip supports bidirectional digital data transfer not only to the standard RFID reader, but also to the microcontroller or similar digital hardware connected directly to it´s terminals. If the RFID tag is to be used as the part of the active wireless sensor in the field, the tag should be able to operate locally until requested to transmit data by the RFID reader (RFID interrogator). Some limited amount of measured data could be stored in the active RFID chip itself, but for prolonged periods of operation without contact with the reader, data should be stored in some local non volatile memory. In ideal case the RFID chip supports two connections: bidirectional wired digital link to the on-board microcontroller, and wireless link when found itself in the RF field produced by the standard RFID reader. In the example demonstrated in this article, the G2iL+ is connected to the ARM Cortex M3 based board. Programmable RFID interrogator is then used to transmit commands and receive sensor data simulated by the microcontroller.