A Wirelessly-Powered Platform for Sensing and Computation” by Joshua R. Smith, Alanson P. Sample, Pauline S. Powledge, Sumit Roy and Alexander Mamishev, 2006:

The WISP platform includes a general-purpose programmable flash microcontroller and implements the bi-directional communication  primitives required by the Electronic Product Code (EPC) RFID  standard, which allows it to communicate arbitrary sensor data via an EPC RFID reader by dynamically changing the ID it presents to the reader. For each 64 bit “packet,” the WISP’s microcontroller  dynamically computes the 16-bit CRC that the EPC standard requires of valid packets. Because the WISP device can control all bits of the  presented ID, 64 bits of sensor data can be communicated with a  single RFID read event.