RFID tags add data logging via external "sensor-enabled" connection

August 27, 2013 // By Paul Buckley
ams has introduced sensor-enabled RFID tags offering new features to medical, automotive safety and other applications where temperature, physiological or environmental data has to be reported.

The SL13A and SL900A enable a simple, low-cost implementation of a new class of wireless data-logging applications, ams says. The SL13A is an ISO15693-compliant tag for use with near field communications (NFC-V) and high-frequency radio-frequency identification (HF RFID) readers. The SL900A is an EPC Gen 2 Class 3 tag for use with RFID readers.
The devices include an on-board temperature sensor, an interface to an external sensor, and can operate in passive (batteryless) mode. In this mode, the tag harvests energy from a reader’s broadcast, using the power to read the temperature or data from an external sensor, and transmits the information back to the reader together with a unique ID. The data is time-stamped by the reader.
The SL13A and SL900A can be powered by a single-cell or 3 V battery. In battery-assisted passive (BAP) mode, the tag’s on-board real-time clock is enabled, and can be used to trigger periodic sensor readings. Up to 762 (SL13A) or 841 (SL900A) time-stamped events may be saved in the on-chip EEPROM, from where they may be read when the device is in range of a reader.
The combination of a sensor interface, NFC compatibility and support for passive mode offers designers the opportunity to invent new kinds of wireless data-logging applications, or to find better ways to implement existing data-logging systems. ams anticipates applications as diverse as patient monitoring, building control and automotive safety to benefit from the ability to read bio-medical, humidity or pressure measurements via the SL13A using harvested energy from an NFC reader such as an Android smartphone or tablet.
Both the SL13A and SL900A feature a serial peripheral interface for connection to a microcontroller. They can operate from a power supply ranging from 1.2 to 3.6V. The tags provide for long battery life, drawing a typical 1.6 µA in stand-by mode with the real-time clock running. The on-board temperature sensor is accurate to up to 0.5%.
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