Optical interface for an intelligent wireless sensor and system

An infrared optical interface has been developed for control and programmability of an intelligent wireless sensor and system ASIC named "wirtx2". The interface transmitter is designed for hand-held applications. The transmitter includes a 4x5 keypad, Field Programmable Gate Array, and an infrared light emitting diode circuit. The data are transmitted at a chipping rate of 3 7. l 2kHz with a baseband data rate of 1.16kHz. The receiver uses a photodiode-transimpedance amplifier topology for the pre- amp, followed by filtering and signal shaping to recover the baseband signal. The optical receiver is included in the wirtx2 ASIC. The recovered data controls the data reporting scheme, PN code used in the spread-spectrum algorithm, enable function for an external PN code, presets for the external PN code, sleep mode, and the ASIC clock rate. The optical interface provides the interface logic necessary for compliance with the IEEE P1451.4 standard for mixed-mode smart-transducer communications. The wirtx2 ASIC includes two on-board temperature sensors, data acquisition, data formatting and a wireless spread spectrum data communications system with a 916 MHz carrier frequency.