A Flexible Data Acquisition System for Aerospace Applications

This paper presents a flexible data acquisition (DAQ) system targeted to aerospace applications. The system is able to acquire raw signals from resistive, capacitive and digital/pulsed output sensors. The flexibility in the read-out capability is made possible thanks to: (1) the adoption of an integrated analog front-end (AFE) circuit for the generic interfacing of resistive and capacitive sensors; (2) the adoption of the same time-to-digital conversion approach for all the connected sensors. The AFE implements the resistance/capacitance-to-time conversion by generating a square wave, whose period is proportional to resistance or capacitance values. The time-to-digital conversion is made by the timer peripheral of a generic microcontroller board, thus avoiding the analog-to-digital converter (ADC). The architecture of the proposed DAQ system is presented and the design of the AFE circuit is detailed with emphasis on the energy-per-measurement (EpM) performance. As an example of operation, a demonstrator with two NTC thermistors and an Hall effect sensor, is made and measurement results are shown.