A communication controller circuit for a wind-tunnel model is undergoing development. The circuit is intended to serve as part of a highly miniaturized, distributed, modular electronic analog/digital data-acquisition system that would be installed inside a wind-tunnel model (see Figure 1). The data-acquisition system would include pressure, temperature, angle, shear-stress, and other sensors plus analog signal-conditioning modules in clusters of as many as eight sensors. The sensors and signal-conditioning modules in each cluster would be connected to a data-acquisition-system (DAS) module, which would contain additional analog signal-conditioning circuits and analog-to-digital converters. Each DAS module, in turn, would be connected to the communication controller, which would effect all digital control and data communications (1) among the sensor modules and (2) between the sensor modules and a remote host computer.

Figure 1. The Communication Controller would effect all digital communications among sensor modules and between the wind-tunnel model and the host computer in the control room.

Each cluster of sensors and signal-conditioning circuits connected to a DAS module would constitute a sensor module. The sensor modules would be configured from the host computer by way of the communication controller. After data had been collected and buffered, the communication controller could send the data to the host computer via a fiber-optic cable or a radio telemetry system. Thus, the host computer would have to be equipped with a fiber-optic or radio-telemetry interface circuitry.

A serial bus would be installed within the wind-tunnel model to provide for communications between the sensor modules and the communication controller. The combination of distributed, modular architecture and the serial bus would impart a high degree of flexibility, in that the number of sensors could readily and efficiently be changed through the addition and/or removal of sensor modules, with minimal changes in power- and communication-bus wiring. Sensors and/or sensor modules could be added by connecting them to the internal bus, without need for redesigning the entire data-acquisition system. Small volumes could be carved out in places distributed throughout the inside of the model to accommodate the small modules of the data-acquisition system, making it unnecessary to find a single internal volume large enough to hold the entire system.

Figure 2. This Prototype Communication Controller includes an FPGA, integrated circuits, and some discrete components on a printed-circuit board. In planned further development, further miniaturization would be achieved by fabricating part of the communication controller as an ASIC.

Thus far, a prototype communication controller and prototype sensor modules have been fabricated on printed-circuit boards. The prototype communication controller (see Figure 2) is based on a commercially available field-programmable gate array (FPGA) chip to provide for reconfigurability. In addition to the FPGA chip, the prototype communication controller includes a buffer random-access memory; a nonvolatile electrically erasable, programmable, read-only memory that retains configuration information; drivers for internal and external communication ports; and passive components. Eventually, as now envisioned, the sensor modules and part of the communication controller would be fabricated as application-specific integrated circuits (ASICs).

This work was done by William C. Wilson of Langley Research Center. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp  under the Electronics & Computers category. L-17816

NASA Tech Briefs Magazine

This article first appeared in the March, 2000 issue of NASA Tech Briefs Magazine.

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