Hard real time implementation of reconfigurable virtual instruments using FPGA

Recent trends in computer technologies have paved way for implementation of virtual instruments [VI] in measurement systems. Conventional virtual instruments are based on a general purpose data acquisition system where the data processing and analysis are implemented by software in personal computers. While the virtual instruments are flexible to use, they suffer a major drawback when it comes to handling time critical instrument tasks. In a conventional virtual instrument, the critical-in-time instrument tasks, which are software implemented, depend on the data transfer rate between the acquisition hardware and the computer and also on the realtime capability of PC´s operating system. Therefore, simple virtual instruments cannot operate at the same frequency as traditional ones where the hardware is dedicated for their specific functionality. Using FPGA chip with embedded software-core processor which provides both software-programmable and hardware-reconfigurable abilities, it is possible to construct a hardware that can serve as the kernel of versatile measurement instruments. In this paper, an architecture for hard real-time implementation of a virtual instrument using a reconfigurable core is presented. Existing drawbacks of conventional virtual instruments with respect to time critical instrument tasks are discussed. The proposed architecture reconfigures the system depending upon the measurement requirement and provides hard real-time capability for time critical instrument tasks. Implementation of virtual instruments in hard real-time mode [HRT] is tested for a typical spectrum analyzer instrument and the results are presented.