Embedded | October 18, 2011

FPGA-Controlled Test (FCT): What it is and why it is needed

Functionally, the role that FPGAs (field programmable gate arrays) have played in computer and communications systems has grown in parallel with the number of gates and the capabilities of these devices.
A recent study by the Linley Group found that the deployment of FPGAs grew 51 percent in 2010, a testament to the rapidly increasing pervasiveness of these devices. Typically, FPGAs have been deployed by system designers for downstream, end-user functionality, such as logic engines, peripheral I/O management, communications coordination, graphics and multimedia processing, as well as other types of functionality.

Now though, these versatile and flexible devices are emerging as a likely platform for next-generation embedded board test and measurement capabilities which can be employed upstream during design, development and manufacturing, and/or in ancillary downstream applications in the field following product launch, such as ongoing continuing engineering, remote diagnostics, troubleshooting and others.

This trend toward FPGA-controlled test (FCT) is a part of the larger shift toward embedded instrumentation as a more effective methodology for validating, testing and debugging circuit boards. Much of today’s leading-edge electronics technology has simply progressed beyond the reach of legacy, intrusive test technologies such as oscilloscopes and in-circuit test (ICT) systems.

Because these legacy methodologies are based on making contact with chips on boards and circuit boards themselves, they are hobbled by the physical nature of probing. The next wave of validation and test technologies – which includes FCT – will be dominated by internal, non- intrusive software-driven embedded instrumentation methodologies.

FPGA-Controlled Test: Board-Tester-in-a-Chip

The precedent for embedding test and measurement instrumentation into semiconductors is well established. Chip suppliers have been doing it for years to characterize, validate and test their devices. Recently, the usefulness of these embedded instruments has been extended to circuit board validation, test and debug. Now, the next logical step is to embed the multiple instruments that would make up a board tester into an FPGA and thereby extend the test coverage capabilities of software-driven non-intrusive board test (NBT) and validation even further.

Such a board tester might be inserted into an FPGA for temporary or permanent purposes. For example, during circuit board development, first prototypes often are delivered before the firmware for an FPGA or the operating system has been completed. At this point, the structural, functional and performance capabilities of the prototype hardware must be tested to validate the design in preparation for software integration.

Previously, functionally validating the hardware was severely limited without the board’s firmware or OS in place. As a result, development schedules might be delayed while software was being completed. Now, FCT offers an alternative. With FCT, testers made up of multiple instruments can be inserted into an FPGA on the prototypes and subsequently removed when they have helped to validate, test and debug the design.

In addition, there could be a need for this FCT tester later in the lifecycle of the circuit board. If so, then some or all of the embedded instruments might remain in the FPGA to perform manufacturing test, ongoing fault analysis, remote diagnostics or troubleshooting by field service.

Author: Al Crouch Chief Technologist, Core Instrumentation ASSET InterTech

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