Functional Verification of an Electronic Module Designed for an Aeronautic Application

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"The use of DIAdem software contributed to reducing development time and simplifying the data manipulation and analysis."

- Francis RAGUIN, Barco Silex

The Challenge:
Designing a fully automated test bench, with a built-in self-test capability, that is qualified for testing complex electronic modules (FPGAs) developed in an aeronautic environment. This test also needs to be integrated in the verification process in line with the recommendations of the DO-254 standard, level A.

The Solution:
Using the NI PXI platform with a customized test interface board driven by a PC running an application developed with NI LabVIEW system design software and NI DIAdem data management software to design the system. The whole system provides acquisition and management of the module signals as well as analysis, verification, and automatic report creation.

Author(s):
Francis RAGUIN - Barco Silex

As a full subsidiary of the Barco group, specializing in professional visualization systems, Barco Silex is a leader in embedded systems engineering services, the development of dedicated hardware and embedded software, and the design of custom IP cores. Barco Silex provides high-performance JPEG 2000 cores (encoder, decoder, and very low latency), Crypto cores (advanced and data encryption standards, hashing, and public key), and memory controllers optimized for the latest generations of FPGAs and application-specific integrated circuits.

As a DO-254 methodology expert, we have developed an automated test bench to achieve the functional verification of a complex electronic module (FPGA) that was designed for an aeronautic application. This verification had to be performed according to the recommendations of the DO-254 methodology at level A. This test bench also needed to integrate an analysis engine as well as a reporting engine following acceptation criteria defined by the user.

Automated and More Reliable Tests

In the original solution, tests were manually performed and analyzed and corresponding results were reported. The new system we developed allows for the optimization of the time required to execute and analyze the tests and it minimizes the risks of making mistakes when reporting the verification results. This new approach provides better integrity of results and analysis and ensures, at a lower cost, the nonregression of the FPGA after the various specification modifications that are typical in such projects.

Different Types of Data at I/O

The module being tested is simultaneously handling analog and digital signals driven by the FPGA both at the inputs and outputs. For this reason, the test bench is made of an NI PXIe-1073 chassis equipped with five NI modules: two NI PXIe-6535 high-speed digital I/O, one NI PXI-6224 M Series DAQ, one NI PXI-6723 analog output, and one NI PXI-4110 programmable, triple-output precision DC power supply.

Data is centralized on a PC via a specific application that manages all collected and produced data. A custom board integrating the module being tested is also driven by this application, thanks to an RS232 link with the PC. The board is connected to the PXI chassis via a set of custom cables.

A Synchronous System to Guarantee Traceability

The boards used here offer different features. This is the case for the sampling frequencies, both for the acquisition and generation signals. The DO-254 flow requires the traceability of the verification tests, making it mandatory to “start” all boards simultaneously. The PXI platform, which integrates the trigger and “hardware” clock lines that connect the various boards, ensures synchronization of all the signals produced by the test bench.

Automated Management of Test Procedures

The document that describes all actions for each test procedure and the corresponding expected results was translated into scripts that are directly usable by the application software. Therefore, a specific instruction set was integrated within the application. The documentation describing the different procedures also uses this instruction set. The documentation is closed to the scripts used by the test application, which facilitates its review and minimizes the time needed for the adaptation or the development of these procedures.

Starting from these scripts, the application fully automates the sequencing and the execution of these procedures on the test bench, the analysis of the various tests, and, finally, the verification of the results. The results are provided as reports for each procedure: the verified requirements, the realized tests, the expected results, the actual results, and the associated status (OK, NOK). It then becomes easy to guarantee the traceability of the results as required by the DO-254 methodology.

A Qualified System

The calibration certificates of the various NI boards ensure the technical features of the hardware. Given the automatic feature of the test bench, a set of dedicated test sequences using all self-verification mechanisms was developed to prove its integrity. The qualification file obtained with these two points helps us to justify the coherence of the verification results.

Taking Advantage of Development Tools

The verification application was developed using LabVIEW software to configure the PXI platform and set up the various hardware synchronization devices for data acquisition and generation. Many examples on the web and technical support greatly facilitated this process. For the results verification, we used DIAdem software, driven by LabVIEW, to reduce development time and simplify the manipulation and analysis of data coming from several sources with several sampling frequencies.

Successful Optimization Despite Constraints

The realization of this test bench optimized the time and resources needed to execute the tests, especially for the evolution of the functionality of the module to be verified, to ensure its nonregression. These optimizations are compatible with the constraints imposed by the DO-254 standard level A because of result coherence and traceability.

Author Information:
Francis RAGUIN
Barco Silex
Z.I. Rousset Peynier Immeuble CCE – Route de Trets
PEYNIER 13790
France
Tel: +33 (0)4 42 16 41 08
francis.raguin@barco.com

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