Software-Based Self-Test is an effective methodology for devising the online testing of Systems-on-Chip. In the automotive field, a set of test programs to be run during mission mode is also called Core Self-Test library. This paper introduces many new contributions: (1) it illustrates the several issues that need to be taken into account when generating test programs for on-line execution; (2) it proposed an overall development flow based on ordered generation of test programs that is minimizing the computational efforts; (3) it is providing guidelines for allowing the coexistence of the Core Self-Test library with the mission application while guaranteeing execution robustness. The proposed methodology has been experimented on a large industrial case study. The coverage level reached after one year of team work is over 87 percent of stuck-at fault coverage, and execution time is compliant with the ISO26262 specification. Experimental results suggest that alternative approaches may request excessive evaluation time thus making the generation flow unfeasible for large designs.

Software-based self-test (SBST) techniques are used to test processors and processor cores against permanent faults introduced by the manufacturing process or to perform in-field test in safety-critical applications. However, the generation of an SBST program is usually associated with high costs as it requires significant manual effort of a skilled engineer with in-depth knowledge about the processor under test. In this paper, we propose an approach for the automatic generation of SBST programs. First, we detail an automatic test pattern generation (ATPG) framework for the generation of functional test sequences. Second, we describe the extension of this framework with the concept of a validity checker module (VCM), which allows the specification of constraints with regard to the generated sequences. Third, we use the VCM to express typical constraints that exist when SBST is adopted for in-field test. In our experimental results, we evaluate the proposed approach with a microprocessor without interlocked pipeline stages (MIPS)-like microprocessor. The results show that the proposed method is the first approach able to automatically generate SBST programs for both end-of-manufacturing and in-field test whose fault efficiency is superior to those produced by state-of-the-art manual approaches.

Due to the increasing usage of embedded instruments in many electronic devices, new solutions to effectively access these instruments appeared, including the new IEEE 1687 standard. The approach supported by IEEE 1687 allows a flexible access to embedded instruments through the Boundary Scan interface. The IEEE 1687 network includes a set of reconfigurable scan chains. This paper addresses the issue of testing the circuitry implementing them, checking whether any permanent hardware fault exists, affecting either the registers associated to the instruments made accessible by the network, or the configuration structures it embeds (e.g., the multiplexers and the associated flip-flops). The paper proposes an approach, in which the IEEE 1687 network undergoes a sequence of test sessions, each composed of a configuration phase and a test phase. By properly selecting the network configurations to be used, we can guarantee that the method can test any permanent fault possibly affecting the network. We also provide some experimental results gathered on a set of benchmark networks, allowing to practically evaluate the viability of the approach.

When the result of a previous instruction is needed in the pipeline before it is available, a “data hazard” occurs. Register Forwarding and Pipeline Interlock (RF&PI) are mechanisms suitable to avoid data corruption and to limit the performance penalty caused by data hazards in pipelined microprocessors. Data hazards handling is part of the microprocessor control logic; its test can hardly be achieved with a functional approach, unless a specific test algorithm is adopted. In this paper we analyze the causes for the low functional testability of the RF&PI logic and propose some techniques able to effectively perform its test. In particular, we describe a strategy to perform Software-Based Self-Test (SBST) on the RF&PI unit. The general structure of the unit is analyzed, a suitable test algorithm is proposed and the strategy to observe the test responses is explained. The method can be exploited for test both at the end of manufacturing and in the operational phase. Feasibility and effectiveness of the proposed approach are demonstrated on both an academic MIPS-like processor and an industrial System-on-Chip based on the Power Architecture™.

The paper is dealing with the in-field test of the decode unit of RISC processors through functional test programs following the SBST approach. The paper details a strategy based on instruction classification and manipulation, and signatures collection. The method does not require the knowledge of detailed implementation information (e.g., the netlist), but is based on the Instruction Set of the processor. The proposed method is evaluated on an industrial SoC device, which includes a PowerPC derived processor. Results demonstrate the efficiency and effectiveness of the strategy; the proposed solution reaches over 90% of stuck-at fault coverage while an instruction coverage based approach does not overcome 70%.

Software-based self-test (SBST) techniques are used to test processors against permanent faults introduced by the manufacturing process (often as a complementary approach with respect to DfT) or to perform in-field test in safety-critical application...