Online self-test wrapper for runtime-reconfigurable systems

Abstract

Reconfigurable Systems-on-a-Chip (SoC) architectures consist of microprocessors and Field Programmable Gate Arrays (FPGAs). In order to implement runtime reconfigurable systems, these SoC devices combine the ease of programmability and the flexibility that FPGAs provide. One representative of these is the new Xilinx Zynq-7000 Extensible Processing Platform (EPP), which integrates a dual-core ARM Cortex-A9 based Processing System (PS) and Programmable Logic (PL) in a single device. After power on, the PS is booted and the PL can subsequently be configured and reconfigured by the PS. Recent FPGA technologies incorporate the dynamic Partial Reconfiguration (PR) feature. PR allows new functionality to be programmed online into specific regions of the FPGA while the performance and functionality of the remaining logic is preserved. This on-the-fly reconfiguration characteristic enables designers to time-multiplex portions of hardware dynamically, load functions into the FPGA on an as-needed basis. The configuration access port on the FPGA can be used to load the configuration data from memory to the reconfigurable block, which enables the user to reconfigure the FPGA online and test runtime systems. Manufactured in the advanced 28 nm technologies, the modern generations of FPGAs are increasingly prone to latent defects and aging-related failure mechanisms. To detect faults contained in the reconfigurable gate arrays, dedicated on and off-line test methods can be employed to test the device in the field. Adaptive systems require that the fault is detected and localized, so that the faulty logic unit will not be used in future reconfiguration steps. This thesis presents the development and evaluation of a self-test wrapper for the reconfigurable parts in such hybrid SoCs. It comprises the implementation of Test Configurations (TCs) of reconfigurable components as well as the generation and application of appropriate test stimuli and response analysis. The self-test wrapper is successfully implemented and is fully compatible with the AMBA protocols. The TC implementation is based on an existing Java framework for Xilinx Virtex-5 FPGA, and extended to the Zynq-7000 EPP family. These TCs are successfully redesigned to have a full logic coverage of FPGA structures. Furthermore, the array-based testing method is adopted and the tests can be applied to any part of the reconfigurable fabric. A complete software project has been developed and built to allow the reconfiguration process to be triggered by the ARM microprocessor. Functional test of the reconfigurable architecture, online self-test execution and retrieval of results are under the control of the embedded processor. Implementation results and analysis demonstrate that TCs are successfully synthesized and can be dynamically reconfigured into the area under test, and subsequent tests can be performed accordingly.