Test pattern and test configuration generation methodology for the logic of RAM-based FPGA

The test of the Configurable Logic Blocks of RAM based FPGAs under a Stuck-At fault model has been studied. The high cost of changing the configuration, by reprogramming the FPGA during testing, forces a strategy to reduce the number of different configurations used for testing purposes. After finding the optimal solutions for the elementary structures of the Logic block, Multiplexers and Look-Up Tables, the problem of testing interconnected elementary structures is addressed. The method is illustrated using an elementary structure and then applied to a popular FPGA (XILINX 3000 family) where a reduced set of configurations (5) and their corresponding test sequences is found to cover all (100%) the Configurable Logic Block faults modelled.