Debugging LBIST safe-stating issues

Abhinav Gaur , Amit Bathla & Gaurav Jain (Freescale)
EDN (July 08, 2015)

Logic built-in self test (LBIST) allows hardware to test its own operation. There is no need for any external hardware or test equipment. LBIST is a “must have” feature for safety compliant SoCs. But care must be exercised when using LBIST in a complex SoC.

Concept of LBIST partitioning

The entire SoC is partitioned into various LBIST partitions and a LBIST controller is present for running LBIST on each of these partitions. There is a central controller which controls all these LBIST controllers so that LBIST can be controlled from one point for the entire SoC (otherwise each of the LBIST controller needs to be programmed separately). The central LBIST controller mentioned above has bit mapping for the various options available for LBIST as well as registers for sequencing the LBIST.

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