Associative Clock Control for Signature Analysis
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
A self-stimulating Signature Analysis (SA) procedure is tailored to test and diagnose printed circuit boards (PCBs) which include functional elements, such as microprocessors and microprocessor-support devices. SA methodology compresses a string of response values (logic 1, 0) into a signature, a distinct 16-bit number usually written in hexadecimal form. SA requires that stimuli drive the device under test (DUT) and that the responses thereto be accumulated in the signature accumulator. The DUT's system clock, in general, controls when the response values are processed into the signature accumulator. The microprocessor op codes are such that some commands (op codes) have cycles that have "don't care" conditions. In the past, the op codes with "don't care" states were not included in the test program.