The Boundary Scan Idea Scan provides a means to arbitrarily observe test results and source test stimulusīased on board structure Not limited by chip function/ complexity Observe/Control cells provide for test and normal function \u2018In-Circuit\u2019 test points onto the silicon, creating \u2018Virtual Nails\u2019īoundary scan cells bound each net, providing for continuity testing The Boundary-Scan Idea 1997 TI Test Symposium Test generation, though automated, requires ICT models Test access limited by: Fine pitch packages In-Circuit Test (\u2018Bed-of-Nails\u2019 Test) Based on board structure, but limited by chip complexityĬhip function can be ignored for shorts testingĬhip function must be considered for continuity test In-Circuit Test (\u2018Bed-of-Nails\u2019 Test) System level Yesterday AL 10Sept.-97 1149.1(JTAG)-Tut.I-9ġ unit of cost 10 units of cost 100 units of cost 1,000 units of cost 1997 TI Test SymposiumĬonventional Methods of Board Test Functional Test (\u2018Edge-Connector\u2019 Test)īased on board function, rather than structure Increasing integration at chip level complicates controllabilityġ. The Increasing Problem of Test Yesterday 1997 TI Test SymposiumĬan\u2019t Afford Not To Test Cost will increase by a factor of ten as fault finding moves from one level of complexity to the next. Miniaturization results in loss of test access Scan effectively partitions digital logic to facilitate control and observation of its functionīoundary-Scan: Partitions boards at chip I/Os for control and observation of board-level nodes User RegisterĬhip-Internal Scan: Partitions chips at storage cells (latches/ flipflops) to effectively partition sequential logic into clusters of combinational logic Solution: Build test facilities/test points into chipsįocus: Ensure compatibility between all compliant ICs 1997 TI Test Symposium Sanctioned by IEEE as Std 1149.1 Test Access Port and Boundary-Scan Architecture in 1990 JTAG (IEEE 1149.1/P1149.4) Tutorial - Introductoryĭeveloped by Joint Test Action Group (over 200 SC, test, and system vendors) starting in mid '80's
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