Backplane test bus selection criteria

The author discusses the architecture of the IEEE 1149.1 Standard, its applications and selection criteria. Although the evaluation and selection of a multi-drop addressable 1149.1 architecture are completed, the hardware has been designed such that alternative architectures could be implemented, if warranted, without a complete redesign of the payload digital electronics. The primary advantage of this architecture is the natural boundary scan test support at all levels of integration. Closed loop chains exist at each integration level and can be exercised to isolate 1149.1-detectable defects that occur at that level prior to any disassembly of the product