Multiplexing in test mode reduces pin count requirements

Abstract

A new integration module in the Motorola Modular Family of Microcontrollers implements a multiplexed test mode which allows internal signals to be driven even when the input pin used to drive that signal is not implemented. This test mode allows the minimum pin set that was defined for this new integration module to provide the same controllability and observability as the full pin set. This produced a significant cost savings, since it maintains the fault coverage of a large number of test patterns that were developed using previous maximum pin set integration modules.<>