Two boundary scan cell switches controlling input to output buffer

摘要

A process initializes the state of an output memory circuit of a scan cell located at the boundary of a logic circuit within an integrated circuit. Data is scanned into an input memory circuit of the cell while maintaining the cell in a mode providing normal operation of the logic circuit. The cell is placed in a test mode that disables normal operation of the logic circuit. The data scanned into the input memory circuit is transferred into the output memory circuit simultaneous with the placing the cell in the test mode. A transmission gate between the logic circuit and the output memory circuit and a transmission gate between the input memory circuit and the output memory circuit effect the changes between normal operation and test modes.