Boundary-Scan Tutorial:

Sample and Preload Instructions

The Sample and Preload instructions, and their predecessor the Sample/Preload instruction, selects the Boundary-Scan register when executed. The instruction sets up the boundary-scan cells either to sample (capture) values or to preload known values into the boundary-scan cells prior to some follow-on operation.

Intest Instruction

The IEEE 1149.1 Standard defines a number of optional instructions – that is, instructions that do not need to be implemented but which have a prescribed operation if they are implemented.

The instruction illustrated here is Intest, the instruction that selects the boundary-scan register preparatory to applying tests to the internal logic of the device.

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