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BOUNDARY SCAN/JTAG: Instructions defined by IEEE standard 1149.1


Record #1174

Problem Title:
BOUNDARY SCAN/JTAG: Instructions defined by IEEE standard 1149.1


Problem Description:
Keywords: manadatory instructions, bypass, extest, sample/preload

Urgency: Standard

General Description:

What are the mandatory Boundary Scan instructions defined by the
IEEE 1149.1 standard?



Solution 1:

The only JTAG instructions which are defined by the IEEE 1149.1
standard are BYPASS, EXTEST and SAMPLE/PRELOAD.

BYPASS is defined as all bits in the IR as all ones.
EXTEST is defined as all bits in the IR as all zeros.

The standard has not designated a manadatory bit pattern for the
SAMPLE/PRELOAD instruction . This is controlled by the IC
manufacturer.

All other JTAG instuctions are defined by the IC manufacturer.



End of Record #1174