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ARM DDI 0337B
Table 12-3 Recommended implementation-defined IR instructions for
IR instruction value
b0000
b0001
b0010
b0011
b0100
b0101
b0110
b0111
a. Reserved, if the instruction is not implemented.
If you require a boundary scan implementation then you must implement the
instructions that are shown as required by IEEE 1149.1 in a wrapper to JTAG-DP. The
other IR instruction values listed in Table 12-3 are Reserved encodings that should be
used if that function is implemented in the boundary scan. If implemented, these
instructions must behave as required by the IEEE 1149.1 specification. If not
implemented, they select the Bypass register.
The IEEE 1149.1 specification also requires the IDCODE and BYPASS instructions.
However these are included in Table 12-2 on page 12-8.
The CLAMPZ instruction
CLAMPZ is not an IEEE 1149.1 instruction.
If implemented, when the CLAMPZ instruction is selected all the 3-state outputs are
placed in their inactive state, but the data supplied to the outputs is derived from the scan
cells.
CLAMPZ can be implemented to ensure that, during production test, each output can
be disabled when its value is 0 or 1. This encoding should be used if this function is
required.
Copyright © 2005, 2006 ARM Limited. All rights reserved.
IEEE 1149.1-compliance
Instruction
Required by IEEE 1149.1?
EXTEST
Yes
SAMPLE
Yes
PRELOAD
Yes
Reserved
-
a
No
INTEST
No
a
CLAMP
a
No
HIGHZ
a
No. See The CLAMPZ instruction.
CLAMPZ
Debug Port
12-9
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