Command Dictionary Report AU Faults
FastScan and FlexTest Reference Manual, V8.6_4 2-265
•All
An optional literal that specifies to display all AU faults which include AU, UI,
PU, HU, OU faults.
•Tristate
An optional literal that specifies to display all AU faults which have a
propagation path to the enable of a tristateable primitive which drives a bus
(with no pullup, pulldown, or bus keeper) to establish a known, reliable
voltage when all drivers of that bus are disabled. It is not possible to reliably
observe the fault effect at the output of such a driver when a fault causes the
driver to be off (when it is the only driver of the bus).
•Tied_constraint
An optional literal that specifies to display all AU faults whose fault site is held
logically constant by a constraint.
For example, a stuck at 0 fault on the output of an AND gate which has one or
more of its inputs constrained to 0 during test is placed in the AU fault
category. It is also reported in the Tied subcategory because the site of the fault
is tied such that a test is impossible. A test for the fault would require a 1 on the
line which is constrained to be 0 during test. The fault is in the AU (rather than
TIED) category because the constraint may only exist in test mode.
•Blocked_constraint
An optional literal that specifies to display all AU faults that have observation
paths blocked by constraints (pin constraints or ATPG constraints). These
faults are in the Blocked subcategory of the AU fault category. There is also a
Blocked fault category which includes faults that are blocked due to circuit
connections to Vss, Vdd, etc. The distinction is important because a stuck at 0
fault on a line which has a Vss connection cannot cause the system operation to
produce an incorrect result. Whereas, an ATPG constraint requiring a line to be
0, might represent a condition which only exists in test mode, and a stuck at 0
fault on such a line might indeed cause an incorrect result. This latter fault is
classified in the AU fault category to indicate that although a test cannot be
generated, the fault might still cause improper system operation.
•Uninitialized
An optional literal that specifies to display all the AU faults whose fault site is
constrained such that fault excitation is not possible.