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ColdFire CF4e Core User’s Manual
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Test Wrapper
logic. The CF4eTW can be operated coincidentally with noncore logic test structures and
can be used to enable structural testing or timing delay testing.
The tbseo signal, together with the non-core logic scan or functional test mode control
signals, allows launching of a single logic value to conduct structural stuck-at testing, or
allows the launching of two consecutive differing logic values (vector pairs) on targeted
input signals, while holding other signals stable for 2 cycles (applying the same value). The
2-cycle transition type of sequence that holds off-path values stable results in what is known
as a robust delay test.
Figure 12-11 shows timing for a wrapper to non-CF4e logic scan stuck-at vector.
Figure 12-11. CF4eTW to Non-Core Input Scan Stuck-At Vector Example
Figure 12-12 shows timing for a wrapper to non-CF4e logic scan delay vector.
clkfast
tbsei
Last Scan Shift In
First Scan Shift Out
Functional
Sample
Registered
Wrapper
Output
Data
Data
Register Setup
Time Point
for Noncore Logic
tbseo
Data
Data
Noncore
Logic Input
Register
Data
Data
Data
Data
Note: inputs not
required for this
example
Noncore Input
Signal Register
Sample Point
tbte
Shifting will apply
the necessary
logic values.
Clock-to-Out
Data Valid Point
from Core Logic
to Noncore Logic
To apply values
from non-registered
CF4eTW output
signals
Fault
Exercise
Fault
Effect
Noncore
Scan SE
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