
12-16
ColdFire CF4e Core User’s Manual
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Test Wrapper
Wrapper scan capture mode testing uses the tbsei signal in conjunction with the noncore
logic scan or functional test mode control signals to allow the capture of single logic values,
or two consecutive, differing logic values on targeted input signals.
The tbsei signal enables the CF4eTW scan architecture to either shift data through the
CF4eTW input side scan chains (launching logic values into the CF4e core) or to capture
data from the noncore logic. If noncore logic can launch transitions (vector pairs), the
wrapper can be used to capture one or both cycles of the transitioning test. It must be noted,
however, that having the ability to capture vector pairs launched from the noncore logic
requires that the noncore logic supports the logic test structures to launch the vector pairs.
Figure 12-13 shows timing for a non-CF4e logic to input wrapper scan stuck-at vector.
Figure 12-13. Non-Core to CF4eTW Input Scan Stuck-At Vector Example
clkfast
tbsei
Last Scan Shift In
First Scan Shift Out
Functional
Sample
Noncore
Logic
Output
Data
Register Setup
Time Point
for noncore logic
to CF4eTW input
tbseo
Data
Data
registered
CF4eTW
input
Data
Data
Data
Note: CF4eTW inputs
come from
noncore logic only
CF4eTW input
functional register
Sample Point
tbte
Inputs to noncore
logic from CF4eTW only
not needed for this
example
Noncore Logic
Functional Register
Sample Point
noncore
Scan SE
Fault
Exercise
Data
Fault
Capture
Samples noncore logic
Data
Fault
Capture
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