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GB1400 User Manual B-17
Stressing through pattern generation
One common stress test employs a pseudorandom binary sequence (PRBS) generator to create
test data. The PRBS generator is seeded with a nonzero pattern of n bits. Using a shift register
with XOR feedback, the PRBS will cycle endlessly through every combination of n-bits (except
for the all-zero state), with no repeats until every combination has been generated (see Figure 3
and Table 2 for the 2
4
-1 PRBS).
A B C D
XOR
Figure 3. 2
4
-1 PRBS (pseudorandom binary sequence) generator
Table 2. 2
4
-1 PRBS pattern
Clock A B C D C XOR D
1 1 0 0 0 0
2 0 1 0 0 0
3 0 0 1 0 1
4 1 0 0 1 1
5 1 1 0 0 0
6 0 1 1 0 1
7 1 0 1 1 0
8 0 1 0 1 1
9 1 0 1 0 1
10 1 1 0 1 1
11 1 1 1 0 1
12 1 1 1 1 0
13 0 1 1 1 0
14 0 0 1 1 0
15 0 0 0 1 1