SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
In compare mismatch test, the number of test patterns is equal to two times the number of CPU output signals to compare in compare mode active. The core compare disabled signal is asserted on entry and de-asserted when complete. An 'all-ones' vector is applied to the CCMR5’s CPU0 input port and the same pattern is also applied to the CCMR5’s CPU1 input port but with one bit flipped starting from signal position 0. The un-equal vector should cause the CCMR5 module to expect a compare mismatch at signal position 0. Note that a mismatch is an expected good result, while a match will indicate hardware fault. When a fault is detected, which means that a compare match is produced by the compare logic, the self test error flag is set and the self test error signal is asserted.
The above compare mismatch test algorithm repeats itself again in a domino fashion with next signal position flipped, while forcing all other signals to logic level '1'. This process is repeated until every single signal position is verified on both CPU signal ports.
The compare mismatch test is terminated if a compare match is detected and the module becomes idle. The compare mismatch test ensures that the compare unit is able to detect a mismatch on every CPU signal being compared.
Table 6-167 illustrates the compare mismatch test sequence.
CPU0 Signal Position | CPU1 Signal Position | Cycle | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
n | ... | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | n | ... | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 2 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 3 |
. . | ||||||||||||||||||||
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n-1 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n+1 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n+2 |
1 | 1's | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n+3 |
1 | 1's | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | n+4 |
. . | ||||||||||||||||||||
0 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1's | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2n |