MPC5777C off-line self test bypass feature don't work according to RM description

[Zhongling_Lang]

Hi team,

1.My customer want to bypass off-line self test by add DCF records, so i followed the RM description:

1).unlock STCU register  2).set BYP bit in STCU2_RUN register

2.configured a DCF record according to the DCF client configurator

3.Added one DCF record at the end of the list of records already programmed.

4.after power on reset check the BYP bit which still is 0 value and off-line self test have finished, means the bypass don't take effect.

So questions is whether there have some other steps which i should to do to bypass the off-line self test?

Thanks!

[petervlna]

Hello,

It should be enough to set pointer to first MBIST for example. Usually it is 0x10.

Once SSCM module sets the pointer SCTU should start execute the test.

Furthermore in final product you want to set test only once and correctly.

best regards,

Peter

[Zhongling_Lang]

Hi Peter,

Thanks for your details answer.

[petervlna · Accepted solution]

Hello,

Reference manual is correct in case you havent programmed STCU RUN register before.

And I can on fresh sample that offline BIST is active by default from NXP fab but it wont execute any tests.

Once the SSCM scans for DCFs, and find valid STCU start record (RUN bit), it immediately starts the BIST procedure.

But if there is no valid pointer to test (0x7h) there will be no test executed and BIST will finish with no effect.

However the RUN flag will remain set (as it was already set once). It is also not recommend to change RUN register BYP once it is programmed.

As some tests may already be in process.

To skip BIST execution you simple set pointer to no execution like 0x7F.

best regards,

Peter

[Zhongling_Lang]

Hi Peter,

It works when set PTR with 0x7F value to bypass offline bist, but how to enable offline bist again?

Because customer disable offline bist is a just temporary operation, and they want to enable it again, so they added DCF record 0x10000009 to enable it again but it failed which still 0x7F value with PTR.

So whether have some other steps to enable offline bist again?

Thanks!