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About STCU2 configuration on MPC5777C (cut 3N45H)

Question asked by Dario Arcaro on Jun 19, 2019
Latest reply on Jun 28, 2019 by Dario Arcaro



I'm trying to run Online BIST on STCU2 peripheral and in order to do so I have had
a look to the following NXP resources:
MPC5777C-Online-MBIST+LBIST-v1_2-GHS614 (as code sample)

AN5288.pdf                                                            (as application note)


After a first analysis on these docs, I have integrated the code sample inside my
environment and with the debugger attached it seems working fine but if I disconnect
the debugger, perform the BIST test and then attach again it, the STCU2 test
always fail. I can see this strange behavior also with the oscilloscope because in
my test I perform this kind of strategy


    if(SIU.RSR.B.STCURS == 0)
        if(read_online_bists_results() == MS_OK)
            /* Here I start a PWM signal */
Do you have any idea about this issue ?


In order to investigate about the behavior described, I'd would like to ask some questions
about the sample code and in general about STCU2 configuration values.

1)  STCU2 core clock in the sample is given from PLL0 frequency (200 MHz) / 2 (PERDIV) / 2 (CLK_CFG).
 Is it right ?
2)  In the code sample the LBISTs seem working at 25 MHz though the comment in my opinion is wrong (SHS = 0).
 Is it right ?
3)  I have also a doubt about the duration of the test in the code sample. In the page where the code
 sample is present (, it's written that the execution
 time is (25.8 ms) for MBIST + LBIST full test but this value seems to be very different from that calculated
 with the Excel sheet attached to the AN5288 where with the same values I get a time of more than 216 ms.
 Am I missing something ?


 Thanks in advance.


 Dario Arcaro