About STCU2 configuration on MPC5777C (cut 3N45H)

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About STCU2 configuration on MPC5777C (cut 3N45H)

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dario_arcaro
Contributor I

Hi,

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)
    {  
        run_online_bists();
       
        while(1){};
    }
    else
    {
        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 (https://community.nxp.com/docs/DOC-335433), 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

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4 Replies

806 Views
petervlna
NXP TechSupport
NXP TechSupport

Hi,

1)  STCU2 core clock in the sample is given from PLL0 frequency (200 MHz) / 2 (PERDIV) / 2 (CLK_CFG).
 Is it right ?

pastedImage_8.png

yes I have used 50MHz STCU clock as it is recommended by design.

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 ?

The comment is not corresponding the data in register:

pastedImage_7.png

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 (https://community.nxp.com/docs/DOC-335433), 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 ?

Hmm I cannot speak for AN values as this was done in application team. But I have measured the 25ms on my own code which seems to me reasonable. 215ms is just weird. All automakers require full micro operation within 100ms. So to have only BIST taking that long is just nonsense. + I have never seen BIST taken so long, not even with IRC 16MHz clock.

regards,

Peter

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806 Views
dario_arcaro
Contributor I

Hi Peter,

thanks for the reply. In these days I've been investigating on the issues/doubts described above but the result remain the same. I'm able to run the On-Line BIST successfully only with the debugger attached but, without it, the BIST test always fail. When I perform an attach of the debugger, I see the following situation in the STCU2 ERR_STAT register:

err_stat.png

It seems that the Watchdog for the Off-Line BIST expires but, as I understand, there is no Off-Line BIST test programmed

in the UTEST memory area (as you can see in the following dump) and moreover in my opinion the two kind of tests should run

in a independent manner.      

dump_utest.png

Could you give me some hints about this issue ?

Another point is the duration of the On-Line BIST. I've performed a test on EVB with the same values of your sample code and I

see that the test duration is around 54 ms so I'm not sure if I can consider wrong the duration declared in the AN5288 and in the Excel attached

or if I'm missing something.

Could you have an internal review about the reliability of the time values declared ?

Thanks in advance.

Regards,

Dario Arcaro

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806 Views
petervlna
NXP TechSupport
NXP TechSupport

Hi,

It seems that the Watchdog for the Off-Line BIST expires but, as I understand, there is no Off-Line BIST test programmed

There is only one watchdog for both BISTs (online and offline).

When BIST is configured the watchdog value must be loaded either form code or from DCF records.

Try to set it to max value, to see if it fails.

By the way, are you talking about BIST on which core? Or on both?

Because you know, core on which the test is executed must be in reset.

regards,

Peter

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805 Views
dario_arcaro
Contributor I

Hi Peter,

first of all thanks for the reply.

Try to set it to max value, to see if it fails.

Yes, I've already performed this kind of setting but the result is the same (LBIST/MBIST failing without debugger, success with debugger)

By the way, are you talking about BIST on which core? Or on both?

I'm running BISTs on core0 while core1 is in reset as you can see in the picture below

hlt1.png

Because you know, core on which the test is executed must be in reset.

This is new for me. Could you provide an use case also as a meta-code ?

I'm executing the test with this strategy:

    if(SIU.RSR.B.STCURS == 0)
    {  
        run_online_bists();
       
        while(1){};
    }
    else
    {
        if(read_online_bists_results() == MS_OK)
        {
            /* Here I start a PWM signal */
        }
    }

Do you have another idea to perform an On-Line BIST test one-shot ?

Because I've the feeling that this check fails without the debugger.

Thanks in advance and best regards

 

 Dario Arcaro

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