MC33907/8 Reset Reasons.

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MC33907/8 Reset Reasons.

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ahmedsoubky
Contributor II

Hi, 

I have a question regarding MC33907/8 reset reasons. 

As per the RM, the reasons which cause reset are:

Unbenannt.PNG

Which registers should I read during startup to identify a reset that was caused by Watchdog, IO_1 FB_Core Delta, or SPI DED ? 

Thanks in advance, 

Best Regards, 

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guoweisun
NXP TechSupport
NXP TechSupport

Yes, we can diagnose Reset activation cause:

  • Reading WD_Answer register for SPI DED error (FS_req_ECC bit)
  • Reading WD_Answer register for bad WD refresh (WD bit)
  • Reading WD _Counter register for bad WD refresh (WD_ERR_CNT bits)
  • Reading in Diag_FS2 register for IO_1_FB_Core_Delta error (IO_1_fail bit)
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ahmedsoubky
Contributor II

Can we identify watchdog reset after it happens by reading WD_Answer during initialization ? 

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petervlna
NXP TechSupport
NXP TechSupport

Hi,

I would read WD ANSWER register bit WD.

pastedImage_1.png

Peter

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pederrogo
Contributor III

Hello,

We are reading bit WD in WD Answer reg to determine if there has been a reset due to watch dog not refreshed as expected. During start-up (in bootloader) we are reading the WD Answer register once. But, maybe we should do it twice? Extract from ref manual (MC33907-MC33908D2 - Rev. 5.0, 10/2016):

"Values of the three registers WD_answer, WD_counter, and DIAG_FS2 are updated at the end of any SPI access to one of these registers. To always get up to date values, it is recommended to make two consecutive SPI accesses to these registers. Example: read WD_answer, read again WD_answer, read WD_counter, read DIAG_FS2. The first read updates the three registers and the second read report the latest information".

But, the WD bit is cleared when reading it. Thus, there is a risk that the bit is set at first read and not at the second read? How should the WD bit actually be read to be sure reading the bit correct?

Best Regards,

Peder

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petervlna
NXP TechSupport
NXP TechSupport

Hi,

How about to read WD_counter in order to refresh these register status bits?

That should be sufficient in order to refresh these register values.

Peter

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petervlna
NXP TechSupport
NXP TechSupport

Hi,

Could you specify micro you are using.

Peter

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ahmedsoubky
Contributor II

Hi, 

MPC5744p, is it possible to know the reset reason only from the SBC registers ? 

Thanks,

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