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TMS320F28377D: XRS pulls down internally how to debug

Colombo Carlo
Mastermind 25215 points

Part Number: TMS320F28377D
Other Parts Discussed in Thread: TMS320F28374S

HI everybody , 

in my application I can see the pinXRS pulls down from time to time : how can I debug it ?

I disabled watchdog , but still happening ...

any suggestion /idea ?

thank you 

BR
Carlo

  • 0
    TI__Guru** 116601 points

    Hi,

    We have NMIWD also which can trigger reset like WD and can pull the XRSn pin low. You should put the breakpoint at reset entry point and let device run. CPU should halt at the breakpoint after reset and then you can check the NMISHDFLG register to see if there was any error and find the cause of the same. If there is no NMI error then you should monitor device power supply and see if there is any dip which is causing the XRSn to go low.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Prodigy 60 points

    Hi Vivek,

    Let me add more information. 

    • TMS320F28374S
    • Watchdog disabled. Verified WDDIS bit is set to 1

    All of sudden CPU stopped working. After investigating the problem, found that reset was occurring periodically about every 18ms on /XRS pin as if WD is enabled. Even power reset did not remove the problem.

    The problem does not come consistently. It is random. After re-flashing the FW, the problem disappears. So my question is that what other possible cases that can pull down the /XRS line? If I read the F2837xD training PDF file, one of the following signals can pull /XRS down.

    • Watchdog timer - Verified it is disabled
    • Power-on Reset - It is not power-on reset case
    • Hibernate Reset - Hibernate is not used
    • /XRS pin active - /XRS pin is pulled up externally.
    • Missing Clock Detect

    Any flash memory corruption could also cause this kind of issue?

    Thanks,

    Justin

  • 0 in reply to Justin Ryu1
    TI__Guru** 116601 points
    Justin Ryu1 said:
    Any flash memory corruption could also cause this kind of issue?

    Yes. In the list you need to add NMI watchdog also which can issue reset and pull XRSn down. 

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Prodigy 60 points

    Since this problem comes randomly, I need to find the possible cause proactively. It was not able to reproduce the problem for several days.

    I wanted to add screen shot, but I cannot, for I need to upload the image somewhere first and link it for this forum. So let me explain here.

    To start with the circuit, /XRS is is connected with a 3.3V pull-up (4.7k) resistor and 68nF capacitor. Can you confirm that resistor and capacitor values are okay?

  • 0 in reply to Justin Ryu1
    TI__Guru** 116601 points
    Justin Ryu1 said:
    To start with the circuit, /XRS is is connected with a 3.3V pull-up (4.7k) resistor and 68nF capacitor. Can you confirm that resistor and capacitor values are okay?

    That looks ok.

    Regards,

    Vivek Singh