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TPS65381 has got stuck, I can't connect emulator to TPS65381

Fatemeh Ehsani-besheli
Intellectual 510 points
Other Parts Discussed in Thread: TMS570LS20216

Hi,

I'm using the TPS65381 connected to the TMS570LS20216. My code is based on the TPS65381/RM46_NoRTOS project. I had the TPS to go to the diagnostic state and watchdog function was running with respect to the watchdog fail count was always 7. At that time, I changed the DIS_NRES_MON (bit D2 in SAFETY_FUNC_CFG register) to 0 and the MCU was starting to reset.  I couldn’t connect to the target because the MCU was resetting. So I externally connected 5V to the ERROR pin on TPS side to clear the error! (There is no pull-up on the ERROR pin in our circuit). Now I cannot connect to the target because of target power loss error, but MCU is getting the VCC and VCCIO correctly and the NRES (POR-RESET) pin is high.

Any help would be appreciated.

 

Regards,

Fatemeh

  • 0
    TI__Mastermind 20590 points

    Hi Fatemeh,

    There appear to be a few things wrong with the communication of the MCU to the TPS65381.

    1) You comment the WD_FAIL_CNT is always 7.  That means you are not successfully "feeding the watchdog". With every good event the MCU gives to the watchdog the WD_FAIL_CNT will decrement. 

    2)  DIS_NRES_MON will monitor only the NRES pin output from TPS65381 to what it reads back on NRES and will cause the TPS65381 to go to SAFE state if there is a mismatch, it should not cause RESET.  

    I would recommend a few things:

    1) confirm you are really in DIAGNOSTIC state (device stat is in register:  SAFETY_STAT_5     reading back 8'h07 = DIAGNOSTIC). 

    2) make sure you set the DIAG_EXIT_MASK bit if this is for software debug.  That will prevent the TPS65381 from going to SAFE state ~600ms after it powers up and releases reset.

    3) Double check when writing to SAFETY_FUNC_CFG that you are not changing other control bits in this register. If you have set WD_RST_EN to 1 during this write it will immediately reset the TPS65381 because the WD_FAIL_CNT = 7.  This could cause a sort of endless reset loop you seem to describe.

    4) You should run the watchdog timer for a few cycles in diagnostic state prior to enabling RESET to confirm the WD_FAIL_CNT is decrementing as expected. 

    5) the ERROR/WDI pin on the TPS65381 is intended for a couple of uses:  watchdog input when the WD is in trigger mode, or MCU Error monitoring.  Are you forcing 5V on it to emulate HIGH from the TMS? 

    Also, for the future you will get direct response for the TPS65381 when you post to the automotive E2E forum as this is supported from our automotive and safety power team. https://e2e.ti.com/support/applications/automotive/

    Best Regards,

    Scott

  • 0 in reply to Scott Monroe
    Intellectual 510 points

    Scott,

    Many Thanks for your valuable comments,

    Please excuse me for my late reply. I wanted to continue this post after applying your recommendations but it took so long to repair the board as I had damaged the micro and after replacing it, some other problems occurred. Anyways, now the board is OK and I can program the micro.

    Also the reason for endless reset as you said was setting the WD_RST_EN bit in SAFETY_FUNC_CFG Register to 1 when the WD_FAIL_CNT was always 7.

    In continue I will ask my another question at the forum you have addressed. 

    Regards,

    Fatemeh