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DRV8889-Q1: Status register

Abhitha E
Prodigy 20 points
Other Parts Discussed in Thread: DRV8889-Q1

Hi ,

  In my project I am suing drv 8889 driver to connect stepper motor. I need to access the status register especially Fault and Diagnostic 2 register .But while reading these register I'm always getting a value 0×84 and 0×18 ,indicates motor stall condition. Could you please let me know why always getting stall condition flag even if the motor is in running condition. 

And also we have tested the motor under temperature (-10).But the UTW is not changing to high.

Please clear my doubts 

Thanks & Regards 

Abhitha

  • 0
    TI__Guru 55615 points

    Abhiitha,

    Are you using your own board and microprocessor or EVM?  If you are using your own board, please send scope capture of the 4 SPI signals to verify what you are reading.  We have seen many times that timing issues result in incorrect data. Only way to verify is with scope captures.

    Also, what is the stall threshold set at?  If you change the threshold to a very low level, do you still get the fault?  

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    Prodigy 20 points

    Ryan ,

    Thank you so much for your response .

    We are using our own board and microprocessor . I will try to provide you the scope capture of SPI signals.

    These are the setting that I have used in my project .Please verify and give your suggestions .

    Value of the CNTRL_1 register - 0xB3 

    Value of the CNTRL_2 register -0x0F     

    Value of the CNTRL_3 register -0x08     

    Value of the CNTRL_4 register -0x39     

    Value of the CNTRL_5 register -0x38     

    Value of the CNTRL_6  register -0x60     (STALL_TH)

    And also please let me know the flag status below -25degC. Since our operating temperature range goes down to -40degC.

    Waiting for your response .

    Regards ,

    Abhitha E

  • 0 in reply to Abhitha E
    TI__Guru 55615 points

    Abhitha,

    It is a US holiday today.  I will respond in 24 hours.  Please help with SPI signals if you are able.

    Regards,

    Ryan

  • 0 in reply to Abhitha E
    TI__Guru 55615 points

    Abhitha,

    Less than -25C should indicate and UTW.  -10C is just a typical.  Minimum per datasheet is -25C.  

    For stall, are you getting nFAULT = LOW.  Based on your register setting, if it is a real stall, you should see this.  Also, bit 5 in CTRL5 is the stall learn. On a successful learn, this will go back to "0".  Does it ever read "0"?  

    Regards,

    Ryan

  • 0 in reply to Ryan Kehr
    Prodigy 20 points

    Thank you Ryan ,

    Yes I'm getting STL_LRN=0 in CNTRL5 register and nFault =Low also , But the STL and STALL is not updating properly . Sometimes the STL and STALL are setting ONE even if the motor is in running condition .

  • 0 in reply to Abhitha E
    TI__Guru 55615 points

    Abhitha,

    Have you tried adjusting the threshold as I proposed before?  It might be that the "learned" value is too high and causing stall even under running conditions.

    Regards,

    Ryan

  • 0 in reply to Abhitha E
    TI__Guru 56650 points

    Abhitha,

    The motor can keep running when the host controller keeps sending STEP pulse to DRV8889-q1. 

    Please send the register value when you think it is wrong. 

    Regards,

    Wang Li

  • 0 in reply to Ryan Kehr
    Prodigy 20 points

    Hi Ryan , Thank you for your support . Stall flag is setting properly now since I have changed the STALL_TH . The under temperature flag yet to test and confirm

    Regards ,

    Abhitha E

  • 0 in reply to Abhitha E
    TI__Guru 55615 points

    Abhitha,

    Thank you for the response.  I will close it for now.  If you see issue with under-temp flag, please re-post and it will open back up on our end.  If thread is locked, you can choose the "ask a related question" button.

    Regards,

    Ryan