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DRV8884: Incorrect operation with STEP mode changing

NAOKI AOYAMA
Guru 11215 points
Part Number: DRV8884

Hello,

Our customer evaluate the DRV8884.

The customer change the STEP mode from 1/2 STEP to full STEP while stepping.

So, at first they set the M1 and M0 pin (1 : 0) , next change the M1 from 1 to 0.

When they use the DRV8884 with DIR=1, it is correct operation. 

But when they use the DRV8884 with DIR=0 (reverse) , it is incorrect operation.

I attach the file include the waveform.

DRV8884_Indexer_quest.pptx

It does not advance to the next state by the rising edge of the next CLK.

Could you tell me the cause it?

Best Regards,

Naoki Aoyama

  • 0
    TI__Mastermind 37683 points

    Hello,

    I looked at your waveforms and ran my own test, using the TI EVM, to see If I got similar results as you. My data (seen below) suggests that the device is stepping correctly when the direction is set to reverse (DIR=0).

    It could be possible that this problem is only occurring on your device. To figure out if that is the case, I need to know the following information.

    • Are you using TI EVM or your own board
      • If using TI EVM, what is the lot trace code?

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    Thank you for your fast reply.

    I will check the test condition of the customer.

    By the way, I can not look your test results.

    Could you attach it again?

    Best Regards,

    Naoki Aoyama

  • 0 in reply to NAOKI AOYAMA
    TI__Mastermind 37683 points

    Hi

    I am sorry. There must have been an issue with the attachment. Here it is again.

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    Thank you for your reply.

    I could check the waveform. It is correct operation.

    I got information of the customer. The customer evaluated the DRV8884 by their own board not TI EVM.

    They said it occurs every time. So I ask the customer to take additional waveform.

    Regards,

    Naoki Aoyama

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    I got additional information from the customer.

    They evaluated the DRV8884 more detail.

    When they use the DRV8884 with DIR=1, then it operates correctly.

    It occurs issue using with DIR=0 and start from certain position.

    The position is 2,4,6 and 8. (This number of the position is using the number listed in Table 3. on the DS)

    It is correct operation when it start from 1,3,5 and 7.

    I attach the file include the waveform.

    DRV8884_Indexer_quest2.pdf

    Could you tell me the cause?

     

    Best Regards,

    Naoki Aoyama

  • 0 in reply to NAOKI AOYAMA
    TI__Mastermind 37683 points

    Hello,

    If I am not mistaken, I believe the waveform I sent you matches the waveform you attached in the fist post. Both of them are at the same position (Aout:0% and Bout: 100%) right when step mode is changed. 

    I will go to the lab and try to recreate the waveforms you have attached. I want to see whether I get different results than the customer.

    I will give you an update soon.

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    Thank you for your reply.

    The waveform you gave me and the waveform I attached in the first post are different start position.

    You start at AOUT=0% and BOUT=+100%. The customer start at AOUT=+70% and BOUT=-70%.

    In their evaluation, it operates correctly when they start from your position (AOUT=0%, BOUT=+100%).

    But when they start from AOUT=+70% and BOUT=-70%, it operates incorrectly.

    Could you evaluate with start from the electric angle of 45, 135, 225 and 315 degrees?

    Best Regards,

    Naoki Aoyama

  • 0 in reply to NAOKI AOYAMA
    TI__Mastermind 37683 points

    Hi,

    I am sorry. I was incorrect about my waveform starting at the same position as yours. I will collect the data and compare it with the customer's data. You can expect a reply from my by Tuesday of next week,

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    Thank you for your reply.

    I will wait for your estimation.

    Regards,

    Naoki Aoyama

  • 0 in reply to NAOKI AOYAMA
    TI__Mastermind 37683 points

    Hello,

    I was able to recreate your customer's waveforms with starting electrical angle position of 45, 135, 225, and 315 degrees for DIR=0 (reverse). We have noted this particular issue and will be updating the datasheet accordingly. 

    Thank you for bringing this up to us and for your patience. 

  • 0 in reply to Pablo Armet
    Guru 11215 points

    Hello,

    Thank you for your estimation.

    I understood that this behavior is as designed.

    I will check the situation of the customer and let you know by e-mail.

    I close this post.

    Thanks,

    Naoki Aoyama