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LAUNCHXL-F280039C: offset_dc_ad values in DMC_LEVEL_1 using F280039C and DEV8329AEVM

raghu dharmana
Intellectual 415 points

Part Number: LAUNCHXL-F280039C
Other Parts Discussed in Thread: DRV8329AEVM, , LAUNCHXL-F280025C

hey TI experts, im trying the universal motor control lab user guide. to start off with ive set the dmc level to 1 and while trying to debug, the values of "offset_Idc_ad"  which should be half of ADC max values i.e. ~2048 is only 510. why is this and also there"s is no phase shift observed . all the 3 outputs are in phase. can someone plea se explain

  • 0
    TI__Genius 11076 points

    Hello Raghu Dharmana,

    1. Looking at your CCS debug window, there's one very important note that you did not mention in your post- you're currently using the USER_MOTOR1_DCLINKSS (or DC-Link Single-Shunt) predefine.

      Essentially, because you're using USER_MOTOR1_DCLINKSS, offset_I_ad does not exist. Additionally, there is not currently characterization for an appropriate value for offset_Idc_ad. This means that unless the ADC results of later build levels appear to be incorrect, you can currently ignore the value of offset_Idc_ad.
    2. Refer to Figure 2-26. Build Level 1: PWM Output Waveforms
      2. If this is not what you're currently seeing on an oscilloscope, please provide a screenshot. (I don't believe this is affected by the USER_MOTOR1_DCLINKSS, but if your waveforms are incorrect, I'll verify that again.)

    Regards,
    Jason Osborn

  • 0 in reply to Jason Osborn
    Intellectual 415 points

    hi jason,

    thanks for replying, i'm using USER_MOTOR1_DCLINKSS  cause im using DRV8329AEVM which supports only single shunt.

     Ive attached the snapshot of output across driver motor terminals A,B,C wrt to GND.

    Regards ,

    Raghu Dharmana

  • 0 in reply to raghu dharmana
    TI__Genius 11076 points

    Hello,

    Glancing at our code, I believe the image in the user's guide might be mislabeled. Your waveform looks correct- in build 1, all three PWMs are set to 50% duty cycle.

    Please let me know if you have any other questions.

    Regards,
    Jason Osborn

  • 0 in reply to Jason Osborn
    Intellectual 415 points

    Hello,

    Duty cycle is set to 50% its working fine. the question is about the phase shift. in the image clearly there's no phase shift. does it really matter or is it any configuration error that i need to change.

    Regards

    Raghu Dharmana

  • 0 in reply to raghu dharmana
    TI__Genius 11076 points

    Raghu,

    You're good to go! I think our user's guide image is mislabeled. The behavior you're seeing is correct according to my understanding. I'll be looking into filing a ticket for that soon.

    Regards,
    Jason Osborn

  • 0 in reply to Jason Osborn
    Intellectual 415 points

    hello jason,

    thanks for replying.

    I'm trying to do the position control of a low power bldc motor for which I'm following dual axis motor example. I'm using LAUNCHXL-F280039C and 3PHGNANIV inverter board. the example is given for LAUNCHXL-F280025C. I'm trying to use migration guide which is a bit confusing. i need your assistance in changing the project spec file, is there any reference to edit this file and what are the other things that are to be taken care of?

  • 0 in reply to raghu dharmana
    TI__Genius 11076 points

    1.8.24 EDIT

    While I referred to the UMCL migration guide, this post is actually about a different TI solution. General porting guidance is also available. Once this effort is resolved, relevant excerpts of the porting guidance will be moved here for future reference.

    Original post:

    Hello,

    We have an updated user's guide for the Universal Motor Control Lab which includes more detailed migration guidance, including for the project spec file. I've sent you a friend request here on e2e. If you accept it, this will allow me to send that document your way.

    Regards,
    Jason Osborn