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TMS320F28377D: IDDK_PM_Servo_F2837x project (II)

Geon Kim
Expert 1070 points
Part Number: TMS320F28377D
Other Parts Discussed in Thread: AMC1304M25, AMC1306E25, CONTROLSUITE

Hello,

We purchased the DesignDRIVE Development Kit IDDK v2.2.1 and I have a question on the  IDDK_PM_Servo_F2837x project.

With respect to the Delta-sigma modulator device for our application, we are planning to use the AMC1306E25 instead of the AMC1304M25 which is used in the IDDK v2.2.1.

As it is obvious, the output bitstream of the AMC1306E25 is Manchester encoded, whereas the output bitstream of the AMC1304M25 is uncoded.

I have a few questions on the Sigma Delta Initialization routine in the IDDK_PM_Servo_F2837x.c file, when using the AMC1306E25.

(1) With respect to the Input Control Module routine, I may have to apply MODE_2 for the Sdfm_configureInputCtrl function.

(2) Then, with respect to the Comparator module routine and the Sinc filter module routine, can I use the program codes as it is without any modification?

(3) With respect to the Feedbacks OFFSET Calibration Routine, can I use the program codes associated with the SDFM as it is without any modification?

(4) It will be appreciated if some advices are provided to me with respect to developing the program codes when the AMC1306E25 is used.

Thank you for your guidance.

G. Kim

  • 0
    TI__Mastermind 27240 points
    1. Right.
    2. Should work
    3. Yes
    4. The IDDK example is fairly straight forward, it should be sufficient. Choosing the right mode should fairly help. If you are interested in more examples, there are some available at
    C:\ti\controlSUITE\device_support\F2837xD\v210\F2837xD_examples_Cpu1
  • 0 in reply to Ramesh Ramamoorthy
    Expert 1070 points

    Dear Ramesh,

    Thank you for your review.

    I have tested the performance of the AMC1306E25 in our test board by executing the same Sigma Delta Initialization routine as in the IDDK_PM_Servo_F2837x.c file and monitored the values of the offset_SDFM1 and offset_SDFM2.

    I have also monitored the values of the offset_SDFM1 and offset_SDFM2 in the IDDK v2.2.1 where AMC1304M25 is mounted.

    I have summarized the monitored values as follows:

    (1) Test result of the AMC1306E25 in our test board:  offset_SDFM1= -0.07 ,   offset_SDFM2= -0.016

    (2) Test result of the AMC1304M25 in the IDDK v2.2.1:  offset_SDFM1= -1.55x10^(-5) ,   offset_SDFM2= --6.24x10^(-5)

    As a result, the AMC1306E25 yields the larger offset_SDFM1 and offset_SDFM2  than the AMC1304M25.

    I will appreciate any comment on these results.

    Thank you for your guidance.

    G. Kim

  • 0 in reply to Geon Kim
    TI__Mastermind 27240 points

    I have not tested this part, so I cant say one way or the other. I would tend to accept it and move on and see how the actual current feedback looks like. If it is not convincing, then I would recommend reviewing the literature for AMC1306 part.

  • 0 in reply to Geon Kim
    Expert 1070 points

    Dear Ramesh,

    Thank you for your review.

    I have a question on the current sensing resistors RS1 and RS2.

    With respect to the IDDK v2.2.1, what will happen in case that I use the resistance value of 3 mohm instead of 20 mohm for RS1 and RS2?

    Do I have to adjust the current control loop gains in case that I use the resistance value of 3 mohm instead of 20 mohm for RS1 and RS2?

    I will appreciate your comment on this case.

    Thank you for your guidance.

    G. Kim

  • 0 in reply to Ramesh Ramamoorthy
    Expert 1070 points

    Dear Ramesh,

    Thank you for your review.

    I have a question on the usage of PWM11 (or) PWM12 for the SDFM filter synchronization.

    This IDDK project does not use the PWM11 or PWM12 synco signals for the SDFM filter synchronization as stated in the file of IDDK_PM_ServoMF2837x.c.

    Let me ask you a couple of questions as follows:

    (1) Why does this IDDK project not use the function of the SDFM filter synchronization through the PWM11 or PWM12 synco signals?

         Please explain me the reason in detail.

    (2) When should I use the function of the SDFM filter synchronization through the PWM11 or PWM12 synco signals?

        Please explain me in detail.

    Thank you for your guidance.

    G. Kim

  • 0 in reply to Geon Kim
    TI__Mastermind 27240 points
    1. In the code, look at the function Sdfm_configureExternalreset()
    2. A reset will clear all input data buffer bits within the filter to zero, and will start a fresh accumulation. It is possible that the PWM period may not be a SDFM frequency may not be proper multiples. Therefore, it is a good practice to start this sequence for every read based on predetermined number of clock cycles in advance in accordance with the OSR and SINC type.
  • 0 in reply to Ramesh Ramamoorthy
    Expert 1070 points

    Dear Ramesh,

    Thank you for your review.

    Let us clarify this issue for me.

    Do you mean that, by using  the function Sdfm_configureExternalreset(), this project has activated the SDFM filter synchronization through the PWM11 or PWM12 synco signals?

    It is stated  in the file of IDDK_PM_ServoMF2837x.c as follows:

     //PWM11.CMPC, PWM11.CMPD, PWM12.CMPC and PWM12.CMPD signals cannot synchronize the filters. This option is not being used in this example.
        Sdfm_configureExternalreset(1,FILTER_1_EXT_RESET_ENABLE, FILTER_2_EXT_RESET_ENABLE, FILTER_3_EXT_RESET_ENABLE, FILTER_4_EXT_RESET_ENABLE);

    Thank you for your guidance.

    G. Kim

  • 0 in reply to Ramesh Ramamoorthy
    Expert 1070 points
    Dear Ramesh,
    Thank you for your review.
    I am now working on LEVEL 3 of the IDDK_PM_Servo_F2837x project.
    In our project we are applying the resistance value of 3 mohm instead of 20 mohm for the current sensing resistors RS1 and RS2.
    Then I am going to adjust the PI control gains for the current control loop with respect to LEVEL 3.
    Would you please kindly provide me with the adjusted PI control gains for the current control loop in this case?

    I appreciate your guidance.
    G. Kim
  • 0 in reply to Geon Kim
    TI__Mastermind 27240 points

    Hi Kim,

    It will be difficult for me to get into the specifics of your project and advice. Pls refer to related publications or reference materials.

  • 0 in reply to Ramesh Ramamoorthy
    Expert 1070 points

    Dear Ramesh,

    Thank you for your review.

    I cannot figure out how the gain of the current sensing element is related to the Id and Iq current loop gains.

    Would you please recommend me some reference materials provided by TI?

    I appreciate your guidance.

    G. Kim

  • 0 in reply to Geon Kim
    TI__Mastermind 27240 points
    Review the TI blog below
    e2e.ti.com/.../teaching-your-pi-controller-to-behave-part-I

    It is a multipart series, just tag on to it for other parts. Hope it helps.