How to write the parameters of SPI input device to interface SSI position encoder?

Mahmoud Gaafar
Mahmoud Gaafar New Altair Community Member
edited July 2023 in Community Q&A

Hello,

I am simulating a motor drive system using PSIM to be implemented on DSP (F28335).  I am using SSI encoder (data sheet is attached) to get the rotor position and using SPI blocks to interface the encoder with the DSP. I’m confused about setting some of the parameters in the SPI blocks. I went through the SPI tutorials and the encoder data sheet many times and could not specify the following items: start initial command value, received data command, data bit position, SPI initial command value in the SPI input block parameters.

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Answers

  • Rhonda_20369
    Rhonda_20369 New Altair Community Member
    edited July 2023

    Hi, Mahamoud,

    PSIM's has not developed code generation to support SSI based sensor interface with the MCUs.

    You may search Texas Instruments' e2e forum to find some help on how to write your own code.

    How can i interface an SSI absolute encoder with F28335 ControlCard?

    However, in the datasheet you have attached, I see that your encoder has pulsed output signals Track A and Track B. You may connect those two signal lines to F28335's Encoder inputs.

     

    Sincerely,

    Rhonda

  • Mahmoud Gaafar
    Mahmoud Gaafar New Altair Community Member
    edited July 2023
    Rhonda_20369 said:

    Hi, Mahamoud,

    PSIM's has not developed code generation to support SSI based sensor interface with the MCUs.

    You may search Texas Instruments' e2e forum to find some help on how to write your own code.

    How can i interface an SSI absolute encoder with F28335 ControlCard?

    However, in the datasheet you have attached, I see that your encoder has pulsed output signals Track A and Track B. You may connect those two signal lines to F28335's Encoder inputs.

     

    Sincerely,

    Rhonda

    Thanks for your reply. Let me explain in more details.

    • I am using SPI pins of F28335 DSP to read SSI output of the encoder. For this purpose, I am using transceiver IC to interface the differential output signals of the SSI encoder (Clock signal and data signal) and the SPI pins of the DSP.
    • The used encoder does not have incremental tracks. The corresponding waveforms are at the end of page 4 in the attached data sheet. I attached the data sheet again and highlighted some parts.
    • My question is how to determine the parameters of the SPI input block in PSIM; especially, start initial command value, received data command, data bit position, SPI initial command value.

     Thanks for your support.

  • Rhonda_20369
    Rhonda_20369 New Altair Community Member
    edited July 2023
    Mahmoud Gaafar said:

    Thanks for your reply. Let me explain in more details.

    • I am using SPI pins of F28335 DSP to read SSI output of the encoder. For this purpose, I am using transceiver IC to interface the differential output signals of the SSI encoder (Clock signal and data signal) and the SPI pins of the DSP.
    • The used encoder does not have incremental tracks. The corresponding waveforms are at the end of page 4 in the attached data sheet. I attached the data sheet again and highlighted some parts.
    • My question is how to determine the parameters of the SPI input block in PSIM; especially, start initial command value, received data command, data bit position, SPI initial command value.

     Thanks for your support.

    PSIM's automatic code generation does not support the functionalities you want.

    You may need to write you own or bring your question to the forum for product "Embed".

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