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  • TI Thinks Resolved

TIDA-00176: Interpolation 18000 sincos signals

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Replies: 3

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Part Number: TIDA-00176

Hello

I have questions about TIDA-00176 Tool.

My application is comparing encoders.

I have a reference encoder with 3 arcsec accuracy 18000 sin/cos track 1 Vpp analog signal

We want to interpolate this sincos tracks to 16 bit SSI output.
Than we want to compare this signal with an encoder which we produce with 16 bit SSI output.

Is it possible to interpolate 18000 sincos track to 16 bit or more SSI interface?

Also if we can connect both encoders to TIDA-00176 we can use it like this.

Do you have any other tool about this application?

  • Dear Sedat,

    Please refer to figure 7 or equation 6 in the TIDA-00176 design guide to see what resolution can be achieved as a function of sin/cos encoder line count and the ADC used for the interpolation.

    In our TIDA-00176 TI design we used a Sin/Cos encoder with a line count of 1024, equals 1024 sinusoidal period per revolution. We apply interpolation with a 16-bit ADC and then get a angle resolution of 27-bits. The signal resolution in that case is 0.01 arcsec. Although the encoder itself won't have such an accuracy, of course.

    The TIDA-00176 allows connection only one sin/cos encoder at a time. If you have two encoders running in parallel two interface are required, but the same C2000 MCU can be used if it has 2x eQEP, like the TMS320F28069.

    I am not sure if I understood your question though.

    Can you clarify what you mean with 18000? And what tool are you looking for?

    Thanks.

    Regards,
    Martin
  • In reply to Martin Staebler:

    Hello,
    I am looking for interpolation tool which has SSI output. TIDA-00176 has what kind of interface output, is there any interface option for output like SSI or SPI or BISS?
    I mean with 18000, my sincos encoder has 18000 resolution. Is it possible to interpolate 18000 sin/cos resolution? 18000 is close to 14 bit resolution If TIDA-00176’s output resolution will be 30 bit it is okay for me.
    Best regards
  • In reply to Sedat Ekici:

    Dear Sedat,

    thank you for clarification. I understand you are looking for an equipment, which interface to Sin/Cos encoders, interpolates the angle and outputs in SSI compliant data interface.

    We do not have a turn-key TI design that does that.

    OPTION 1:
    --------------
    If you plan develop hardware and software yourself you may take the below listed TI designs and C2000 software libraries as an example to start development. It still requires coding of the SSI protocol on C2000 MCU, which is not available yet:

    1) Sin/Cos encoder interface (analog): TIDA-00176
    2) C2000 MCU software for Sin/Cos encoders angle interpolation user's guide: Please see: www.ti.com/.../sprui54.pdf
    3) C2000 MCU SSI interface: Please see C2000 e2e link: e2e.ti.com/.../539796 encoder
    4) BiSS/SSI interface (analog): See www.ti.com/tool/tida-00175

    As mentioned beside the hardware, there's firmware development on C2000 MCU required. For questions on C2000 MCU and related software, I'd recommend the C2000 e2e forum: e2e.ti.com/.../171

    OPTION 2:
    -------------
    If you are looking for a turn-key tool or ready-to-use test equipment for encoders you can buy, you may check with encoder vendors such as HEIDENHAIN or other encoder vendors.

    Hope this answered your question.

    Regards,
    Martin Staebler

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