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Can we configure proximity distance 30cm on CapTIvate DK？

Yuji Kuroki
Intellectual 550 points

Hi,

Can we configure proximity distance 30cm with PROXIMITY Board of MSP CapTIvate MCU Development Kit(MSP-CAPT-FR2633)?

I want to make 30cm proximity sensing on PROXIMITY Board of MSP CapTIvate MCU Development Kit.
I tried to tune as conversion count up, and conversion gain down according to the description of userguide.
But I succeeded with just 6cm or something. And, when I tune conversion count over 1,600, it wasn't reflected. It seems processing fall.
Are those usual?

I guess CapTIvate DK can't configure proximity distance 30cm because of size of the electrodes, and to configure proximity sensing range 30cm, we have to use bigger one. Am I correct?

I am afraid, but please teach me above descriptions.

Regards,

Yuji

  • 0
    TI__Expert 4215 points
    Hi Yuji,

    I have reached out to someone regarding this issue and will have an answer shortly.

    Sincerely,
    Sean
  • 0
    TI__Mastermind 29405 points

    Hello Yuji,

    30 cm is a pretty large distance. I don't believe that the PROXIMITY Board of the MSP CapTIvate MCU Development Kit can reach that distance.

    You are correct in trying to increase your conversion count and decrease your conversion gain, but it is not guaranteed that the device can calibrate to any value that you input. To view more detailed information on the gain/offset settings after calibration you will need to enable Adavanced mode in the CapTIvate Design Center's features menu.

    Use the following steps to do this:

    1. Go to Options->Features
    2. Select Advanced
    3. Hit 'OK'

    This will enable you to view more detailed information about the device configuration for your sensors. After enabling Advanced mode, you can open the proximityGroupSensor, select Conversion_Control, and scroll to the bottom of the settings to view Coarse/Fine Gain Ratios and Parasitic Offset. These values might be maxed out, which may prevent you from calibrating to your selected conversion count and conversion gain.

    I've attached an image that shows what your proximityGroupSensor menu will look like in Advanced mode.

    Higher sensitivity can be achieved with larger electrodes and more separation between electrodes and conductors. However, you should note that as the size of an electrode increases, so does the parasitic capacitance.

    Best Regards,

    Benjamin Moore

  • 0 in reply to Sean Huang15
    Intellectual 550 points
    Hi Sean,

    Thank you very much for your cooperation.

    Sincerely
    Yuji
  • 0 in reply to Benjamin Moore
    Intellectual 550 points
    Hello Benjamin,

    Thank you very much for your detailed answer.
    I use Design Center with advanced mode, but I didn't touch Coarse/Fine Gain Ratios and Parasitic Offset parameters.
    So, I'm going to try it again with your manner and report it to here after that.
    Thank you very much.

    Best Regards,

    Yuji Kuroki
  • 0 in reply to Yuji Kuroki
    TI__Mastermind 29405 points
    Yuji,

    The Coarse/Fine Gain Ratios and Parasitic Offset are not set by the user. You will only change the Conversion Count/Conversion Gain which will be used by the calibration algorithm to determine the necessary Coarse/Fine Gain Ratios and Parasitic Offset.

    This is discussed in more detail in the CapTIvate Technology Guide under Technology -> Capacitance Measurement -> Signal Conditioning (Sensitivity Related Functions).

    Best Regards,
    Benjamin
  • 0 in reply to Benjamin Moore
    TI__Expert 4215 points

    Great answers Ben!

  • 0 in reply to Benjamin Moore
    Intellectual 550 points
    Benjamin,

    I've misunderstood it!
    Thank you so much.

    Best Regards,

    Yuji

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