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FDC1004EVM: Calculate reference environmental

Part Number: FDC1004EVM
Other Parts Discussed in Thread: FDC1004, TIDA-00317

Hi:

      I come to ask another again. I  have a experiment  to test the liquid level in the bottle,so I have already read the guidelines from TI's FDC1004 document.

But in my experiment I have a  question,the question is about how  FDC1004 can calculate the reference environmental  value  and what's the formula based on?

  • Hi Guei Hung,

    The reference environmental capacitance is measured by the reference environment sensor,  which is a small sensor placed above the maximum allowable level of liquid. This sensor is able to track environmental factors uninterrupted by the liquid level in the container.

    The capacitance from the reference environmental sensor, along with the level sensor and reference liquid sensor, are used to calculate the liquid level using the following equation:

    You could find more information about liquid level sensing from the TIDA-00317 Reference Design Document.

    Best,

    Jiashow

  • Hi:

    The setup is as you suggested. I am sorry that I sould be more specific.
    The most annoying question is how do you obtain CRE. Could you please give me some hints about how it is calculated and what definition it is.
    We basically donn't know how come the CRE so no idea about how your provided formula can derive the liquid level....

  • Hi Guei Hung,

    CRE is the capacitance measured by the reference environmental sensor, a small sensor placed above the maximum allowed liquid level. Since it is always above the liquid, you can use it to track environmental factors that could cause a shift in capacitance in the level sensor.

    To measure CRE, you would look at the data in the channel you connected your reference environmental sensor to. In the case of our TIDA-00317 reference design, this would be CIN3.

    You can refer to section 4.1 in the TIDA-00317 reference design for more information.

    Best,

    Jiashow