How to get capacitance in higher resolution in fF or 10fF order?

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naku_3600561
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Hi experts.

I am building water level sensor using CY8C4014+PsoC Creator4.2+CapSense CSD 2.60.

Now I am using  CapSense_GetSensorCp() API but it reports capacitance of electrode in pF

order. I need much higher resolution like in fF or 10fF order.

I tried  CapSense_ReadSensorRaw() API but raw count is initialized to different value

every time power is turned on even capacitance of the electrode (i.e. water level) is

maintained. (Once raw count is initialized to a certain value, change of raw count value

is proportional to a change of capacitance of the electrode. )

Is there any way to get capacitance of electrodes in higher resolution (in fF or 10fF order)?

Thanks in advance.

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1 Solution
LinglingG_46
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500 solutions authored 1000 replies posted 10 questions asked

According to my understanding, it is impossible to get such resolution using "CapSense_GetSensorCp()".

View solution in original post

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3 Replies
LinglingG_46
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500 solutions authored 1000 replies posted 10 questions asked

According to my understanding, it is impossible to get such resolution using "CapSense_GetSensorCp()".

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Hi LinglinG_46

  Thanks for your reply. I understand that It is impossible to get capacitance ni

higher resolution with "CapSense_GetSensorCp()" API.

  I got an advice from another expert to see "CY8CKIT-022 CapSenseR Liquid Level Sensing Shield."

I looked into the project and I found that they saved raw count value in case of no water into EEPROM

and they restored the value from EEPROM as an initial offset and subtract it from the raw count

value for the next time.

I will try this method.

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If you only want to do the water detection, you can refer the CY8CKIT-022 :

https://www.cypress.com/documentation/development-kitsboards/cy8ckit-022-capsense-liquid-level-sensi...

But you may take "temp, different kind of liquid" into consideration.

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