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FDC2114EVM: FDC 2114 doesn't show linear increase in value on Arduino

Part Number: FDC2114EVM
Other Parts Discussed in Thread: FDC2114

Dear Sir,

I have one question; I have transferred the data from FDC 2114 to Arduino successfully. I verified this thing by connecting various capacitors from the 3pF to 100nF range on the FDC 2114 port. All capacitors are detected well by FDC 2114 and FDC 2114 shows the increase in value according to the increase in high-capacity capacitor connected.


But there is one problem, The value shown by Arduino by connecting the capacitors is not linear e, g The increase in value trend shown by FDC 2214 in the pF range is the same as  in the nF range. In reality, the increase in value trend in the nF range should be very high as compared to the pF range. Because pF is very small as compared to nF. So, FDC 2114 doesn't show a linear increase in value.
For clarification i am going to attach two pictures having grap of values from 3pF to 100nF, which i measured on Arduino 
If you remove my confusion, I would be very thankful to you?


                                                            

  • Hello, 

    The FDC2114 is better at determining a change in capacitance for a given sensor than it is at determining an exact capacitance of an attached capacitor. We recommend keeping the same capacitor attached to the LC tank of the device and sensing the capacitive change on a sensing electrode. For the most consistent results across boards, we recommend using LC values with less tolerance. 

    Best Regards, 

    Justin Beigel