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FDC2212: FDC2212 Get No sensor values

Jack LEE
Prodigy 80 points
Part Number: FDC2212

Hello, I am currently using FDC2212 as our capacitance sensor. But I couldn't get any value. So I want to know if this is the software problem or hardware problem.(Because a data value of 0x0000000 = under range for FDC2212). Please check the software and schematic in the attachment. Thank you. fdc2212.TXT

  • 0
    TI__Genius 17440 points

    Hi Jack,

    I don't see a problem with your schematic, as long as your I2C pull-up resistors are on another page.

    There are two things that I recommend checking. First, even if your hardware is set up correctly, you may not be using the correct settings in the device. Any easy way to make sure your sensor is oscillating correctly is to probe the LC tank with an oscilloscope. Though this application note is written for inductive sensing devices, it is also applicable to the FDC2212. Your sensor oscillations should look like Figure 4. If the amplitude is outside of the recommended range, adjust the drive current. If you do not see sensor oscillations at all, double-check that the device is not in sleep mode or shutdown mode and that the correct channels have been enabled.

    If your sensor oscillation looks good, I recommend reading back the Manufacturer ID register to make sure that you've established proper communication with the device. If you do not get back the correct value, check the I2C pull-up resistors, verify the address you are using matches the ADDR pin selection, and ensure your communication protocol matches section 9.5 of the datasheet.

    Best Regards,

  • 0 in reply to Kristin Jones93
    Prodigy 80 points

    Thank you Kristin for the reply.

     I am using the sensor in differential mode. In order to make the amplitude in the recommended range, which two electrodes should I test? It's between one plate and gnd or between two plates. I have tested both. I got some values below zero, is it correct?  Vosc should be smaller than 1.8Vp. What does that mean?It means  V+max< 1.8Vp   or    (V+max-V-max)<1.8Vp

    Thank you

  • 0 in reply to Jack LEE
    TI__Genius 17440 points

    Hi Jack,

    This application note should clear things up. It's applicable to the FDC2212 as well as the inductive sensing devices mentioned in the title.

    Best Regards,