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Original question:

FDC2214EVM: Sensor not detected

FDC2214EVM: The data obtained by ADC will suddenly become 0XFF

Gabriel Wang1
Genius 4715 points
Part Number: FDC2214EVM
Other Parts Discussed in Thread: FDC2214, FDC1004

Tool/software:

Hi Expert

During the liquid level detection of FDC2214, the following issue was found: When FDC2214 is continuously detected and does not reach full range, it will result in a fault where the capacitor ADC data is full F, and then it will return to normal data.
Some basic information:
1. The situation where FDC2214 outputs full F has only occurred before when detecting a capacitor short circuit to ground. Currently, the short circuit situation can be ruled out;
2. The SD pin is connected to the GPIO of the MCU and configured with push-pull output low.
The situation of outputting all F is occasional and cannot be reproduced through specific means.

  • 0
    TI__Mastermind 40295 points

    Gabriel,

    You could be getting an EMI "hit" or the sensor waveforms are near a limit.
    If you monitor the sensor signals with a high impedance probe, what do you see?

    Regards,
    John

  • 0 in reply to John Miller - Sensing
    Genius 4715 points

    Dear Sir

    As this sensor is used for IVD liquid level detection.And it has already been sent to the end customer, but there is no way to measure it,

    I would like to confirm the following question:

    1 If the deglitch register is set to 10MHz, does this mean that interference above 10MHz will be filtered out?

    2. If SD is disturbed, will the registers be reset to their default state?

  • 0 in reply to Gabriel Wang1
    TI__Mastermind 40295 points

    Gabriel,

    The deglitch filter is intended to filter out external interference above the filter's frequency.
    So if the deglitch filter is set to 10MHz, it should filter out interference above 10MHz.

    Just so you know, past customers have struggled to get to production with the FDC2x1y parts because of EMI.
    These parts do not have built-in active shield drivers like the FDC1004, a capacitive sensor we offer.
    The FDC1004 has a fixed 25kHz sensor frequency, and does not require a resonant LC tank circuit to work.

    If you want to know more about the FDC1004, please see the E2E FDC1004 Frequently Asked Questions Page.
    It has a comprehensive set of app notes, as well as a crash course for the device.

    According to the data sheet, entering SD will return all registers to their default state.

    Regards,
    John