FDC2214EVM: how to explain the test result in application note Ground Shifting in Capacitive Sensing Applications?

Matthew Chen

Part Number: FDC2214EVM

Hi team,

i see the application note using FDC2214evm, https://www.ti.com.cn/cn/lit/pdf/snoa952

1.What is the unit of the x-axis?

2. Why there are pulse waveform of several points measured? It seems that the pulse duration is too short, So the reason shouldn't be the hand move close to the sensor then move away. I think after the capacitance changes, the waveform should be similar to a step response, the waveform does not fall back. In the picture, why there is a fall and when it does not fall back?

Thanks a lot.

Matthew Chen

over 3 years ago

0 Justin Beigel over 3 years ago

TI__Mastermind 18545 points

Hello Mathew,

The X axis is the number of samples collected. To correlate this to time, you would need the sample rate that the data was logged.
The pulses are for when a hand moves within range and out of range. Once the hand is removed, the capacitance will return to the normal value.

Best Regards,

Justin Beigel

0 Matthew Chen over 3 years ago in reply to Justin Beigel

TI__Intellectual 1400 points

Hi Justin,

Thanks a lot. that solves my problem.

Matthew

0 Justin Beigel over 3 years ago in reply to Matthew Chen

TI__Mastermind 18545 points

Hello Mathew,

Glad it helped. Let us know if you have any other questions.

Best Regards,

Justin Beigel

Sensors

Sensors forum

FDC2214EVM: how to explain the test result in application note Ground Shifting in Capacitive Sensing Applications?