The finger capacitance given in the configuration window is the measure of Capsense sensitivity. If you reduce the value of Cf, SmartSense increases sensitivity by increasing the scan resolution. Could you please let us know your exact observations when you decreased the Cf value?
1. Raw counts before and after reducing Cf
3. Thickness of overlay
4. Cp of the sensor
Note: SmartSense supports a sensor parasitic capacitance range of 5 pF to 45 pF if the expected finger capacitance is higher than 0.2 pF. If the expected finger capacitance is lower than 0.2 pF, but higher than or equal to 0.1 pF, the supported parasitic capacitance range is 5 pF to 35 pF. In case you don't see any touch, this might be due to Cp greater than 35pF.
Thank you for reply.
But how could I measure the Cp of the sensor when i'm using smartsense (full auto tune).
You have to use the Self Test library (BIST) to measure the Cp of the sensor. But you have to use either SmartSense (hardware parameters only) or Manual tuning to use this feature. SmarSense (Full Auto-Tune) and BIST (built in self test) feature can't be used together.
Use any of the above two mentioned modes to measure Cp and then switch back to SmarSense (Full Auto-Tune) for normal operation.
You can also use a LCR meter to measure the Cp.