How to measure capacitance value of capacitor while using TSC ?

[goutham gumm_2]

I have written a TSC code for STM32L476RG . I have attached a sampling capacitor of 47nF and have connected it between sampling IO pin and GND. I have another capacitor which I have connected between a channel IO pin and GND. I want to measure the value(capacitance) of this capacitor. Is there any formula or method by which I can measure it? When only the sampling capacitor is connected to sampling IO pin, the value in uhTSCAcquisitionValue is about 240. When I connect my the capacitor which i want to measure to channel IO pin, the value in uhTSCAcquisitionValue is close to 50. How can I measure it capacitance?

[OlivierR]

We never play with this interesting use case. Should work for small capacitance values (1pF to few nF).

In opposite with real touch sensing setup, work inside linear area of charge/discharge (1xtau).

For this set DIV=CTPH=CTPL=1 and HCLK as fast as possible.

TSC group handle 4 IOs, this mean you can add 2 references capacitance (CRef1, CRef2) to compute references measurements (M1, M2).

And do something like this:

Rgs.