I am working on touch detection with STM32L412cbt6 MCU. I am applying difference taking process in two channels of G1 and there are fluctuations in very small values (like between 0-100). When I look at the other group (i.e. G2), there are fluctuations in values from time to time but these values are very large (like 0-1500). I could not observe any situation on the card that could cause this noise. I checked the sampling capacitors with an oscilloscope and I could not see any difference with the working group. The sampling capacitor value was used as 47nF in both groups. This design was made by taking into consideration the guides given by ST regarding design in my previous PCB design.I also tried this with ST's TSC library while doing this work, but these jumps occurred again.
