QTouch acquisition method libraries are available for different port combinations.
Some of the key constraints while configuring the sensors are
Rotors/sliders have to be connected on three adjacent channels. (e.g. (1,2,3) or (3,4,5) …) within the same port. Possible combinations are (0,1,2), (1,2,3) for a configuration which supports 4 channels. Possible combinations (0,1,2), (1,2,3), (2,3,4), (3,4,5), (4,5,6), (5,6,7) for a configuration which supports 8 channels.
If two port pairs are used for the design, all the channels for a sensor have to be connected on a single port pair. Combining channels from multiple ports is not possible when designing sensors. e.g. It is not possible to have a rotor with channel numbers ( 7,8,9 ) on a 16 channel library variant which uses two port-pairs.
Note: The above constraints are explained with respect to 8bit AVR. The same could be extended to 32bit AVR and ATSAM for 32 channel libraries where each port has 32 pins.