So we need to use one extra component? And how about the accuracy of such approach?
The CapSense block has two IDACs which can be used for
general purposes if CapSense is not being used.(both IDACs are
available in that case) or if CapSense is used without water
tolerance (one IDAC is available).
IDAC is not using UDB, its part of the system resources.
The reference is +/- 1%, the IDAC accuracy is ~ 3 lsbs, so dominant
accuracy set by reference.
Please note that if you use IDAC with an external resistor to generate reference voltage, complete mux bus will be utilized. This will limit your routing possibilities.