SAMD11 Touch Mode Support Ambiguity

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Hi everyone,

 

I'm new to using capacitive touch, and I am in the midst of designing my first PCB to take advantage of this cool tech. I have been reading through the documentation, and I caught an interesting exception in AN2934 Appendix C that seems to imply that the ATSAMD11 cannot make use of flooded X sensor designs because the X lines do not support I/O drive.

 

My understanding was that mutual capacitance measurements as a whole require the X lines to be driven. Does this mean that mutual capacitance is actually not supported, or does this have to do with the overall increase in capacitive load of the flooded X design? I'd be interested to hear if anyone has tried this for themselves or otherwise knows whether that appendix is accurate.

 

Thanks!