1.1.1 Masked Input (MASK)

This is the default option for the inputs. When an input is masked, the value on the corresponding input will always be zero. If only two inputs are of interest, the unused input should be masked to ensure that its value is constant. Masked input is selected by writing the Input y Source Selection bit group in the LUT Control x register (LUTCTRLx.INSELy) to 0x0.