Channel numbering when routing SNS and SNSK pins to different ports

Figure 1 illustrates a sample QTouch capacitive sensing solution which uses four ports (two port pairs ) on a device for routing the SNS and SNSK lines required.

When SNS and SNSK pins are available on different ports, the channel numbering follows the pin numbering in the ports selected, when pin configurability is not used.

  1. 1.

    The channel numbers follow the pin numbers starting with the LSB (pin 0 is channel 0 and pin 7 is channel 7).

  2. 2.

    When a library on corresponding device is configured to use more than two ports for SNS and SNSK pins, the channel numbers in the second set of SNS/SNSK port pair continue from the preceding pair as illustrated in Figure 1 (pin 0 of next port pair is channel 8 and pin 7 of the next port pair is channel 15).

  3. 3.

    Support for more than one pair of SNS and SNSK ports are not available for UC3™ devices.

  4. 4.

    SNS pins within a single port and SNSK pins within another single port can only be used as channels for slider/rotor. Slider/Rotor channels cannot share SNS/SNSK pins on different ports.

  5. 5.

    Since the channel numbers are fixed to the pins of the SNS and SNSK ports, if the design calls for use of a subset of the pins available in the SNS and SNSK ports, the user has to skip the channel numbers of the unused SNS and SNSK pins.

Figure 1. Channel numbering for QTouch acquisition method when the SNS and SNSK pins are connected to different ports