A typical trackpad layout consists of diamond shape electrodes that fill the surface of the active area. Around the perimeter of the trackpad there is a non-linear or "dead-zone" where the trackpad may not respond to a finger touch.

Trackpad trim parameters provide a way to help "stretch" or scale the left, right, upper and lower end points of a trackpad to compensate for this effect.

The desired operation of a trackpad is to have the left-most or bottom-most point be represented by the lowest possible value (0), and the right-most or top-most point be represented by the maximum possible value (resolution of the trackpad - 1). This concept is illustrated in the example below.

Implementation Notes
To tune the left and lower parameters, move your finger along the edge of the trackpad and determine the region where the finger transitions from a valid touch to a "no touch" state. This is the transition point into the dead zone. Note the smallest value and set the corresponding X and Y lower trim trackpad parameters to this value.

Perform the same procedure along the right and upper regions, note the largest value and set the corresponding X and Y upper trim trackpad parameters. It may take several iterations to obtain the desired performance. Don't forget to click on the "Apply" button after you change any parameter.

Range of Valid Values for TrackPad Trim Parameters
Trackpad trim values must be between 0 and Desired_Resolution-1. In addition, the lower trim must be less than the upper trim. To disable trackpad trim, set the lower trim to 0 and the upper trim to the Desired_Resolution.

Affected Software Parameters
The Lower_Trim X parameter corresponds to the ui16LowerTrim_X member of the tTrackPadSensorParams type in the CapTIvate Touch Library.
The Upper_Trim X parameter corresponds to the ui16UpperTrim_X member of the tTrackPadSensorParams type in the CapTIvate Touch Library.
The Lower_Trim Y parameter corresponds to the ui16LowerTrim_Y member of the tTrackPadSensorParams type in the CapTIvate Touch Library.
The Upper_Trim Y parameter corresponds to the ui16UpperTrim_Y member of the tTrackPadSensorParams type in the CapTIvate Touch Library.