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Table 13. Calibration Response
Command Status
Byte
0
1
2
3
This command corrects for touch screen display orientation and touch screen pinout
variations. This information will be maintained by the controller. The Calibrate 2
Point command initiates an interactive calibration procedure which defines the active
area of the touch screen by mapping locations to an absolute X,Y coordinate system.
Touch points generated subsequent to a successful calibration operation are calculated
based upon these calibration points. Calibrate 2-point utilizes inset calibration points
located 12½ percent inboard from the screen corners (at touch X,Y locations 128,128,
895,895 and 128,895) for accuracy and ease of operation.
Determining Target Areas
The default calibration targets (points) are located 12.5% (1/8) inward from the
corners of the video image. For example, suppose the display resolution of your
Windows-based monitor is 1024 x 768. The Calibration command calculates the
amount to move inward as follows:
•
Amount to move inward in the X direction: 1024 x 1/8 = 128
•
Amount to move inward in the Y direction: 768 x 1/8 = 96
The Calibration command then positions the first calibration target inward from the
lower left corner (0,767) and the second calibration target inward from the upper right
corner (1023,0). The following illustration shows how the calibration targets are
calculated for a Windows-based system. Your operating system may be different.
Description
Calibration Failed
Controller is waiting for a touch in the lower left corner
Controller is waiting for a touch in the upper right corner
Calibration completed successfully
3M Touch Systems Proprietary Information
SC500 USB Controller Reference Guide
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