22
3M™ MicroTouch™ Controller RX151 Reference Guide
3M Touch Systems, Inc. Proprietary Information
This command corrects for sensor display orientation and sensor 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 sensor 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 sensor 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.
Figure 2. Calibration Target Locations
*
The coordinates are in
video
terms, with the origin (0, 0) in the upper left corner of the sensor. Examples from the
controller’s
perspective, however, place the origin at the lower left corner of the sensor (numbers in brackets). The
controller outputs 0 to 64K on both axes independent of display sensor resolution.
Get Feature – Get Status
This is a request to send information that indicates the status of the controller. Among the
uses for this request are determining whether there were any power on check errors
determining whether the last request was completed successfully.
(0, 767) [0, 0]*
[64k,0]*
Upper Right Calibration Target
X = 1023 – (1024 x 1/8) = 1023 – 128 = 895
Y = 0 + (768 x 1/8) = 0 + 96 = 96
Lower Left Calibration Target
X = 0 + (1024 x 1/8) = 0 + 128 = 128
Y = 767 - (768 x 1/8) = 767 - 96 = 671
(
1023, 0) [64K, 64k]*
(128, 671)
(895, 96)
0,0
