3M™ MicroTouch™ Controller RX142 Reference Guide

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3M Touch Systems, Inc. Proprietary Information

Figure 2 Calibration Target Locations

Enter Sleep

Syntax:

<SOH>ES<CR>

Response:

<SOH>0<CR>

Positive response.

Description:

This command is a power management feature that lets you put the controller into a low

power mode (4-5 mA) when not in use. Send this command to put the controller in a low

power state. The controller returns to a normal power level on touch. If you need to send

a command to the controller when it is in a low power state, first raise CTS.

Format Tablet

Syntax:

<SOH>FT<CR>

Response:

<SOH>0<CR>

Positive response.

The controller will respond with ACK for compatibility with older controllers. This

format is the only format supported by this controller.

With the controller in Format Tablet mode, touching the sensor causes the controller to

return a response in the following format:

SXxYy

S

= Status byte, first byte of data. Refer to Table 4.

Xx

= X (horizontal) coordinate data; second and third bytes of data.

Yy

= Y (vertical) coordinate data; fourth and fifth bytes of data.

Description:

Outputs the X/Y touch coordinate data in a 5-byte packet. The packet includes 1 status

byte and 4 bytes of binary X/Y coordinate data. The protocol also establishes the X and Y

coordinate output as 14 binary bits providing a range of 0 to 16,383.

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

(0, 0) [0, 1024]*

(0, 767) [0, 0]*

(128, 671)

(895, 96)

[1024, 0]*

* 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 1024 for both axes, regardless of display resolution.

(128, 96)

Upper Left Calibration Target

X = 1024 x 1/8 = 128

Y = 768 x 1/8) = 96