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APPENDIX A
3M™ PX USB Controller Communications
This appendix is intended for software developers only and discusses the fundamentals of communicating with the PX controller. The firmware commands, which are usually issued by a driver or utility program on the host system, control the operation of the controller. This appendix lists the recommended firmware commands and describes how to use each of these commands.
Overview of USB Firmware Communications
Developers may use this information when writing touch applications, developing custom drivers or touch configurations, or testing their touch systems. Developers can issue commands to initialize the controller, select operating modes, and execute diagnostic functions.
Note: This document assumes you are familiar with USB standards and modes of communication with USB devices, as well as firmware commands and how to use them. Executing some commands may alter the performance of your sensor and render it inoperable. You should be aware of the results before executing any firmware commands.
To optimize the performance of the PX controller and simplify the development of custom drivers, 3M Touch Systems recommends you use the commands listed in this appendix for current development.
Communication Basics
This section provides information on sending firmware commands to the controller and interpreting the responses that the controller returns. The default operation of the PX controller is USB Rev 2.0 full speed.
The USB command set is implemented by using vendor requests and vendor reports, i.e., vendor specific transactions. The controller issues some reports without prompting the computer. The computer can also send requests to the controller to change how it operates or receives information about the controller. The controller issues a
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