UR7HCTS2-P840 Datasheet, PDF (8/16 Pages) Semtech Corporation – High-Performance, Low Power PS/2 Touch Screen Controller/Digitizer

SEQUENTIAL COMMANDS
Unlike normal commands, sequential commands must be enacted with a
sequence of commands. If the sequence is not consecutive or is incorrect,
the ScreenCoder^TM PS2 aborts the detection and responds the way it would
normally respond to a command.
The individual commands that comprise a sequential command have been
designed so that the elements of a sequential command can be sent to the
ScreenCoder^TM PS2 via the standard IBM PS/2 BIOS calls and the device
returns a valid response to the Status Request. This ensures that, if the
sequential command is sent via the BIOS, the status response will be
accurately returned even if the BIOS performs error detection. Thus, a
programmer can have complete control of the mouse without having to
access the device hardware port directly.
The UR7HCTS2-P840 implements a special sequential command that can
be used to determine its ability to report three buttons. The sequential
command is a series of commands to the ScreenCoder^TM PS2 that cause
the device to respond to the last command (Read Status) with alternate
information.
The sequence of commands is as follows.
1. Set Resolution = one count/ mm
2. Set Scaling = 1:1
3. Set Scaling = 1:1
4. Set Scaling = 1:1
5. Read Status
(E8H)
(E6H)
(E6H)
(E6H)
(E9H)
The response to the Read Status Command is in the following format.
Byte 1: Standard Status Information (buttons, scaling, etc.)
Byte 2: Number of mouse buttons (3)
Byte 3: Firmware Revision Number (encoded) or current sampling rate
Copyright ©1999-2001 Semtech Corporation
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DOC7-TS2-P840-DS-106
www.semtech.com