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CARROLL TOUCH Chapter 5 - Smart-Frame Protocol II
Touch System Programmer’s Guide 5-3
Protocol version numbers greater than 1.0 but less than 2.0 will be used
during the development of the SFP-II protocol. When the SFP-II
protocol is complete, that is, when it incorporates the initial set of
desired features, that version of the protocol will be given a version
number of 2.0. Subsequent changes to the protocol will result in
changes to the subminor, minor, or major portions of the protocol
version number, depending upon the extent of the changes.
One of the main purposes for extensibility is to allow properly written
applications and drivers to work with touch systems that support SFP
and touch systems that support SFP-II. A “properly written” application
or driver uses the following sequence of steps during touch system
initialization to determine the protocol version and act accordingly:
1. Initialize the touch system using the common initialization
sequence.
2. Attempt to switch to SFP-II mode by issuing the SwitchToSFP-II
(65H) SFP command.
3. If the touch system does not respond with a Protocol Version
Report within the SFP timeout time (one second), the application
or driver should assume that the touch system supports only the
SFP (SFP 1.0), and use only SFP commands and expect only SFP
reports.
4. If the touch system responds with a protocol version report that
indicates a protocol version number of 2.0 or above, the
application or driver may use all of the standard SFP-II commands
and reports. The application or driver may also (optionally) use
SetReportProperties (21H) command to request Report Properties
Reports to ensure that each command that it uses is supported. This
optional step is recommended if the application uses commands or
reports that were not included in the original SFP-II protocol (SFP
2.0).
In summary, applications or drivers can use the Protocol Version
Report to determine the firmware protocol version. The protocol
version can be used to determine whether the touch system supports
only SFP or SFP and SFP-II. The application or driver may also use the
Protocol Version Report in conjunction with the protocol version
revision history to determine the exact features that the firmware
supports. Finally, for maximum protection against protocol changes,
the application or driver can use the SetReportProperties (21H)
function to ensure that each command that it intends to use is supported.