MM II 37
Chapter 5: Guidelines for Writing a Device Driver
For the computer to make use of the data being sent to it from the tablet, the software
(system or application) must contain a tablet device driver. The driver needs to be written
for your specific MM II configuration.
The device driver is a program that collects and decodes the tablet data.
The driver usually sits between the application and serial interface. The driver should be
able to:
Receive reports and status information from the tablet via the serial interface
Transmit data to the application
Present high level commands from the application that control the tablet
A typical driver consists of four major parts:
Configure Host and Tablet
o
Structure the host communications port (port address, baud rate, etc.)
o
Shape the tablet (resolution, report mode, etc.)
Report Collection – Interrupt Routines
o
Assemble the report: collect the report’s data bytes into an array
o
Check for errors
Process Reports from the Tablet
o
Decode the report
o
Filter reports, if required by the application
o
Notify the application, if applicable, that a report is ready to be issued to the
application
Process Errors
o
Parity errors
o
Short report errors after time-out
o
Long report errors
o
Missing report errors after time-out
o
Host buffer full errors (automatic XON/XOFF support)
Summary of Contents for MM II 1201
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