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Epson Research and Development
Page 13
Vancouver Design Center
Windows® CE 3.x Display Drivers S1D13505
Issue Date: 01/05/17 X23A-E-006-01
Note that all dword values are in hexadecimal, therefore 280h = 640, 1E0h = 480, and 3Ch
= 60. The value for “Flags” should be 1 (LCD), 2 (CRT), or 3 (both LCD and CRT). When
the display driver starts, it will read these values in the registry and attempt to match a mode
table against them. All values must be present and valid for a match to occur, otherwise the
display driver will default to the first mode table in your list.
A WinCE desktop application (or control panel applet) can change these registry values,
and the display driver will select a different mode upon warmboot. This allows the display
driver to support different display configurations and/or orientations. An example appli-
cation that controls these registry values will be made available upon the next release of the
display driver; preliminary alpha code is available by special request.
Resource Management Issues
The Windows CE 3.0 OEM must deal with certain display driver issues relevant to
Windows CE 3.0. These issues require the OEM balance factors such as: system vs. display
memory utilization, video performance, and power off capabilities.
The section “Simple Display Driver Configuration” on page 15 provides a configuration
which should work with most Windows CE platforms. This section is only intended as a
means of getting started. Once the developer has a functional system, it is recommended to
optimize the display driver configuration as described below in “Description of Windows
CE Display Driver Issues”.
Description of Windows CE Display Driver Issues
The following are some issues to consider when configuring the display driver to work with
Windows CE:
1. When Windows CE enters the Suspend state (power-off), the LCD controller and dis-
play memory may lose power, depending on how the system is designed. If display
memory loses power, all images stored in display memory are lost.
If power-off/power-on features are required, the OEM has several options:
• If display memory power is turned off, add code to the display driver to save any
images in display memory to system memory before power-off, and add code to
restore these images after power-on.
• If display memory power is turned off, instruct Windows CE to redraw all images
upon power-on. Unfortunately it is not possible to instruct Windows CE to redraw
any off-screen images, such as icons, slider bars, etc., so in this case the OEM
must also configure the display driver to never use off-screen memory.
• Ensure that display memory never loses power.