Epson S1D13706 Technical Manual page 365

Epson Research and Development
Vancouver Design Center
Resource Management Issues
Description of Windows CE Display Driver Issues
Windows® CE 3.x Display Drivers
Issue Date: 01/05/25
"Rotation"=dword:0
"RefreshRate"=dword:3C
"Flags"=dword:1
Note that all dword values are in hexadecimal, therefore 140h = 320, F0h = 240, and 3Ch
= 60. The value for "Flags" should be 1 (LCD). 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.
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".
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.
Page 13
S1D13706
X31B-E-006-01