APOLLO user manual
Issue G
96
LVDS data cable
When interfacing to an LVDS display, the data signals IYA+/-, IYB+/-, ICLKA, ICLKB
require a twisted pair cable with a nominal impedance of 100
Ω
to prevent signal
reflections due to impedance discontinuities. For connections over long distances, a
ground connection should be used for each LVDS data pair.
LCD backlight connector
A backlight connector (J15) interfaces to and can be configured to control an external
CCFL backlight inverter. The header pr12V, +5V, a backlight enable control line
and a software-controllable PWM interface.
The backlight enable signal (Backlight En) pin 5 on connector J15 provides a 3.3V output
control signal that is designed to be interfaced to the ON/OFF input common on most
backlight inverters. This is an active high signal with a 100K pull down resistor. It is
sequenced by the video BIOS to enable the backlight when the display is active.
The backlight control signal (Backlight Control) pin 4 on connector J15 provides a 3.3V
PWM output control signal that has been designed to interface to the intensity control
input available on most backlight inverters. Buffering may be required for some backlight
inverters if the 3.3V PWM signal does not provide the required output range.
The PWM frequency is fixed in the Video BIOS to 200Hz. The duty cycle has been set to
predetermined values that can be accessed using the ACPI _BCL control method
supported under Windows XP and Linux. When interfaced correctly, this signal allows
software control of the backlight intensity.
For connector details, see page
.
Windows XP/XP Embedded Video Drivers
Two drivers are available for Windows XP and XP Embedded: the Intel Mobile Graphics
division Extreme Graphics driver and the Intel Embedded Graphics Driver (IEGD).
Intel Mobile Graphics Division XP Driver – Extreme Graphics
The Intel Extreme Graphics XP driver is a fully featured driver however as it is designed
for use primarily with laptop computers some of its features are not fully compatible with
Embedded PC design. One aspect of this is if a VGA monitor is not attached when the
graphics driver loads then the LVDS display will be selected as the primary display
output. This is the expected behaviour for a laptop PC, the LVDS display selection will
remain until the VGA display port is selected through the display configuration or using
the CTRL-ALT-F1 hotkey combination. These options will only be available if a Windows
password login is bypassed. If a login console is to be used the Intel Embedded Graphics
Driver is recommended.
Intel Embedded Graphics Driver – IEGD Graphics
The Intel Embedded Graphics Driver (IEGD) driver is a user customisable driver that can
be used to support unique display configurations and capabilities not natively supported
by the mobile division driver. This allows for features such as forcing the VGA output ON
regardless of there being an attached display. IEGD Version 8.0 supports the Intel
855GME chipset used on the APOLLO board. Further information on the IEGD
configuration tools are avaiA preconfigured IEGD VGA output only driver is also available from Eurotech support,
please refer to the contact details on page
.
