301467-005 Datasheet, PDF (233/426 Pages) Intel Corporation – Express Chipset

Functional Description
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12.5
12.5.1
Intel^® Serial Digital Video Output (SDVO) (Intel^®
82915G/82915GV/82915GL/82910GL GMCH Only)
The 82915G/82915GV/82915GL/82910GL GMCH SDVO ports are multiplexed with the PCI
Express x16 interface. PCI Express and SDVO simultaneous operation is NOT supported, even
though SDVO does not require all of the PCI Express lanes.
The Intel^® SDVO port is the second generation of digital video output from compliant GMCH.
The electrical interface is based on the PCI Express interface, although the protocol and timings
are completely unique. Where PCI Express runs at a fixed frequency, the frequency of the SDVO
interface is dependant upon the active display resolution and timing. The port can be dynamically
configured in several modes to support display configurations.
Essentially, an SDVO port will transmit display data in a high speed, serial format across
differential AC coupled signals. An SDVO port consists of a sideband differential clock pair and
a number of differential data pairs.
Intel^® SDVO Capabilities
SDVO ports can support a variety of display types including LVDS, DVI, Analog CRT, TV-Out
and external CE type devices. The GMCH uses an external SDVO device to translate from SDVO
protocol and timings to the desired display format and timings.
The Internal Graphics Device on the 82915G/82915GV/82915GL/82910GL GMCH can have one
or two SDVO ports multiplexed on the x16 PCI Express interface. When an external x16 PCI
Express graphics accelerator is not in use, an ADD2 card may be plugged into the x16 connector
or if a x16 slot is not present, the SDVO(s) may be located ‘down’ on the motherboard to access
the multiplexed SDVO ports and provide a variety of digital display options.
The ADD2 card is designed to fit in a x16 PCI Express connector. The ADD2 card can support
one or two devices. If a single channel SDVO device is used, it should be attached to the channel
B SDVO pins. The ADD2 card can support two separate SDVO devices when the interface is in
Dual Independent (82915G only) or Dual Simultaneous Standard modes.
The SDVO port defines a two-wire point-to-point communication path between the SDVO device
and GMCH. The SDVO control clock and data provide similar functionality to I²C. However,
unlike I²C, this interface is intended to be point-to-point (from the GMCH to the SDVO device)
and will require the SDVO device to act as a switch and direct traffic from the SDVO control bus
to the appropriate receiver. Additionally, this control bus will be able to run at faster speeds (up to
1 MHz) than a traditional I²C interface would.
Datasheet
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