Functional Description
Data Link Layer
The middle layer in the PCI Express stack, the Data Link Layer, serves as an
intermediate stage between the Transaction Layer and the Physical Layer.
Responsibilities of Data Link Layer include link management, error detection, and
error correction.
Physical Layer
The Physical Layer includes all circuitry for interface operation, including driver and
input buffers, parallel-to-serial and serial-to-parallel conversion, PLL(s), and
impedance matching circuitry.
10.3.2
Intel® Serial Digital Video Output (SDVO)
The SDVO description is located here because it is multiplexed onto the PCI Express
x16 port pins. The Intel® SDVO Port is the second generation of digital video output
from compliant Intel® GMCHs. The electrical interface is based on the PCI Express
interface, though the protocol and timings are completely unique. Whereas 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.
10.3.2.1
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 utilizes an external SDVO device to
translate from SDVO protocol and timings to the desired display format and timings.
The Internal Graphics Controller 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/Media Expansion card is designed to fit in a x16 PCI Express connector. The
ADD2/Media Expansion card can support one or two devices. If a single channel SDVO
device is utilized, 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 or
Dual Simultaneous Standard modes. The Media Expansion card adds Video in
capabilities.
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.
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Datasheet
INTEL [ INTEL ]
