Kontron COMe Starterkit Eval T2 - Manual (Page 61)

COM Express Interfaces
2.5.2. SDVO
SDVO was developed by the Intel ® Corporation to interface third party SDVO compliant
display controller devices that may have a variety of output formats, including DVI, LVDS,
HDMI and TV-Out. 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 dependent upon the active display
resolution and timing.
Note: As SDVO is not supported in future chipsets and graphic controllers it is not
recommended to use this interface in future designs.
2.5.2.1. Signal Definitions
The SDVO interface of the COM Express Module features its own dedicated I²C bus
(SDVO_I2C_CLK and SDVO_I2C_DAT). It is used to control the external SDVO devices
and to read out the display timing data from the connected display.
Type 6 Modules allow one SDVO port on DDI[1]. The DDI port needs to be configured to be
used as SDVO usually via the Module's BIOS.
On Type 2 Modules the pins for SDVO ports B and C are shared with the PEG port.
If the Type 2 Module supports SDVO, the Module graphics controller configures the PEG lines for
SDVO operation if it detects that COM Express signals SDVO_I2C_CLK and SDVO_I2C_DATA
are pulled high to 2.5V, and if the PEG_ENABLE# line is left floating. This combination leaves
the Module's internal graphics engine enabled but converts the output format to SDVO. The
SDVO_I2C_CLK and SDVO_I2C_DATA lines are pulled to 2.5V on an ADD2 card.
For a device “down” SDVO converter, the SDVO_I2C_CLK and SDVO_I2C_DATA lines have to
be pulled up to 2.5V on the Carrier Board and PEG_ENABLE# left open.
SDVO Port Configuration
The SDVO port and device configuration is fixed within the Intel ® Graphics Video BIOS
implementation of the COM Express Module. All COM Express Modules assume a I²C bus
address 0111 000x for SDVO devices connected to port B and an I²C bus address of 0111 001x
for SDVO devices connected to port C. Table 12 below lists the supported SDVO port
configurations.
Table 12: SDVO Port Configuration
SDVO Port B SDVO Port C
Device Type Selectable in BIOS Setup Program. Selectable in BIOS Setup Program.
I²C Address 0111 000x 0111 001x
I²C Bus SDVO I²C GPIO pins SDVO I²C GPIO pins
DDC Bus SDVO I²C GPIO pins SDVO I²C GPIO pins
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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