Guide

Integrated Graphics Display Port
R
142 Intel
®
852GM Chipset Platform Design Guide
Table 56. GMBUS Pair Mapping and Options
Pair # Signal Name Buffer
Type
Description Notes
DDCADATA 0
DDCACLK
3.3 V DDC for Analog monitor (CRT)
connection.
This cannot be shared with
other DDC or I2C pairs due to
legacy monitor issues.
LCLKCTRLA
1
LCLKCTRLB
3.3 V For control of SSC clock generator
devices down on motherboard.
If SSC is not supported then
can be used for DVOC
GMBUS.
DDCPDATA
2
DDCPCLK
3.3 V DDC for Digital Display connection via
the integrated LVDS display port for
support for EDID panel.
If EDID panels are not
supported. Can optionally use
as GMBUS for DVOC.
MDVIDATA
3
MDVICLK
1.5 V GMBUS control of DVI devices (TMDS
or TV encoder)
Can optionally use as
GMBUS for DVOC.
MI2CDATA
4
MI2CCLK
1.5 V GMBUS control of DVI devices (TMDS
or TV encoder)
Can optionally use as
GMBUS for DVOC.
MDDCDATA
5
MDDCCLK
1.5 V DDC for Digital Display connection via
TMDS device
Can optionally use as
GMBUS for DVOC.
NOTE: All GMBUS pairs can be optionally programmed to support any interface and is programmed through the
BMP utility.
If any of GMBUS pairs (expect DDCADATA/DDCCLK for CRT) are not used, 2.2 k – 100 kΩ pull-up
(or pull-ups with the appropriate value derived from simulating the signal), resistors are required except
for LCLKCTRLA/LCLKCTRLB GMBUS pair. LCLKCTRLA/LCLKCTRLB are used as bootup
straps, please refer to Chapter 13 for details on strapping option. This will prevent the DVO interface
from confusing noise on these lines for false cycles.
8.4.1. Leaving the DVO Port Unconnected
If the motherboard does not implement any of the possible video devices with the DVO port, please
follow the guidelines recommended on the motherboard. DVO Output signals may be left unconnected
if they are not used.
Pull-down resistors are required for the following signals if not used:
• DVOCFLDSTL
• DVOBCCLKINT
Pull-up resistors are required for the following signals if not used:
• DVOBCINTR#
8.5. Miscellaneous Input Signals and Voltage Reference
• ADDID[7]: Pulldown to ground with a 1 kΩ resistor when using the DVOC port. This is a vBIOS
strapping option to load the TPV AIM module for DVOC port. Pulldown not required DVOC is not
enabled.
• ADDID[6:0]: Leave unconnected (NC).