User Guide

8081
8081
N/B Maintenance
N/B Maintenance
81
5.2 Intel 82855GM Graphics and Memory Controller Hub (GMCH)
Dedicated LVDS LCD Flat Panel Interface Signals (Continued)
Signal Name Type Voltage Description
ICLKBP
O
LVDS
1.25 V±
225 mV
Channel B differential clock pair output (true): 245-800 MHz.
ICLKBM
O
LVDS
1.25 V±
225 mV
Channel B differential clock pair output (compliment): 245-
800 MHz.
IYBP[3:0]
O
LVDS
1.25 V±
225 mV
Channel B differential data pair 3:0 output (true): 245-800
MHz.
IYBM[3:0]
O
LVDS
1.25 V±
225 mV
Channel B differential data pair 3:0 output (compliment):
245-800 MHz.
Digital Video Output B (DVOB) Port Signals
Signal Name Type Description
DVOBD[11:0]
O
DVO
DVOB Data: This data bus is used to drive 12-bit RGB data on
each edge of the differential clock signals, DVOBCLK and
DVOBCLK#. This provides 24-bits of data per clock period. In dual
channel mode, this provides the lower 12-bits of pixel data.
DVOBD[11:0] should be left as left as NC (“Not Connected”) if not
used.
DVOBHSYNC
O
DVO
Horizontal Sync: HSYNC signal for the DVOB interface.
DVOBHSYNC should be left as left as NC (“Not Connected”) if
not used.
DVOBVSYNC
O
DVO
Vertical Sync: VSYNC signal for the DVOB interface.
DVOBVSYNC should be left as left as NC (“Not Connected”) if the
signal is NOT used when using internal graphics device.
DVOBBLANK#
O
DVO
Flicker Blank or Border Period Indication: DVOBBLANK# is a
programmable output pin driven by the GMCH.
When programmed as a blank period indication, this pin indicates
active pixels excluding the border. When programmed as a border
period indication, this pin indicates active pixel including the border
pixels.
DVOBBLANK# should be left as left as NC (“Not Connected”) if
not used.
DVOBFLDSTL
I
DVO
TV Field and Flat Panel Stall Signal. This input can be
programmed to be either a TV Field input from the TV encoder or
Stall input from the flat panel.
DVOB TV Field Signal: When used as a Field input, it synchronizes
the overlay field with the TV encoder field when the overlay is
displaying an interleaved source.
DVOB Flat Panel Stall Signal: When used as the Stall input, it
indicates that the pixel pipeline should stall one horizontal line. The
signal changes during horizontal blanking. The panel fitting logic,
when expanding the image vertically, uses this.
DVOBFLDSTL needs to be pulled down if not used.
Digital Video Output C (DVOC) Port Signals
Signal Name Type Description
DVOCD[11:0]
O
DVO
DVOC Data: This data bus is used to drive 12-bit RGB data on
each edge of the differential clock signals, DVOCCLK and
DVOCCLK#. This provides 24-bits of data per clock period. In dual
channel mode, this provides the upper 12-bits of pixel data.
DVOCD[11:0] should be left as left as NC (“Not Connected”) if not
used.
DVOCHSYNC
O
DVO
Horizontal Sync: HSYNC signal for the DVOC interface.
DVOCHSYNC should be left as left as NC (“Not Connected”) if
not used.
DVOCVSYNC
O
DVO
Vertical Sync: VSYNC signal for the DVOC interface.
DVOCVSYNC should be left as left as NC (“Not Connected”) if the
signal is NOT used when using internal graphics device.
DVOCBLANK#
O
DVO
Flicker Blank or Border Period Indication: DVOCBLANK# is a
programmable output pin driven by the GMCH.
When programmed as a blank period indication, this pin indicates
active pixels excluding the border. When programmed as a border
period indication, this pin indicates active pixel including the border
pixels.
DVOCBLANK# should be left as left as NC (“Not Connected”) if
not used.
DVOCFLDSTL
I
DVO
TV Field and Flat Panel Stall Signal. This input can be
programmed to be either a TV Field input from the TV encoder or
Stall input from the flat panel.
DVOC TV Field Signal: When used as a Field input, it synchronizes
the overlay field with the TV encoder field when the overlay is
displaying an interleaved source.
DVOC Flat Panel Stall Signal: When used as the Stall input, it
indicates that the pixel pipeline should stall one horizontal line. The
signal changes during horizontal blanking. The panel fitting logic,
when expanding the image vertically, uses this.
DVOCFLDSTL needs to be pulled down if not used.
DVOB and DVOC Port Common Signals
Signal Name Type Description
DVOBCINTR#
I
DVO
DVOBC Interrupt: This pin is used to signal an interrupt, typically
used to indicate a hot plug or unplug of a digital display.
ADDID[7:0]
I
DVO
ADDID[7:0]: These pins are used to communicate to the Video
BIOS when an external device is interfaced to the DVO port.
Note: Bit[7] needs to be strapped low when an on-board DVO
device is present. The other pins should be left as NC.
DVODETECT
I
DVO
DVODETECT: This strapping signal indicates to the GMCH
whether a DVO device is present or not. When a DVO device is
connected, then DVODETECT = 0.