Datasheet

Signal Descriptions
R
46 Datasheet
3.6.6 General Purpose Input/Output Signals
Table 18. GPIO Signal Descriptions
GPIO I/F Total Type Comments
RSTIN# I
CMOS
Reset: Primary Reset, Connected to PCIRST# of ICH4-M.
PWROK I
CMOS
Power OK: Indicates that power to GMCH is stable.
AGPBUSY# O
CMOS
AGPBUSY: Output of the GMCH IGD to the ICH4-M, which indicates that certain graphics
activity is taking place. It will indicate to the ACPI software not to enter the C3 state. It will also
cause a C3/C4 exit if C3/C4 was being entered, or was already entered when AGPBUSY# went
active. Not active when the IGD is in any ACPI state other than D0.
EXTTS_0 I
CMOS
External Thermal Sensor Input: This signal is an active low input to the GMCH and is used to
monitor the thermal condition around the system memory and is used for triggering a read
throttle. The GMCH can be optionally programmed to send a SERR, SCI, or SMI message to
the ICH4-M upon the triggering of this signal.
LCLKCTLA O
CMOS
SSC Chip Clock Control: Can be used to control an external clock chip with SSC control.
LCLKCTLB O
CMOS
SSC Chip Data Control: Can be used to control an external clock chip for SSC control.
PANELVDDEN O
CMOS
LVDS LCD Flat Panel Power Control: This signal is used enable power to the panel interface.
PANELBKLTEN O
CMOS
LVDS LCD Flat Panel Backlight Enable: This signal is used to enable the backlight inverter
(BLI).
PANELBKLTCTL O
CMOS
LVDS LCD Flat Panel Backlight Brightness Control: This signal is used as the Pulse Width
Modulated (PWM) control signal to control the backlight inverter.
DDCACLK I/O
CMOS
CRT DDC Clock: This signal is used as the DDC clock signal between the CRT monitor and
the GMCH.
DDCADATA I/O
CMOS
CRT DDC Data: This signal is used as the DDC data signal between the CRT monitor and the
GMCH.
DDCPCLK I/O
CMOS
Panel DDC Clock: This signal is used as the DDC clock signal between the LFP and the
GMCH.
DDCPDATA I/O
CMOS
Panel DDC Data: This signal is used as the DDC data signal between the LFP and the GMCH.
MI2CCLK I/O
DVO
DVO I2C Clock: This signal is used as the I2C_CLK for a digital display (i.e. TV-Out Encoder,
TMDS transmitter). This signal is tri-stated during a hard reset.
MI2CDATA I/O
DVO
DVO I2C Data: This signal is used as the I2C_DATA for a digital display (i.e. TV-Out Encoder,
TMDS transmitter). This signal is tri-stated during a hard reset.