ESM-2850

2.4.2.1.6 Miscellaneous Signals

 

Signal

 

Signal Description

 

I2C_CK

 

 

General purpose I2C port clock output

 

I2C_DAT

 

General purpose I2C port data I/O line

 

SPKR

 

Output for audio enunciator - the "speaker" in PC-AT systems

 

BIOS_DISABLE#

 

Module BIOS disable input. Pull low to disable module BIOS. Used to allow

 

 

off-module BIOS implementations.

 

 

 

 

 

 

 

 

 

 

KB_RST#

 

 

Input to module from (optional) external keyboard controller that can force a reset.

 

 

 

Pulled high on the module. This is a legacy artifact of the PC-AT.

 

 

 

 

 

 

 

 

Input to module from (optional) external keyboard controller that can be used to

 

KB_A20GATE

 

control the CPU A20 gate line. The A20GATE restricts the memory access to the

 

 

 

 

bottom megabyte and is a legacy artifact of the PC-AT. Pulled low on the module.

 

 

 

 

 

2.4.2.1.7 PCI Express Signals

Signal

Signal Description

 

 

PCIE_TX[0:2] +/- PCI Express Differential Transmit Pair 0-2

PCIE_RX[0:2] +/- PCI Express Differential Receive Pair 0-2

PCIE0_CK_REF+/-

Reference clock output for PCI Express lanes 0-7 and for PCI Express Graphics lanes 0-15

2.4.2.1.8 Power Signals

Signal

Signal Description

 

 

VCC_5V_SBY

Standby power input: +5.0V nominal. See Electrical Specifications for allowable input range. If VCC5_SBY is used, all available VCC_5V_SBY pins on the connector(s) must be used. Only used for standby and suspend functions. May be left unconnected if these functions are not used in the system design.

VCC_RTC

Real-time clock circuit-power input. Nominally +3.0V. See Electrical Specifications section for details.

30 ESM-2850 User’s Manual