System Support

4.6.2 GPIO Functions

PCH-DO Functions

The PCH-D0 provides various functions through the use of programmable general purpose input/output (GPIO) ports. These systems use GPIO ports and associate registers of the PCH for the following functions:

PCI interrupt request control

Chassis and board ID

Hood (cover) sensor and lock detect

Media card reader detect

S4 state indicator

USB port over-current detect

Flash security override

Serial port detect

REQn#/GNTn# sigal control

Password enable

Boot block enable

SIO Controller Functions

In addition to the serial and parallel port functions, the SIO controller provides the following specialized functions through GPIO ports:

Power/Hard drive LED control for indicating system events (refer to Table 4-8)

Hood lock/unlock controls the lock bar mechanism

Thermal shutdown control turns off the CPU when temperature reaches certain level

Processor present/speed detection detects if the processor has been removed. The occurrence of this event will, during the next boot sequence, initiate the speed selection routine for the processor.

Legacy/ACPI power button mode control uses the pulse signal from the system's power button and produces the PS On signal according to the mode (legacy or ACPI) selected. Refer to chapter 7 for more information regarding power management.

Technical Reference Guide

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