Intel® 500 Series Chipset Family On-Package PCH Datasheet Volume 1

Datasheet

ID 631119
Date 13/07/2021 00:00:00
Public Content
Document Table of Contents

Functional Description

GPIO Serial Expander (GSX) uses serial-to-parallel or parallel-to-serial shift register discrete components to increase number of the GPIO pins for system use. It expands in the multiples of 8 for input or output with 8 pins per expander. The total shift register component supported is 8, which can expand the GPIOs by up to 64.

The below figure illustrates a GPIO expansion topology with 16 GPIs and 16 GPOs.

Example of GSX Topology

Coming out of system reset, GSX is in reset with the following behaviors:

  • GSXSRESET# asserted by default. The signal remains asserted until BIOS/SW initialization has been completed and CxCMD.ST set to 1.

  • GSXSLOAD is 0 by default until CxCMD.ST is set to 1.
  • GSXSCLK is not toggling until CxCMD.ST is set to 1.