MEC1322 Datasheet, PDF (128/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
10.0 ACPI EMBEDDED CONTROLLER INTERFACE (ACPI-ECI)
10.1 Introduction
The ACPI Embedded Controller Interface (ACPI-ECI) is a Host/EC Message Interface. The ACPI specification defines
the standard hardware and software communications interface between the OS and an embedded controller. This inter-
face allows the OS to support a standard driver that can directly communicate with the embedded controller, allowing
other drivers within the system to communicate with and use the EC resources; for example, Smart Battery and AML
code.
The ACPI Embedded Controller Interface (ACPI-ECI) provides a four byte full duplex data interface which is a superset
of the standard ACPI Embedded Controller Interface (ACPI-ECI) one byte data interface. The ACPI Embedded Control-
ler Interface (ACPI-ECI) defaults to the standard one byte interface.
The MEC1322 has two instances of the ACPI Embedded Controller Interface.
1. The EC host in Table 10-8 and Table 10-10 corresponds to the EC in the ACPI specification. This interface is
referred to elsewhere in this chapter as ACPI_EC.
2. The LPC host in Table 10-8 and Table 10-10 corresponds to the “System Host Interface to OS” in the ACPI
specification. This interface is referred to elsewhere in this chapter as ACPI_OS.
10.2 References
• Advanced Configuration and Power Interface Specification, Revision 4.0 June 16, 2009, Hewlett-Packard Corpo-
ration Intel Corporation Microsoft Corporation Phoenix Technologies Ltd. Toshiba Corporation
10.3 Terminology
TABLE 10-1:
ACPI_EC
ACPI_OS
TERMINOLOGY
Term
Definition
The EC host corresponding to the ACPI specification interface to the EC.
The LPC host corresponding to the ACPI specification interface to the “Sys-
tem Host Interface to OS”.
ACPI_OS terminology is not meant to distinguish the ACPI System Man-
agement from Operating System but merely the hardware path upstream
towards the CPU.
DS00001719D-page 128
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