MEC1404 Datasheet, PDF (225/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
14.0 ACPI EMBEDDED CONTROLLER INTERFACE (ACPI-ECI)
14.1 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 MEC140X/1X has two instances of the ACPI Embedded Controller Interface.
1. The EC host in TABLE 14-4: and TABLE 14-6: 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 14-4: and TABLE 14-6: corresponds to the “System Host Interface to OS” in the ACPI
specification. This interface is referred to elsewhere in this chapter as ACPI_OS.
14.2 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
14.3 Terminology
TABLE 14-1: TERMINOLOGY
ACPI_EC
ACPI_OS
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
“System 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.
14.4 Interface
This block is designed to be accessed externally and internally via a register interface.
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