MEC1404 Datasheet, PDF (238/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
14.12.7 OS BYTE CONTROL REGISTER
This register is aliased to the EC Byte Control Register on page 243. No behavioral differences occur due to address
aliasing.
Offset ⁰⁵
Bits
Description
Type
7:1 Reserved
R
0 FOUR_BYTE_ACCESS
R
When this bit is set to ‘1’, the ACPI Embedded Controller Interface
(ACPI-ECI) accesses four bytes through the ACPI-OS DATA
BYTES[3:0].
When this bit is cleared to ‘0’, the ACPI Embedded Controller Inter-
face (ACPI-ECI) accesses one byte through the ACPI OS Data
Register Byte 0 Register. The corresponds to Legacy Mode
described in Section 14.10, "Description," on page 227.
Note 1: This bit effects the behavior of the IBF & OBF bits in the
OS STATUS OS Register.
2: See ACPI-OS DATA BYTES[3:0] on page 232, OS2EC
DATA BYTES[3:0] on page 239, and EC2OS DATA
BYTES[3:0] on page 241 for detailed description of
access rules.
Default
-
0b
Reset
Event
-
nSYSR
ST
Note:
The ACPI_OS access Base Address Register (BAR) should be configured to match the access width
selected by the Four Byte Access bit in the OS Byte Control Register. This BAR in not described in this
chapter.
14.13 EC-Only Registers
The registers listed in the EC-Only Register Summary table are for four instances of the ACPI Embedded Controller
Interface (ACPI-ECI). The addresses of each register listed in this table are defined as a relative offset to the host
“Base Address” defined in the EC-Only Register Base Address Table.
TABLE 14-6: EC-ONLY REGISTER BASE ADDRESS TABLE
Block Instance
ACPI-EC
ACPI-EC
ACPI-EC
ACPI-EC
Instance
Number
0
1
2
3
Host
EC
EC
EC
EC
Address Space
32-bit internal
address space
32-bit internal
address space
32-bit internal
address space
32-bit internal
address space
Base Address
000F_0C00h
000F_1000h
000F_2800h
000F_2C00h
The Base Address indicates where the first register can be accessed in a particular address space for a block instance.
DS00001956D-page 238
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