MEC1404 Datasheet, PDF (202/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
into the internal 32-bit address space as indicated by the ACCESS_TYPE bits. This configuration option is done to
ensure that data the EC treats as 16-bit or 32-bit will be consistent in the Host, even though one byte of the data may
change between two or more 8-bit accesses by the Host.
In addition, there is an auto-increment function for the Embedded Memory Interface address register. When enabled,
the Host can read or write blocks of memory in the 32- bit internal address space by repeatedly accessing the Embedded
Memory Interface data register, without requiring Host updates to the Embedded Memory Interface address register.
Finally, the Application ID Register may be used by the host to provide an arbitration mechanism if more than one soft-
ware thread requires access through the EMI interface. See Section 12.8.4, "Embedded Memory Interface Usage," on
page 203 for more details.
12.8.1 EMBEDDED MEMORY MAP
Each Embedded Memory interface provides direct access for the Host into two windows in the EC 32-bit internal
address space. This mapping is shown in Figure , "":
FIGURE 12-3:
EMBEDDED MEMORY ADDRESSING
FFFF_FFFFh
32-bit internal address
space
Region_1_Read_Limit
Region_1_Write_Limit
Region_1_Base_Address
No Host Access
Host Read Only
Host Read/Write
No Host Access
Region_0_Read_Limit
Region_0_Write_Limit
Region_0_Base_Address
0000_0000h
Host Read Only
Host Read/Write
No Host Access
The Base addresses, the Read limits and the Write limits are defined by registers that are in the EC address space and
cannot be accessed by the Host. In each region, the Read limit need not be greater than the Write limit. The regions
can be contiguous or overlapping. For example, if the Region 0 Read limit is set to 0 and the Write limit is set to a positive
DS00001956D-page 202
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