MEC1322 Datasheet, PDF (117/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
9.8.1 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 9-3, "Embedded Memory Addressing":
FIGURE 9-3:
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
number, then the Embedded Memory interface defines a region in the EC memory that the EC can read and write but
is write-only for the host. This might be useful for storage of security data, which the Host might wish to send to the EC
but should not be readable in the event a virus invades the Host.
Each window into the EC memory can be as large as 32k bytes in the 32-bit internal address space. See FIGURE 8-1:
Memory Layout on page 113 for host accessible regions.
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DS00001719D-page 117