MEC1404 Datasheet, PDF (204/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
nal address space, the Embedded Memory Interface can be used by the Host to download new program seg-
ments for the EC in the upper 32KB SRAM. The Read/Write window would be configured by the Host to point to
the beginning of the loadable program region, which could then be loaded by the Host.
• Data exchange. The Read/Write portion of the memory window can be used to contain a communication packet.
The Host, by default, “owns” the packet, and can write it at any time. When the Host wishes to communicate with
the EC, it sends the EC a command, through the Host-to-EC message facility, to read the packet and perform
some operations as a result. When it is completed processing the packet, the EC can inform the Host, either
through a message in the EC-to-Host channel or by triggering an event such as an SMI directly. If return results
are required, the EC can write the results into the Read/Write region, which the Host can read directly when it is
informed that the EC has completed processing. Depending on the command, the operations could entail update
of virtual registers in the 32-bit internal address space, reads of any register in the EC address space, or writes of
any register in the EC address space. Because there are two regions that are defined by the base registers, the
memory used for the communication packet does not have to be contiguous with a set of virtual registers.
Because there are two Embedded Memory Interface memory regions, the Embedded Memory Interface cannot be used
for more than two of these functions at a time. The Host can request that the EC switch from one function to another
through the use of the Host-to-EC mailbox register.
The Application ID Register is provided to help software applications track ownership of an Embedded Memory Inter-
face. An application can write the register with its Application ID, then immediately read it back. If the read value is not
the same as the value written, then another application has ownership of the interface.
Note:
The protocol used to pass commands back and forth through the Embedded Memory Interface Registers
Interface is left to the System designer. Microchip can provide an application example of working code in
which the host uses the Embedded Memory Interface registers to gain access to all of the EC registers.
12.9 Runtime Registers
The registers listed in the Runtime Register Summary table are for a single instance of the EMI. The addresses of each
register listed in this table are defined as a relative offset to the host “Base Address” defined in the Runtime Register
Base Address Table.
TABLE 12-2: RUNTIME REGISTER BASE ADDRESS TABLE
Block Instance
EMI
Instance
Number
0
Host
EC
LPC
Address Space
32-bit internal
address space
I/O
Base Address
000F_0000h
Programmed BAR
The Base Address indicates where the first register can be accessed in a particular address space for a block instance.
TABLE 12-3: RUNTIME REGISTER SUMMARY
Offset
00h
01h
Register Name (Mnemonic)
HOST-to-EC Mailbox Register
EC-to-HOST Mailbox Register
DS00001956D-page 204
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