82NM10 Datasheet, PDF (197/671 Pages) Intel Corporation – Intel® NM10 Family Express Chipset

Functional Description
5.20.1.1
The host controller supports 8 command protocols of the SMBus interface (see System
Management Bus (SMBus) Specification, Version 2.0): Quick Command, Send Byte,
Receive Byte, Write Byte/Word, Read Byte/Word, Process Call, Block Read/Write, Block
Write–Block Read Process Call, and Host Notify.
The SMBus host controller requires that the various data and command fields be setup
for the type of command to be sent. When software sets the START bit, the SMBus Host
controller performs the requested transaction, and interrupts the processor (or
generates an SMI#) when the transaction is completed. Once a START command has
been issued, the values of the “active registers” (Host Control, Host Command,
Transmit Slave Address, Data 0, Data 1) should not be changed or read until the
interrupt status bit (INTR) has been set (indicating the completion of the command).
Any register values needed for computation purposes should be saved prior to issuing
of a new command, as the SMBus host controller updates all registers while completing
the new command.
Using the SMB host controller to send commands to chipset’s SMB slave port is
supported. Chipset supports the System Management Bus (SMBus) Specification,
Version 2.0. Slave functionality, including the Host Notify protocol, is available on the
SMBus pins. The SMLink and SMBus signals should not be tied together externally.
Command Protocols
In all of the following commands, the Host Status Register (offset 00h) is used to
determine the progress of the command. While the command is in operation, the
HOST_BUSY bit is set. If the command completes successfully, the INTR bit will be set
in the Host Status Register. If the device does not respond with an acknowledge, and
the transaction times out, the DEV_ERR bit is set. If software sets the KILL bit in the
Host Control Register while the command is running, the transaction will stop and the
FAILED bit will be set.
Quick Command
When programmed for a Quick Command, the Transmit Slave Address Register is sent.
The PEC byte is not appended to the Quick Protocol. Software should force the PEC_EN
bit to 0 when performing the Quick Command. Software must force the I2C_EN bit to 0
when running this command. See section 5.5.1 of the System Management Bus
(SMBus) Specification, Version 2.0 for the format of the protocol.
Datasheet
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