System Management Bus (SMBus) Specification, version 2.

System Management Bus (SMBus) Specification Version 2.0
Appendixes at the end of this document contain additional information and guides to implementation that
the reader may find useful.
1.5. Supporting documents
This specification assumes that the reader is familiar with or has access to the following documents:
• The I²C-bus and how to use it, Philips Semiconductors document #98-8080-575-01.
• ACPI Specification, Version 1.0b, Intel Corporation, Microsoft Corporation, Toshiba Corp., February
2, 1999 (http://www.teleport.com/~acpi)
• PCI Local Bus Specification, revision 2.2, December 18, 1998, (http://www.pcisig.com)
• SMBus Control Method Interface Specification, Version 1.0, Smart Battery System Implementers
Forum, December 1999
1.6. Definitions of terms
The following terms are defined with respect to this specification and may have other meanings in other
contexts. Some of these terms are used throughout the specification while others have meaning only within
limited portions. They are defined here so that the reader may be able to find their definitions in one place.
Address Resolution Protocol
Address Resolved flag (AR)
Address Valid flag (AV)
ARP
SMBus ARP Enumerator
ARP Master
Assigned Slave Address
Bus Master
Bus Slave
Fixed Slave Address
A protocol by which SMBus devices with assignable addresses on the
bus are enumerated and assigned non-conflicting slave addresses.
A flag bit or state internal to a device that indicates whether or not the
device’s slave address has been resolved by the ARP Master.
A flag bit or state internal to a device that indicates whether or not the
device’s slave address is valid. This bit must be non-volatile for devices
that support the Persistent Slave Address.
Address Resolution Protocol
An SMBus master that uses a subset of the ARP for the purpose of
discovering ARP-capable slave devices and their assigned slave
addresses.
The SMBus master (hardware, software or a combination) responsible
for executing the ARP and assigning addresses to ARP-capable slave
devices. The SMBus Host will usually be the ARP Master but under
some circumstances another SMBus master may assume the role. There
is only one active ARP Master at any time.
The address assigned to a slave device by the ARP Master. This address
is then used for accesses to the device’s core function. Legal values are
in the range 0010 000 to 1111 110 with some exceptions (associated
with reserved addresses and those consumed by Fixed Slave Address
devices).
Any device that initiates SMBus transactions and drives the clock.
Target of an SMBus transaction which is driven by some master.
A slave address that cannot be changed. Non-ARP-capable SMBus
devices fall into this category. The ARP Master must not assign a used
SBS Implementers Forum 6