82598EB Datasheet, PDF (431/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - SMBus Transactions
• AR (Address Resolved): This flag is set when 82598EB SMBus address is resolved (SMBus address
was assigned by the SMBus ARP process).
Note: These flags are internal 82598EB flags and are not exposed to external SMBus devices.
Since 82598EB is a Persistent SMBus Address (PSA) device, the AV flag is always set, while the AR flag
is cleared after power up until the SMBus ARP process completes. Since AV is always set, 82598EB
always has a valid SMBus address.
When the SMBus master needs to start an SMBus ARP process, it resets (in terms of ARP functionality)
all devices on the SMBus by issuing either Prepare to ARP or Reset Device commands. When 82598EB
accepts one of these commands, it clears its AR flag (if set from previous SMBus ARP process), but not
its AV flag (The current SMBus address remains valid until the end of the SMBus ARP process).
Clearing the AR flag means that 82598EB responds to the following SMBus ARP transactions that are
issued by the master. The SMBus master issues a Get UDID command (general or directed) to identify
the devices on the SMBus. The 82598EB always responds to the Directed command and to the General
command only if its AR flag is not set. After the Get UDID, The master assigns SMBus address by
issuing an Assign Address command. 82598EB checks whether the UDID matches its own UDID and if it
matches, it switches its SMBus address to the address assigned by the command (byte 17). After
accepting the Assign Address command, the AR flag is set and from this point (as long as the AR flag is
set), the 82598EB does not respond to the Get UDID General command. Note that all other commands
are processed even if the AR flag is set. The 82598EB stores the SMBus address that was assigned in
the SMBus ARP process in the EEPROM, so at the next power up, it returns to its assigned SMBus
address.
SMBus ARP Flow shows the 82598EB SMBus ARP flow.
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