Data Sheet

System Manageability—Ethernet Controller I210
649
10.5.4 SMBus Transactions
This section gives a brief overview of the SMBus protocol. Following is an example for a format of a
typical SMBus transaction.
The top row of the table identifies the bit length of the field in a decimal bit count. The middle row
(bordered) identifies the name of the fields used in the transaction. The last row appears only with
some transactions, and lists the value expected for the corresponding field. This value can be either
hexadecimal or binary.
The SMBus controller is a master for some transactions and a slave for others. The differences are
identified in this document.
Shorthand field names are listed in Table 10-8 and are fully defined in the SMBus specification.
10.5.4.1 SMBus Addressing
SMBus addresses (enabled from the Flash) can be re-assigned using the SMBus ARP protocol.
In addition to the SMBus address values, all parameters of the SMBus (SMBus channel selection,
address mode, and address enable) can be set only through Flash configuration. Note that the Flash is
read at the I210’s power up and resets.
All SMBus addresses should be in Network Byte Order (NBO); MSB first.
28+ S + D 4 Sender IP Address Programmed from Flash or MC
32 +S + D 6 Target HW Address ARP Request Sender HW Address
38 +S + D 4 Target IP Address ARP Request Sender IP Address
17 1181811
S Slave Address Wr A Command A PEC A P
1100 001 0 0 0000 0010 0 [Data Dependent] 0
Table 10-8. Shorthand Field Names
Field Name Definition
S SMBus START Symbol
PSMBus STOP Symbol
PEC Packet Error Code
A ACK (Acknowledge)
NNACK (Not Acknowledge)
Rd Read Operation (Read Value = 1b)
Wr Write Operation (Write Value = 0b)
Table 10-7. ARP Response Packet (Continued)
Offset
(Continued
# of
bytes
Field Value