Data Sheet

Ethernet Controller I210 — Programming Interface
484
8.17.7 Link Partner Ability Next Page - PCS_LPABNP (0x4224; RO)
8.17.8 SFP I
2
C Command- I2CCMD (0x1028; R/W)
This register is used by software or firmware to read or write to the configuration registers in an SFP
module when either the CTRL_EXT.I2C Enabled or the CTRL_EXT.I2C over SDP Enabled bit is set to 1b.
Prior to write accessing this register, the I
2
C semaphore ownership must be taken, and released at the
end of the access sequence.
Note: According to the SFP specification, only reads are allowed from this interface; however, SFP
vendors also provide a writable register through this interface (for example, PHY registers).
As a result, write capability is also supported.
Field Bit(s) Initial Value Description
CODE 10:0 -
Message/Unformatted Code Field.
The Message field is an 11-bit wide field that encodes 2048 possible messages. The
Unformatted Code field is an 11-bit wide field that might contain an arbitrary value.
TOGGLE 11 -
Toggle.
This bit is used to ensure synchronization with the link partner during next page
exchange. This bit always takes the opposite value of the Toggle bit in the previously
exchanged Link Code word. The initial value of the Toggle bit in the first next page
transmitted is the inverse of bit 11 in the base Link Code word and, therefore, can
assume a value of 0b or 1b. The Toggle bit is set as follows:
0b = Previous value of the transmitted Link Code word when 1b.
1b = Previous value of the transmitted Link Code word when 0b.
ACK2 12 -
Acknowledge 2.
Used to indicate that a device has successfully received its Link Partners' Link Code
word.
MSGPG 13 -
Message Page.
This bit is used to differentiate a message page from an unformatted page. The
encoding is:
0b = Unformatted page.
1b = Message page.
ACK 14 -
Acknowledge.
The link partner has acknowledged receiving a next page.
NXTPG 15 -
Next Page.
Used to indicate whether or not this is the last next page to be transmitted. The
encoding is:
0b = Last page.
1b = Additional Next Pages follow.
Reserved 31:16 -
Reserved.
Write 0x0, ignore on read.