FTLX3871DCCxx Product Specification
VIII. Digital Diagnostic Functions
Finisar FTLX3871DCCxx SFP+ transceivers support the 2-wire serial
communication protocol as defined in the SFP MSA1. It is very closely related to the
memory map defined in the GBIC standard, with the same electrical specifications.
The standard SFP serial ID provides access to identification information that
describes the transceiver’s capabilities, standard interfaces, manufacturer, and other
information.
Additionally, Finisar SFP+ transceivers provide a enhanced digital diagnostic
monitoring interface, which allows real-time access to device operating parameters such
as transceiver temperature, laser bias current, transmitted optical power, received optical
power and transceiver supply voltage. It also defines a sophisticated system of alarm and
warning flags, which alerts end-users when particular operating parameters are outside of
a factory set normal range.
The SFP MSA defines a 256-byte memory map that is accessible over a
2-wire serial interface at the 8 bit address 1010000X (A0h). The digital diagnostic
monitoring interface makes use of the 8 bit address 1010001X (A2h), so the originally
defined serial ID memory map remains unchanged. The interface is identical to, and is
thus fully backward compatible with both the GBIC Specification and the SFP Multi
Source Agreement. The complete interface is described in Finisar Application Note AN-
2030: “Digital Diagnostics Monitoring Interface for SFP Optical Transceivers” 7.
The operating and diagnostics information is monitored and reported by a Digital
Diagnostics Transceiver Controller (DDTC) inside the transceiver, which is accessed
through a 2-wire serial interface. When the serial protocol is activated, the serial clock
signal (SCL, Mod Def 1) is generated by the host. The positive edge clocks data into the
SFP transceiver into those segments of the E2PROM that are not write-protected. The
negative edge clocks data from the SFP transceiver. The serial data signal (SDA, Mod
Def 2) is bi-directional for serial data transfer. The host uses SDA in conjunction with
SCL to mark the start and end of serial protocol activation. The memories are organized
as a series of 8-bit data words that can be addressed individually or sequentially.
For more information, please see the SFP MSA documentation6 and Finisar
Application Note AN-2030.
Please note that evaluation board FDB-1027 is available with Finisar ModDEMO
software that allows simple to use communication over the 2-wire serial interface.
Finisar Corporation – September 2015
Rev. C1
Page 7
FINISAR [ FINISAR CORPORATION. ]
