What is Smart SFP Optical Module

What is Smart SFP Optical Module

The so-called intelligent SFP optical module refers to the SFP optical module with digital diagnosis function. In SFF-8472 MSA, the digital diagnostic function and details about SFF-8472 are specified. This specification specifies that parametric signals are detected and digitized on the circuit board on the north side of the module. Then provide the calibrated results or provide digitized measurement results and calibration parameters.

Introduction to SFP Optical Module:

This information is stored in standard memory results for reading via the dual-cable serial interface. In the protocol SFF-8472, the original SFP/GBIC address map at address A0h is preserved, and a 256-byte storage unit is added at address A2h. In addition to providing parameter detection information, this memory also defines alarm flags or alarm conditions, state mirroring of individual pins, limited digital control capabilities, and user-writable memory locations. Generally speaking, through the digital diagnosis function of the optical module, the relevant information and status of the optical module itself can be obtained.

Also, We provide detection methods and methods in the debugging, use and maintenance of the entire network of optical communication products; providing a performance detection method for the system, which can help system management predict the life of SFP optical modules; isolate system failures and verify in field installations module compatibility, etc. Based on the application of the intelligent SFP optical module, generally speaking, the two pins (PIN4 and PIN5; which are the data bus SDA and clock bus SCL in the I2C bus); of the SFP optical module mainly used to read the data in the optical module.

Its realized by storing the information in the chip which providing the relevant information that can read by the I2C bus mainly includes the type of the SFP optical module (STM-1/STM-4/STM-16, etc.), the current laser state (ON/OFF); and the module life prediction (mainly through Real-time detection of the working voltage and temperature inside the SFP optical module, as well as the bias current of the laser; etc. to roughly predict the life of the laser), fault location (in the fault location; Tx_power, Rx_power, Temp, Vcc, Tx-Vias Comprehensive analysis of the alarms and alarm installation status.

Compatibility verification:

The state variables Tx_Fault and Rx_Los in the memory image play an important role in the analysis of faults); compatibility verification (the new compatibility verification is to analyze whether the working environment of the module complies with the data code or whether Compatible with relevant standards; the performance of the module can only guaranteed in this compatible working environment) and other functions; and all these functions can directly or comprehensively read and stored in the EEPROM in the SFP optical module; registers are obtained and implemented. At the same time, it can also read and write the readable; and writable registers inside the chip according to the needs; which is beneficial to the debugging and maintenance of a single disk or a system.

According to the I2C bus communication method; we use the FPGA chip EP1C4F324C8 of ALTERA Company to carry out the programming of the I2C analog bus (using VHDL language; in order to save space, there is no detailed introduction to the realization idea). The basic idea is to transfer the bus in different states at different times through the state machine method according to the protocol of the I2C bus, and virtually obtain the interface in the form of the I2C bus. Figure 4 is the simulation (the simulation diagram shows part of the function of the I2C bus read and write function module.

How to use it?

It needs to communicate with the CPU through the FPGA when in use; so the communication port with the CPU and some control and feedback status information added. In In the simulation diagram, clk is the clock, addin, comindatin, and dout are the data address lines; rd is the read and write control; the execute control program starts to read and write the SFP optical module; ack_fault is the response indication signal; busy is to indicate whether the read and write completed; reset a global reset signal. The use of these status and feedback signals is mainly for the convenience of debugging and testing programs).

Through the FPGA module, its ports mapped and connected with PIN4 and 5 (respectively MOD1 and MOD2) provided by the SFP optical module; so that the pre-set registers in the relevant FPGA can be operated; and the SFP optical module The relevant registers can read and written; thus realizing the intelligence of the SFP optical module; which provides convenience for the debugging, control of the equipment and the maintenance of the system network.


In the development of today’s optical communication; the requirements for intelligence are getting higher and higher; and the requirements for the use of optical modules are also getting higher and higher. The emergence of intelligent SFP optical modules is in line with this trend, so its widely used. The technical strength and R&D capabilities of transceiver manufacturers have also become very important.

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