Digital Diagnostic Monitoring Interface on Avago Fiber-Optic Transceivers: Applications and Implementation -App Note

The present application note describes Avago's transceiver implementation of an enhanced digital diagnostic interface, compliant to the "Digital Diagnostic Monitoring Interface for Optical Transceivers" SFF-8472 Multi-Source Agreement (MSA.) The document also outlines the range of application options, both hardware and software, available to the host system for exploiting the digital diagnostic features of the transceiver. The enhanced digital interface allows real-time access to device operating parameters, and includes optional digital features such as soft control and monitoring of SFP I/O signals. In addition, it fully incorporates the functionality needed to implement digital alarms and warnings, as defined by the SFF-8472 MSA. With the digital diagnostic monitoring interface, the user has capability of performing component monitoring, fault isolation and failure prediction functions on their transceiver based applications. As stated in the SFF-8472 MSA, the diagnostic monitoring interface (DMI) is an extension of the serial ID interface defined in the GBIC specification, as well as the SFP MSA. Both specifications define a 256- byte memory map in EEPROM that is accessible over a two-wire serial interface at the 8-bit address 1010000X (0xA0). The digital diagnostic monitoring interface makes use of the 8-bit address 1010001X (0xA2), so the originally defined serial ID memory map remains unchanged. The interface is backward compatible with both the GBIC specification and the SFP MSA.