Basic I2C Data Fields

In this section

This section describes some basic I²C data fields, which are all static.

NIM ID

A vital field is the NIM ID field, which is located as the very first byte. In the example in Example of Real I2C NIM Data the value is 0x03. This value indicates an SFP28/SFP+/SFP module. This byte must be read first, since the locations of many of the other fields depend on this.

Note: The locations mentioned in I2C NIM Data Interpretation are therefore only relevant to SFP28/SFP+/SFP modules.

Vendor name

The field at address 0x14, length 0x10 (16 bytes) gives the name of the vendor, which in the example is "SumitomoElectric".

DDM options

The DDM options field is located at address 0x5C, length 0x01 (1 byte). The value in the example is 0x68, or in binary notation, 01101000, where the values of the individual bits in the example have the following interpretation:

01101000
 ||||_____ Bit 3: Optical average power is indicated.
 |||______ Bit 4: External calibration is not used.
 ||_______ Bit 5: Internal calibration is used.
 |________ Bit 6: DDM is implemented.