Data Sheet

9

Figure 7. Interface Design with Bezel (mm)

Management Interface

Digital diagnostics is an available interface on all Bookham XFP

transceivers. A 2-wire Serial ID interface provides user access

to vendor/module identification, customer specific data, link

type, static and dynamic monitor hooks, and a check code

mechanism for verifying accuracy in the data registers. These

“static” and “dynamic” diagnostics allow users to remotely and

accurately identify modules and their vendors, make

determinations about its compatibility with the system, verify

which “Enhanced” diagnostics are supported, and monitor

module parameters to determine the module and link

condition.

The module’s “Enhanced Digital Diagnostics” features provide

real-time monitoring of receiver input power, transmitter power,

internal module temperature, laser bias current, and supply

voltage parameters.

The 2-wire serial ID interface was originally defined by the GBIC

(GigaBit Interface Converter) and SFF-8472 specifications. The

XFP MSA (Multi-Source Agreement) document further defined

the diagnostics features and introduced a new memory map of

the diagnostic information. This interface is a 2-wire interface

that allows read-only access to separate memory locations.

The memory location starting at A0h (data address 0 ~ 127)

contains the Digital Diagnostic Functions.

The normal 256 Byte I2C address space is divided into lower

and upper blocks of 128 Bytes. The lower block of 128 Bytes

is always directly available and is used for the diagnostics and

control functions that must be accessed repeatedly.

One exception to this is that the standard module identifier

Byte defined in the GBIC and SFP is located in Byte 0 of the

memory map (in the diagnostics space) to allow software

developed for multiple module types to have a common

branching decision point. This Byte is repeated in the Serial ID

section so that it also appears in the expected relationship to

other serial ID bits.

Multiple blocks of memories are available in the upper 128

Bytes of the address space. These are individually addressed

through a table select Byte which the user enters into a

location in the lower address space. Thus, there is a total

available address space of 128 * 256 = 32Kbytes in this upper

memory space. The upper address space tables are used for

less frequently accessed functions such as serial ID, user

writable EEPROM, reserved EEPROM and diagnostics and

control spaces for future standards definition, as well as ample

space for vendor specific functions. These are allocated as

follows:

• Table 01h: Serial ID EEPROM

• Table 02h: User writable EEPROM

The details of each memory space are found in the XFP MSA

specification Chapter 5.

Reference Documents:

1. XFP MSA revision 4.0 found at www.xfpmsa.org;

April 13, 2004