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