Finisar AN-2030 Ddtc Electrical Interface Definition Overview, Wire Interface Operation

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AN-2030: Digital Diagnostic Monitoring Interface for Optical Transceivers

F i n i s a r

4.DDTC Electrical Interface Definition Overview

The Digital Diagnostics Transceiver Controller (DDTC) IC manages all system monitoring functions in the SFP transceiver module.

The DDTC is accessed through a 2-wire serial interface, utilizing the serial ID pins defined by the SFP MSA:

§SFP Pin 4 – MOD_DEF(2): Serial Data interface (SDA). The serial data pin is for serial data transfer to and from the DDTC. The pin is open drain and may be wire-ORed with other open drain or open collector interfaces.

§SFP Pin 5 – MOD_DEF(1): Serial Clock interface (SCL). The serial clock input is used to clock data into the DDTC on rising edges and clock data out on falling edges.

2-Wire Interface Operation

Clock and Data Transitions : The SDA pin must be pulled high with an external resistor or device. Data on the SDA pin may only change during SCL low time periods. Data changes during SCL high periods will indicate a start or stop conditions depending on the conditions discussed below. Refer to the timing diagram Figure 1 for further details.

Start Condition: A high-to-low transition of SDA with SCL high is a start condition that must precede any other command. Refer to the timing diagram Figure 1 for further details.

Stop Condition: A low-to-high transition of SDA with SCL high is a stop condition. After a read sequence, the stop command places the DDTC into a low-power Standby Mode. Refer to the timing diagram Figure 2 for further details.

Acknowledge Bit: All address bytes and data bytes are transmitted via a serial protocol. The DDTC pulls SDA low during the ninth clock pulse to acknowledge that it has received each word.

Standby Mode: The DDTC features a low-power mode that is automatically enabled after power-on, after a stop command, and after the completion of all internal operations.

9/26/02 Revision D

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Contents Scope and Overview 35 2. Applicable DocumentsEnhanced Digital Diagnostic Interface Definition Overview Password Entry 8 bytes Specific Data Field DescriptionsCal Constants Bytes Control Functions 8 bytesData Serial ID Data Fields Address A0Name Bytes Description of Field Address Connector IdentifierIdentifier values Extended IdentifierConnector values Description of connectorTransceiver Transceiver codes4a Sonet Reach Specifiers EncodingSpeed Reach Specifier bit Description Code Description of encoding mechanismBR, nominal Length 9μ-kmLength 9μ Length 50μLength Copper Vendor nameDwdm Channel Spacing Vendor OUILaser Wavelength Vendor RevDwdm Wavelength Fraction Options Option valuesBR, max 13 BR, minDate Code Diagnostic Monitoring TypeData Description of field Address N i s a r Enhanced Options SFF-8472 Compliance 10 I/O Timing for Soft Control & Status Functions11 SFF-8472 Compliance Diagnostics 12 Bit weights C for temperature reporting registers 13 Digital temperature format TemperatureN i s a r Alarm and Warning Thresholds 14 Alarm and Warning Thresholds 2-Wire Address A2hN i s a r 16a Unsigned fixed-point binary format for slopes 16b Format for offsets16c IEEE-754 Single-Precision Floating Point Number Format 16d Example of Floating Point RepresentationBit Name Description Alarm and Warning Flags LOS18 Alarm and Warning Flag Bits 2-Wire Address A2h 19 Password Addresses 2-Wire Address A2h 20 User Eeprom 2-Wire Address A2hByte Bit Name Description Address # Bytes Name DescriptionWire Interface Operation Ddtc Electrical Interface Definition OverviewN i s a r Current Address Read Detailed 2 -Wire Serial Port Operation N i s a r Wire Protocol Data Transfer Protocol DC Electrical Characteristics Vcc = 3.15V toFor More Information
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