Finisar AN-2030 specifications Current Address Read

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AN-2030: Digital Diagnostic Monitoring Interface for Optical Transceivers

F i n i s a r

Acknowledge Polling: Once the internally-timed write has started and the DDTC inputs are disabled, acknowledge polling can be initiated. The process involves transmitting a start condition followed by the device address. The R/W bit signifies the type of operation that is desired. The read or write sequence will only be allowed to proceed if the internal write cycle has completed and the DDTC responds with a zero.

Read Operations: After receiving a matching address byte with the R/W bit set high, the

device goes into the read mode of operation. There are three read operations: current address read, random read and sequential address read, described as follows:

Current Address Read

The DDTC has an internal address register that contains the address used during the last read or write operation, incremented by one. This data is maintained as long as Vcc is valid. If the most recent address was the last byte in memory, then the register resets to the first address. This address stays va lid between operations as long as power is available.

Once the device address is clocked in and acknowledged by the DDTC with the R/W bit set to high, the current address data word is clocked out. The master does not respond with a zero, but does generate a stop condition afterwards.

Random Read

A random read requires a dummy byte write sequence to load in the data word address. Once the device and data address bytes are clocked in by the master, and acknowledged by the DDTC, the master must generate another start condition. The master now initiates a current address read by sending the device address with the read/write bit set high. The DDTC will acknowledge the device address and serially clocks out the data byte.

Sequential Address Read

Sequential reads are initiated by either a current address read or a random address read. After the master receives the first data byte, the master responds with an Acknowledge Bit. As long as the DDTC receives this acknowledge after a byte is read, the maste r may clock out additional data words from the DDTC. After reaching address FFh, it resets to address 00h.

The sequential read operation is terminated when the master initiates a stop condition. The master does not respond with a zero.

9/26/02 Revision D

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Contents Scope and Overview 35 2. Applicable DocumentsEnhanced Digital Diagnostic Interface Definition Overview Cal Constants Bytes Password Entry 8 bytesSpecific Data Field Descriptions Control Functions 8 bytesSerial ID Data Fields Address A0 DataName Bytes Description of Field Address Identifier values ConnectorIdentifier Extended IdentifierConnector values Description of connectorTransceiver Transceiver codesSpeed Reach Specifier bit Description 4a Sonet Reach SpecifiersEncoding Code Description of encoding mechanismLength 9μ BR, nominalLength 9μ-km Length 50μDwdm Channel Spacing Length CopperVendor name Vendor OUIVendor Rev Laser WavelengthDwdm Wavelength Fraction BR, max OptionsOption values 13 BR, minDiagnostic Monitoring Type Date CodeData Description of field Address N i s a r Enhanced Options 10 I/O Timing for Soft Control & Status Functions SFF-8472 Compliance11 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 Byte Bit Name Description 19 Password Addresses 2-Wire Address A2h20 User Eeprom 2-Wire Address A2h 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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