OR-tied signals | Seagate Ultra 320, Ultra 160 specification

I–

– SIGNAL

I+ Vs

+ SIGNAL		V–
		V–

V+

– TRANSCEIVER

Figure 3. Voltage and current definitions

Figure 4 defines the signaling sense of the voltages appearing on the – signal and + signal lines as follows:

a.The – signal terminal of the driver shall be negative with respect to the + signal terminal for an asserted state.

b.The – signal terminal of the driver shall be positive with respect to the + signal terminal for a negated state.

	LOGICAL 1	LOGICAL 0	LOGICAL 1
	(ASSERTED)	(NEGATED)	(ASSERTED)
VOLTAGE	(TRUE)	(FALSE)	(TRUE)
	+
	V	VCM=(V++V–)/2	VCM
BUS	–
BUS	V
DIFFERENTIAL			VN
	+		VBIAS
	–V		VBIAS
	–V		0V (OFF)
	–		0V (OFF)
	V		VA
			VA
		TIME

Figure 4. LVD Signaling sense

Note. For a description of VBIAS see Section 7.3.1 of ANSI specification (SPI-5), T10/1525D.

2.3OR-tied signals

The BSY, SEL, and RST signals shall be OR-tied. BSY and RST signals may be simultaneously driven true by several SCSI devices. No signals other than BSY, SEL, RST, DB(P_CRCA), and DB(P1) are simultaneously driven by two or more SCSI devices. DB(P_CRCA) and DB(P1) shall not be driven false during the ARBITRA- TION PHASE but may be driven false in other phases.

18	Parallel SCSI Interface Product Manual, Rev. A )

Image 32

Seagate Ultra 320, Ultra 160 manual OR-tied signals, Voltage and current definitions

Contents

Parallel Scsi Interface Page Parallel Scsi Interface Page Revision status summary sheet Revision Date Writer/Engineer Parallel Scsi Interface Product Manual, Rev. a Table of Contents Parallel Scsi Interface Product Manual, Rev. a Logical characteristics Wide transfer Message system specification SPI information units Miscellaneous Scsi bus characteristicsScsi commands Drive features List of Figures Xii Parallel Scsi Interface Product Manual, Rev. a How to use this interface manual Interface requirements Scope of Scsi standards General interface description Applicable standards Glossary Scsi client-server modelPage Page Page Page Page Page Keywords Message Name Hex Code Number Physical interface characteristicsSummary of Scsi messages Scsi bus Scsi IDs and associated Scsi bus arbitration priorities Priority Scsi bus signals overview Pcrc signal usage requirements Scsi target usage of Pcrca Signal states Signal valuesSE signals LVD signals OR-tied signals Voltage and current definitions Signal sources Signal sourcesData bit P cable Data bit a cable I/O DB15-8 Scsi bus phase DB7-0 Scsi bus timing Scsi bus control timing values in nanosecondsTiming Reference Type Value ns Unless Timing description Scsi bus data and information phase ST timing values Timing values for negotiated transfer rateNanoseconds unless otherwise noted Timing values for negotiated transfer rate in nanosecondsPage ATN transmit setup time Min Receive Scsi bus data and information phase DT timing values Interconnect and system margin Total transmitter error budget Receiver errorsFast-160 Fast-320 Comments ATN transmit setup time ATN receive setup timeCrosstalk time shift ISI of data Bus clear delay Bus free delayBus set delay Bus settle delay Flow control receive setup time Flow control transmit setup timePCRC receive setup time PCRC transmit setup time Data release delay Physical disconnection delayPower on to selection QAS arbitration delay Receive internal setup time Receive setup timeReceive internal hold time Receive negation period Reset delay Reset hold timeReset to selection Residual skew error System deskew delay Skew correction rangeStrobe offset tolerance System noise at launch Measurement points Clocking methods for data transfers LVD measurement points ST latching data vs. DT latching data Paced transfer on a Scsi bus DT synchronous transfer example Data transfer modes Asynchronous transfersSynchronous transfers Paced transfers ST Data phase parallel transfers DT Data phase parallel transfersData group transfers Information unit transfers Negotiation Negotiation algorithm When to negotiate Negotiable fieldsNegotiable fields and effects of successful negotiation Negotiation message pair Field name Field Name Message Numerically Responding message requirementsResponse shall be Transfer agreements Transfer period factor Transfer period factor relationshipsValue Description Message Transfer rate Synchronous 12.6 REQ/ACK offset Transfer width exponent Iureq Protocol optionsProtocol options bits Bus phases resulting from Iureq changes Sdtr negotiation PPR negotiation setting Iureq to onePPR negotiation setting Iureq to zero PPR negotiation keeping Iureq set to zero Wrflow RdstrmRTI Retain Training Information Pcompen Transfer Period Negotiable field combinationsTransfer Message restrictions Negotiation message sequences Parallel Scsi Interface Product Manual, Rev. a Unexpected and expected bus free phases Scsi bus phases overviewBUS Free phase Expected bus free phases Arbitration and QAS overview Normal Arbitration phase QAS phase overview QAS protocol Selection phase Selection overview Information unit transfers disabledInformation unit transfers enabled Selection using attention condition timeout procedure Physical reconnection Reselection phaseReselection phase overview Physical reconnection timeout procedure Scsi bus fairness Signal Phase Direction of transfer Comment Information transfer phasesInformation transfer phases ST synchronous data transfer Asynchronous transferSynchronous transfer DT synchronous transfer Information unit transferPage Data group data field transfer Page Page Page Paced transfer Paced transfer training pattern Start of section B DT Data in phase training patternStart of section a DT Data OUT phase training pattern Start of section C 3.2 P1 data valid/invalid state transitions Starting pacing transfers at end of training pattern Starting pacing transfers with no training pattern Ending pacing transfers Paced information unit transfer Deskewing Wide transfer Command phase Data phase Status phase Message phase Signal restrictions between phases Message in phase exception condition handlingMessage OUT phase Message OUT phase exception condition handling Scsi bus phase sequences Scsi bus phase sequences overview Hard reset or protocol error Reselection Selection Arbitration DT Data Message OUT ST data bus protection using parity Parity checking rules for Selection and Reselection phasesData bus protection Data bus protection overview Error detection capabilities Order of bytes in the CRC field General message protocols and formats Message formats Message format One-byte messagesTwo-byte messages Extended messages Link Control Messages Link Control message codes Message categoriesExtended Message Codes Key Disconnect IdentifyIdentify message format Bit Byte Ignore Wide Residue Ignore Wide Residue message formatIgnore field definition Invalid data bits Initiator Detected Error Linked Command CompleteMessage Parity Error Message Reject Modify Data Pointer message format Modify Bidirectional Data Pointer Modify Bidirectional Data Pointer message format No Operation Parallel Protocol Request Parallel Protocol Request message format Value 00h 01h-FEh FFh Description Timing values Use QAS for arbitration Use ST Data in and ST Data OUT phases to transfer dataValid protocol options bit combinations Parallel Protocol Request messages implied agreement Save Data Pointers Restore PointersQAS Request Synchronous Data Transfer Request Synchronous Data Transfer Request message format Sdtr messages implied agreements Task Complete Target initiated Sdtr negotiationInitiator initiated Sdtr negotiation Wide Data Transfer Request Wide Data Transfer Request message format Responding Scsi device Wdtr response Implied agreement Wdtr message implied agreementTarget initiated Wdtr negotiation Task attribute messages Task attribute message overview and codes ACA message format Task attribute message codesACA Auto Contingent Allegiance Head of Queue Ordered Task management messages Task management message codes Task management message codesAbort Task 0Eh Logical Unit Reset Target ResetAbort Task SET Clear ACA Miscellaneous Scsi bus characteristics Bus reset condition Hard reset Reset events Asynchronous condition recovery Active pointers Saved pointers Incorrect initiator connection Command processing considerations and exception conditionsAsynchronous event notification Unexpected Reselection phase SPI information units Information unit transfer logical operationsPage Parallel Scsi Interface Product Manual, Rev. a 115 116 Parallel Scsi Interface Product Manual, Rev. a Parallel Scsi Interface Product Manual, Rev. a 117 SPI command information unit SPI information units SPI command information unit Bit Byte Task Attribute Codes Description Task Management flags Codes Description SPI LQ information unit SPI LQ information unit Bit Byte Bidi Direction SPI LQ information unit type Codes Type DescriptionF0H FFh AllPage SPI data information unit Bit Byte SPI data information unitSPI data stream information unit SPI status data stream information unit Bit Byte Reserved Reserved for FCP SPI status information unitSPI status information unit Bit Byte SPI command information unit fields invalid Packetized Failures field Bit BytePacketized Failures code Codes Description Task management function not supportedPage 130 Parallel Scsi Interface Product Manual, Rev. a Reserved Command implementation requirementsCommand Descriptor Block CDB Page Fixed and variable length Command Descriptor Block formats Additional CDB Data if required Typical CDB for 12-byte commands Bit ByteTypical CDB for 16-byte commands Bit Byte Typical variable length CDB Bit Byte Operation Code 7Fh Additional CDB Length n-7Page Link b Control field Bit Byte LastNaca a Status Status precedence Command examples Single command example Disconnect example Disconnect example Timing examples Auto Contingent Allegiance or Contingent Allegiance Overlapped commands Clearing an Auto Contingent Allegiance condition Asynchronous Event Reporting Incorrect logical unit selectionSense data Autosense Unit Attention condition Target hard reset Logical unit resetQueued tasks formerly queued I/O processes Untagged task queuing Tagged task queuing Parameter rounding Programmable operating definition Incorrect initiator connection Default self-test S.M.A.R.T. systemSelf-test operations Short and extended self-tests Self-test modes Foreground modeBackground mode Exception commands for background self-tests Device type a Command Reference All device types Protection code Self-test mode summaryError detection for asynchronous information phases Covered signals Word Location Signal MeaningPage Protection code usage Error detection propertiesCode description Error handling Protection code transmissionEnabling protection code checking Disabling protection code checking Case 1-Power off during removal or insertion SPI-3 equivalent term SCSI-2 term SPI-3 to SCSI-2 terminology mappingSPI-3 to SCSI-2 terminology mapping Index Code value reserved Disconnect privilege 148 domain 5, 9 dormant Initiator 3, 6, 14, 131, 140 faulted Multidrop 7 multimode Page Scsi Page Wdtr 40 170 Parallel Scsi Interface Product Manual, Rev. a Page Seagate Technology LLC