Backoff, Dcr, Algorithm | Kawasaki 80C51, KS152JB, 80C152 guide

KS152JB Universal Communications Controller Technical Specifications

If a transmitting 8XC152 detects a collision during the preamble/BOF part of the frame that it is trying to transmit, it will complete the preamble/BOF and then begin the jam signal in the ﬁrst bit time after BOF. If the collision is detected later in the frame., the jam signal will begin in the next bit time after the collision was detected.

The jam signal lasts for the same number of bit times as the selected CRC length-either 16- or 32- bit times.

The 8XC152 provides two types of jam signals that can be selected by user software. If the node is DC-coupled to the network, the DC jam can be selected. In this case the GTXD pin is pulled to a logic 0 for the duration of the jam. If the node is AC-coupled to the network, then AC jam must be selected. In this case the GSC takes the CRC it has calculated thus far in the transmission, inverts each bit, and transmits the inverted CRC.The selection of DC or AC jam is made by setting or clearing the DCJ bit, which resides in the SFR named MYSLOT.

When the jam signal is completed, the 8XC152 goes into an idle state. Presumably, other stations on the network are also generating their own jam signals, after which they too go into an idle state. When the 8XC152 detects the idle state at its own GRXD pin, the backoff sequence begins.

Backoff

There are three software selectable collision resolution algorithms in the 8XC152. The selection is made by writing values to 3 bits:

			Table 12:

DCR	M1	M0	Algorithm

0	0	0	Normal Random
0	1	1	Alternate Random
1	1	1	Deterministic

M1 and M0 reside in GMOD, and DCR is in MYSLOT.

In the Normal Random algorithm, the GSC backs off for a random number of slot times and then decides whether to restart the transmission. The backoff time begins as soon as a line idle condi- tion is detected.

The Alternate Random algorithm is the same as the Normal Random except the backoff time doesn’t start until an IFS has transpired.

In the Deterministic algorithm, the GSC backs off to await its pre-determined turn.

Kawasaki LSI USA, Inc.

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Ver. 0.9 KS152JB2

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Kawasaki 80C51, KS152JB, 80C152 technical specifications Backoff, Dcr, Algorithm

Contents

Introduction Technical Specifications Pin Description PIN DescriptionName Description Port Pin Name Alternate Function RST XTAL1XTAL2 ALE PsenEben Epsen Special function Registers SFR map for the cpu Reset Timing Reset Values of the SFRs Configurations SconSbuf Indeterminate Tmod Pcon Port 0 I/O Pad Port 2 I/O Pad Port bit I/O Pads Ports 4,5 Program Psen EpsenComments Fetch via TIMER/COUNTERS Tmod Timer/Counter Mode Control Register Tcon Timer/Counter Control Register Mode Timer/Counter in Mode Interrupts Timer/Counter 0 in ModeIE Interrupt Enable Register Priority Level Structure Egste EDMA1 Egstv EDMA0 Egsre Egsrv Pgste PDMA1 Pgstv PDMA0 Pgsre Pgsrv PX0 EX0Pgsrv Egsrv 2BH PDMA1 EDMA1PT1 ET1 1BH Kawasaki LSI USA, Inc Ver .9 KS152JB2 ALE Psen Power Down and IdleStatus of the External Pins during Idle and Power Down Pcon Power Control Register Smod IDL Local Serial Channel Local Serial Port Mode Controller Serial Port Mode Mode Load Sbuf Baud Rates MHZ Timer 1 generated commonly used Baud ratesSmod Reti SINGLE-STEP OperationJNB Kawasaki LSI USA Inc Global Serial Channel Introduction 11/IDLE CRC None DC JAM CRC Csma Sdlc 11/IDLE External clock Internal clock Control cpu Control dma Raw Receive Raw Transmit Preamble BOF Address Info CRC EOF CSMA/CD OverviewCSMA/CD Frame Format Kawasaki LSI USA, Inc Ver .9 KS152JB2 23 24 Interframe Space CSMA/CD Data Encoding Manchester Encoding BIT TimeCollision Detection Jitter Tolerance Unexpected 1-to-0 Transition Narrow PulsesMissing 0-to-1 Transition Resolution of Collisions GSC InactiveResponse to a Detected Collision What the GSC was doing Tfifo Algorithm BackoffDCR BKOFF= Myslot Random BackoffPrbs Tcdcnt Load Bkoff Slot Clock Myslot Deterministic Backoff Hardware Based Acknowledge Kawasaki LSI USA, Inc Ver .9 KS152JB2 Sdlc Frame Format BOF Address Control Info CRC EOF Kawasaki LSI USA, Inc Ver .9 KS152JB2 BIT STUFFING/STRIPPING Data EncodingNrzi BIT Time Acknowledgement Sending Abort CharacterLine Idle PRIMARY/SECONDARY Stations Point-to-point NetworkMulti-Drop Network Ring Network Using a Preamble in Sdlc HDLC/SDLC ComparisonSdlc Hdlc User Deﬁned Protocols Line Discipline Planning for Network Changes and Expansions DMA Servicing of GSC Channels Kawasaki LSI USA, Inc Ver .9 KS152JB2 Baud Rate Initialization Test Modes External Driver Interface Jitter Receive Local Value Manchester Encoding BIT Time Receive Sampling Rate ReceivedBIT Time Received Transmit Waveforms Receiver Clock Recovery CSMA/CD Clock Recovery Determining Receiver Errors External ClockingRcbat Crce Addressing Determining Line Discipline 2 CPU/DMA Control of the GSC Collisions and Backoff What the GSC was doing Response GSC Register Descriptions Successful Ending of Transmissions and Receptions GMOD84H Xtclk PL1 PL0 PL1 PL0 Length Bits Kawasaki LSI USA, Inc Ver .9 KS152JB2 DCJ DCR SA5 SA4 SA3 SA2 SA1 SA0 ARB REQ Garen Xrclk Gfien IDL Rcabt Crce RDN Rfne Gren Haben Kawasaki LSI USA, Inc Ver .9 KS152JB2 LNI Noack Tcdt TDN Tfnf TEN DMA Kawasaki LSI USA, Inc Ver .9 KS152JB2 DMA Operation DMA with the 80C152 DMA Registers Alternate Cycle Mode Burst ModeDAS IDA SAS ISA Serial Port Demand Mode External Demand Mode Timing Diagrams 12 OSC.PERIODS ALE Psen P1 Inst FloatPCH P2 SFR DMA Cycle Resume Program Execution DMA Transfer from Internal Memory to Internal Memory DMA Cycle Resume Program Execution 12 OSC. Periods ALE Psen Inst DMA Data OUT PCL Inst PCHDMA Cycle 12 OSC. Periods Resume Program Execution ALE Psen Hold/Hold Acknowledge Request ModeArbiter Mode Using the HOLD/HLDA Acknowledge ARB REQ Dmxrq ALE ARB If Hlda = ALE AEQ ALE REQInternal Logic of the Arbiter Internal Logic of the Requester DMA Arbitration Kawasaki LSI USA, Inc.oup, Inc Ver .9 KS152JB2 Kawasaki LSI USA, Inc Ver .9 KS152JB2 Kawasaki LSI USA, Inc Ver .9 KS152JB2 DMA Arbitration with Hold/Hold Ack Summary of DMA Control Bits DAS IDA SAS ISA Done Interrupt Structure IE0 TI+RI ET1 EX1 ET0 EX0 PT1 PX1 PT0 PX0 IPN1 GSC Transmitter Error Conditions Transmit Error Flags Logic for Clearing TEN, Setting TDN GSC Receiver Error Conditions Glossary Kawasaki LSI USA, Inc Ver .9 KS152JB2 DCON0/1 092H,093H Xtclk PL1 PL0 Kawasaki LSI USA, Inc 102 Ver .9 KS152JB2 Kawasaki LSI USA, Inc 103 Ver .9 KS152JB2 PT1 PX1 PT0 EX0 Myslot 0F5H DCJ DCR SA5 SA4 SA3 SA2 SA1 SA0 Smod ARB REQ Garen Xrclk Gfien IDL OVR Rcabt Crce RDN Rfne Gren Haben Kawasaki LSI USA, Inc 108 Ver .9 KS152JB2 SM0 SM1 SM2 REN TB8 RB8 TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 Gate Kawasaki LSI USA, Inc 111 Ver .9 KS152JB2 Port Stack PointerData Pointer LOW DPL.7 DPL.6 DPL5 DPL.4 DPL.3 DPL.2 DPL.1 DPL.0 Timer Control Data Pointer HighDPH.7 DPH.6 DPH.5 DPH.4 DPH.3 DPH.2 DPH.1 DPH.0 DPH Timer Mode Control Gate TimerTimer 0 LSB Timer 1 LSB Timer 0 MSB Timer 1 MSB Serial Port Control SM0Serial Data Buffer SBUF.7 Program Status Word RS1 RS0 Accumulator ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 Kawasaki LSI USA, Inc 119 Ver .9 KS152JB2 Kawasaki LSI USA, Inc 120 Ver .9 KS152JB2