Kawasaki 80C152, 80C51 CSMA/CD Overview, CSMA/CD Frame Format, Preamble BOF Address Info CRC EOF

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KS152JB Universal Communications Controller Technical Specifications

be in some other mode than the user intends for a significant amount of time after reset. To pre- vent unwanted GSC errors from occurring, the user should not enable the GSC or the GSC inter- rupts for 170 machine cycles ((256 X 8) /12) after LNI bit is set.

3.2 CSMA/CD Operation

3.2.1 CSMA/CD OVERVIEW

CSMA/CD Operates by sensing the transmission line for a carrier, which indicates link activity. At the end of link activity, a station must wait a period of time, called the deference period, before transmission may begin. The deference period is also known as the interframe space. The inter- frame space is explained in Section 3.2.3

With this type of operation, there is always the possibility of a collision occurring after the defer- ence period due to line delays. If a collision is detected after transmission is started, a jamming mechanism is used to ensure that all stations monitoring the line are aware of the collision. A res- olution algorithm is then executed to resolve the contention. There are three different modes of collision resolution made available to the user on the C152. Re-transmission is attempted when a resolution algorithm indicates that a station’s opportunity has arrived.

Normally, in CSMA/CD, re-transmission slot assignments are intended to be random. This method gives all stations an equal opportunity to utilize the serial communication link but also leaves the possibility of another collision due to two stations having the same slot assignment. There is an option on the C152 which allows all the stations to have their slot assignments previ- ously determined by user software. This pre-assignment of slots is called the deterministic resolu- tion mode. This method allows resolution after the first collision and ensures the access of the link to each station during the resolution. Deterministic resolution can be advantageous when the link is being heavily used and collisions are frequently occurring and in real time applications where determinism is required. Deterministic resolution may also be desirable if it is known before hand that a certain station’s communication needs to be prioritized over those of other stations if it is involved in a collision.

3.2.2 CSMA/CD FRAME FORMAT

The frame format in CSMA/CD consists of preamble, Beginning of Frame flag (BOF), address field, information field, CRC, and End of Frame flag (EOF) as shown in Figure

PREAMBLE

BOF

ADDRESS

INFO

CRC

EOF

Typical CSMA/CD Frame

Kawasaki LSI USA, Inc.

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Ver. 0.9 KS152JB2

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Contents Introduction Technical Specifications PIN Description Pin DescriptionName Description Port Pin Name Alternate FunctionXTAL2 XTAL1RST Psen ALEEben EpsenSFR map for the cpu Special function RegistersReset Timing Reset Values of the SFRs Scon ConfigurationsSbuf Indeterminate Tmod PconPort bit I/O Pads Port 0 I/O Pad Port 2 I/O PadPorts 4,5 Psen Epsen ProgramComments Fetch viaTmod Timer/Counter Mode Control Register TIMER/COUNTERSMode Tcon Timer/Counter Control RegisterTimer/Counter in Mode IE Interrupt Enable Register Timer/Counter 0 in ModeInterrupts Priority Level Structure Pgste PDMA1 Pgstv PDMA0 Pgsre Pgsrv Egste EDMA1 Egstv EDMA0 Egsre EgsrvEX0 PX0Pgsrv Egsrv 2BHEDMA1 PDMA1PT1 ET1 1BHKawasaki LSI USA, Inc Ver .9 KS152JB2 Status of the External Pins during Idle and Power Down Power Down and IdleALE Psen Smod IDL Pcon Power Control RegisterLocal Serial Channel Controller Local Serial Port ModeSerial Port Mode Mode Load Sbuf Baud Rates Smod Timer 1 generated commonly used Baud ratesMHZ JNB SINGLE-STEP OperationReti Kawasaki LSI USA Inc Introduction Global Serial ChannelDC JAM CRC 11/IDLE CRC None 11/IDLE Csma SdlcExternal clock Internal clock Control cpu Control dma Raw Receive Raw Transmit CSMA/CD Frame Format CSMA/CD OverviewPreamble BOF Address Info CRC EOF Kawasaki LSI USA, Inc Ver .9 KS152JB2 23 24 Interframe Space Manchester Encoding BIT Time CSMA/CD Data EncodingCollision Detection Jitter ToleranceMissing 0-to-1 Transition Narrow PulsesUnexpected 1-to-0 Transition GSC Inactive Resolution of CollisionsResponse to a Detected Collision What the GSC was doing TfifoDCR BackoffAlgorithm Prbs Tcdcnt Load Bkoff Slot Clock Myslot Random BackoffBKOFF= Myslot Deterministic Backoff Hardware Based Acknowledge Kawasaki LSI USA, Inc Ver .9 KS152JB2 BOF Address Control Info CRC EOF Sdlc Frame FormatKawasaki LSI USA, Inc Ver .9 KS152JB2 Nrzi BIT Time Data EncodingBIT STUFFING/STRIPPING Line Idle Sending Abort CharacterAcknowledgement Point-to-point Network PRIMARY/SECONDARY StationsMulti-Drop Network Ring NetworkHDLC/SDLC Comparison Using a Preamble in SdlcSdlc Hdlc User Defined ProtocolsPlanning for Network Changes and Expansions Line DisciplineDMA Servicing of GSC Channels Kawasaki LSI USA, Inc Ver .9 KS152JB2 Baud Rate Initialization External Driver Interface Test ModesJitter Receive Receive Sampling Rate Received Local Value Manchester Encoding BIT TimeBIT Time Received Transmit WaveformsCSMA/CD Clock Recovery Receiver Clock RecoveryExternal Clocking Determining Receiver ErrorsRcbat Crce Addressing2 CPU/DMA Control of the GSC Determining Line DisciplineCollisions and Backoff What the GSC was doing Response Successful Ending of Transmissions and Receptions GSC Register DescriptionsPL1 PL0 Length Bits GMOD84H Xtclk PL1 PL0Kawasaki LSI USA, Inc Ver .9 KS152JB2 ARB REQ Garen Xrclk Gfien IDL DCJ DCR SA5 SA4 SA3 SA2 SA1 SA0Rcabt 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 with the 80C152 DMA OperationDMA Registers Burst Mode Alternate Cycle ModeDAS IDA SAS ISAExternal Demand Mode Serial Port Demand Mode12 OSC.PERIODS ALE Psen P1 Inst Float Timing DiagramsPCH P2 SFR DMA Cycle Resume Program Execution DMA Transfer from Internal Memory to Internal MemoryDMA Cycle 12 OSC. Periods Resume Program Execution ALE Psen 12 OSC. Periods ALE Psen Inst DMA Data OUT PCL Inst PCHDMA Cycle Resume Program Execution Arbiter Mode Request ModeHold/Hold Acknowledge ARB REQ Using the HOLD/HLDA AcknowledgeInternal Logic of the Arbiter ALE ARB If Hlda = ALE AEQ ALE REQDmxrq 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 DAS IDA SAS ISA Done Summary of DMA Control BitsInterrupt Structure IE0 ET1 EX1 ET0 EX0 TI+RIIPN1 PT1 PX1 PT0 PX0Transmit Error Flags Logic for Clearing TEN, Setting TDN GSC Transmitter Error ConditionsGSC 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 TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 SM0 SM1 SM2 REN TB8 RB8Gate Kawasaki LSI USA, Inc 111 Ver .9 KS152JB2 Stack Pointer PortData Pointer LOW DPL.7 DPL.6 DPL5 DPL.4 DPL.3 DPL.2 DPL.1 DPL.0Data Pointer High Timer ControlDPH.7 DPH.6 DPH.5 DPH.4 DPH.3 DPH.2 DPH.1 DPH.0 DPHGate Timer Timer Mode ControlTimer 0 LSB Timer 1 LSBTimer 1 MSB Timer 0 MSBSM0 Serial Port ControlSerial Data Buffer SBUF.7RS1 RS0 Program Status WordACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 AccumulatorKawasaki LSI USA, Inc 119 Ver .9 KS152JB2 Kawasaki LSI USA, Inc 120 Ver .9 KS152JB2
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