Kawasaki 80C152, KS152JB, 80C51 Sdlc Frame Format, BOF Address Control Info CRC EOF

Page 49

KS152JB Universal Communications Controller Technical Specifications

3.3 SDLC Operation

SDLC is a communication protocol developed by IBM and widely used in industry. It is based on a primary/ secondary architecture and requires that each secondary station have a unique address. The secondary stations can only communicate to the primary station, and then, only when the pri- mary station allows communication to take place. This eliminates the possibility of contention on the serial line caused by the secondary station’s trying to transmit simultaneously.

In the C152, SDLC can be configured to work in either full or half duplex. When adhering to strict SDLC protocol, full duplex is required. Full duplex is selected whenever a 16-bit CRC is selected. At the end of a valid reset the 16-bit CRC is selected. To select half duplex with a 16-bit CRC, the receiver must be turned off by user software before transmission. The receiver is turned off by clearing the GREN bit (RSTAT.1). The receiver needs to be turned off because the address that is transmitted is the address of the secondary station’s receiver. If not turned off, the receiver could mistake the outgoing message as being intended for itself. When 32-bit CRCs are used, half duplex is the only method available for transmission.

3.3.2 SDLC Frame Format

The format of an SDLC frame is shown in Figure. The frame consists of a Beginning of Frame flag, Address field, Control Field, Information field (optional), a CRC, and the End of Frame flag.

BOF

ADDRESS

CONTROL

INFO

CRC

EOF

Typical SDLC Frame

BOF - The begin of frame flag for SDLC is 01111110. It is only one of two possible combinations that have six consecutive ones in SDLC. The other possibility is an abort character which consists of eight or more consecutive ones. This is because SDLC utilizes a process called bit stuffing. Bit stuffing is the insertion of a 0 as the next bit every time a sequence of five consecutive 1s is detected. The receiver automatically removes a 0 after every consecutive group of five ones. This removal of the 0 bit is referred to as bit stripping. Bit stuffing is discussed in Section 3.3.4. All the procedures required for bit stuffing and bit stripping are automatically handled by the GSC.

In standard SDLC protocol the BOF signals the start of a frame and is limited to 8 bits in length. Since there is no preamble in SDLC the BOF is considered an entire separate field and marks the beginning of the frame. The BOF also serves as the clock synchronization mechanism and the ref- erence point for determining the position of the address and control fields.

ADDRESS - The address field is used to identify which stations the message is intended for. Each secondary station must have a unique address. The primary station must then be made aware of which addresses are assigned to each station. The address length is specified as 8-bits in standard SDLC protocols but it is expandable to 16-bits in the C152. User software can further expand the

Kawasaki LSI USA, Inc.

Page 49 of 120

Ver. 0.9 KS152JB2

Page 48 Page 50
Image 49
Page 48 Page 50
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 None11/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
Top Page Image Contents