SMSC COM20020 manual Timing Diagrams, Multiplexed BUS, 68XX-LIKE Control Signals Read Cycle

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TIMING DIAGRAMS

AD0-AD2,

D3-D7

VALID

t1	t2,
nCS	t4

t3

VALID DATA

ALE

nDS

DIR

t5

t9

t6

t7

t8

t10

	Parameter	min	max	units

t1	Address Setup to ALE Low	30		nS
t2	Address Hold from ALE Low	10		nS
t3	nCS Setup to ALE Low	10		nS
t4	nCS Hold from ALE Low	20		nS
t5	ALE Low to nDS Low	15	40	nS
t6	nDS Low to Valid Data		40	nS
t7	nDS High to Data High Impedance	0	20	nS
t8	Cycle Time (nDS Low to Next Time Low)	4T*		nS
t9	DIR Setup to nDS Active	10		nS
t10	DIR Hold from nDS Inactive	10		nS

*T is the Arbitration Clock Period.

T is identical to XTAL1 if SLOW ARB = 0, T is twice XTAL1 period if SLOW ARB = 1

Note 1: The Microcontroller typically accesses the COM20020 on every other cycle. Therefore, the cycle time specified in the microcontroller's datasheet should be doubled when considering back-to-back COM20020 cycles.

FIGURE 10 - MULTIPLEXED BUS, 68XX-LIKE CONTROL SIGNALS; READ CYCLE

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Contents Features General DescriptionTable of Contents PIN Configuration Description of PIN Functions A1,A2/ALETransmission Media Interface DIP PIN Plcc PIN Name Symbol DescriptionMiscellaneous Instead, it must be connected to XTAL1 with COM20020 Operation Network Protocol Network ReconfigurationProtocol Description Data RatesBroadcast Messages Extended Timeout FunctionResponse Time Line Protocol Reconfiguration TimeIdle Time Invitations To TransmitAcknowledgements Data PacketsNegative Acknowledgements System Description MULTIPLEXED, 8051-LIKE BUS Interface with RS-485 Interface Figure C Backplane Configuration Traditional Hybrid InterfaceCOM20020 Network Using RS-485 Differential Transceivers Differential Driver Configuration Programmable Txen PolarityInternal Block Diagram Nominal Functional DescriptionAttenuation Cable Type Impedance AT 5MHZRead Register Summary Write Data Register Internal RegistersInterrupt Mask Register IMR Tentative ID RegisterNext ID Register Diagnostic Status RegisterCommand Register Status RegisterConfiguration Register Setup Register BIT BIT Name Symbol Description BIT BIT Name Symbol Description DupidData Command Description Address Pointer High Register Address Pointer Low RegisterConfiguration Register ResetCKP3 CKP2 CKP1 Sequential Access Operation Internal RAM Sequential Access MemoryAccess Speed Software InterfaceSelecting RAM Page Size Transmit SequenceRAM Buffer Packet Configuration Page Receive Sequence Command Chaining Transmit Command ChainingReceive Command Chaining Reset Details Internal Reset LogicImproved Diagnostics Initialization SequenceNormal Results Abnormal ResultsOscillator Parameter Symbol MIN TYP MAX Unit Comment Maximum Guaranteed Ratings DC Electrical Characteristics Operational DescriptionXTAL1, XTAL2 Input Capacitance Timing Diagrams Multiplexed BUS, 68XX-LIKE Control Signals Read CycleMultiplexed BUS, 80XX-LIKE Control Signals Read Cycle Multiplexed BUS, 68XX-LIKE Control Signals Write Cycle Multiplexed BUS, 80XX-LIKE Control Signals Write Cycle NON-MULTIPLEXED BUS, 80XX-LIKE Control Signals Read Cycle NON-MULTIPLEXED BUS, 68XX-LIKE Control Signals Read Cycle NON-MULTIPLEXED BUS, 80XX-LIKE Control Signals Write Cycle NON-MULTIPLEXED BUS, 68XX-LIKE Control Signals Write Cycle Normal Mode Transmit or Receive Timing These signals are to and from the hybridNTXEN NPULSE1 TTL Input Timing on XTAL1 PIN 28-PIN Plcc Package Dimensions 24-PIN DIP Package Dimensions Date SECTION/FIGURE/ENTRY Correction RevisedStandard Microsystems Corp