SMSC manual COM20020 Operation

Page 7

Reconfigure Timer has

Timed Out

Power On

Send

Reconfigure

Burst

Read Node ID

Write ID to

RAM Buffer

1

Set NID=ID

Start

Y

Invitation

N

Reconfiguration

to Transmit to

Timer (840 mS)

this ID?

N

Y

Y

Free Buffer

N

TA?

Enquiry to

this ID?

Y

N

Transmit

Y

N

SOH?

NAK

RI?

Y

N

RI?

Transmit

Write SID

Broadcast?

ACK

No Activity

N

to Buffer

N

Transmit

for 82

uS?

Y

Free Buffer

Send

Enquiry

No

Y

DID

Y

Y

=0?

Packet

Activity

N

for 74.7

Set NID=ID

N

N

Y

N

us?

Broadcast

ACK?

DID

Enabled?

Start Timer:

Y

Y

N

=ID?

Y

Was Packet

Set TA

Y

N

T=(255-ID)

Broadcast?

NAK?

x 146 us

N

1

Write Buffer

with Packet

Activity

Y

No

On Line?

Pass the

Y

Set TA

Activity

Token

N

for 74.7

us?

N

CRC

N

N

T=0?

No

OK?

Increment

Y

N

Y

Activity

N

Y

NID

Y

for 74.7

Set TMA

ACK?

us?

N

LENGTH

OK?

Y

Y

	ID refers to the identification number of the ID assigned to this node.	DID					Set RI
		DID					Set RI
-		=0?
-	NID refers to the next identification number that receives the token after	N
	after this ID passes it.	DID		N
-	SID refers to the source identification.			N
-	SID refers to the source identification.
-	DID refers to the destination identification.	=ID?
-	DID refers to the destination identification.

-	SOH refers to the start of header character; preceeds all data packets.	Y
		SEND ACK
		SEND ACK

FIGURE 1 - COM20020 OPERATION

7

Image 7

Contents General Description FeaturesTable of Contents PIN Configuration A1,A2/ALE Description of PIN FunctionsTransmission Media Interface DIP PIN Plcc PIN Name Symbol DescriptionMiscellaneous Instead, it must be connected to XTAL1 with COM20020 Operation Data Rates Network ReconfigurationProtocol Description Network ProtocolBroadcast Messages Extended Timeout FunctionResponse Time Invitations To Transmit Reconfiguration TimeIdle Time Line ProtocolAcknowledgements Data PacketsNegative Acknowledgements System Description MULTIPLEXED, 8051-LIKE BUS Interface with RS-485 Interface Figure C Traditional Hybrid Interface Backplane ConfigurationCOM20020 Network Using RS-485 Differential Transceivers Programmable Txen Polarity Differential Driver ConfigurationInternal Block Diagram Cable Type Impedance AT 5MHZ Functional DescriptionAttenuation NominalRead Register Summary Write Tentative ID Register Internal RegistersInterrupt Mask Register IMR Data RegisterStatus Register Diagnostic Status RegisterCommand Register Next ID RegisterConfiguration Register Setup Register BIT BIT Name Symbol Description Dupid BIT BIT Name Symbol DescriptionData Command Description Address Pointer Low Register Address Pointer High RegisterReset Configuration RegisterCKP3 CKP2 CKP1 Sequential Access Operation Software Interface Sequential Access MemoryAccess Speed Internal RAMTransmit Sequence Selecting RAM Page SizeRAM Buffer Packet Configuration Page Receive Sequence Transmit Command Chaining Command ChainingReceive Command Chaining Internal Reset Logic Reset DetailsInitialization Sequence Improved DiagnosticsAbnormal Results Normal ResultsOscillator Operational Description Maximum Guaranteed RatingsDC Electrical Characteristics Parameter Symbol MIN TYP MAX Unit CommentXTAL1, XTAL2 Input Capacitance Multiplexed BUS, 68XX-LIKE Control Signals Read Cycle Timing DiagramsMultiplexed 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 These signals are to and from the hybrid Normal Mode Transmit or Receive TimingNTXEN NPULSE1 TTL Input Timing on XTAL1 PIN 28-PIN Plcc Package Dimensions 24-PIN DIP Package Dimensions SECTION/FIGURE/ENTRY Correction Revised DateStandard Microsystems Corp