2

TABLE OF CONTENTS

FEATURES ........................................................................................................................................................................ 1

GENERAL DESCRIPTION ................................................................................................................................................ 1

PIN CONFIGURATION...................................................................................................................................................... 3

DESCRIPTION OF PIN FUNCTIONS ............................................................................................................................... 4

PROTOCOL DESCRIPTION ............................................................................................................................................. 9

NETWORK PROTOCOL........................................................................................................................................... 9

NETWORK RECONFIGURATION ........................................................................................................................... 9

BROADCAST MESSAGES ..................................................................................................................................... 10

EXTENDED TIMEOUT FUNCTION ........................................................................................................................ 10

LINE PROTOCOL .................................................................................................................................................... 10

SYSTEM DESCRIPTION..................................................................................................................................................12

MICROPROCESSOR INTERFACE .........................................................................................................................12

TRANSMISSION MEDIA INTERFACE ....................................................................................................................13

FUNCTIONAL DESCRIPTION .........................................................................................................................................13

MICROSEQUENCER ...............................................................................................................................................13

ADDRESS DECODING ............................................................................................................................................19

INTERNAL REGISTERS ..........................................................................................................................................22

INTERNAL RAM .......................................................................................................................................................29

SOFTWARE INTERFACE........................................................................................................................................29

SOFTWARE COMPATIBILITY CONSIDERATIONS ..............................................................................................31

COMMAND CHAINING ............................................................................................................................................32

RESET DETAILS ......................................................................................................................................................34

READ AND WRITE CYCLES ...................................................................................................................................35

NODE ID LOGIC .......................................................................................................................................................43

TRANSMIT/RECEIVE LOGIC ..................................................................................................................................43

IMPROVED DIAGNOSTICS.....................................................................................................................................43

OSCILLATOR ...........................................................................................................................................................45

OPERATIONAL DESCRIPTION ......................................................................................................................................46

MAXIMUM GUARANTEED RATINGS .....................................................................................................................46

DC CHARACTERISTICS..........................................................................................................................................46

TIMING DIAGRAMS .........................................................................................................................................................49

Please see Addendum 1 entitled Data Sheet Errata for Revision B COM90C66, which discusses changes to this

data sheet which apply to the Revision B device, on Page 62.

Please see Addendum 2 entitled Data Sheet Errata for Revision D COM90C66, which discusses changes to this

data sheet which apply to the Revision D device, on Page 64.

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