UPD72042 Datasheet, PDF (4/92 Pages) NEC – LSI DEVICES FOR Inter Equipment BusTM (IEBusTM) PROTOCOL CONTROL

CONTENTS
µPD72042
1. PIN FUNCTIONS ............................................................................................................................ 6
1.1 PIN FUNCTIONS ................................................................................................................................... 6
2. IEBus OPERATION ....................................................................................................................... 8
2.1 OVERVIEW .............................................................................................................................................. 8
2.2 IEBus COMMUNICATION PROTOCOL .............................................................................................. 9
2.2.1 Bus Mastership Determination (Arbitration) ............................................................................... 10
2.2.2 Communication Mode ................................................................................................................. 10
2.2.3 Communication Address ............................................................................................................. 11
2.2.4 Broadcast ..................................................................................................................................... 11
2.3 TRANSMISSION PROTOCOL .............................................................................................................. 11
2.4 TRANSMISSION DATA (CONTENTS OF THE DATA FIELD) ........................................................ 17
2.5 BIT FORMAT .......................................................................................................................................... 21
3. MICROCOMPUTER INTERFACE ................................................................................................. 22
3.1 TRANSFER METHOD ........................................................................................................................... 22
3.2 DATA TRANSFER FORMAT ................................................................................................................ 23
3.2.1 Three-Wire Data Transfer (SEL = 1) .......................................................................................... 23
3.2.2 Two-Wire Data Transfer (SEL = 0) ............................................................................................. 25
3.3 CONNECTION TO A MICROCOMPUTER ......................................................................................... 27
3.4 STANDBY MODE SETTING AND CANCELLATION ....................................................................... 28
3.5 RESET MODE SETTING AND CANCELLATION ............................................................................ 28
4. REGISTERS .................................................................................................................................... 29
5. EXAMPLE TIMINGS FOR COMMUNICATION .......................................................................... 59
6. EXAMPLE MICROCOMPUTER PROCESSING FLOW ............................................................. 67
6.1 COMMUNICATION FLAGS ................................................................................................................... 68
6.2 MAIN ROUTINE ..................................................................................................................................... 69
6.3 INTERRUPT ROUTINE ......................................................................................................................... 70
6.4 PROCESSING ROUTINES .................................................................................................................... 72
6.4.1 µPD72042 Initial Setting Routine ............................................................................................... 72
6.4.2 Communication Flag Initialization Routine ................................................................................. 72
6.4.3 Command Processing Routine ................................................................................................... 73
6.4.4 Master Communication Processing Routine .............................................................................. 73
6.4.5 Slave Data Transmission Processing Routine ........................................................................... 77
6.4.6 Transmission Processing Routine .............................................................................................. 80
6.4.7 Reception Processing Routine ................................................................................................... 81
7. ELECTRICAL CHARACTERISTICS ............................................................................................. 82
8. PACKAGE DRAWING .................................................................................................................... 86
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Data Sheet S14870EJ1V0DS00