SMSC COM20020 manual MULTIPLEXED, 8051-LIKE BUS Interface with RS-485 Interface

XTAL1	COM20020
XTAL2
AD0-AD7	AD0-AD2, D3-D7
ALE	A2/BALE	RXIN
A15	nCS
RESET	nRESET IN	nTXEN	75176B or
			Equiv.
		nPULSE1
nRD	nRD/nDS	nPULSE2
nWR	nWR/DIR	GND
nINT1	nINTR
			Differential Driver
	A0/nMUX		Configuration
	XTAL1	XTAL2	*Media Interface
			may be replaced
8051			with Figure A, B or C.
	27 pF	27 pF

FIGURE 2 - MULTIPLEXED, 8051-LIKE BUS INTERFACE WITH RS-485 INTERFACE

RXIN

TXEN

nPULSE1

nPULSE2

GND

+5V

100 Ohm

+5V

2

6 Receiver

RXIN

HFD3212-002

7

Transmitter

3 HFE4211-014

nPULSE1

+5V

2

6

7

2 Fiber Interface

(ST Connectors)

BACKPLANE CONFIGURATION

NOTE: COM20020 must be in backplane mode

FIGURE A FIGURE B

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