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dc2364af

DEMO MANUAL DC2364A

Quick start proceDure

OvERvIEw

The LTC2873 multiprotocol transceiver comprises one

RS485 driver and receiver and one RS232 driver and

receiver. A two-pin bus interface is shared with the RS485

and RS232 transceivers and only one can be active at a

The DC2364A is designed to be used stand-alone or

interface directly with a Linduino microcontroller board

(DC2026)inashieldconfiguration.Itisequallycompatible

with Arduino, although Linduino is preferred because it

adds a fully isolated USB port, offering added protection

to the connecting computer. A Linduino sketch is provided

that, when loaded and run, displays a menu of options for

controlling and using the DC2364A. This sketch can be

customized as needed.

The DC2364A provides a means to control and observe

nearly every pin on the LTC2873. The control pins can be

driven externally, set high or low with a jumper, or con-

trolled with a Linduino microcontroller (when attached).

Level shifting buffers are included on the DC2364A so

that the Linduino can control the signals to the LTC2873,

More Features of the DC2364A:

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Turrets for supply connections are on the right edge

of the board. These connections are optional if used

with a Linduino.

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Test points and terminal block connections for bus

pins on are on the right edge of the board.

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Test points and jumpers for logic-level signals are on

the left edge of the board.

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A Green LED indicates the presence of a low on Data

Input, DI.

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A Yellow LED indicates the presence of a low on

Receiver Output, RO.

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100k pull-up or pull-down resistors on all logic I/O

pins provide a defined logic state in the absence of a

driving signal or jumper.

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Four switches near the bottom left of the board can

be used to give the board a unique address acces-

sible by the Linduino, allowing the code to support

multiple boards, uniquely addressed.

LTC2873 OPERATION

The LTC2873 enables a single channel RS232 driver and

RS232 receiver or one RS485 driver and one RS485 re-

ceiver, selectable with the 485/232 control pin.

In RS232 mode (485/232 low), the driver and receiver

are always active and DE485/F232 enables fast mode for

up to 1Mbps.

In RS485 mode (485/232 high), the driver and receiver

are only active if their associated enable pins (DE485/

F232 and RE485) are driven high and low, respectively.

RS485 termination can be switched in by setting the

TE485 pin low. This enables a 120Ω resistor between

A/DO and B/RI.

JUMPERS

Logic Level Jumpers:

Logic interface pins (LB, TE485, 485/232, RE485, DE485/

F232, DI, SHDN) all have jumpers that can be set in three

high. “ENuC” enables Linduino control of the pin.

To drive the signal from an external source, set the jumper

for that pin to the GND position. This connects a 50Ω

termination resistor from the pin to ground that can be

overdriven with an external source connected to the test

point on the left side of the board. Alternately, the jumper

can be removed entirely if the 50Ω load is undesirable.

Supply Jumpers:

There are two jumpers that control the Logic Supply

the “3V3” or “5V” settings connects the Linduino 3.3V

or 5V regulated supply to those pins. With the jumper

LTC2873 from the turrets on the right edge of the board.

If the DC2364A is used without the Linduino, the “EXT”

setting must be used.