DC2364A - Demo Manual

DEMO MANUAL DC2364A
LTC2873
Single-Bus RS485/RS232 Multiprotocol
Transceiver with Switchable Termination
Description
Demonstration circuit 2364A showcases the LTC®2873
RS232/RS485 multiprotocol transceiver with integrated
termination. The DC2364A operates as a stand-alone evaluation platform or can be used as a shield with a Linduino®
or Arduino microcontroller board for quick and versatile
evaluation of the LTC2873.
Control signals on the LTC2873 are accessible via test
points for external monitoring or control, or they can be set
by jumpers or by the Linduino GPIO. Bus lines are routed
Performance Summary
to test points as well as a terminal block for convenient
connections to a transmission line. The DC2364A operates from external supplies or directly from the Linduino’s
regulated output supplies, configured to 3.3V or 5V with
a jumper setting.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2364A
L, LT, LTC, LTM, Linear Technology, Linduino and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
Specifications are at TA = 25°C
PARAMETER
CONDITIONS
MIN
Input Supply
VCC Operating
VL Operating
3.0
1.7
Maximum Data Rate
RS232
RS485
1
20
TYP
MAX
UNITS
5.5
VCC
V
V
Mbps
Mbps
Board LAYOUT
Figure 1. DC2364A. Default Jumper Settings Indicated by the Rectangles at the Jumpers. Default Is for Use with Linduino
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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
given time. The LTC2873 requires a Main Supply, VCC
(3V to 5.5V) and a Logic Supply, VL (1.7V to 5.5V).
The DC2364A is designed to be used stand-alone or
interface directly with a Linduino microcontroller board
(DC2026) in a shield configuration. It is equally compatible
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 controlled 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,
yet support and preserve the full range of VL voltages
and logic levels applied to the LTC2873 from 1.7V to VCC.
More Features of the DC2364A:
Turrets for supply connections are on the right edge
of the board. These connections are optional if used
with a Linduino.
nn Test points and terminal block connections for bus
pins on are on the right edge of the board.
nn Test points and jumpers for logic-level signals are on
the left edge of the board.
nn A Green LED indicates the presence of a low on Data
Input, DI.
nn A Yellow LED indicates the presence of a low on
Receiver Output, RO.
nn 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.
nn Four switches near the bottom left of the board can
be used to give the board a unique address accesnn
2
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 receiver, 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
positions to control the pin state: “GND,” “VL” and “ENuC.”
“GND” and “VL” are used to set the state of the pin low or
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
(VL) and Main Supply (VCC) to the LTC2873. For each,
the “3V3” or “5V” settings connects the Linduino 3.3V
or 5V regulated supply to those pins. With the jumper
in the “EXT” position, VCC and VL will be routed to the
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.
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DEMO MANUAL DC2364A
Quick Start Procedure
TE = DE and RE = DE Jumpers:
2.Set the logic level jumpers to the “ENuC” position.
In some applications it may be beneficial to connect TE
to DE or RE to DE. The two jumpers marked in this way,
present a convenient means of making these connections.
3.Set the VL and VCC jumpers to the desired position
(“VL,” “EXT,” and “VCC” are all valid choices)
Probe Pads for VDD and VEE
Probe pads are included on the board for examination of
the VDD, and VEE generated supplies.
How to Operate DC2364A without a Linduino:
1.Move supply jumpers to “EXT” position.
2. Connect VCC and VL supplies and Ground to the turrets.
There are no power supply sequencing restrictions.
3.Move logic level jumpers to the desired position to set
the pin states or drive externally as described in the
Logic Level Jumpers section.
How to Operate DC2364A with a Linduino:
By default the DC2364A jumpers are arranged for Linduino
control as indicated in Figure 1
1.Attach the DC2364A to the Linduino board by direct
insertion, like a shield is installed.
4.If using external supplies, connect them to the turrets;
otherwise the Linduino will supply the board. The supply
jumpers (see Step 3 above) must be set to match this
configuration.
5. Plug the Linduino into a computer running the Arduino
IDE application using a USB cable.
6.On the computer, open the sketch that is written for
this board (this can be found at http://www.linear.com/
solutions/linduino), and upload to the Linduino.
7.Open the Arduino serial monitor. Set communication
rate to “115200 baud” and choose “Both NL & CR.”
8.A menu is displayed offering options to run the program that exercises the demonstration circuit and the
LTC2873 as shown in Figure 2.
The logic pins can be controlled individually by typing 1-7
and hitting ENTER. Selections 8 and 9 apply a 31.4kHz
signal to DI. Options 10 to 26 control multiple pins, configuring the LTC2873 to the specified mode of operation.
All logic inputs can be monitored at test points on left side
of board at all times.
Figure 2. Serial Monitor Start-Up Menu Screen
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DEMO MANUAL DC2364A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
U1
IC, Single-Bus RS485/RS232 Transceiver
LINEAR, LTC2873IUFD#PBF
2
1
C1
Cap, 0.22µF 10% 0603 16V X7R
TDK, C1608X7R1C224K080AC
3
1
C2
Cap, 2.2µF 10% 0603 16V X7S
TDK, CGA3E1X7S1C225K080AC
4
2
C3-4
Cap, 1µF 10% 0603 16V X7R
TDK, C1608X7R1C105K080AC
5
2
C5-6
Cap, Tant, 6.8µF 10% 3216 16V
KEMET, T491A685K016AT
6
11
C7-17
Cap, 10nF 10% 0603 50V X7R
TDK, C1608X7R1H103K080AA
7
1
D1
Diode, LED, Green, 0805
WURTH ELEKTRONIK, 150080VS75000
8
1
D2
Diode, LED, Yellow, 0805
WURTH ELEKTRONIK, 150080YS75000
9
13
E1-13
SMT, Test Point
KEYSTONE, 5019
10
3
E14-16
Turret
MILL-MAX, 2501-2-00-80-00-00-07-0
11
1
J1
Term Block, 3 Pos, 3.5mm, Header
WURTH ELEKTRONIK, 691214110003
12
1
J2-5
Arduino Header Kit, 2x8pin, 1x6pin, 1x10pin
SPARKFUN, PRT-11417
13
7
JP1-7
Header, 1x4 0.1"
WURTH ELEKTRONIK, 61300411121
14
2
JP8-9
Header, 1x3 0.1"
WURTH ELEKTRONIK, 61300311121
15
2
JP10-11
Header, 2x3 0.1"
WURTH ELEKTRONIK, 61300621121
16
11
JP1-11
Shunt, 1x2 0.1", Blue
WURTH ELEKTRONIK, 60900213621
17
1
L1
Inductor, 10µH 0806 0.25Ω 1A
WURTH ELEKTRONIK, 74479778310
18
24
R1-24
Resistor, 100kΩ 1% 0603
VISHAY, CRCW0603100KFKEA
19
7
R25-R31
Resistor, 249Ω 1% 0603
VISHAY, CRCW0603249RFKEA
20
7
R32-38
Resistor, 49.9Ω 1% 1210
VISHAY, CRCW121049R9FKEA
21
1
R39
Resistor, 261Ω 1% 0603
VISHAY, CRCW0603261RFKEA
22
1
R40
Resistor, 649Ω 1% 0603
VISHAY, CRCW0603649RFKEA
23
1
RA1
Resistor Array, 100kΩ 5% 1206
CTS, 742C083104JP
24
1
SW1
Switch DIP 4-Pos Slide
COPAL, CHS-04TA
25
9
U2-10
IC, Buffer/Line Driver, Non-Inverting
TI, SN74LV1T126DCKR
26
1
U11
IC, Translator, Bidirectional, 3-State
TI, SN74LVC1T45DCKR
4
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DEMO MANUAL DC2364A
Schematic Diagram
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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DEMO MANUAL DC2364A
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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dc2364af
Linear Technology Corporation
LT 1215 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
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