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 dc2364af 1 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. dc2364af 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 dc2364af 3 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 dc2364af DEMO MANUAL DC2364A Schematic Diagram dc2364af 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. 5 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 6 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 © LINEAR TECHNOLOGY CORPORATION 2015