Application Note AN_207 USB-DUO

Application Note
AN_207
USB-DUO
Version 1.0
Issue Date: 2013-06-06
FTDI’s USB-DUO is a kit of parts (FT231XS and FT3243S) offered by FTDI to
enable customers to create their own USB to RS232 converters with FTDI
silicon.
Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the
user agrees to defend, indemnify and hold FTDI harmless from any and all damages, claims, suits
or expense resulting from such use.
Future Technology Devices International Limited (FTDI)
Unit 1, 2 Seaward Place, Glasgow G41 1HH, United Kingdom
Tel.: +44 (0) 141 429 2777 Fax: + 44 (0) 141 429 2758
Web Site: http://ftdichip.com
Copyright © 2012 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
Table of Contents
1
Introduction .................................................................................................................................... 2
1.1
Overview ................................................................................................................................. 2
2
Example Circuit ............................................................................................................................... 3
3
Ordering Information. ..................................................................................................................... 5
4
Contact Information........................................................................................................................ 6
Appendix A – References ........................................................................................................................ 7
Document References......................................................................................................................... 7
Acronyms and Abbreviations .............................................................................................................. 7
Appendix B – List of Tables & Figures ..................................................................................................... 8
List of Tables ....................................................................................................................................... 8
List of Figures ...................................................................................................................................... 8
Appendix C – Revision History ................................................................................................................ 9
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
1 Introduction
FTDI is well known for developing silicon and drivers that allow engineers to convert a peripheral
device serial port to USB. The silicon available from FTDI typically interfaces at levels between 1V8
and 5V0, whereas designs for cables and external modules often require RS232, RS422 or RS485
voltage levels. To enable customers to benefit from an easy to implement design FTDI has created
an USB to RS232 kit called the USB Duo, which contains an FT231XS (USB to UART chip) and a
FT3243S (line driver integrated circuit).
1.1 Overview
A UART is an industry standard universal asynchronous receiver, transmitter interface for serial
data. The protocol is fixed within a set of basic parameters e.g. a start bit, a number of data bits
(7, 8, or 9), parity bit (optional) and 1, 1.5, or 2 stop bits. The voltage levels and whether these
signals are delivered on a single ended wire or a differential pair of wires does not affect the
protocol but does affect how a system is wired.
RS232 is a recognized industry standard interface for serial communication. It is a single ended
interface, with separate receive and transmit data lines which operate between +/-5V to +/-15V.
As the FT231XS provides a +3V3 IO interface, any design requiring RS232 interface voltage levels
requires an additional IC referred in order to establish the correct voltage signaling level. This
additional IC is commonly referred to as an RS232 transceiver (or line driver). Therefore, with
the USB-DUO a two chip solution is provided; the FT231XS, which bridges USB to UART +3V3
signals, and a FT3243S transceiver, to convert the 3V3 level UART signals to RS232 voltage levels.
For more information on UARTs refer to TN_111_What Is UART?
For datasheets on the IC’s in the kit see the Document References section of this application note.
2
Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
2 Example Circuit
The diagram below shows how the USB-DUO kit may be connected to create a USB to RS232
interface device.
Figure 2.1 FT231XS/FT3243S Schematic
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
The FT231XS provides the USB to UART conversion while the FT3243S provides the digital to
RS232 voltage level conversion.
Minimal additional components are required to complete the design. Primarily interface connectors
and decoupling capacitors for the IC supplies.
In addition to the basic hardware on the PCB, the FT231XS device contains an internal EEPROM to
allow for customising the device descriptors to match an OEMs preferred description.
The maximum speed of the USB to RS232 link with these devices is 250kbaud.
More information on the FT231XS may be obtained from the datasheet at:
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT231X.pdf
More information on the FT3243S may be obtained from the datasheet at:
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT3243S.pdf
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
3 Ordering Information.
Part Number
USB-DUO
Package
2 reels – one with 2000 FT231XS devices and
one with 2000 FT3243S devices
Table 3.1 Part numbers
Note: Although the FT231XS may be bought separately the FT3243S is only available as part of
the USB-DUO.
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
4 Contact Information
Head Office – Glasgow, UK
Branch Office – Tigard, Oregon, USA
Future Technology Devices International Limited
Unit 1, 2 Seaward Place, Centurion Business Park
Glasgow G41 1HH
United Kingdom
Tel: +44 (0) 141 429 2777
Fax: +44 (0) 141 429 2758
Future Technology Devices International Limited
(USA)
7130 SW Fir Loop
Tigard, OR 97223
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
s[email protected]
[email protected]
E-Mail (Sales)
E-Mail (Support)
E-Mail (General Enquiries)
[email protected]
[email protected]
[email protected]
Branch Office – Taipei, Taiwan
Branch Office – Shanghai, China
Future Technology Devices International Limited
(Taiwan)
2F, No. 516, Sec. 1, NeiHu Road
Taipei 114
Taiwan , R.O.C.
Tel: +886 (0) 2 8791 3570
Fax: +886 (0) 2 8791 3576
Future Technology Devices International Limited
(China)
Room 1103, No. 666 West Huaihai Road,
Shanghai, 200052
China
Tel: +86 21 62351596
Fax: +86 21 62351595
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Web Site
http://ftdichip.com
System and equipment manufacturers and designers are responsible to ensure that their systems, and any Future Technology
Devices International Ltd (FTDI) devices incorporated in their systems, meet all applicable safety, regulatory and system-level
performance requirements. All application-related information in this document (including application descriptions, suggested
FTDI devices and other materials) is provided for reference only. While FTDI has taken care to assure it is accurate, this
information is subject to customer confirmation, and FTDI disclaims all liability for system designs and for any applications
assistance provided by FTDI. Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the
user agrees to defend, indemnify and hold harmless FTDI from any and all damages, claims, suits or expense resulting from
such use. This document is subject to change without notice. No freedom to use patents or other intellectual property rights is
implied by the publication of this document. Neither the whole nor any part of the information contained in, or the product
described in this document, may be adapted or reproduced in any material or electronic form without the prior written consent
of the copyright holder. Future Technology Devices International Ltd, Unit 1, 2 Seaward Place, Centurion Business Park,
Glasgow G41 1HH, United Kingdom. Scotland Registered Company Number: SC136640
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
Appendix A – References
Document References
FT231X Data Sheet
FT3243S Data Sheet
TN_111_What_Is_UART?
Acronyms and Abbreviations
Terms
UART
USB
USB-IF
Description
Universal Asynchronous Receiver Transmitter
Universal Serial Bus
USB Implementers Forum
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Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
Appendix B – List of Tables & Figures
List of Tables
Table 3.1 Part numbers ....................................................................................................... 5
List of Figures
Figure 2.1 FT231XS/FT3243S Schematic ................................................................................ 3
8
Copyright © 2013 Future Technology Devices International Limited
Application Note
AN_207 USB-DUO
Version 1.0
Document Reference No.: FT_000654
Clearance No.: FTDI# 341
Appendix C – Revision History
Document Title:
AN_207 USB-DUO
Document Reference No.:
FT_000654
Clearance No.:
FTDI# 341
Product Page:
http://www.ftdichip.com/FTProducts.htm
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Revision
1.0
Changes
Initial Release
Date
2013-06-19
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Copyright © 2013 Future Technology Devices International Limited