Vinculum II USB Slave Detecting Disconnect

Future Technology Devices International Ltd.
Application Note
AN_163
Vinculum-II USB Slave Disconnect Detection
Document Reference No.: FT_000365
Version 1.0
Issue Date: 2010-11-30
This application note provides an example of how to detect when an FTDI VinculumII (VNC2) USB Slave device has been disconnected from USB. Sample source code
is included for reference.
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
E-Mail (Support): support1@ftdichip.com Web: http://www.ftdichip.com
Copyright © 2010 Future Technology Devices International Limited
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.
Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
Table of Contents
1
2
Introduction .................................................................... 2
1.1
Overview ................................................................................... 2
1.2
Hardware Requirements ........................................................... 2
Implementation .............................................................. 3
2.1
Hardware Configuration ............................................................ 3
2.2
Firmware Configuration ............................................................ 4
2.2.1
IOMux Configuration .................................................................................. 4
2.2.2
GPIO Configuration .................................................................................... 4
2.2.3
Monitoring the GPIO Input .......................................................................... 5
3
Contact Information ........................................................ 6
4
Appendix A – References................................................. 8
Document References ....................................................................... 8
Acronyms and Abbreviations ............................................................. 8
5
Appendix B – Revision History ........................................ 9
Copyright © 2010 Future Technology Devices International Limited
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
1
Introduction
This application note describes how an application can detect that a Vinculum-II USB slave device has
been disconnected from USB.
The sample source code for the application is provided as an example and is neither guaranteed nor
supported by FTDI.
1.1 Overview
The method involves connecting the 5V bus power from the USB Slave to a GPIO input, and
implementing an application thread to monitor the GPIO input.
The remainder of this application note describes a specific implementation of this method.
1.2 Hardware Requirements
V2EVAL board
64-pin Vinculum II daughter board
See Appendix A for references to the datasheets.
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
2
Implementation
This section describes a specific implementation of disconnect detection. The reader should have a
sound understanding of firmware application structure and the fundamental concepts of how the
Vinculum Operating System (VOS) works. For an introduction to VinIDE, VOS and an overview of the
general application structure please refer to Vinculum-II_Tool_Chain_Getting_Started_Guide [1]. The
Vinculum-II tool-chain consists of a compiler, assembler, linker and debugger encapsulated in a graphical
interface (the IDE) and is used to develop customised firmware for VNC2 [2].
2.1 Hardware Configuration
For the purpose of this application note, disconnect is detected on GPIO Port B pin 0 which is routed to
IOBUS8 on the V2Eval Board [7]. A jumper wire is connected from VBUS Enable on the VII Slave JP4 to
physically detect the VBUS from the USB Host.
Figure 1: Connecting VBUS Enable to IOBUS8
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Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
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2.2 Firmware Configuration
2.2.1 IOMux Configuration
Signals on VNC2 must be configured using the IOMux. In addition, FTDI provides an IOMux configuration
utility, as part of the IDE, to aid with configuring IOMux signals. For more information on IOMux and the
IOMux configuration utility, see [3] and [4].
For this implementation using a 64-pin VNC2, Pin 19 is defined as an input and is controlled by GPIO Port
B 0. The following source code performs this configuration, and sets the IO cell characteristics for the
pin. See [5] for more details.
// Route GPIO Port B 0 to pin 19
// this is used to detect a disconnect
vos_iomux_define_input(19, IOMUX_IN_GPIO_PORT_B_0);
// Also configure GPIO Port B 0 with a pull-down
vos_iocell_set_config(19,
VOS_IOCELL_DRIVE_CURRENT_4MA,
VOS_IOCELL_TRIGGER_NORMAL,
VOS_IOCELL_SLEW_RATE_FAST,
VOS_IOCELL_PULL_DOWN_75K);
2.2.2 GPIO Configuration
The VNC2 GPIO driver supports configurable interrupts. GPIO Port B is configured to interrupt when a
state change occurs on pin 0. The following source code shows how to setup interrupt 0 on GPIO Port B
to interrupt on the negative edge of the signal on Pin 0:
#define GPIOB
2
// user-defined device number
VOS_HANDLE hGpioB;
// Open GPIO port B
hGpioB = vos_dev_open(GPIOB);
// Set GPIO mask
gpio_iocb.ioctl_code = VOS_IOCTL_GPIO_SET_MASK;
gpio_iocb.value = 0x00; // all input
vos_dev_ioctl(hGpioB, &gpio_iocb);
// configure interrupt for GPIO B 0 for falling edge
gpio_iocb.ioctl_code = VOS_IOCTL_GPIO_SET_PROG_INT0_PIN;
gpio_iocb.value = GPIO_PIN_0;
vos_dev_ioctl(hGpioB, &gpio_iocb);
gpio_iocb.ioctl_code = VOS_IOCTL_GPIO_SET_PROG_INT0_MODE;
gpio_iocb.value = GPIO_INT_ON_NEG_EDGE;
vos_dev_ioctl(hGpioB, &gpio_iocb);
vos_enable_interrupts(VOS_GPIO_INT_IEN);
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
2.2.3 Monitoring the GPIO Input
An application thread is dedicated to monitoring the GPIO Port B 0 input signal. The thread blocks on a
call to VOS_IOCTL_GPIO_WAIT_ON_INT0. When the USB Slave device is disconnected from the bus, the
change in state of VBUS Enable causes an interrupt on GPIO Port B 0, and the thread is unblocked as the
IOCTL completes.
The thread sends a VOS_IOCTL_USBSLAVE_DISCONNECT to the USB Slave driver to reset the USB Slave
port. In this state, it is ready to be reconnected.
Finally, the thread calls VOS_IOCTL_GPIO_SET_PROG_INT0_MODE to re-enable the interrupt.
Note that the thread must be of sufficiently high priority that it will get to run when the GPIO interrupt
has fired, and not be starved of CPU time by other higher priority threads. Since this thread will normally
be blocked, it is safe to make this thread the highest priority in the application.
An implementation of a monitor thread is shown in the following source code:
void monitor_usb_disconnect(void) {
gpio_ioctl_cb_t gpio_iocb;
usbslave_ioctl_cb_t iocb;
while (1) {
// GPIO interrupt is configured - wait on detecting a disconnect
gpio_iocb.ioctl_code = VOS_IOCTL_GPIO_WAIT_ON_INT0;
vos_dev_ioctl(hGpioB, &gpio_iocb);
// if we get here, we've been disconnected from the host!
// put our slave back in a known state ready to be re-connected
iocb.ioctl_code = VOS_IOCTL_USBSLAVE_DISCONNECT;
iocb.set = (void *) 0;
vos_dev_ioctl(hA,&iocb);
// re-enable GPIO interrupt
gpio_iocb.ioctl_code = VOS_IOCTL_GPIO_SET_PROG_INT0_MODE;
gpio_iocb.value = GPIO_INT_ON_NEG_EDGE;
vos_dev_ioctl(hGpioB, &gpio_iocb);
}
}
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
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Contact Information
Head Office – Glasgow, UK
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
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
Web Site URL
Web Shop URL
sales1@ftdichip.com
support1@ftdichip.com
admin1@ftdichip.com
http://www.ftdichip.com
http://www.ftdichip.com
Branch Office – Taipei, Taiwan
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
E-mail (Sales)
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E-mail (General Enquiries)
Web Site URL
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tw.support1@ftdichip.com
tw.admin1@ftdichip.com
http://www.ftdichip.com
Branch Office – Hillsboro, Oregon, USA
Future Technology Devices International Limited (USA)
7235 NW Evergreen Parkway, Suite 600
Hillsboro, OR 97123-5803
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-Mail (Sales)
E-Mail (Support)
E-Mail (General Enquiries)
Web Site URL
us.sales@ftdichip.com
us.support@ftdichip.com
us.admin@ftdichip.com
http://www.ftdichip.com
Branch Office – Shanghai, China
Future Technology Devices International Limited (China)
Room 408, 317 Xianxia Road,
Shanghai, 200051
China
Tel: +86 21 62351596
Fax: +86 21 62351595
E-mail (Sales)
E-mail (Support)
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Web Site URL
cn.sales@ftdichip.com
cn.support@ftdichip.com
cn.admin@ftdichip.com
http://www.ftdichip.com
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
Distributor and Sales Representatives
Please visit the Sales Network page of the FTDI Web site for the contact details of our distributor(s) and
sales representative(s) in your country.
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
Copyright © 2010 Future Technology Devices International Limited
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
4
Appendix A – References
Document References
[1] FTDI Application Note 142, Vinculum-II_Tool_Chain_Getting_Started_Guide, FTDI, 2010.
[2] FTDI Application Note 151, Vinculum-II User Guide, FTDI, 2010.
[3] FTDI Application Note 139, IO_MUX Explained, FTDI, 2010.
[4] FTDI Application Note 144, Vinculum-II_IO_Mux_Config_Utility_User_Guide, FTDI, 2010.
[5] FTDI Application Note 137, Vinculum-II IO Cell Description, FTDI, 2010.
[6] FTDI Datasheet, Vinculum II Embedded Dual USB Host Controller IC, Version 1.2, FTDI, 2010.
[7] FTDI Datasheet, V2-EVAL Vinculum II Evaluation Board, FTDI, 2010.
Acronyms and Abbreviations
Terms
IOMux
V2EVAL
Description
Input Output Multiplexer – Used to configure pin selection on different package
types of the VNC2.
Vinculum II Evaluation Board- Customer evaluation board for the VNC2 allowing
prototype development.
VOS
Vinculum Operating System
IDE
Integrated Development Environment
VNC2
Vinculum II
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Document Reference No.: FT_000365
Vinculum II USB Slave Detecting Disconnect AN_163
Application Note Version 1.0
Clearance No.: FTDI#191
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Appendix B – Revision History
Revision
1.0
Changes
Initial Release
Copyright © 2010 Future Technology Devices International Limited
Date
2010-11-30
9