an SPI Master to UART bridge

Application Note
AN_195
Vinculum-II UART to SPI Master
Bridge
Version 1.0
Issue Date: 2011-11-15
This application note forms part of a series of application notes detailing the
new simplified ROM images for VNC2. It will detail the implementation and
use of a VNC2 ROM file for bridging a UART interface to an SPI Slave device
connected to a VNC2 SPI Master interface.
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.
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 © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
Table of Contents
1
Introduction .................................................................................................................................... 2
1.1
VNC2 Devices .......................................................................................................................... 2
2
Using the Sample Code ................................................................................................................... 3
3
Default Pin-out ................................................................................................................................ 4
4
Building and Loading the Firmware into the VNC2......................................................................... 6
5
4.1
Build ........................................................................................................................................ 6
4.2
Load ......................................................................................................................................... 6
4.3
Loading with FT_Prog.............................................................................................................. 7
Source Code for the VNC2 Application ........................................................................................... 8
5.1
6
UART_SPIM.C .......................................................................................................................... 8
5.1.1
main() .............................................................................................................................. 8
5.1.2
iomux_setup() ................................................................................................................. 8
5.1.3
Open drivers/close drivers .............................................................................................. 8
5.1.4
UARTSPIM ....................................................................................................................... 9
5.1.5
SPIMUART ....................................................................................................................... 9
Contact Information...................................................................................................................... 10
Appendix A – References ...................................................................................................................... 11
Document References....................................................................................................................... 11
Acronyms and Abbreviations ............................................................................................................ 11
Appendix B – List of Tables & Figures ................................................................................................... 12
List of Tables ..................................................................................................................................... 12
List of Figures .................................................................................................................................... 12
Appendix C – Revision History .............................................................................................................. 13
1
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
1 Introduction
FTDI have introduced a new suite of simplified “bridging” ROM files to allow for fast interconnect
between differing interfaces. These ROM images (and sample source code) are targeted at those
users who would like to implement VNC2 into a design without creating their own firmware.
As well as providing the source code for users wishing to modify setup parameters the default
project is supplied as a precompiled ROM file ready for installation into the VNC2.
This application note forms part of a series of application notes detailing the new simplified ROM
images for VNC2. It will detail the implementation and use of a VNC2 ROM file for bridging a UART
interface to an SPI Slave device connected to a VNC2 SPI Master interface. This particular project
may be used in 32, 48 or 64 pin packages.
For users not intending to edit the code in any way the precompiled code may be loaded over the
UART interface with FT_PROG as an alternative to using the IDE. Links for the project file
UART_SPIM.vproj and the precompiled ROM file UART_SPIM.rom file may be found at the end of
the document in Appendix A.
1.1 VNC2 Devices
VNC2 is the second of FTDI’s Vinculum family of embedded dual USB host controller devices. The
VNC2 device provides USB Host interfacing capability for a variety of different USB device classes
including support for BOMS (bulk only mass storage), Printer and HID (human interface devices).
For mass storage devices such as USB Flash drives, VNC2 transparently handles the FAT file
structure.
Communication with non USB devices, such as a low cost microcontroller, is accomplished via
either UART, SPI or parallel FIFO interfaces. VNC2 provides a new, cost effective solution for
providing USB Host capability into products that previously did not have the hardware resources
available to do this.
VNC2 allows designers to develop their own firmware using the Vinculum-II software development
tool suite. These development tools provide compiler, assembler, linker and debugger tools
complete within an integrated development environment (IDE).
The Vinculum-II VNC2 family of devices are available in Pb-free (RoHS compliant) 32-lead LQFP,
32-lead QFN, 48-lead LQFP, 48-lead QFN, 64-Lead LQFP and 64-lead QFN packages For more
information on the ICs refer to http://www.ftdichip.com/Products/ICs/VNC2.htm.
2
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
2 Using the Sample Code
3V3
VREGOUT
1V8 PLL IN
UART DATA
VNC2
XTIN
XTOUT
DEBUGGER I/F
SPI MASTER
DATA
SPI SLAVE
DEVICE
TEST
UART
DEVICE
VCCIO
3V3VREGIN
RESET
PROG#
1V8
12MHz
GND
Figure 2.1 Connecting the Demo
When the VNC2 is programmed, the user simply passes data from the UART device to the VNC2.
The VNC2 will process this data to pass it out to the SPI Slave device via the SPI Master interface.
Similarly any data passed from the SPI Slave device via SPI Master interface to the VNC2 will be
processed by the VNC2 and passed out the UART port to the UART device.
There are no additional commands required it is a simple data bridge.
The project default sets the UART to 9600-8-N-1 (RTS/CTS flow control).
The project uses VNC2 SPI Master interface. The default interface sends data most significant bit
first, with a clock speed of 50kHHz. The mode is SPI mode 0.
3
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
3 Default Pin-out
The VNC2 can assign the same signal to a variety of pins. The default pins used for this ROM
image are shown in Table 3.1:
Signal
32-pin pkg
48-pin pkg
64-pin pkg
Description
GND
1, 16, 19, 27
1, 24, 27, 39
1, 30, 35, 53
Device ground supply pins
3V3 VREGIN
2
2
2
1V8 VCC PLL IN
3
3
3
GND PLL
6
6
6
VREG OUT
7
7*
7
+3.3VDC supply to the regulator
+1.8VDC supply to internal clock
multiplier
Requires 100nF decoupling
capacitor close to pin
Device analog ground supply for
internal clock multiplier
+1.8VDC output from regulator to
device core
*Not used on 48-pin LQFP package
VCCIO
13, 22, 28
17, 30, 40
21, 38, 54
+3.3VDC supply to I/O interface
pins (IOBUS)
VCCIO must be connected for
proper operation
Input to 12MHz Oscillator
XTIN
4
4
4
Connect 12MHz crystal across pins
4 and 5 with proper loading
capacitance
Output from 12MHz Oscillator
Connect 12MHz crystal across pins
4 and 5 with proper loading
capacitance
XTOUT
5
5
5
TEST
8
8
8
Test – Must be connected to GND
for normal operation
RESET#
10
9
9
Can be used by an external device
to reset VNC2
PROG#
9
10
10
Asserting PROG# enables program
mode
DEBUGGER I/F
11
11
11
I/O for programming and in-circuit
debugging
spi_m_clk
29
20
61
SPI master clock input
spi_m_mosi
12
21
62
Master Out Slave In Synchronous
Data from master to slave
4
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
Signal
32-pin pkg
48-pin pkg
64-pin pkg
Description
spi_m_miso
14
22
63
spi_m_ss_0#
15
23
64
Active low slave select 0 from
master to slave 0
spi_m_clk
UART RXD
24
32
40
UART data input to VNC2
UART TXD
23
31
39
UART data output from VNC2
UART RTS#
25
33
41
UART CTS#
26
34
42
Master In Slave Out Synchronous
Data from slave to master
UART RTS# output from VNC2
Logic 0 implies the VNC2 can
accept more data
UART CTS# input to VNC2
Logic 0 allows the VNC2 to send
more data on UART TXD
Table 3.1 VNC2 Pin-Out
Designers wishing to customize the design should refer to the iomux.c file for changing pin-out
options.
5
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
4 Building and Loading the Firmware into the VNC2
Everything can be controlled by the IDE. To access the application simply use the Project -> Open
tab to browse to the UART_SPIM.vproj file for your project.
Figure 4.1 Vinculum-II Project Open Button
4.1 Build
This step is only necessary if you are not using the precompiled version of the ROM. Otherwise
proceed to loading the ROM file.
To build the application you simply press the Build button on the IDE ribbon bar under the build
tab.
Figure 4.2 Vinculum-II IDE Build Button
4.2 Load
Loading the code is equally simple. Just click on the “Flash” button on the ribbon bar under the
debug tab. The Flash button will automatically pick up the Rom file in your project but for
reference the filename is UART_SPIM.rom.
Figure 4.3 Vinculum-II IDE Flash Button
Note the Debugger Interface is listed as V2EVAL Board C. It is important that this box shows a
device is connected before attempting to flash a device.
6
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
4.3 Loading with FT_Prog
If the precompiled ROM file meets all the requirements of the end design then the IDE and source
code are not required. The precompiled UART_SPIM.rom file may be loaded into the VNC2 with
FT_PROG over the UART interface.
FT_Prog is used to program the VNC2 with a ROM file. FT_Prog is available from the FTDI website
utilities page (version 1.12 or later supports VNC2).
Select the flash ROM tab at the top of the window.
Select VNC2 from the pull down tab.
Select D2xx or VCP interface (either will work).
Select the location where the ROM file resides.
Press the program button.
Perform a hard reset (power cycle) prior to running the firmware.
Figure 4.4 is an example of programming the VNC2 Evaluation board revision 2 with the V2DAP
firmware.
Figure 4.4 FT_Prog Programming Utility
For more information on loading ROM files onto a VNC2 device refer to:
AN_159_Vinculum_II_Firmware_Flash_Programming.pdf
7
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
5 Source Code for the VNC2 Application
This section is aimed at those wanting to learn about coding VNC2 devices or modifying the
existing project.
All VNC2 application firmware follows a similar format and most of the code can be “written” using
the IDE application wizard.
The basic steps are:
1. Initialise device drivers
2. Define pin-outs
3. Open ports to be used
4. Configure ports to be used
5. Read/write data
6. Close ports
The VNC2 source code for this project can be viewed in appendix A and can also be downloaded
free from the FTDI website.
5.1 UART_SPIM.C
UART_SPIM.c is the main firmware file. This file is split into multiple functions.
void
void
void
void
void
void
5.1.1
main();
iomux_setup(void);
open_drivers(void);
close_drivers(void);
UARTSPIM();
SPIMUART();
main()
Main is the entry point for all VNC2 applications. It is used to definethe VNC2 core clock speed,
loads the drivers to be used and creates the threads to be used in the application. At the very end
of main is the call:
vos_start_scheduler();
After this call there can be no further configuration of the device.
5.1.2
iomux_setup()
iomux_setup calls a function in the file UART_SPIM_iomux.c within the project; this file is used to
define the VNC2 pin-out. Most signals can be programmed to appear on different pins;notable
exceptions are power, GND and the USB ports.
5.1.3
Open drivers/close drivers
The open drivers function call will provide a handle to each hardware block used in the project and
this handle can be used by subsequent commands to control the hardware. The close_drivers
function is used to close handles to all open devices.
8
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
5.1.4
UARTSPIM
5.1.5
This function will configure the UART port 9600-8-N-1 (RTS/CTS flow control).
The function will also read data from the UART port and write it out to the SPI
Slave device via the SPI Master interface. In this function a semaphore is used to
control access to the SPIMUART thread. In this way the application will never
transfer data before interface configuration is complete.SPIMUART
This function will read from the SPI Slave device connected to an SPI Master interface and write
out to the UART. Data is read from the slave at the same time that data is written to the slave.
Therefore data can only be received from the slave when data is written to it.
9
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
6 Contact Information
Head Office – Glasgow, UK
Branch Office – Hillsboro, 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)
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)
[email protected]
[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 408, 317 Xianxia Road,
Shanghai, 200051
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
10
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
Appendix A – References
Document References
Application and Technical Notes available at
http://www.ftdichip.com/Support/Documents/AppNotes.htm
VNC2 Datasheet
V2-EVAL datasheet
Vinculum II Toolchain
AN_139 IO_Mux explained
AN_151 Vinculum II User Guide
AN_159_Vinculum_II_Firmware_Flash_Programming.pdf
Project source code download
http://www.ftdichip.com/Firmware/Precompiled/UART_SPIM.zip
Project precompiled ROM file download
http://www.ftdichip.com/Firmware/Precompiled/UART_SPIM.ROM
Acronyms and Abbreviations
Terms
UART
USB
USB-IF
Description
Universal Asynchronous Receiver Transmitter
Universal Serial Bus
USB Implementers Forum
11
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
Appendix B – List of Tables & Figures
List of Tables
Table 3.1 VNC2 Pin-Out ....................................................................................................... 5
List of Figures
Figure 2.1 Connecting the Demo ........................................................................................... 3
Figure 4.1 Vinculum-II Project Open Button ........................................................................... 6
Figure 4.2 Vinculum-II IDE Build Button ................................................................................ 6
Figure 4.3 Vinculum-II IDE Flash Button ................................................................................ 6
Figure 4.4 FT_Prog Programming Utility ................................................................................. 7
12
Copyright © 2011 Future Technology Devices International Limited
Application Note
AN_195 Vinculum-II UART to SPI Master Bridge
Version 1.0
Document Reference No.: FT_000542
Clearance No.: FTDI#235
Appendix C – Revision History
Document Title:
AN_195 Vinculum-II UART to SPI_Master Bridge
Document Reference No.:
FT_000542
Clearance No.:
FTDI#235
Product Page:
http://www.ftdichip.com/Products/ICs/VNC2.htm
Document Feedback:
Send Feedback
Revision
1.0
Changes
Initial Release
Date
15/11/11
13
Copyright © 2011 Future Technology Devices International Limited