Home

Embedded Platform Software Development

Contents

1. 28 Embedded Platform Software Development 2008 05 22 distributions released which is not recommended to be used in production systems One recommended way to get a distribution up to date is to visit the website http www uclinux org pub uClinux dist When the distribution is in hand next thing to do is to get a tool chain used for building the uClinux image 5 3 Build example The first step is to install a suitable tool chain depending on which kernel one intends to build The distribution package is downloaded and unpacked using the following command line tar xzf uClinux dist xxxx tar gz Code 5 1 Command line to unpack the distribution on host system This will extract the source into an uClinux dist directory Code 5 2 shows how to add the tool chain path of the system PATH environment variable cd uClinux dist export PATH SPATH search path to the compiler of choice Code 5 2 Commands used for enter the distribution directory and add the compiler path When this is done a configuration and build can be done as follows make clean clean out the source tree 3 ake menuconfig kernel configuration alternatives ake config ake xconfig 3 3 ake dep builds the dependencies 3 ake trying to build kernel image Code 5 3 Commands used when building an image file on host PC The third command make dep is not needed if the choice of kernel
2. Problems El Console 3 Properties 4 SBC View 25 C Build HelloWorld D leg M5208EVB uClinux B a uDemoDIOFile Building target HelloWorld uDemoEmail uDenoSerial uDenoWVebCGI Wl elf2flt mnt workspace HelloWorld Release He LC SBCToolsV2 uClinux ColdFire m5 208evb RIL 1ib m5307 o HelloWorig j Hello world Helloworld o 1m5208evbrtl lc 7 lgcc Finished building HelloWorld m68k uclinux gcc msep data Figure 4 3 Figure showing the IDE of SBC Tools 4 6 1 Debugging with gdb SBCTools have a conveniently integrated debugging interface It makes use of gdb the GNU Project Debugger but hides all the inner workings of gdb and provides a neat and easy to use interface It requires that gdbserver is available on the target platform and that the application is compiled in debug mode Once those requirements are met debugging an application is pretty straightforward It allows you to set breakpoints single step through the source code view contents of variables and registers and much more All in all it s a solid debugging environment which is easy to get used to and easy to use 4 7 Custom makefile When a project grows larger it s definitely justified using an IDE but it is not always necessary One alternative is to use a text editor to write both programming code and 22 Embedded Platform Software Development 2008 05 22 makefiles A makefile is writt
3. 30 September 2002 Cited 14 May 2008 http www ucdot org article pl sid202 09 30 0523232 10 Andersen Erik A C library for embedded Linux uClibc Online 3 January 2001 Cited 14 May 2008 http uclibc org about html 11 Hertel Chris Samba Team and jCIFS Team Samba An Introduction Samba Online 27 November 2001 Cited 13 May 2008 http www samba org 12 NCSA HTTPd Development Team The Common Gateway Interface NCSA HTTPd Online 1 January 1998 Cited 13 May 2008 http hoohoo ncsa uiuc edu cgi 13 Wikipedia Common Gateway Interface Wikipedia Online February 2008 Citat den 13 May 2008 http en wikipedia org wiki Common Gateway Interface 14 Shepherd Devan Teach Yourself XML in 21 Days 2nd edition s l SAMS 2001 ISBN 0 672 32093 2 15 Wikipedia XSL Transformations Wikipedia Online 2008 Cited 5 May 2008 http en wikipedia org wiki XSL Transformations 44 Embedded Platform Software Development 2008 05 22 16 Adobe Systems Incorporated Scalable Vector Graphics SVG Zone Adobe Online 30 March 2007 Cited 5 May 2008 http www adobe com svg 17 Wikipedia Scalable Vector Graphics Wikipedia Online May 2008 Cited 5 May 2008 http en wikipedia org wiki Scalable Vector Graphics 18 Venn Brian Render dynamic graphs in SVG IBM DeveloperWorks Online 29 October 2004 Cited 15 April 2008 http www 128 ibm com developerworks xml library
4. The next technique was to use CGI to parse a data file generated by the application and then present it to the user CGI itself presents certain security issues however as it is basically an application started by the web server and any application have the potential to crash the system In the end XML and XSLT was the technique that was deemed as the most viable given that it would be the most flexible way to add data to the website It would also completely separate any formatting and layout from the data as well as not requiring having an application launch every time someone accessed the website except for Boa itself 6 1 Boa web server Boa is an open source HTTP web server working with single tasking and internal multiplexing to handle multiple connections It has support for common gateway interface CGI that allows web servers to run programs which must be separate processes automatic directory generation and automatic file gunzipping which involves unzipping files on the fly Boa was created in 1991 with the primary design goals to advocate speed and security Boa is enabled in the configuration which was used in this project shown in Figure 6 1 31 Embedded Platform Software Development 2008 05 22 Figure 6 1 Screen dump showing boa enabled using menuconfig Before building the uClinux image it can be good having a look into boa conf which can be found at uClinux dist vendors Generic httpd w
5. the MMU and if the application requires more than the allocated stack space a potential system crash is at hand This makes stack profiling a very interesting topic Erwin Authried has developed a small patch for 2 4 x uClinux kernels together with a small application that works like the ps command These tools initialize the stack area with a known value and then check how deep the stack has overwritten these values during runtime When profiling the stack of an application one can override the 4096 default size to a much larger value using the m68k uclinux flthdr command and then profile the actual stack usage for all possible runtime scenarios and then adjust the stack down as needed The kernel patch is shown in Code 4 9 diff u linux 2 4 20 fs proc array c orig linux 2 4 20 fs proc array c linux 2 4 20 fs proc array c orig Mon Nov 17 20 57 46 2003 Ttt linux 2 4 20 fs proc array c Sun Nov 16 23 10 30 2003 413 7 413 7 read unlock amp tasklist lock res sprintf butter IS 3s c d Sd d Sd Sd Slu 1u lu 1u Slu lu lu 1d 1d 21d 1d 1d 1d 1u 1u 1d 1u lu 1u lu lu lu lu lu lu 1u 1u 1u 1u d d n T51u Slu Slo lu 2lu lu Slow tlw Se sd Slaven task pid task gt comm state Qa 456 7 456 8 task gt nswap task gt cnswap task gt exit signal task gt processor task gt processor mm mm end brk 0 if mm mmput mm return res diff u l
6. 0 lt xml stylesheet type text xsl href style xsl gt lt temps gt lt temp gt 30 lt temp gt lt temp gt 25 lt temp gt temp 5 temp lt temps gt Code 6 5 Generated XML file Now that we have an XML file with the necessary data we can start with the accompanying XSL transformation file Say that we want all temperatures to be in a table with a header for each temperature reading The necessary transformations can be seen in Code 6 6 lt xml version 1 0 gt lt xsl stylesheet version 1 0 xmlns xsl http www w3 org 1999 XSL Transform xmlns http www w3 0rg 1999 xhtml xsl output method html lt Root template gt lt xsl template match temps gt lt html xmlns http www w3 org 1999 xhtml lt head gt lt title gt Temperature Readings lt title gt lt head gt lt body gt lt hl gt Temperature readings lt hl gt lt table gt EES lt th gt Temp 1 lt th gt lt th gt Temp 2 lt th gt lt th gt Temp 3 lt th gt S pu trt lt xsl for each select temp gt td xsl value of select gt lt td gt lt xsl for each gt lt tr gt 37 Embedded Platform Software Development 2008 05 22 lt table gt lt body gt lt html gt lt xsl template gt lt xsl stylesheet gt Code 6 6 XSLT style sheet used to transform an XML file Combining the XML data file with the XSLT
7. 1 2 1 2 Ethernet The board supports 10 100 Ethernet with the feature of auto negotiate connection speed and RX TX switch to adapt to the polarity of the connection With this feature no consideration regarding network cables has to be made The traffic can be overviewed with 2 LEDs on the front of the connector which is summarized in Table 2 2 1 LED State Significance Speed On 100Mbps Off 10Mbps Link Traffic On Good link Blink Traffic Embedded Platform Software Development 2008 05 22 Off No link Table 2 2 Ethernet indicator LEDs 2 1 3 BDM JTAG Port There is two possible ways for debugging the M5208EVB board One is using serial connection RS232 and the on board dBUG monitor which is stored in the first few sectors of the Flash memory The other possible way is to use the background debug mode BDM that in comparison with dBUG can have total control over the processor even after a program has crashed BDM can also be used to monitor the processor status without interfering with the execution The same header that is used for BDM can also optionally be transformed and used as a JTAG interface 1 2 1 4 Jumpers There are 16 jumpers placed on the EVB which is used together with the switches for deciding all configurations that can be done listed in Table 2 3 1 BDM JTAG selection JP1 Selects either pin 6 or pin 24 of the CN2 BDM JTAG Port to be connected to the TCLK PST
8. 2 4 kernel It was a continuation of uClinux 2 0 3x since the 2 2 Linux kernel where never really rewritten into uClinux The 2 4 kernel had numerous of additional features like USB support IrDA and QoS quality of service support to mention some As the version status is said to be final at 2 4 32 up until now that s the kernel most widely used and popular due to stability The version upgrades that is done to the 2 4 3x from now is only reported fatal bugs and similar 5 1 2 2 6 x At the time of this writing 2 6 19 is the latest kernel and the one tested during this project work but it was not elected for reasons handled in section 7 1 Additional processor support improved security upgrading networking and support for hardware acceleration are some of the things added to the 2 6 x kernel in comparison with the 2 4 x This kernel is still under development and evaluation why it will continuously be improved 5 2 Distributions A distribution contains kernel vendor tree libraries and application code The latest stable package distributed when this report is written also includes all three latest kernel versions 2 0 39 2 4 32 and 2 6 19 together with both the older uC libc and newer uClibc 0 9 27 libraries The packages are also able to support various CPU architectures like M68k ColdFire ARM Sparc Altera NIOS Xilinx Microblaze to mention some As most parts in the distribution is under continuous development there is also beta
9. Rene TS GNU Trae auer e U a GNU Target 7 Language Settings Output Directory GNU Assembler Choose GNU Disassembler Project 0000 0 0 0 0 000000000000 Less GNU Compiler Clear ee Linker GNU Linker ee Editor Custom Keywords 7 Debugger Other Executables Debugger Settings Remote deele ng Revert Panel Export Panel import Panel Save O Save project entries using relative paths Figure 4 6 Configuration window for the current project Central things to set this early in the project could look something like Table 4 3 24 Embedded Platform Software Development 2008 05 22 Category Option Recommended Setting Target Settings Linker ColdFire Linker GNU Target Output File name Optional GNU Compiler Command Line Arguments Wall m5307 GNU Linker Linker Archiver Flags m5307 elf2flt GNU Tools Use Custom Tool Commands Select Tool chain to use Table 4 3 Recommended settings for a CodeWarrior project When all settings are saved and the code is finished the next thing to do is compiling run and hopefully end up with a working program An example program source and output can be seen in Figure 4 7 helloworld c t oX po GodeWarriorrrk Console for Proc t O X File Edit Search Project Debug Tools Window i Search Project Debug Tools d j nl i Path home helloworld helloworld c Help include lt stdio h gt int
10. System was designed for Linux 2 0 and later ported to newer versions JFFS was developed by a Swedish company called Axis Communications AB The improvements listed below are a summary of improvements that came with the JFFS that eliminated the problems mentioned earlier in the text e Wear levelling e No data corruption on sudden power loss e Direct use of the MTD level APIs instead of going through the flash translation layers Wear levelling improves the problem with a limited number of write cycles by distributing the writings equally over the blocks Despite this fact flash memories should only be used as write occasional and special care should be taken with processes that writes frequently e g systems logs A functionality that makes these things possible is the log structures that store all changes made to files in the system Below is a list of what s logged for making it possible to re create files when a read is intended but also used for block erase e Identification of the file to which the log belong e Version that is unique per log belonging to particular file e Metadata such as timestamp e Data and data size e Offset of the data in the file JFFS2 second generation Journaling Flash File System were released with Linux kernel version 2 4 to overcome an issue in JFFS regarding compression and were soon the file system of choice JFFS2 manages erase blocks by using logs to assign them to lists e Aclean list only
11. break when the illegal access to the FLASH was made was to hook the FLASH CS signal to the BKPT pin on the BDM port on the board With a simple 2 way switch and a couple of resistors everything could be booted and gdb started using the USB Multilink pod and then flip the switch to route the FLASH CS signal to BKPT instead of letting the BDM pod control BKPT Executing something in bin caused a break to be triggered as can be seen below 39 Embedded Platform Software Development 2008 05 22 Program received signal SIGTRAP Trace breakpoint trap 0x40022e9a in timer interrupt irq 68 dummy 0x0 regs 0xe4a0 at arch m68knommu kernel time c 54 54 update process times user mode regs Code 7 2 A break being triggered while debugging with gdb The source of the problem was caused by the regs pointer not being given a valid value in the timer interrupt function in arch m68knommu kernel time c due to the general change of how the regs pointer is handled in the later kernel versions A dereference of the regs pointer was made with regs uninitialized which coincided with the FLASH address range causing the spurious FLASH access The regs pointer bug was fixed in a patch from Greg Ungerer on February 2007 02 09 When applying this patch everything works perfectly No more spurious FLASH accesses causing problems with the dq6 polling JFFS2 works without any problems For more information about the process of tr
12. contains valid logs if they have not been invalidated by newer ones e Adirty list contains the logs which are obsolete and can be garbage collected e A free list does not contains any logs Erases are handled by a garbage collector who is initialized as a separate thread when JFFS2 is mounted It reserves five blocks for doing garbage collection and erase blocks from the dirty list with an exception in one percent of the cases where a block is picked from the clean list to ensure wear levelling JFFS2 are also able to give compression possibilities using zlib and rubin 7 3 5 Boot loader There are lots of boot loaders on the market today both open source and commercial versions As this project started with the MCF5208EVB development board from Freescale shipped with the dBUG boot loader that was the one chosen 11 Embedded Platform Software Development 2008 05 22 In general the first task for a boot loader after power up of the processor board is to initialize hardware elements needed for the system to run and also to fetch start up code from predefined on board storage device often flash memory This start up address is often predefined and used for the initial boot loader code with the purpose for configuring the memory interfaces SDRAMs etc When the initialization steps are accomplished the boot loader s next task is to locate load and pass execution to the primary operating system There are similarities between
13. creating a development environment that is separated into two branches Software Description License Eclipse IDE Eclipse is an open source project which can be Eclipse Public found at http www eclipse org Eclipse has been License EPL modified by Intec to better support embedded and development with the ColdFire microprocessor Intec family The unique plug ins added by Intec are Automation licensed under the Intec software license and are Software not open source License GCC SBCTools includes two distinct versions of the GNU Public GCC compiler One for bare board applications License GPL and one for uClinux applications GCC is compiled by Intec against the mingw libraries for standalone execution on windows GDB Two versions of GDB are included one for serial GNU Public debugging and one for TCP IP debugging under License GPL uClinux with gdbserver uClinux uClinux is a port of the Linux operating system to GNU Public microprocessors without Memory Management License GPL Units MMU uClinux has been modified and enhanced by Intec to support features of their products and all modifications are subject to the GPL dBUG The dBUG monitor allows a target board to Intec Software download run and debug applications on the License target without the use of a Background Debug Module BDM Intec has enhanced the dBUG monitor for tighter integration with SBCTools The base dBUG source code can be downloaded from Freescale TC
14. domain com 1000 Log Communications Data to Log Window Revert Pani Figure 4 8 Connection settings to target In the target terminal the following command line is used to run the AppTRK application as a background process and with port number in this case set to be 6969 mnt flash AppTRK 6969 amp 34 Code 4 15 Command line to run AppTRK as a background process on port 6969 When running in debug mode a new window will appear giving a huge amount of helpful options A simple Hello World example which can be seen in Figure 4 9 is only scratching the surface of the possibilities offered when using AppTRK 26 Embedded Platform Software Development 2008 05 22 hello out lt tid 0 gt lt lIwpid 33 gt Stopped Project Debug Data Linux Info Tools Window Variables Live Value 1 x41C67F40 x41C67F8C x41C67F44 include lt stdio h gt int main int argc char argv printf Hello World return OQ Figure 4 9 Debugging window in CodeWarrior showing a breakpoint in the code as well as various other information relating to program execution With the debugger there is also a possibility to get the output printed in the target console which was chosen in Table 4 3 and the result is given in Code 4 16 mnt flash gt Connected on 6969 Hello World Disconnected Code 4 16 Example showing console I O output of the H
15. fopen fname r if f NULL exit 1 fscanf f d Sa s d d d d d d grd d d d d d Std d d d Bea ord d d d d d d d d grd fog Seet Schei ztd wg Seet d krd d Sa amp pid prog amp stack fclose f printf 6d 30s pid prog if q char stack iz0 while q 0xa5 i printf Sd i printf Mn closedir dir return 0 Code 4 11 Stackcheck c application code f m68k uclinux gcc m5307 o stackcheck stackcheck c Code 4 12 Compile line for stackcheck c After these steps are executed the kernel is built and downloaded see section 5 When the new kernel is up and running stackcheck is run from the target terminal preferably over NFS mnt workspace stackcheck PID Command Free Stack 1 init 3182 2 keventd 3 ksoftirqd CPUO 4 kswapd 5 bdflush 6 kupdated 20 Embedded Platform Software Development 2008 05 22 7 mtdblockd 10 jffs2 gcd mtdl 29 sh 18420 30 inetd 2979 31 boa 14239 34 rpciod 39 stackcheck 2562 Code 4 13 Output of the stackcheck application after running on the target board This original source and kernel patch can be found at http home at cgi bin viewcvs cgi midori sources debugtools src 4 6 SBCTools and Eclipse SBC Tools is put together by Intec Automation from various number of tools listed below in Table 4 2
16. more or less full virtualization of x86 architecture hardware 8 As can be seen virtualization can be a very powerful tool The ability to run multiple different machines with different operating systems on one and the same physical machine is unrivalled In the case of this thesis Linux was run as a virtual machine on top of Windows Vista with the help of an application called VirtualBox That allows making use of Linux based compilers and IDEs without having to switch to another computer 4 2 Tool chains A tool chain is a package of tools that is used when developing applications and operating systems For the subject issued in this report the tool chain should be tailored for development in uClinux Usually including what s listed in Table 4 1 Even though the development platform limits the choices there proved to be some dilemma according to which of the different versions that should be used There had to be taken in consideration that the tool chain should fit together with the uClinux distribution In the 14 Embedded Platform Software Development 2008 05 22 end there were three versions of interest and each of them is the described in the chapters below Utility Description GNU make Automation tool for compilation and build GNU Compiler Collection Suite of compilers for several programming GCC languages GNU Binutils Suite of tools including linker assembler and other tools GNU Debugger GDB Code debu
17. x svggrph 19 Surguy Inigo Client side image generation with SVG and XSLT Online Cited 25 April 2008 http surguy net articles client side svg xml 45 Embedded Platform Software Development Appendix A 2008 05 22 Appendix A Written by Matt Waddel Freescale M52277EVB On Board BDM Setup and Usage Using the following procedure I was able to setup a host to communicate with the on board BDM Host Setup 1 Download the publically available Linux Ethernet Device Drivers for P amp E devices from http www pemicro com support download_processor cfm Untar the device driver In this case the downloaded file was named pe driver ver 324 81l tar gz and it untared to the pe driver ver 324 811 directory Build and install the driver as root This version of the driver was written for kernels later than 2 6 17 I had to copy the utsrelease h file into a directory that was accessible from my compiler After these changes the devic driver installed cd pe driver ver 324 811 sudo setup sh lots of build messages Installing the WinDriver kernel module mkdir p lib modules 2 6 18 8 0 7 default kernel drivers misc cp LINUX 2 6 18 8 0 7 default i386 windrvr6 ko lib modules 2 6 18 8 0 7 default kernel drivers misc wdreg windrvr6 no Waiting 15 seconds for windriver s kernel module to load wdreg windrvr6 auto If you want everyone to access the modul chmod 66
18. 000000 put it in line with the alignment requirements and the error message disappeared Another error message that appeared especially during heavy FTP activity was MAP SHARED not completely supported on MMU The origin of this error message was traced to linux 2 4 x mmnommu mmap c on line 1452 and was generated because of a function call to mmap in the ftpd application Usage of mmap is toggled using the define HAVE MMAP in user ftpd config h A question about this was sent to the uClinux dev mailing list and the response from Jamie Lokie can be seen below 40 Embedded Platform Software Development 2008 05 22 Using mmap is just an optimisation it can save data copying time and RAM when serving files sendfile is even better than mmap but I think that s not supported in 2 4 nommu This message means mmap is refused and presumably ftpd falls back to read write That s completely safe So if you get this message every time disabling mmap in ftpd makes sense it s pointless trying to mmap If you don t get it for some files it may be worth keeping the mmap optimisation in ftpd and commenting out the printk instead keep th return EINVAL Though it might not really improve anything mmap optimisations are not always an improvement Code 7 3 Reply from Jamie Lokie about the MAP SHARED issue found in the 2 4 kernel 7 3 Issues in user land With the 20080305 distribution a few iss
19. 41 8 Conclusions E 43 Referees csse icit iura uera EE ED DR eT Us Ropa Pure AREE dee 44 Appendix ver DE 1 Appendix A oett M52277EVB On Board BDM Setup and Usage Embedded Platform Software Development 2008 05 22 1 Introduction The scope of this report is to present how a modern low cost ColdFire based system can be used to run Linux as an embedded operating system to add advanced features such as web interface ftp server etc The practical work was done in spring 2008 at Br Voss Ingenj rsfirma AB located in Boras Sweden www brv se The main purpose of the thesis work was to find a new way of presenting data produced by a measurement system running uClinux on a ColdFire v2 MCU This required an upgrade of the currently used uClinux version tool chain and user application executing in the system The new presentation of measurement data should be presented in a way so it would contain all the information the system produces and at the same time be easy to overview and easy to access As there already was a custom made program designed for handling the presentation of data from the instrument it was not a question if it would be possible to design the new interface instead the problem was how to do it in the best possible way to meet the given requirement of easy access and simplicity The main technique used is a web based approach where XML played an important role To be able to incorporate all the wanted functionality SVG
20. 6 dev windrvr6 Ck ck ckck ckckckck Ckckckckck ckckckck ck kkkkkkkk kk Ckckck ck ck ckck ko kk ck k kk kk Ckckckckckckckck o Ckockckckck ckckckckck Ckckckck ck ck ckckckck Ckckckckck kk ko kk ck k kk kk Ck ck ckck ckck KK Ckockckckck kckckck ck Ckckckckckck kck kk Ckckck ck ck ck ck ko kk ck k kk kk RKKAKKKES PEW Install has been success KKKKKKKKK KKKKKKKKKK KKKKKKKKKK KKKKKKKK KKKKKKKKK Ckckckckckckckck KKK KKKKKKK KKK KKKKKKK KKKKKKKK KKKKKKKKK KKEKKKKKKK KKKKKKKKKK KKK KKKKKKK KKKKKKKK KKKKKKKKK lsmod Module Size Used by windrvr6 160192 0 Connect the P amp E USB connector to the host Make sure the m68knommu uClinux toolchain is in your PATH As of this document it s at opt freescale usr local gcc 4 2 47 uclibc 0 9 47 m68k uclinux bin On the host determine the USB id m68k uclinux sprite i CodeSourcery ColdFire Debug Sprite Sourcery G Lite 4 2 47 pe speed n 0 31 amp memory timeout n 0 99 P amp E Adaptor pe USBMultilink PE6 USB1 USB ML CF REF Embedded ColdFire Debug PE6 Embedded Platform Software Development Appendix A 2008 05 22 7 8 9 10 11 12 The pe ccs timeout lt n gt amp speed lt n gt CCS Adaptor ccs Host Port Chain position CCS address USBMultilink PE6 is the important information you need from the previous step You ll use it in the next step Start the CodeSourcer
21. CLK signal from the M5208EVB TCLK is used when JTAG mode is enabled PSTCLK is used when BDM mode is enabled see BDM JTAG Port section JP2 This jumper is required for some of the legacy BDM cables that connect pins 9 amp 25 of the BDM interface internally More recent cables support both core amp I O voltages Please check with your BDM cable supplier The BDM cable supplied with the M5208EVB supports both core and I O voltages and requires JP5 to be fitted dBUG mode selection JP3 When fitted this jumper causes dBUG monitor to automatically load a program and run it Typically this program is uClinux When this jumper is open dBUG monitor will not run any user program and instead display the dBUG prompt on the terminal and wait for input Test mode ON OFF JP4 When fitted this jumper disables the factory test mode of the MCF5208 This jumper is normally always fitted Reset configuration switches ON OFF JP5 When fitted this jumper asserts the RCON signal and causes the MCF5208 to load the CCR register based on the signals D9 D 7 1 These signals are conditioned out of reset by the DIP switch Memory selection JP6 This jumper selects between DDR and SDR mode for the SDRAM module Embedded Platform Software Development 2008 05 22 Should always be fitted to support DDR mode Power jumpers JP7 JP8 fitted JP9 3 3V JP10 When fitted connects 1 5V to the PLL fil
22. Code 4 3 Execution command line and result from the terminal window of the target board will look like this This of course assume that mnt workspace has been mounted using NFS or Samba beforehand When a project grows lager it is almost a necessity to have a professional IDE which is being described in separate section 4 4 1 Samba To enable Linux and Windows systems to share files between them a tool called Samba is commonly used Samba is a server which runs on Linux and allows sharing of files and printers to Windows based systems It works in both directions allowing Linux based systems to access Windows shares But that is only one part of what Samba is capable of Samba is also a Linux equivalent of the business servers available for Windows It can act as an NT Domain Controller in a business network being in charge of user accounts and authentication of all the users on the network be it Windows Mac or Linux 11 16 Embedded Platform Software Development 2008 05 22 f Coda file system support advanced network fs Nl upport mounting NFS file systems Figure 4 1 Kernel and user application configuration settings to enable NFS Samba support To enable support for mounting Windows shares from Linux one need to make changes to the Linux kernel to enable the SMB file system as well as enabling support for the SMB file system in the mount command The options in question can be seen in Figure 4 1
23. K KK KR OK KK I I I I KI I IR A I OR RK kk FUNCTION writeXML INPUT iTempl iTemp2 iTemp3 Temperatures in degrees celcius OUTUT None NOTES Requires header file stdio h KOKCKCKCKCKCKCkCk kCkCk k kk Ck kk Ck kCk ck k kc k k kc k Ck kc k Ck k kc k k kc k Ck kck ck kck ck kck ck ckck kc kok kx ke ke e kx kx void writeXML int iTempl int iTemp2 int iTemp3 FILE fp fp fopen temps xml w if fp NULL return Unable to open file Write XML header and stylesheet definition fprintf fp lt xml version 1 0 gt n fprintf fp lt xml stylesheet type text xsl href style xsl 2 gt n Write root element and each of the thr temperatures fprintf fp lt temps gt n fprintf fp t lt temp gt d lt temp gt n iTempl 36 Embedded Platform Software Development 2008 05 22 fprintf fp t lt temp gt d lt temp gt n iTemp2 fprintf fp t lt temp gt d lt temp gt n iTemp3 fprintf fp temps An Flush buffer and close file fflush fp fclose fp Code 6 4 Function writeXML which is used to write three temperatures to an XML file The function shown in Code 6 4 generates an XML file with the XML header and style sheet instructions followed by a root element with three children each containing a temperature reading The result of this function can be seen below lt xml version 1
24. N QSPI_CSO 12 U1CTS PUARTL7 DT1IN QSPI CS1 13 I2C SDA PFECI2CO U2RXD 14 I2C SCL PFECI2C1 U2TXD 15 3V3 16 GND Embedded Platform Software Development 2008 05 22 Table 2 4 CN1 signal summary When handled in I O mode the pins 7 11 and 12 have a maximum source sink current of 4mA while it is 8 16mA for the other ones except 3V and ground 1 2 1 6 Power reset switches All four switches are summarized in Table 2 5 1 Switches Function Power Switch M5208EVB main power switch Reset Button Asserts the RSTI signal forcing the MCF5208 and peripheral systems to reset Abort Button Asserts the IRQ7 signal causing an interrupt in the MCF5208 This interrupt is handled by dBUG monitor Configuration Determines the out of reset configuration of the MCF5208 Switch Table 2 5 Power reset switch summary 2 1 7 DIP switch The switch can be used for reset configuration of the processor All options available are shown in Table 2 6 where the red markings are default values 1 Switches Function SW1 1 PLL Mode OFF 166 67MHz Core bus 83 33MHz External Bus operation ON 88MHz Core bus 44MHz External Bus operation SW1 2 Oscillator Mode OFF Crystal oscillator mode ON Oscillator bypass mode SW1 3 SW1 4 Boot Port Size OFF OFF 16 bit port OFF ON 32 bit port ON OFF 32 bit port ON ON 8 bit port SW1 5 Output Pad Drive Strength OFF High drive strength ON Lo
25. Once the appropriate options have been enabled and the image has been generated one can mount Windows share To do so the command below is used gt mount t smb o username User password Password computername sharename mnt workspace Code 4 4 Command used to mount Windows Samba shares 4 4 2 NFS NFS stands for Network File System and is commonly used in Linux based systems The reason why it was added to the application platform handled in this report was from the start the benefit of using cross compiling between client machine and the target board under the development phase Later during the project CodeWarrior AppTRK which are described in a separate chapter proved to be the development environment to use Still NFS is useful to share directories between two platforms in this case the host PC and the target board Before NFS can be used on the platform it has to be enabled and configured on both the host and target The first thing is to enable the NFS functionality on the target see Figure 4 1 which is optional in 20080305 uClinux distribution The directories that should be shared using NFS have to be configured on the host PC and this is done in the file etc exports as shown in Code 4 5 4 etc exports NFS file systems being exported See exports 5 home directory name 192 168 100 0 255 255 255 0 async rw no subtree check Code 4 5 etc exports showing an example of how to export a file sy
26. P IP Stack The TCP IP stack for bare board applications isa OpenTCP Bare board port of the OpenTCP stack with some License 21 Embedded Platform Software Development 2008 05 22 only enhancements and modifications by Intec Run Time The runtime library is a set of C functions which Intec Software Library RTL can be called by both bare board applications and License from within uClinux Table 4 2 From SBCTools User Manual Version 2 0 0 One of the branches is supposed to be used for development of applications which run without the need of uClinux The other one is to be used for user application development running under uClinux SBCTools was only used initially during the project hence why there is only given a short summary and a glimpse of the environment see Figure 4 3 More information can be found in the user manual for SBCTools distributed by Intec Automations DR C C Helloworld c Eclipse Platform File Edit Navigate Search Run Project SBC Window Help si m awhe A E E0 yj Ej C C rOvrQ 9 u oer 3 Debug ec 33 7 A E Helloworld c 2 Oz 0 X E include uc5208evb h rtl uclinux init ae e E amp BI uc5208evb h int main void e LE HelloWorld main H Q Binaries printf An Hello world n n H 9 Includes return 0 Les Debug Le Release e Helloworld c
27. a boot loader and the BIOS known from a traditional PC platform One thing that is special for the boot loaders in embedded systems is that it s often overwritten when OS takes control dBUG is a program that in the case of the development board mentioned above resides in the bottom of flash taking approximately 256KB in possession At startup it maps 16MB onto SDRAM as follows The lower 128KB of SDRAM is used for dBUG s vector table data and stack 0x40000000 to 0x4001FFFF Consequently this memory space is out of bounds to the user program It expects the user program to always start at 0x40020000 in SDRAM A user program can use the MCF5208 s on chip SRAM for stack space since it is very fast and dBUG does not use this memory On start up dBUG check if the JP3 is connected If JP3 is fitted ON dBUG automatically load and run a program from a defined memory start address If the jumper is open OFF one will instead enter a dBUG prompt from terminal for entering commands to dBUG Figure 3 1 Example picture of on board jumper appearance dBUG can be serviced directly through any serial consol program using RS232 interface e g Windows HyperTerminal 115200bps With the dBUG command interface running on the console one is enable to load debug and run programs without the use of specialized debug programs But also set up a couple of board parameters such as baud rate server IP and watchdog 2 3 6 Console dBUG do
28. acking down and fixing this bug see the following posts from the uClinux dev mailing list http mailman uclinux org pipermail uclinux dev 2007 August 043886 html http mailman uclinux org pipermail uclinux dev 2007 November 044695 html http mailman uclinux org pipermail uclinux dev 2007 December 044973 html http mailman uclinux org pipermail uclinux dev 2008 January 04507 6 html When the uClinux distribution was patched to 20080305 another problem occurred when using JFFS2 During file system idling error messages like Newly erased block contained word 0xXXXXXX at offset OxYYYYYYYY appeared at random This could occur at any time and the nature of the error is severe basically meaning that an erase of a block did not succeed successfully It was speculated that the error message originated from the JFFS2 garbage collector which runs while there is no or low activity on the file system A solution to this issue was never found 7 2 Issues kernel 2 4 x During boot of the 2 4 kernel a disturbing error message was posted in the beginning of the boot process stating BUG wrong zone alignment it will crash The origin of this error message was from PAGE OFFSET RAW which is defined in linux 2 4 x include asm arch page offset h For the M5208EVB board this was set to 0x40020000 This value needs to be alignment to a step of a power of 2 such that 2 PAGE_SHIFT MAX_ORDER 1 which in this case was not true A simple change ofthe value to 0x40
29. an thanks to the virtual memory be run anywhere in the virtual memory The base address of the application can be well beyond the physical memory address space and the memory used by the application can grow and shrink as necessary 2 3 2 Non MMU based CPU An MMU is a very complex device and are only available in the larger more complex CPUs Because of this you have to consider a few things when choosing a CPU More often than not it would not be required to use a powerful enough CPU that implements an MMU because the applications being run on it won t make use of the available Embedded Platform Software Development 2008 05 22 performance Another issue to consider is the memory protection features of having an MMU If the only applications running on the platform will be developed by you and made sure to work within the limitations of not having an MMU why spend the extra money to use a CPU with an MMU While on the subject on non MMU based CPUs and Linux there is actually a distribution of Linux that will run on CPUs without an MMU This distribution of Linux is called uClinux pronounced as you see Linux uClinux is a distribution specifically tailored to work on microcontrollers without the luxury of having access to an MMU It has been around since 1998 starting around the time Linux kernel 2 0 was actively used The core of uClinux along with all of the available tools and utilities has been slimmed down immensely
30. cation it is not necessary to have knowledge about how to access for example a hard drive prior to opening and writing data to a file instead you let the device driver handle the complex operations necessary to do that and rely on the much easier to use API which is available Application development for embedded Linux can be done on either a Linux or Windows host On a Linux host you have a wider variety of choices on how you wish to develop the application because of the fact that you are working in a native Linux environment with native Linux application development There are however also IDEs for Windows specifically designed to facilitate development of user application for embedded Linux 4 1 Virtual Machine The idea of running multiple machines on the same hardware is something that has been taken more seriously in recent years Previously if you wanted to run a different operating system or wanted to run a number of applications on a clean newly installed PC you had to have a physical PC available to install on With the advent of virtualization technologies that is a thing of the past Although virtualization has been around since around the 1960s when IBM used it for mainframe partitioning it has really been taken to a whole new level in the last two decades Some of the more prominent companies in virtualization technologies are VMware Connectix later acquired by Microsoft and Microsoft each having developed applications that provide
31. compared to regular Linux and a fully working image can be generated which is less than 1 MB in size using kernel 2 4 x all the while keeping much of the functionality available to users of regular Linux distributions 3 For more information regarding uClinux visit the official website at http www uclinux org 3 3 Limitations in uClinux uClinux is primarily developed to be run on MMU less devices that is to say devices without a built in memory management unit The implications of having a Linux platform without a MMU is quite severe for instance memory in an uClinux platform cannot be protected There is no virtual memory and as such running applications cannot dynamically allocate more memory during runtime because doing so might use another application s memory This limitation also applies to the application s stack In turn this means that a poorly written application could potentially crash the entire system Because of not having virtual memory memory fragmentation is a big problem Each application needs a contiguous memory space to work with and this gets increasingly difficult the longer the system is running and the more applications get started Another very important limitation in uClinux can be found in use of the fork command often used in Linux applications especially in daemons fork is a system call used in Linux to clone the application calling it creating an identical version of it running independently on the
32. e level and in case of empty elements prefer to leave the stand alone closing tag and end with a slash i As mentioned earlier the benefit with XML is the ability to transform in so many ways to best suit the use In this case the usage were decided to be web based why the XML document was transformed using XSLT in a combination with CSS style sheets to produce a webpage By adding XSLT style sheets it is possible to generate transform markup in this case XML into HTML In combination with CSS style sheet that s enough to make rather complex web presentations for the web browser to know how to use the translated content 14 15 6 2 3 Graphics using SVG SVG Scalable Vector Graphics is a language for describing two dimensional graphics and graphical applications in XML As the name implies SVG describes vector graphics Vector graphics is different compared to the more commonly used raster graphics such as that which can be seen with e g JPEG GIF or PNG formats as can be seen in Figure 6 2 The idea behind vector graphics is that each object is described in a way that no matter how much you zoom the object will always be reconstructed perfectly without any of the artefacts such as jagged edges usually seen when zooming raster images 16 34 Embedded Platform Software Development 2008 05 22 BITMAP OUTLINE jpeg gif png S Figure 6 2 A figure displaying the differences between raster graphics left a
33. e s an additional new property here which sets the opacity of the square to 7096 hence why the blue square is slightly transparent in the image below 17 35 Embedded Platform Software Development 2008 05 22 Figure 6 3 Figure showing the end result of the XML based SVG image SVG itself is a very capable graphics format but since it is based on XML it can also be combined with most of the available XML technologies One such example is the ability to generate dynamic graphs such as bar charts or line graphs To do that one can use various number of server side languages such as PHP ASP or even Java to generate the SVG file but to really take advantage of the fact that it is XML based one can use XSL transformations With an XML file coupled with a XSL style sheet it is possible to transform the XML data into a SVG based graph The transformation is not very difficult to accomplish and the result can be amazing 18 19 6 3 Practical example To showcase some of the capabilities of using XML and XSL transformations an example is in order Imagine you have a measuring application running on a target board It measures a number of temperatures at a regular interval and these temperatures need to be presented on a website For this you need to add a means to output an XML data file from the application itself This can be done pretty easily by using simple file I O operations as can be seen below KOR RR KK
34. elloworld program 27 Embedded Platform Software Development 2008 05 22 5 Customizing the uClinux image Each uClinux distribution contains a number of things First off you have the kernel which is the core of the operating system The kernel itself has many different settings relating to what type of hardware you are running it on For example it is possible to decide what type of flash device is used if you wish to have Ethernet support and in that case what type of Ethernet device you are using if you wish to have USB SPI I2C support and much more In addition to drivers for various hardware platforms there are also settings that affect how the kernel behave and operate Of course all these settings are different depending on what version of the kernel you choose In short the currently most common kernel versions are the 2 4 and 2 6 branches Also included in the distribution are a number of different user applications that can be enabled or disabled based on what type of functionality you would like to have in the final image These include a choice of shell various system utilities as well as daemons such as web server ftp server etc Once all the choices have been made what you get is a single image file which can easily be downloaded using e g TFTP or similar method to the target board 5 1 Kernel versions 5 1 1 2 4 x The kernel development began around the 20 century just slightly after the original Linux
35. en to link and compile all the project files in a structured way by just executing the command make Makefil xample on f compiler m68k elf gcc EXEC main CC m68k elf gcc LDFLAGS m5307 W1l elf2flt iDLIB lc OBJS main o loop o S EXEC OBJS CC S LDFLAGS o EXEC OBJS LDLIB main o main c CC c m5307 main c loop o loop c S CC c m5307 loop c clean rm f S EXEC elf gdb o Code 4 14 Example of a basic Makefile If either of the object to the right source of is changed later in time then the object on the left side target at make time the target is rebuilt The first execution line implies that main o and loop o shall be built before comparing their timestamp with main Which in this case will mean that if main c is newer than main o then main o will be rebuilt leading to a rebuild of main And the same thing applies for loop 4 8 CodeWarrior CodeWarrior is an integrated development environment for embedded systems It s available for Macintosh Windows Linux and Solaris based PCs CodeWarrior was originally developed for the Macintosh platform by a company called Metrowerks There has been versions including a various number of programming languages such as Pascal Object Pascal Objective C and Java but the main focus for the tool has always been C and C Around year 1999 Metrowerks was acqui
36. es not have any graphical user interface GUI and although uClinux can be configured to run a minimalistic GUI this is not commonplace So the communication between board and client machine was in this project managed via RS232 and a client terminal program named PuTTY which is shown in the Figure 3 2 12 Embedded Platform Software Development 2008 05 22 a 1 EP COM3 PuTTY EET Figure 3 2 Showing putty console window with some basic dBUG commands When the flash is programmed one uses the command gfl to run the system If everything is done properly something like Figure 3 3 shall be displayed of course depending on system and versions chosen e fe COMB PuTTY gt B Figure 3 3 The actual uClinux console after the system has fully booted 13 Embedded Platform Software Development 2008 05 22 4 Application Development In Linux you have two contexts of application execution user space and kernel space In essence what this means is that in order for a user application to be able to access kernel features it has to work through an API which itself operates in kernel space The reason to have this separation between user and kernel space is two fold First of all to make sure that user applications does not have access to critical kernel data structures and secondly to hide the complexities of accessing the hardware directly to the user application For a user appli
37. file you get the result as seen in Figure 6 4 This can with more elaborate HTML and combined with CSS styling be made to look anyway you want Temperature readings Temp 1 Temp 2 Temp 3 30 25 5 Figure 6 4 Result of transforming the XML file 38 Embedded Platform Software Development 2008 05 22 7 Issues encountered Linux although extremely powerful and flexible does have its quirks For a beginner it can be seen as a daunting task to learn to operate It is a very complex operating system and before you understand how to get around in Linux it is very possible to make some disastrous mistakes Someone once said I love Linux because it lets you shoot yourself in the foot There is nothing like pain because it makes you learn and that is very true The surest way to learn your way around Linux is by making mistakes When you finally do learn it however you have a very powerful operating system at your fingertips People who have been around Linux for a while and especially the open source community have gotten to know the hard way that if you happen to find a problem and no one else have encountered it yet you probably have to fix it yourself There s a famous expression Open source you own the problem There are many discussion forums and mailing lists where people can ask for advice but in the end you are in a way expected to find the solution to the problem yourself When doing a project inv
38. gging tool GNU build system Autoconf Autoheader Automake Libtool autotools Table 4 1 List of the tools used that comprises a tool chain 4 2 1 2 95 3 The 2 95 3 tool chain was used when compiling the application that was already running on the measurement system initially This is an old tool chain that doesn t support compilation of 2 6 x kernels but has been around for a long time and is therefore well tested The 2 95 3 tool chain can be retrieved at http uclinux org pub uClinux m68k elf tools 4 2 2 4 1 1 The 4 1 1 tool chain was the latest release at the start of this project It is therefore up to date and one can hope for a better response in case of trouble but it would not be as widely tested as 2 95 3 although that does not necessarily mean it has more issues The 4 1 1 tool chain can be retrieved at the same web address as the 2 95 3 tool chain 4 2 3 CodeSourcery 4 2 1 This tool chain was included in the package available with CodeWarrior available from Freescale It was the tool chain later used during the project because it was the only tool chain that made it possible to debug with the AppTRK application distributed alongside with CodeWarrior The CodeSourcery 4 2 1 tool chain can be retrieved at their official website http www codesourcery com 4 3 uClibc uClibc and uC libc is C runtime libraries that is developed and ported from the original GNU C library glibc used for Linux The
39. gin V Mee IBORAS INSTITUTIONEN INGENJORSHOGSKOLAN ay LO Embedded Platform Software Development uClinux on a ColdFire v2 platform Henric Eriksson Par Leandersson 2008 05 22 The Thesis comprises 15 credits and is a compulsory part in the Master of Science with a Major in Electrical Engineering with specialization in Biomedical Engineering 60 credits No 3 2008 Embedded Platform Software Development 2008 05 22 Acknowledgements We would like to extend special thanks to Martin Voss who has been our supervisor and made this project possible We also want to thank Jonas Svennebring and Stanescu Razvan Tudor at Freescale as well as people on the uClinux dev mailing list for helping us out during the project This report has been purposely stripped of product and technology specific details because of non disclosure agreements A separate document containing such details has been created which is not available to the general public Embedded Platform Software Development 2008 05 22 Abstract This thesis involves working with an embedded hardware platform based on the Freescale ColdFire v2 core namely the MCF5208EVB development board It s an architecture that allows the use of running a special branch of Linux called uClinux which is specifically tailored to run on systems without a MMU Memory Management Unit It brings certain limitations to the system which needs to be taken into consideration whe
40. hat we re proud of and it is working very well 43 Embedded Platform Software Development 2008 05 22 References 1 Intec Automation Inc M5208EVB RevB 32 bit Microcontroller User Manual Freescale Semiconductor Online 7 September 2005 Cited 8 May 2008 http www freescale com files 32bit doc ref_manual M5208EVBUM pdf 2 Hallinan Christopher Embedded Linux Primer A Practical Real world Approach s Prentice Hall 2006 ISBN 978 0 13 167984 9 3 Drabik John uClinux World s most popular embedded Linux distro linuxdevices com Online 24 September 2002 Cited 12 May 2008 http www linuxdevices com articles AT3267251481 html 4 McCullough David uClinux for Linux Programmers Linux Journal Online 1 July 2004 Cited 14 May 2008 http www linuxjournal com article 7221 5 romfs information SourceForge Online 26 June 2007 Cited 12 May 2008 http romfs sourceforge net 6 Landley Rob Linux Kernel 2 6 Documentation ramfs rootfs and initramfs 2005 7 Raghavan Pichai Lad Amol and Neelakandan Sriram Embedded Linux System Design and Development s l Auerbach Publications 2006 ISBN 978 0 8493 4058 1 8 Singh Amit An Introduction to Virtualization kernelthread com Online 9 April 2006 Cited 13 May 2008 http www kernelthread com publications virtualization 9 McCullough David Should I use uClibc or uC libc uCdot Embedded Linux Developer Forum Online
41. he flash memory is a block device which uses sectors of same or different sizes Flash memories is a non volatile memory i e when power is lost the information is not lost as in RAM memories Flash memories have relatively fast read access time but very slow write performance Flash memories have better resistance against kinetic shock than ordinary hard drives since it s a pure semiconductor device The flash memories have two major drawbacks The first is caused by what mentioned earlier about the block architecture where the blocks tends to be a lot larger than most of the files to be stored in fact it turns out that almost all of the files to be stored from the system is rather small The problem here lies within that when a flash memory shall change one of these small files then a whole block has to be copied and rewritten after that the referred file has been changed This is very time consuming in comparison with e g a hard disk drive and with that comes an increased time window for data corruption from power loss which is more common in embedded systems The second issue is the fact that the blocks sectors of a flash memory gets worn out when they are being written to and erased Today a common number for write cycles is 10 Embedded Platform Software Development 2008 05 22 around 100000 times which is quite a lot but definitely something to take into consideration 2 To solve these issues JFFS Journaling Flash File
42. here boa can be configured For this project the lines marked in the left column in Code 6 1 were changed or added to meet functionalities needed A minimal config that makes the home page an unauthenticated CGI ServerName uClinux DocumentRoot var httpd Alias img var httpd img ScriptAlias cgi bin home httpd cgi bin Auth cgi bin cgi demo etc config config DirectoryIndex index xml AddType text plain txt AddType image gif gif AddType text html html AddType text html htm AddType text xml xml AddType text xsl xsi AddType text css css AddType image jpeg jpe AddType image jpeg jpeg AddType image jpeg jpg AddType image x icon ico AddType image svg xml svg Code 6 1 Changed boa conf asterisk marks modified lines and plus marks added lines 6 2 Dynamic web pages A website can be done in many different ways the most simple being plain HTML documents Such documents are static in nature and can only be changed by editing the files directly Today the web is more interactive more dynamic and as such websites which have some form of dynamic content generation is much more common than the old ways of having static HTML documents Generating content in such websites can be done in many different ways but can be divided into two categories server side processing and client side processing 32 Embedded Platform Software Development 2008 05 22 There are many techniques tha
43. inux 2 4 20 fs binfmt flat c orig linux 2 4 20 fs binfmt flat c linux 2 4 20 fs binfmt flat c orig Thu Nov 27 09 15 29 2003 Tct linux 2 4 20 fs bintfmt flat c Thu Nov 27 09 22 20 2003 751 9 4751 11 zero the BSS BRK and stack areas memset void datapos data len 0 bss len memp ksize void memp stack len end brk E lipinfto 5213b list id start DEK S start brc stack Leni libintorslib li stlid start bDrk start brk fill stack with 0xa5 starting at end brk memset void memp ksize void memp stack len Oxa5 stack len return 0 Code 4 9 The patch written by Erwin Authried Saved as stackcheck patch To apply the patch the following command is executed uClinux dist linux 2 4 x patch p1 lt stackcheck patch Code 4 10 Command line to patch the 2 4 kernel to work with the stackcheck application 19 Embedded Platform Software Development 2008 05 22 include lt stdio h gt include lt ctype h gt include lt dirent h gt int main int argc char argv FILE f char fname 80 prog 100 char q int i pid stack struct dirent entry DIR dir dir opendir proc if dir exit 1 printf PID 30sFree Stack n Command while entry readdir dir NULL if isdigit entry d name continue sprintf fname proc s stat entry d name f
44. inux dist user busybox util linux mount c 2008 03 25 14 27 19 000000000 0100 726 6 726 7 return amp p if defined UCLIBC amp amp defined UCLIBC HAS MMU static int daemonize void 41 Embedded Platform Software Development 2008 05 22 int fd 745 6 746 12 logmode LOGMODE SYSLOG return 1 t else static int daemonize void return OF SEN endif TODO static inline int we saw this host before const char hostname Code 7 5 Patch for the busybox mount command to support non MMU architectures Debugging is an important tool to be able to use Previously mentioned is the AppTRK application which is distributed alongside of CodeWarrior Attempts was made to use AppTRK with the 4 1 1 tool chain but there was an issue with the application debug information generated by that tool chain which caused the application to fall through the debugging traps In effect this meant that debugging with AppTRK using the 4 1 1 tool chain was not possible An issue that was encountered late in the project was that the CodeSourcery tool chain did not take into account certain environment variables during compilation of the uClinux distribution package An important environment variable called FLTFLAGS is set for various user applications to tell the compiler what header flags to use for the flat binary format A flag that was commonly set using that environmen
45. is 2 6 x If the building process is done properly can take a while depending on machine 10 30 minutes the finished image can be found in the subdirectory called images 5 4 Downloading image to target There are possibly several ways to handle this step but the one used in this case was tftp which was enabled by assuring that the proper configuration were set on the host machine etc hosts allow all all etc conf d in tftpd INTFTPD PATH var tftp INTFTPD OPTS R 4096 32767 s S INTFTPD PATH 29 Embedded Platform Software Development 2008 05 22 Code 5 4 Configuration done on host PC to enable tftp This particular configuration is done on a Gentoo Linux distribution Next step would be to copy the imagez bin file into the shared directory var tftp using command cp The kernel image will be available over the network and by using dBUG on the target board see section 3 6 it is a straight forward task to download the new image as can be seen below dBUG gt set server lt host IP gt setting correct IP to host dBUG dnfl imagez bin downloading image to flash processing dBUG gt gfl used when finished to start the system Code 5 5 User commands in the target board console for downloading image 5 5 Debugging the kernel During the project some debugging on the uClinux 2 4 kernel was done using a BDM pod and gdb This effort was taken when trying to track dow
46. ity makes it possible to run Linux on virtually any hardware platform you can think of be it an off the shelf platform or a custom design In addition to being a flexible operating system it is also scalable and can be used in any device from small consumer oriented devices to large heavy iron carrier class switches and routers As opposed to many of the commercial proprietary embedded operating system Linux can be used royalty free 2 3 1 MMU based CPU An MMU or Memory Management Unit is a hardware device used to allow the kernel to manage and control the address space it uses The MMU itself is a very complex device allowing the use of so called virtual memory Virtual memory is in the simplest of terms the physical available memory plus any additional storage medium which has been designated for use as swap space In an MMU based system memory allocation does not have to be contiguous i e memory does not have to be allocated in one big chunk it can instead be allocated by using bits and pieces of the available physical memory Another important aspect of having an MMU is that the kernel can set access rights to memory segments Certain memory segments can be set as read only for instance This is especially useful when you have multiple running user applications at the same time because they cannot access the other applications memory and thus run the risk of causing a system wide crash User applications in an MMU based system c
47. main int argc char arqv printf Hello World return 0 Figure 4 7 Editor Console window 4 8 1 Debugging with AppTRK Application development is not always as simple as it may seem when looking at the previous chapters and often one will end up with errors and warnings that needs to be sorted out Freescale have equipped CodeWarrior with a tool to simplify debugging on uClinux based platforms The debugging system used is called AppTRK By downloading the AppTRK program to the target board using NFS or similar it is possible to run the AppTRK program as a background process This will give access to debug any uClinux application directly on target much like gdbserver The following example expects the AppTRK to already be compiled and downloaded to the flash directory on target In project name settings there has to be some changes done under the Debugger tab as shown in Table 4 4 Debugger Option Recommended Setting Remote Debugging Connection Edited as Figure 4 8 Remote download path tmp Console I O Settings Stdout Console I O Table 4 4 Recommended settings for the debugger 25 Embedded Platform Software Development 2008 05 22 po ColdFire Linux CW_TRK X Debugger CF Linux CodeWarriorTRK Show in processes list Connection Type TCP IP gt IP Address 192 168 100 249 6969 Enter an IP address in the format of 127 0 0 1 1000 or host
48. n and gain information about the issue discussed in section 7 2 the MAP SHARED kernel message There is also a possibility to use CodeWarrior for kernel debugging purposes but this way of debugging has not been tested during this project For more detailed information about how to do debugging with the BDM pod see Appendix A as well as the article about gdb which is available at http www ucdot org article pl sid 03 01 30 0548223 30 Embedded Platform Software Development 2008 05 22 6 Web interface The thesis involved creating a web interface containing all the information generated by the application To do this a number of different techniques of presenting the data were examined First of all a web server was needed and Boa appeared to suit the needs It s one of the web servers available in the official uClinux distribution and as such is readily available to implement Secondly a technique for presenting the data had to be selected Basically there were three options available Generating complete HTML through the application Create a CGI application to parse and present data Usethe extensive capabilities of XML files which are generated by the application and then transformed using XSLT The first option was quickly dismissed as it would require that too much formatting and layout information had to be hardcoded into the application Preferably the data had to be completely separate from any layout or formatting
49. n developing applications On the target platform a measuring application is running which generates data files that are processed and presented using a web server The data files are generated as XML files and are in the user s browser combined with an XSLT style sheet to transform the raw data into an easy to use web interface Embedded Platform Software Development 2008 05 22 Table of Contents Acknowledgements adaceiadco tardan Dana rna dx mb cct ai E D e i RD i E d Qd m ii Table of Contents ae ege de REED ctc DNA da EE ere iii EFC O GUTOR o a m 1 2 Hardware platform EN 2 2 1 MCF5208 and MCP520BEV EEN 2 Zu Eeer 3 SE 3 2 13 BDMJ TTAG PO E 4 Ze net 4 201 5 1 0 Header CNI lensmann eana a a a 5 2 1 6 Power reset SWItCeS eese ase Besa oie aan Ae aaa a dite d eae Heed 6 2 1 7 DIP swit EE 6 NEE oo aS e 7 EM E 7 2 2 Custom MCF5208 DIE OFT ergeet 7 3 Embedded LIBUX iit runi ipi eege 8 Ad MMU based GPL Loa itte abet eio etate quiescat eet tatu tense 8 3 2 Non MMU based CPU iaa etta a ea du eia Cede dpi at 8 3 3 Limitations in UCGINUX aoa tora a Ad Len ter beue 9 3 4 File systems qm WIN 2i cote ott tette teta tate niet ott ate eer 10 AL ROME m 10 SE 10 Er sglgg cm Eeer 10 Ends 11 Ee 12 4 Application Development sisissciecscsecscsninecsasecnsencesnsisnacnesaresidecetasonssersnineeetisneavsuasdtenecasinss 14 e ET 14 2 bgolchalls octies c uta A LL e M
50. n summary 2 1 MCF5208 and MCF5208EVB MCF5208EVB is a development board kit equipped with the MCF5208 processor member of the ColdFire v2 family and shipped with all development tools necessary for hands on development of both uClinux and bare metal applications The card has lots of functionalities and during this project just a couple where tested In this chapter a short description of the MCF5208EVB will be given Figure 2 1 illustrates the layout of the board Embedded Platform Software Development 2008 05 22 A 2 freescale EXT CLK semiconductor Intec Automation Inc www steroidmicros com Oscillator osc EXT CLK JP11 US VB D S BDM 1EJTAG Crystal W Ed e N O go is iL d i e o 32MB DDR SDRAM ZIGBEE UART1 AUX MI TOUT3E i TOUT2E me TOUTE mi TOUTOE Figure 2 1 M5208EVB development board layout 2 1 1 Memory The M5208EVB board has four memory types on board 16KB Internal on chip SRAM 128KB External SRAM optional 32MB External DDR SDRAM 2MB External Flash which is shipped pre loaded with the dBUG monitor the uClinux kernel and uClinux services Depending on jumper settings the dBUG either check if there is an executable OS in flash and execute uClinux or enter a dBUG prompt All the external memory devices run and interface at 2 5V This allows a single bus to interface all devices without the need for buffers and level translators
51. nd vector graphics right The layout of an SVG file is an XML document lt xml version 1 0 gt lt DOCTYPE svg PUBLIC W3C DTD SVG 1 1 EN http www w3 org Graphics SVG 1 1 DTD svgll dtd lt svg xmlns http www w3 org 2000 svg version 1 1 width 467 height 462 gt lt This is for the red square gt lt rect x 80 y 60 width 250 height 250 rx 20 fill red stroke black stroke width 2px gt lt This is for the blue square gt lt rect x 140 y 120 width 250 height 250 rx 40 fill blue fill opacity 0 7 stroke black stroke width 2px gt lt svg gt Code 6 3 Code example showing the XML behind a very simple SVG image The two rect elements each draw a square one with red and one with blue fill The result of the SVG image described in Code 6 3 can be seen below The different attributes set on the two rect objects describe how each square should look as well as positioning it in the coordinate system set up by the root element In this case we see that the first square has a width and height of 250 pixels with 20 pixels radius rounded corners has a fill colour of red and a 2 pixel wide black stroke line around it The second square has the same size and stroke properties but is positioned slightly more to the right and slightly below compared to the red square Its fill colour is blue the rounded corners are 40 pixels radius and ther
52. neltromfs in srec format cntl c Program received signal SIGINT Interrupt 0x40000a60 in gdb load tftpboot vmlinux srec 0x40020000 Loading section secl size 0x105000 lma 0x40020000 Start address 0x0 load size 1069056 Transfer rate 40 KB sec 7803 bytes write gdb c From this point you can run the recently downloaded code from the dBUG prompt Ignor any error messages that are displayed on the dBUG screen after continuing they don t seem to affect kernel operation dBUG go 0x40020000 Linux version 2 6 22 ucl gb1f6286b mattw loa gcc version 4 2 1 Sourcery G Lite 4 2 47 19 Tue Nov 6 15 01 25 MST 2007 uClinux COLDFIRE m5227x COLDFIRE port done by Greg Ungerer gerg snapgear com Flat model support C 1998 1999 Kenneth Albanowski D Jeff Dionne Built 1 zonelists Total pages 8128 Kernel command line rootfstype romfs PID hash table entries 128 order 7 512 bytes
53. of memory is limited romfs is a good choice Romfs is therefore included in almost every uClinux distribution but not always compiled in enabled The fact that it is read only means that the image has to be built beforehand and have to be rebuilt when changes are done to it It also eliminates the possibilities to use UNIX permissions But these drawbacks has proved to be not all that crucial in the benefit of space efficiency 5 3 4 2 RAMfs Linux has a number of disk caching mechanisms that it uses to cache files to memory before writing the data to disk These features have been reused to create a completely RAM based file system In the case of a normal hard drive data is read from a backing store usually the hard drive itself and is then stored in memory although marked as free able Similarly data which is to be written to files are also stored in memory for caching purposes This data remains there until the memory subsystem reallocates memory or claims it to be used for something else Ramfs makes use of this feature but instead takes away the backing store What this means is that data is cached in RAM but is never marked as free able and as such is never able to be reallocated or claimed by the memory subsystem thus creating a dynamically resizable RAM based file system 6 3 4 3 JFFS2 Flash memory is used extensively when talking about embedded systems today And the application in this thesis work is not an exception T
54. oi SPE er 14 dE D ethane aradeateea 15 pacer NM MT 15 4 2 3 COUBSOHLCOLy d Ut nase ates utu ER Sa eC 15 A O pL tetotianatatoitia ditsed een 15 4 4 Transfer executable COALS Cb S ose eaten esti enecel cried oca tefie tA os outre c 16 E ee E 16 4 CH 17 APES KONG E 18 4 5 Stack usage DEOLLIDE ee 18 4 5 5BCToolsand Eclipse esaii deo ce ale EE 21 4 6 1 regeert tte entertain iens 22 2 OG ISO Take sen ebenso ate et e M MA LS 22 A BAGO GE WY AV LUO Pee pase beset a 23 4 8 1 Debugging with ADDDRE xs usoenien rettet etre t rote istos edite tu eiu isenients 25 5 Customizing the uClinux image eese nette tn tnenn tnnt tatnen nna a tata 28 GL e 28 SQ s c 28 CM BUM qM PD ee Par Ce ORE nC eg 28 Embedded Platform Software Development 2008 05 22 5 2 DISET UELO Beete ere een AA E ien 28 2 3 B llldexamplg eege 29 5 4 Downloading image to target cao dace b e aia bte 29 5 5 Debugging the kernels sente rete te e Dette tu et dada mere 30 mn W OD MUO TBA CE ERE 31 GAG B Oa Web SC EE 31 6 2 Dynamic EE 32 MUN EE 33 UNE ENEE 33 6 2 3 Graphics using Meet 34 5 3 een 36 Te ISSUES encountered EE 39 7 1 Issues KEG Cl Osx EE citat ctt deer at ado te teta a dei unt a BA da RS 39 7 2 Issues E 40 7 3 Issues in user land esent tette tete tette tnter t itia te toto to sa so seas 08
55. olving Linux this is a big risk that has to be taken into consideration There are usually no 3rd party vendors where you can get a 24 7 support agreements without paying huge fees 7 1 Issues kernel 2 6 x An issue has been observed in the 20070130 distribution when used with the 5208 platform or any other ColdFire platform as well The problem was observed when a JFFS2 partition was written to Occasionally the following error message was printed on the console Data CRC 3flaceac calculated CRC 91126571 for node at 0014551c Code 7 1 Error message printed on console when accessing JFFS2 partition The source for the problem could be narrowed down to the case where it was observed that a spurious read to the FLASH memory was done in the middle of the busy poll of dq6 after a word write buffer write This toggle dq6 in the FLASH and fooled the code checking for a completed operating to exit prematurely Disabling the interrupts in the busy poll parts in cfi cmdset 0002 c made the error messages disappear This was however not a solution just an observation Measurements on the CS signal on the FLASH memory showed that the spurious access was made randomly when accessing files in the ROMfs stored in SDRAM Just by running for instance ifconfig caused the CS to show activity a number of times When doing the same measurements on the 2 4 27 kernel the FLASH CS was always high as expected A semi dirty way of generating a
56. red by Freescale and since then they have developed and distributed CodeWarrior Freescale chose to concentrate their continued development of CodeWarrior towards embedded systems and in 2005 the last Macintosh version was released For this particular project the Linux version of CodeWarrior IDE Version 5 9 0 Build 2482 was the one used As CodeWarrior is a sophisticated development IDE a complete description will be out of the scope of this report but the following example will show the basic functions and benefits 23 Embedded Platform Software Development 2008 05 22 CodeWarrior ta xX Search fypiec Debug Tools Window Help we Figure 4 4 Main menu of the CodeWarrior Linux version Under the tab File in the main menu showed in Figure 4 4 there is an option for creating a new project and also a new file r CD helloworld x Hie Em Search Projec Debug Tecis VAniaw Help gt gt B all elg D helloworld c Figure 4 5 Main window for the project called helloworld To add the new file into the project as in Figure 4 5 it is first necessary to make sure a linker is selected in the target settings see Figure 4 6 which can be found under the Edit tab and lt project_name gt settings helloworld Settings helloworld Target Name helloworld Access Paths Build Extras Linker ColdFire Linker Runtime Settings file Mappings Pre tiker
57. rocess databases onto the web but almost any program can be translated There are eventually two important things to take into consideration when using CGI which is the time and workload effort together with security aspects The first issue demands inquiry of intended amount of traffic and complexity of the transaction with a trade off for the functionality There are some alternatives available such as FastCGI and developed third party tools which will not be described in depth here The security has to be handled by the web server administrator and is case dependent As a simple explanation of the procedure say a user selection will give an input URL to the web server That will execute the corresponding program giving an output back to the server augmented with the proper CGI standards and handled back to the user 12 13 6 2 2 XML and XSLT XML and XSLT are markup languages which have been derived from the ancestor of all markup languages Standard Generalized Markup Language SGML To start with the XML eXtensible Markup Language were founded by World Wide Web Consortium W3C to transfer data over the web but soon gained popularity among other user groups such as economical businesses to mention one of many The strength of XML is simplicity of transferring information to suit your needs and to various types of devices XML documents are used to categorize and organize information under user defined tags of individual choice b
58. s is changed using the command ifconfig which is used to configure network interface settings see Linux manual pages for more info Code 4 7 below is an example how to change the IP address ifconfig ethO 192 168 100 10 Code 4 7 Command used to set the IP address of a network interface In this case network interface eth0 is given the IP address 192 168 100 10 The user related configuration on the ftp server shall preferably be stored at some place on flash memory and linked from etc to flash to the actual system when it s running The passwd file can be found under etc and is has a format which can be seen in Code 4 8 username password UID GID Full Name home dir bin shell Code 4 8 Format ofthe etc passwd file UID and GID are numeric representations of the user and group ID associated with the user On the client machine but not that often in embedded systems there is a shadow file that is built and can be used in a similar manner as the passwd file except this file is used to contain the encrypted passwords for all users on the system 4 5 Stack usage profiling One critical issue when working with uClinux is the growth of an user application s stack In uClinux the stack size for each application is fixed in size with a default value of 4096 bytes The stack size cannot grow during program execution due to the absence of 18 Embedded Platform Software Development 2008 05 22
59. se two libraries are supposed to be used for developing embedded Linux systems were memory usage is of great importance uClibc is smaller then glibc but still support almost every function including support for shared libraries and threading It is also compatible with a lot of the popular 15 Embedded Platform Software Development 2008 05 22 processors on the market today uC libc is even more slimmed down with the trade off that only ARM and m68k processors are supported uC libc s shared library functionality is also more limited comparing with uClibc 9 10 4 4 Transfer executable to target Cross compiling is best done one a Linux based machine At the client machine side a basic text editor of choice can be used to write the program When finished the cross complier is used to compile a binary flat file suitable for executing on the uClinux platform See Code 4 1 Code 4 2 and Code 4 3 below for a simple example The executable file can be transferred to the target with several different methods each described in the chapters below include lt stdio h gt int main int argc char argv printf Hello World return 0 Code 4 1 main c located on the host PC f m68k uclinux gcc m5307 o main main c Code 4 2 Compile command line on host PC Making an executable file called main which can be executed on the target board mnt workspace main Hello World
60. stem using NFS Note that each entry should beonasingle line without newlines After these steps are completed the last thing to do is to mount NFS on the target board as can be seen in Code 4 6 17 Embedded Platform Software Development 2008 05 22 gt mount t nfs o nolock rsize 1024 wsize 1024 192 168 100 100 home directory name mnt workspace Code 4 6 Command used on target board to mount the exported NFS file system on the host PC 4 4 3 FTP Ftp stands for File Transfer Protocol and is a standardized way to transfer files A deep explanation of how it works is outside the scope of this report and here just some basics of how to work with ftp and uClinux is given The first thing to do is enabling FTP in uClinux distribution menu configuration by enabling ftpd as shows in Figure 4 2 Ftpd is short for ftp daemon and is a name to differ ftp server from client Network Applications selects submenus gt Highlighted letters gt to exit lt gt for Help lt gt for Search Lege fees ftp IIS frox treeswan apps Figure 4 2 Screen dump from uClinux configuration enabling ftpd under network applications When the system is up and running with the ftpd enabled the best way to test is to get an ftp client to handle a simple file transfer A proper IP address together with login name and password has to be used to access the ftp server IP addres
61. system The parent the one calling fork can create many children and each child run completely independently from the parent In uClinux this system call is not available instead a similar system call is available called vfork While similar in many ways there are a few important differences vfork does create a child process but it does not make it run independently of the parent Instead the parent is suspended until the child exits or calls exec a system call used to start a new application In addition it does not have its own memory and space but instead runs on the parent s stack and is using the parent s memory and data In essence this means that a child can corrupt the parent process so that when the child exits the parent will crash To avoid this the child needs to use a special exit call exit when finished as well as making sure not to make changes to any existing global data structures or variables These limitations especially the fork vfork issue can make porting applications to uClinux incredibly easy or almost impossible 4 Embedded Platform Software Development 2008 05 22 3 4 File systems in uClinux 3 4 1 ROMs Romfs is a read only minimalistic file system that was developed for Linux but is most common when talking about uClinux nowadays The reason is that all Linux systems including uClinux needs an initial file system to run some programs at start up In the case of uClinux where the amount
62. t can be used for server side content generation The most common techniques are programming languages such as PHP ASP and various CGI languages All of them offer similar capabilities but is carried out in different ways PHP and ASP both require separate software which work alongside the web server to process the code CGI on the other hand are simply executable files which are executed by the server and generate content based on a specification Which one of these techniques are used depend mostly on personal preference but also on the capabilities of the platform and web server it s run on Embedded systems rarely have the capabilities of using one of the more powerful techniques such as PHP or ASP but instead rely on CGI Client side content generation is often combined with some sort of server side technique Examples of client side content generation can be seen with JavaScript applications or perhaps more commonly used Flash Even Java is sometimes used although more for very specific applications rather than whole websites 6 2 1 CGI Common Gateway Interface CGI was agreed on by the WC3 organization in 1995 CGI is a protocol that is used for interfacing external applications with an information server such as web servers As the name implies it s not a programming language but just a way to execute programs and scripts in real time that dynamically produces information for the web browser to process The method is commonly used to p
63. t variable was the stack size flag which is used to increase or decrease the stack size for the given application from the default value of 4096 bytes This means that all applications in the uClinux distribution were using the default stack size when compiled using the CodeSourcery tool chain which is a very bad thing 42 Embedded Platform Software Development 2008 05 22 8 Conclusions In the weeks we have been working on this project there have been many difficulties to get around as well as a lot of different things to take into consideration It has definitely not been a straightforward process but instead been a path filled with obstacles Most of them have been solved but some of them have been too technical and time consuming that we simply haven t had the time to investigate There has been a lot of reading and learning in order to successfully complete the project Things like learning about the workings of uClinux in order to make the best out of the resources at hand or learning about the different technologies available for web based presentation The biggest challenge in the project has probably been getting the uClinux kernel and user applications up and running without issues As can be seen above there were a number of different problems that we had to face and that s what took the majority of the time Developing the actual web based interface took only a fraction of the total time The end result however is something t
64. ter and to JP8 When fitted connects the processor core voltage to 1 5V JP7 must also be When fitted connects the processor I O voltage to 3 3V Also connects JP11 to When fitted connects the processor external bus voltage to 2 5V Oscillator modes JP11 This jumper selects between an external oscillator and an off board frequency source This jumper is only relevant if JP15 is in position 1 2 By default it is set to position 2 3 JP12 This jumper selects between the on board crystal or an external oscillator It is in position 1 2 by default to select the on board crystal with a 16 MHz frequency Timer jumpers JP13 JP14 JP15 JP16 This jumper connects TOUTS to a LED It is normally fitted This jumper connects TOUT2 to a LED It is normally fitted This jumper connects TOUT1 to a LED It is normally fitted This jumper connects TOUTO to a LED It is normally fitted Table 2 3 Jumper summary 2 1 5 I O Header CN1 On the EVB a 2x8 connector is located that contains signals for DMA timer QSPI IRQ and I C signals but it can also be configured as general purpose I O pins Pin Signal GPIO Alt 1 Alt 2 1 3V3 2 GND 3 DTOIN PTIMERO DTOOUT U2TXD 4 DT1IN PTIMER1 DT1OUT U2RXD 5 DT2IN PTIMER2 DT2OUT U2RTS 6 DT3IN PTIMER3 DT30UT U2CTS 7 IRQ4 PIRQ4 DREQO 8 QSPICLK PQSPIO I2C SCL 9 QSPI DOUT PQSPH I2C SDA 10 QSPI DIN PQSPI2 DREQO U2CTS 11 UOCTS PUARTL3 DTOI
65. ues were encountered in user land Another issue in the ftpd application was a bug which appeared while transferring many small files rapidly It would return odd socket errors and cause the ftpd application to crash This bug was quickly fixed and a patch for it can be found in Code 7 4 uOlinux dist 20080305 user ftpd ftpd c 2004 08 06 08 32 16 000000000 0200 uClinux dist user ftpd ftpd c 2008 04 21 11 50 56 000000000 0200 198 7 198 7 static char bufs NUM SIMUL OFF TO STRS 80 static char next_buf 80 bufs if next buf gt bufs NUM_ SIMUL OFF TO STRS if next buf gt bufs NUM_SIMUL OFF TO STRS next buf bufs if sizeof off sizeof long Code 7 4 Patch for ftpd to correct a pointer issue In addition the busybox have a version of the mount command and in the source was added a function to be able to daemonize the mount operation to perform a mount in the background This operation relied on the fork system call which as previously discussed is not available on non MMU based systems It was not a simple task to replace fork with vfork so instead a workaround was devised where a separate empty function was defined if it was compiled without MMU support This new function simply returns 0 in effect disabling the functionality of the daemonize feature uClinux dist 20080305 user busybox util linux mount c 2008 03 25 14 59 50 000000000 0100 uCl
66. ut with a strict specification of rules to follow When you got an XML document that complies with the specifications there are several ways to transform the information into e g a graphical view using style sheets or synthetic speech for vision impaired people as an example The following properties are all met by the XML standard and give a good summary of the benefits 33 Embedded Platform Software Development 2008 05 22 e Extensible It can be tailored or customized for specific applications e Open It s well documented and widely available e Non proprietary It uses standard form of notations that s free for all and widely used lt xml version 1 0 lt persons gt lt person username JS1 gt lt name gt John lt name gt lt family name gt Smith lt family name gt lt person gt lt person username MI1 gt lt name gt Morka lt name gt lt family name gt Ismincius lt family name gt lt person gt lt persons gt Code 6 2 Code example showing a simple XML document structure In this case lt persons gt is the root element which have two children which in turn have two children Each root child describes a person with a name and a family name Code 6 2 covers the XML document well Everything needed to create a basic XML sheet is the declaration root element and handling the opening and closing tags with great care according to uppercase sensitivity opening closing at the sam
67. w drive strength SW1 6 LIMP Mode OFF Normal operation PLL drives internal clocks ON LIMP mode low power clock divider drives internal clocks SW1 7 Oscillator Frequency Select OFF 16MHz is used as input to processor ON 16 67MHz is used as input to processor SW1 8 Chip Select Configuration OFF A 23 22 A 23 22 ON A 23 22 FB_CS 5 4 Table 2 6 Summary of the different DIP switches Embedded Platform Software Development 2008 05 22 2 1 8 Watchdog Timer In case a program enters an unexpected state there is a watchdog timer WDT implemented in the MCF5208 to time out and generate a reset If the watchdog is enabled it cannot be disabled without resetting the MPU And an enabled WTD also has to be serviced periodically by writing a 0x5555 and OxAAAA sequence to a watchdog service register to avoid the reset 1 2 1 9 ZigBee ZigBee is a wireless communication protocol with low power consumption A MC13192 ZigBee Capable Transceiver chip and printed circuit board antenna have been integrated on the M5208EVB with the purpose to have the possibility of evaluating it together with the MCF5208 processor 1 2 2 Custom MCF5208 platform Because of the non disclosure agreements regarding this project no detailed information about the measurement platform is given in this report The hardware is built around the same microprocessor as the EVB card and in a very similar manner with some exceptions in memory si
68. was added to expand the functionality to include graphics drawing Embedded Platform Software Development 2008 05 22 2 Hardware platform The ColdFire family plays a key role for Freescale s Motorola s semiconductor division changed name to Freescale 32 bits microprocessor family which has been frequently used in the electronic industries for around ten years They have gained trust and popularity due to flexibility in terms of memories system modules and communications peripherals Freescale gives the opportunity to buy product solutions ready to integrate use and debug Many devices support several connection alternatives such as Ethernet USB CAN and PCI coupled with sophisticated development tools And in a broad range of price and performance these things will most likely have ColdFire stay in the front and keep expanding A summary of the different ColdFire versions can be seen in Table 2 1 Version Launch year Description v1 2006 12 years A cut down version of the v2 It is designed to after the original easily replace the 8 bit Freescale 68HC08 ColdFire processors and compete with low end ARM chips v2 1994 The original ColdFire core Single issue pipeline no MMU no FPU v3 Added an optional MAC unit v4 Limited superscalar core v4e also 2000 Enhanced version of the v4 Adds optional MMU called ev4 FPU and enhanced MAC unit to the architecture v5 Fully superscalar core Table 2 1 Coldfire versio
69. y debugger included with the toolchain Run the If the m68k uclinux gdb GNU gdb Sourcery G Lite 4 2 47 6 6 50 20070821 cvs Copyright C 2007 Free Software Foundation Inc GDB is free software covered by the GNU General Public License and you are welcome to change it and or distribute copies of it under certain conditions Type show copying to see the conditions There is absolutely no warranty for GDB Type show warranty for details This GDB was configured as host i686 pc linux gnu target m68k uclinux For bug reporting instructions please see lt https support codesourcery com GNUToolchain gt gdb target remote m68k uclinux sprite pe USBMultilink PE6 Remote debugging using m68k uclinux sprite pe USBMultilink PE6 m68k uclinux sprite Opening P amp E USBMultilink port 1 USB1 USB ML CF REF Embedded ColdFire Debug PE6 m68k uclinux sprite Missing config file this may not work m68k uclinux sprite Target reset 0x00000000 in dBUG bootloader installed in flash It should run to a dBUG gt prompt gdb set pc 20x400 gdb c Continuing dBUG gt code is binary you can convert it to an srec file with this command m68k uclinux objcopy O srec I binary vmlinux bin vmlinux srec m68k uclinux objcopy O srec I binary image bin image srec cp vmlinux srec tftpboot cp image srec tftpboot Halt execution with a cntl c and download the kernel or ker
70. ze and peripherals An overview of the platform is shown in Figure 2 2 P o Le w ADC oC e UO expanders r Expansions PCB RTC p 2s CPU n LCD Interface d SPI Panel interface B etc lt D X SDRAM Ethernet RS232 USB 32Mbyte Figure 2 2 Project platform Embedded Platform Software Development 2008 05 22 3 Embedded Linux Linux has been in use in PCs around the world for many years Even from its early days Linux was ported to be run on the handheld computer PalmPilot and has since been ported to a whole range of different architectures It has turned out be a mature high performance and stable alternative to other operating systems Nowadays you can find Linux running on a myriad of different embedded products such as mobile phones PDAs networking products printers etc and its usage areas continues to expand Linux is an extremely flexible operating system it can be tailored to almost any architecture Since the only thing that is in direct contact with the hardware is the kernel that s what has been customized to work on a myriad of different hardware platforms each requiring slight adjustments to work The source code for all this is openly available and can be modified to support new hardware given enough knowledge of C programming and of the kernel s internal workings All this flexibil

Download Pdf Manuals

Related Search

Related Contents

3A2088C Matrix 3.0 Basic Software Installation, Setup  SATA - IDE CONVERTER User Manual  lnstallation manual cateqorv AQ (aluminum mudguards)  USER MANUAL  Acer 505 series Laptop User Manual  Manuel d`utilisation du logiciel Interact  Hasbro 98057/98047 Games User Manual  Keys Fitness MS3200GT User's Manual  Westinghouse LCM-27w4 Computer Monitor User Manual  Télécharger La Castellane - juin 2012  

Copyright © All rights reserved. Failed to retrieve file