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performance evaluation of embedded linux on

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2. 230MHZ Nominal frequency of 200MHz maximum 266MHz RAM Memory 64MByte PC133 SDRAM 32bit Bus Width Bus frequency 100MHZ FLASH Memory Nand Flash Small Page 512B Page 64MByte Other hardware interface 10M Ethernet interface Bus expansion IDE interface 25 16bit data bus Abit address bus 2 chip select signals External Interrupt Read and write signals Reset signal GPIO expansion port SPI IIC 4 channel ADC 3 external interrupt signal LCD expansion interfaces 24bit true color with touch screen interface SD card interface RS232 serial port USB HOST interface USBI 1 USB DEVICE Interface USBI 1 Stereo audio output interface Microphone interface JTAG standard 20PIN interface 2 54mm pitch 5V Power Supply 5 1 2 Software Specifications Linux Kernel 2 4 VIVI Bootloader Y AFFS File System JFlash for programming bootloader in PC side SJF Downloader 26 5 2 Installation Steps 5 2 1 Installing the vivi bootloader using JTAG SEC JTAG FLASH SJF can program SMDK2410 flash memory K9S1208 E28F128 through JTAG port and read write data from to a specified address For this purpose we need to install GIVEIO SYS file Only for this operation a host running Windows OS is used 5 2 1 1 Installing GIVEIO SYS In windows NT 2000 XP an application cannot access any I O such as the parallel port So GIVEIO SYS enables SJF exe to access the parallel port without any memory
3. Applications Places System amp root 21 5 14PM 4 Gnuplot farm 2c start txt using 1 2 Farm no load txt using 1 2 untitled folder 88 root localhost ax2c jpeg INVERTED 2 arm 2c arm Fig 11 3 Gnuplot of force v s time for ARM with varying load 3 Applications Places System BOSE 4 root Tue Apr 21 516 4j Gnuplot farm 2c start txt using 1 3 farm no load txt using 1 3 untitled folder root localhost ax2c jpeg INVERTED PEN arm 2c arm n Fig 11 4 Gnuplot of theta v s time for ARM with varying load 55 6 Applications Places system 4 amp root Tue 21 5 18PM 4 Gnuplot farm_2c_2sref txt using 1 2 farm no load txt using 1 2 2 funtitled folder 88 root localhost _ ax2cjpeg INVERTED PEN arm 2c arm n gplt JI Fig 11 5 Gnuplot of force v s time for ARM with varying load with 2 sec refresh Applications Places System amp root Tue 21 5 21 4 Gnuplot farm 2c 2sref txt using 1 3 farm no load txt using 1 3 untitled folder root localhost 2 INVERTED arm 2c 2sref im gplt Fig 11 6 Gnuplot of theta v s time
4. d_theta 0 dt 0 008192 n 0 acc 0 m 0 t 0 g 9 8 fail 0 if f 0 sesS A LO e 2 INDICATE FAIL OR READY B if fail 1 printf E fasm cli goto isr else printf printf Mn itt fe x sgyYNC PROTOCOL END BEGIN x if fail 0 while UCSRA 7 20 while 5 1 scanf c amp f i if i lt 5 while UCSRA 7 0 itt 68 KKK KKK KKK THE ACCN END 1 0 amp 2 if 1 SCALE acc 10 accn g 9 8 put 1 FORCE RECD SEND THETA VALUES VALUE OF ACCELERATION FROM ARM END x kk oe e x e e e e e e e e e x f VALUES OF THETA D THETA ARM Xxx if put 1 if fail 0 send theta int theta 180 0 3 142 degrees send d theta int theta 10 0 180 0 3 142 1 by 10 degrees if send_theta gt 0 prinkt 0 PADDING SIGN AND ZEROES else printf 1 send theta send theta if send_theta lt 10 print 0 printf d send theta if send d theta 0 PADDING SIGN AND ZEROES prantf 0 else printt 1 send d theta send d theta if send d theta 100 if send_d_theta lt 10 pruntf
5. 20 0 22940 0 20 0 229 0 inetd 35864 0 reboot 0 16 33 5 26488 gdbserver 7 52 33720 ping x 3 TER sz 62544 expand 7 0 22600 home 6 5 0 0 link to Ox20 1 link to 1 link 0x20 1 0 0 link to Oxfce00 1 Fig 3 4 Screenshot of completion of make step Once the kernal images are made the images are stored in uClinux dist images directory copy the skyeye conf file to images and edit romfs img to boot rom cpu arm7tdmi mach at91 mem bank type RW addr 0x00000000 size 0x00004000 mem bank map M type RW addr 0x01000000 size 0x00400000 mem bank map M type R addr 0x01400000 size 0x00400000 file boot rom mem_bank map M type RW addr 0x02000000 size 0x00400000 mem_bank map M type RW addr 0x02400000 size 0x00008000 mem_bank map M type RW addr 0x04000000 size 0x00400000 mem_bank map I type RW addr 0xf0000000 size 0x 10000000 net type rtl8019 mac 0 4 3 2 1 f ethmod tuntap hostip 10 0 0 1 net type rtl8019 16 ethmod tuntap hostip 10 0 0 1 dbct state on 10 execute the file as images e linux 8 18 builtin Atme a builtin Atmel mount t proc pr te dev Sash command shell versic Fig 3 5 Screenshot of the Skyeye simulator 3 3 5 Running a Sample Program on uClinux The following are the steps to be taken to run a program on uCl
6. 5 2 Running command on the vivi command line esee 30 Fig 7 1 Schematic for Inverted Pendulum 33 Free Body Diagram 34 Fig 7 3 Flowchart for inverted pendulum model seen 37 Fig 9 1 Timing diagram of asynchronous mode eese eene 42 Fig 9 2 Serial port architecture in 3C2410 essere 44 Fig 9 3 Minicom setup screenshot enne 45 Fig 9 4 Screenshot of Baud rate setting in Minicom essen 46 Fig 11 1 Gnuplot of force v s time for desktop and sisse 54 Fig 11 2 Gnuplot of theta v s time for desktop and ARM sse 54 Fig 11 3 Gnuplot of force v s time for ARM with varying load sss 55 Fig 11 4 Gnuplot of theta v s time for ARM with varying load sss 55 Fig 11 5 Gnuplot of force v s time for ARM with varying load with 2 sec refresh 56 Fig 11 6 Gnuplot of theta v s time for ARM with varying load with 2 sec refresh 56 vii 5 The aim of the project is to build an application to test the real time performance of the ARM processor The inverted pendulum is chosen as the application because it is a very good benchmark for testing any control algorithm An approximate mathematical model of the inverted pendulum is developed on Atmega8535 The controlling algorithm is run on the ARM board which controls the inverted pendulum The project also involves sim
7. This pipeline remained unchanged from the first ARM processor to the ARM7TDMI core 4 4 2 The 5 stage pipeline The 3 stage pipeline has the problem of pipeline stall when a memory read or write operation is going on and the next instruction is to be fetched The solution to this problem was to use a separate instruction and data cache First to make the pipeline more balanced ARM9TDMI moved the register read step to the decode stage since instruction decode stage was much shorter than the execute stage Second the execute stage was split into 3 stages The first stage performs arithmetic computations the second stage performs memory accesses this stage remains idle when executing data processing instructions and the third stage writes the results back to the register file This results in a much better balanced pipeline which can run at faster clock rate but there is one new complication the need to forward data among pipeline stages to resolve data dependencies between stages without stalling the pipeline The ARM10 and ARM11 came up with the 6 stage and the 8 stage pipeline 9 24 5 THE ARM TARGET BOARD 5 1 Specifications The ARM target board is a SMDK2410 MERITECH board The following are its specifications 5 1 1 Hardware Specifications Control Unit Samsung S3C2410A CPU ARM920T 5 Stage pipeline design 16 KByte Instruction cache 16 KByte Data cache Operating speed
8. 0 i 7 i return 0 e J RR e e e e e e e e e e e e e x THE MAIN FUNCTION e ke e ke e e int main int argc char argv rLocal variables are initialized x FILE fpl fp2 int deri theta int op theta int prev theta int prev deri theta int w r int i j 7 char result 8 receiveb 2 sendz 7 The value of Theta Proportional constant float 1 17 The value of Deri theta Proportional Constant float kp2 1 5 The value of Theta Derivative constant float 1 10 The value of Deri Theta derivative constant float kd220 7 0 theta 0 prev theta 0 deri theta 0 prev deri theta 0 fe e o local variable initializatiens ends w x xwxwk k x JR eoe ee ke e eR eee oe oe oen serial port processors wo open dev ttyS1 O RDWR O NDELAY if fd 1 perror open port Unable to open dev ttyS1 return 1 else font l fd 5 0 64 the previous baud rate set current baud rate printf baud d n getbaud fd initport fd printf baud d n getbaud fd RK e e e e e e e e Ok Open files for data loggirg 4 oboe ooo oor theta txt is a file use
9. 2 1844425 5vd 5 4 a i 5 3 a i m m oto APPENDIX IV SCHEMATIC FOR ATMEGA8535 BOARD 5440 299140 bee ONS QNO UNO 001053 83 APPENDIX V WHETSTONE BENCHMARK TOOL History The Whetstone programs were the first general purpose benchmarks that set industry standards of computer system performance The Whetstone benchmark tool measures the floating point arithmetic performance of the target processor It was first developed in FORTRAN by Harold Curnow in 1970 s Since then it has been modified and converted into other popular languages such as C numerous times to make it compatible with various processors Working and Use The Whetstone benchmark was the first intentionally written to measure computer performance and was designed to simulate floating point numerical applications Whetstone programs also address the question of the efficiency of different programming languages an important issue which is not covered by more contemporary standard benchmarks The latest C version of the benchmark has the following features e It contains a large percentage of floating point data and instructions high percentage of execution time approximately 50 is spent in mathematical library functions lt math h gt The majority of its variables are global Hence the test will not show up the advantages of architect
10. 2 Approximate Model of the Inverted Pendulum 2 9 34 7 3 Communication protocol between the model and the 35 8 PD CONTROLLER APPLICATION ON ARM 38 Si Proportional mode vetitis etas he 38 e dod 38 SEM PD AVI OGG MET 39 8 4 Controller Algorithm en 39 9 SERTALACCOMMUNIGCA FION 41 9 T RS 232 Standard Goin odd tds cot Mbit 41 9 2 Asynchronous 1 nennen nnns 41 9 3 Accessing the Serial POrt ih 42 931 Opening a Serial Port us 42 9 3 2 Writing Data to the eene nennen nennen 43 9 3 3 Reading Data from the Port 43 9 34 Closing a Serial Port ioa eee t eee 14 43 9 4 Serial Communication in 5302410 44 betta Erat E 45 10 EMBEDDED WEB SER VER thttpd 47 10 1 Thttpd Tiny Turbo Throttling HTTP server An 47 6 47 10 1 2 CGI Common Gateway Interface essere 48 10 1 3 Throttling 48 10 1 4 Multihoming na 49 10 1 5 Symlinks and Permissions ener 49 10 1 6 Instal
11. AS LZHWN99 1025 4 9800 AE E 00L AS ZSB AS L ZHIN99 W19S dOWQGA AE E 00L AS Z S8 AB LZHIN99 W19S dOWOGA AE E 00L AS Z S8 A8 L ZHIN99 W10S dOWQOGA IAE E 00L AS Z 68 A8 L ZHIN99 X19S dOWQGA g L uueiagA g L uueiqgA g L uueiggA amp L uueiqgA 8 1 8 1 S L TIdW e man 8 IODA hOGA 8 GGA 8 LIGA 8 18 1 gen En 99 91H 77 2 Flash Memory 896191 pews obrer flVIYNUI GONYN 78 3 Exbus 10 6 1013 5 uvvuu 5994 509 55994 25990 15994 05990 0 1 01 01922 5 4 88d9 LO3HGXu onio 309 147195 04125 9 49 450299 3705 SI VdO rSoou Svusu vIVdO ESODU Svosu ElydDizsopu 752915250 21 491539 395990 05959 05299 EWOQ E38M 38U 238 06 1 0 1380 62v1va 82 1 0 92 1 0 HivdS Szuaav Sev1va 0 49 42 00 2 1 0 62194 0 9vd9 LeHOQV 6 1 00 8 00 vivivd 100 EIVIVO iaav
12. Ping function tftp lt serverip gt lt filename gt Download code From TFTP Server flash lt partname gt Flash downloaded code to part set lt ipadd lt mask gt lt gateway gt Set IP Configuration show Show Current network Configuration save Save parameter table to flash memeory help Fig 5 2 Running net command on the vivi command line At this time we can see the network settings 2 The IP address must be set up and the TFTP server should be started Refer to section 5 2 2 1 3 In vivi command line run the command net set ipaddr 192 168 1 241 Then use the net command to view status we see that the target board s IP address is changed 4 Atthis time we run the net save command to save the settings 5 Our next step is to download a kernel image Run the following command from the host net tfip 192 168 1 156 0x30008000 zImage At this time the zImage has been downloaded from the computer to the SDRAM of the target board 6 To write it to the Flash partition Run the command net flash kernel Here kernel refers to the kernel partition 30 7 download the file system to the flash use the following commands net tftp 192 168 1 156 0x30008000 root 1 yaffs net flash root Restart the target board to boot into Embedded Linux 10 Here are the steps for installing the Embedded Linux on target board from host PC having Fedora Linux 09 as operating system 5 2 3 Bu
13. combination of features that makes ARM the most popular embedded architecture today First ARM cores are very simple compared to most other general purpose processors which means that they can be manufactured using a comparatively small number of transistors leaving plenty of space on the chip for application specific macrocells A typical ARM chip can contain several peripheral controllers a digital signal processor and some amount of on chip memory along with an ARM core Second both ARM ISA and pipeline design are aimed at minimising energy consumption a critical requirement in mobile embedded systems Third the ARM architecture is highly modular the only mandatory component of an ARM processor is the integer pipeline all other components including caches MMU floating point and other co processors are optional which gives a lot of flexibility in building application specific ARM based processors Finally while being small and low power ARM processors provide high performance for embedded applications For example the PXA255 XScale processor running at 400MHz provides performance comparable to Pentium 2 at 300M Hz while using fifty times less energy 4 2 ARM vs RISC In most respects ARM is a RISC architecture Like all RISC architectures the ARM ISA is a load store one that is instructions that process data operate only on registers and are separate from instructions that access memory All ARM instructions are 32 bit long and
14. constant 2 is an error for every 1 of error a correction of kp is added or subtracted from depending on the sign 3 There is a band of error about zero of magnitude within which the output is not saturated at 0 or 100 8 2 Derivative mode For derivative controller the controller output 18 p t kd d dt e t where kd derivative mode gain Characteristics of Derivative controller 1 Iferror 0 this mode provides no output 2 Iferror constant this mode provides no output 38 3 error is changing with time the mode contributes an output of kd for every 1 sec rate of change of error 4 For direct action a positive rate of change of error produces a positive derivative mode output The derivative mode is used with a small gain because rapid rate of change of error produces a very large sudden change in controller output leading to instability The derivative control action is also called as rate action or anticipatory action This derivative action is not used alone because it produces no output if error is constant 8 3 PD Mode PD controller combines the advantages of both proportional and derivative controller The expression for PD controller output is p t kp e t kd d dt e t PO The proportional mode of the PD controller produces a permanent residual error about its operating point of the controlled variable when a change in load occurs This error is called offs
15. device is being transferred between the target and the host The host contains the cross platform development environment while the target contains an appropriate bootloader a functional kernel and a minimal root filesystem Removable Storage Setup In the removable setup there are no direct physical links between the host and the target Instead a storage device is written by the host is then transferred into the target and 1 used to boot the device The host contains the cross platform development environment The target however contains only a minimal bootloader The rest of the components are stored on a removable storage media such as a CompactFlash IDE device MMC Card or any other type of removable storage device Standalone Setup The target is a self contained development system and includes all the required software to boot operate and develop additional software In essence this setup is similar to an actual workstation except the underlying hardware is not a conventional workstation but rather the embedded system itself This one does not require any cross platform development environment since all development tools run in their native environments Furthermore it does not require any transfer between the target and the host because all the required storage is local to the target 1 1 2 Operating Systems In an embedded system when there is only a single task that is to be performed then only a binary
16. fault In windows 95 98 GIVEIO SYS is not needed For Windows 2000 XP use the following procedure 1 2 3 4 5 Login administrator Copy the giveio sys file to systemrootsystem32 drivers Choose Control Panel and choose Add Remove Hardware Select Add Troubleshoot a device Select Add a new device and choose Next and select No I want to select the hardware from a list Select Other devices and choose Have Disk Choose Browse locate the folder where giveio inf file is present Complete the remaining process 27 5 2 1 2 To program the 951208 NAND Flash with the Bootloader code 1 Prepare your own boot loader image For example 2410loader bin is used here 2 Open the CD Software directory double click the DownloadVivi Vga bat batch file you will get a command window as shown below F Documents Settings asap Desktop dont delete pls Images gt sjf2416 SEC JTAG FLASHCSJF gt 0 3 lt 53 2410 amp SMDK2416 B D gt SJF f lt filename gt d lt delay gt ERROR No CPU is detected ID xfffFFFFFF gt ISJF Main Menu K9S1268 program 1 28F128J3A program 2 Rd Wr Select the function to test 1 951208 NAND Flash JTAG Programmer 951208 is detected ID xec76 B K981208 Program 1 951208 Pr BlkPage 2 16 Select the function to test 0 SMCCK981208UBM NAND Flash Writing Program Source size Gh 1i5ab3h Avail
17. hence we need a cross compiler on the host machine for making the compiled uClinux assemble on ARM machine language The basic requirements include 1 arm elf toolchain 2 arm linux toolchain 3 A hardware simulator Skyeye 3 4 1 arm elf toolchain arm elf toolchain is used for compiling the linux 2 4 and below kernels For instance arm elf gcc is a c compiler for arm processor which generates a binary in executable linux format elf similarly arm elf elf2flt converts elf to flat memory format flt We install the arm elf toolchain as follows 1 copy arm elf tools 20040427 sh in root uClinux directory 2 cd root uClinux 3 sh arm elf tools 200303 14 sh 6 3 4 2 toolchain Since it is not recommended to compile the arm linux toolchain source on the host machine precompiled tool chain for arm linux obtained online from here http www snapgear org snapgear downloads html download the following file http fip snapgear org pub snapgear tools arm linux arm linux tools 2006 1213 tar gz The arm linux tool chain is used for compiling the linux 2 6 x kernels The steps for installation are briefly as follows 1 Extract the tool chain into the usr local directory You must get the usr local arm linux bin containing all the pre compiled binary files 2 usr local arm linux bin is then appended to the PATH variable as PATH S PATH usr local arm linux bin export PATH 7 15 3 4 3 Skyeye
18. is to loaded into the target controller and is to be executed However when there are multiple tasks to be executed or multiple events to be handled then there has to be a program that handles and prioritizes these events This program is the Operating System OS which one is very familiar with in desktop PCs Various Operating Systems Embedded Operating Systems are classified into two categories 1 Real time Operating Systems RTOS Real Time Operating Systems are those which guarantee responses to each event within a defined amount of time This type of operating system is mainly used by time critical applications such as measurement and control systems Some commonly used RTOS for embedded systems are Vx Works OS 9 Symbian RTLinux Non Real time Operating Systems Non Real Time Operating Systems do not guarantee defined response times These systems are mostly used if multiple applications are needed Windows CE and PalmOS are examples for such embedded operating systems Why Linux There are a wide range of motivations for choosing Linux over a traditional embedded OS The following are the criteria due to which Linux is preferred l Quality and Reliability of Code Quality and reliability are subjective measures of the level of confidence in the code that comprises software such as the kernel and the applications that are provided by distributions Some properties that professional programmers expect fro
19. memory map so that each peripheral is addressed properly For a uClinux developer the difference most likely to cause an application to fail under uClinux is the lack of a dynamic stack On desktop Linux whenever an application tries to write off the top of the stack some more memory is mapped in at the top of the stack to allow the stack to grow Under uClinux no such facility is available as the stack must be allocated at compile time only By default the uClinux toolchains allocate 4KB for the stack which is too small as compared to desktop OS The second major difference is the lack of a dynamic heap which is the area used to allocate memory allocations with malloc and other related functions in C Hence complete information about the memory map and efficient use of available memory is required while programming 4 Another difference between standard Linux and uClinux is the lack of the fork system call This can require quite a lot of work on the developer s part when porting applications that use fork The option under uClinux is to use vfork vfork shares many properties 10 with fork These system calls allow a process to split into two processes a parent and child A process can split many times to create multiple children When a process calls fork the child is a duplicate of the parent in all ways but it shares nothing with the parent and can operate independently as can the parent With vfork this is n
20. military medical sciences and the aerospace and automobile industries Today they are widely used to serve various purposes like Network equipment such as firewall router switch and so on e Consumer equipment such as players cell phones PDAs digital cameras camcorders home entertainment systems and so on Household appliances such as microwaves washing machines televisions and so on Mission critical systems such as satellites and flight control The key factors that differentiate an embedded system from a desktop computer e They are cost sensitive e Most embedded systems have real time constraints e There are multitudes of CPU architectures such as ARM MIPS PowerPC that are used in embedded systems Application specific processors are employed in embedded systems e Embedded Systems have and require very few resources in terms of ROM or other I O devices as compared to a desktop computer 1 1 1 1 Types of Setup Embedded systems generally have a setup that includes a host which is generally a personal computer and a target that actually executes all the embedded applications The various types of host desktop architectures that are used in embedded systems are Linked Setup In this setup the target and the host are permanently linked together using a physical cable This link is typically a serial cable or an Ethernet link The main property of this setup is that no physical hardware storage
21. most of them have a regular three operand encoding Finally the ARM architecture features a large register file with 16 general purpose registers All of the above features facilitate pipelining of the ARM architecture However the ARM architecture deviated from the RISC architecture in some respects to improve its performance The ARM did not include register windows that were used by original RISC architectures to reduce complexity The ARM architecture introduced an auto indexing addressing mode where the value of an index register is incremented or decremented while a load or store is in progress ARM supports multiple register transfer instructions that allow to load or store up to 16 registers at once 22 4 3 Thumb instruction set extension The Thumb instruction set was introduced in the fourth version of the ARM architecture in order to achieve higher code density for embedded applications Thumb provides a subset of the most commonly used 32 bit ARM instructions which have been compressed into 16 bit wide opcodes On execution these 16 bit instructions can be either decompressed to full 32 bit ARM instructions or executed directly using a dedicated Thumb decoding unit Although Thumb code uses 40 more instructions than equivalent 32 bit ARM code it typically requires 3096 less space Thumb code 15 40 slower than ARM code therefore Thumb 15 usually used only in non performance critical routines in order to reduce memory and power
22. multiple such patterns separated by The patterns get checked against the filename part of the incoming URL One must not forget to quote any wildcard characters to avoid any misunderstanding by the shell Restricting CGI programs to a single directory lets the site administrator review them for security holes and 1s strongly recommended If there are individual users that you trust you can enable their directories too If no CGI pattern is specified at the compile time or at the command line then CGI programs cannot be run 10 1 3 Throttling The throttle file lets you set maximum byte rates on URLs or URL groups You can optionally set a minimum rate too The format of the throttle file is very simple starts a comment and the rest of the line is ignored Blank lines are ignored The rest of the lines should consist of a pattern whitespace and a number The pattern is a simple shell style filename pattern using or multiple such patterns separated by Throttling is implemented by checking each incoming URL filename against all of the patterns in the throttle file The server accumulates statistics on how much bandwidth each pattern has accounted for recently If a URL matches a pattern that has been exceeding its specified limit then the data returned is actually slowed down with pauses between each block If that s not possible e g for CGI programs or if the bandwidth has gotten way larger than the lim
23. page is returned Thttpd is very particular about the permissions of the files that it serves For data files it requires that these files are world readable This means that not only root or a particular group but any user must be permitted to read the file It also requires that the execute bit be off for data files For a CGI program the execute bit has to be set and it must match the CGI pattern In summary the data files should have a permission pattern of 644 r w directories should have a permission pattern of 755 r w x r x r x and CGI programs should have 755 r wx r x r x The configuration of the server can be mentioned either in a configuration file or it can be specified at the command line in the form of flags At the command line the following flags are available as options C Specifies a config file to read These options can also be mentioned at the command line 49 44 5 gt g id Specifies an alternate port number to listen on The default is 80 The config file option name for this flag is port and the corresponding option in the config h file is DEFAULT PORT Specifies a directory to chdir to at startup The config file option name for this flag is dir and the config h options are Do a chroot at initialization time restricting file access to the program s current for directory If r is the compiled in default then nor disables it T
24. returns the number of characters if written successfully else it will return a negative value n write fd chars count if n 0 fputs write failed n stderr return 0 60 return 1 Je x e e e To read from serial port int readport int fd char result int count It is initialized to 1 so that read function is called repitatively in the while loop that is followed serial port ine irn read file descriptor ptr num chars characters if read successfully while 111 lt 0 iIn read fd return 1 this is to read till data arrive at the returns the number of else it will return a negative value count result f x To get the baud rate of serial port int getbaud int fd ok ce x e e x struct termios termAttr int inputSpeed 1 Speed t baudRate tcgetattr fd amp termAttr Get the input speed baudRate cfgetispeed amp termAttr switch baudRate case BO inputSpeed 0 break case B50 inputSpeed 50 break case B110 inputSpeed 110 break case B134 inputSpeed 134 break case B150 inputSpeed 150 break case B200 inputSpeed 200 break case B300 inputSpeed 300 break case B600 inputSpeed 600 break case B1200 inputSpeed 1200 break case B1800 inputSpeed 1800 break case B2400 inputSpeed 2400 break case B4800 inputSpeed 4800 break case B9600 inputSpeed 9600 break case B
25. set extensions 23 4 4 Pipeline Design in 1 2 2 02 0 0 0 0 244000006000500000000 nennen eene 23 4 41 The 3 stage pipeline iot ee terre rere RR RS 24 4 4 2 The 5 stage nosiri eterne 24 5 THE TARGET BOXRD itecto testet chee dose Pi 25 5 T Specifications eer HE eere D e ad aedi ta dnd 25 5 1 1 Hardware Specifications sereine nres ieaie eene enne nnne nnn nnns 25 5 1 2 Software Specificaftiggsgssss 26 5 2 Installation Steps ze mE tee 27 5 2 1 Installing the vivi bootloader using 27 5 2 1 1 Installing GIVEIO SYS Sioe repiano rna aE a eene 27 5 2 1 2 To program the 951208 NAND Flash with the Bootloader code 28 iv 5 2 2 Installation of kernel and filesystem using TFTP server 2 28 5 2 2 1 Configuring a TFTP server on the host sss 28 5 2 2 2 Partition and format Flash memory sese nennen 29 5 2 2 3 Download the Kernel and File System 1 30 5 2 3 Building Linux image on the host 31 5 2 3 1 Installing cross compiler toolchain esses 3 5 232 Compiling Linu Source eee 66 3 6 OVERVIEW OF THE PROJE O T vg oe 32 7 MODEL OF AN INVERTED PENDULUM 33 eai E SETAE iet 33 7
26. tar untar tar is an archiving program designed to store and extract files from an archive file known asa tarfile A tarfile may be made on a tape drive however it is also common to write tarfile to a normal file The first argument to tar must be one of the options Acdrtux followed by any optional functions The final arguments to tar are the names of the files or directories which should be archived The use of a directory name always implies that the subdirectories below should be included in the archive 2 make The purpose of the make utility is to determine automatically which pieces of a large program need to be recompiled and issue the commands to recompile them The manual describes the GNU implementation of make which was written by Richard Stallman and Roland McGrath and is currently maintained by Paul Smith Our examples show C programs since they are most common but you can use make with any programming language whose compiler can be run with a shell command In fact make is not limited to programs You can use it to describe any task where some files must be updated automatically from others whenever the others change To prepare to use make you must write a file called the makefile that describes the relationships among files in your program and the states the commands for updating each file In a program typically the executable file is updated from object files which are in turn made by compiling source files 3 m
27. the name of which the server executes Eg thttpd p 8000 d usr local www cgi bin c u root The flow of the code of web application that we are using in our project is as follows The index page offers two options 1 hyperlink to start the pendulum and its control Clicking on the link runs shell script that executes the executable file generated from the controller s C program The process begins by sending the character Z to the Atmega indicating that it should reset its software hyperlink to check the current status of the pendulum ie the current inclination the current rate of change of inclination and the most recent force that was supplied by the controller algorithm in the ARM to the model in the Atmega The controller stores the values of the force it supplies and the recently received values of theta and d theta in a file When the link 1 clicked an executable generated from a C program executes to read this file and print the values to the browser of the client 52 11 RESULTS AND ANALYSIS This section of the report shows the results that we have obtained during the course of the project The control system i e the ARM Embedded Linux System and the Inverted Pendulum model as a whole has been tested under various load conditions As already mentioned the load corresponds to the process load that builds when the thttpd web server is started in parallel with the control program and the
28. thttpd proceeds as 1f the option was not set first looking for a local htpasswd file and if that doesn t exist either then serving the file without any 50 password If g is the compiled in default then nog disables it The config file option names for this flag globalpasswd and noglobalpasswd and the config h option ALWAYS GLOBAL PASSWD u Specifies what user to switch to after initialization when started as root The default is nobody The config file option name for this flag is user and the config h option is DEFAULT USER c Specifies a wildcard pattern for CGI programs for instance cgi or cgi bin The config file option name for this flag is cgipat and the config h option is CGI PATTERN t Specifies a file of throttle settings The config file option name for this flag is throttles h Specifies a hostname to bind to for multihoming The default is to bind to all hostnames supported on the local machine The config file option name for this flag 15 host and the config h option is SERVER NAME l Specifies a file for logging If no l argument is specified thttpd logs via syslog If 1 dev null is specified thttpd doesn t log at all The config file option name for this flag is logfile i Specifies a file to write the process id to If no file is specified no process id is written You can use this file to send signals to thttpd The config file option name for this fl
29. 0 y przntf 0 printf d send d theta printf put 0 DISABLE SENDING VALUES TO ARM TILL NEXT FORCE IS RECD 69 1 TIMSK 0x00 get 0 put 0 e e e ke e e e e e e e e e MODEL CALCULATION BEGIN t tt dt m sin theta n sqrt 1 m m d theta 2 sqrt g sin theta 2 dt 0 5 0 75 g m acc n dt dt EQUATION FOR D THETA IN DT theta theta rd theta led display if theta gt 1 570796 theta 1 570796 IF PENDULUM FAILS MAKE FAIL 1 11 1 if theta gt 1 570796 t90 else t_90 asm sei J KOK RRR koe ek e ek e e e e e AMODET CALCULATION e isr end ko ke ke ke ke ke e e Sk END OF TSR Declare your global variables here void main void 0 Declare your local variables here Input Output Ports initialization Port A initialization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Funci In Func0 In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTA 0x00 DDRA OxFF Port B initialization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Funci In Func0 In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTB OxFF DDRB OxFF 70 Port initialization Func7 In Func In Func5 In Func4 In Func3 In Func2 In Funci In 0 S
30. 19200 inputSpeed 19200 break case B38400 inputSpeed 38400 break case B57600 inputSpeed 57600 break return inputSpeed Protocol Implementation of Write Xo e oe ek e e e e e e e e e e e e e e int write ser int op The Protocol for writing data to the serial port is l Send Z if it is the 1st time else send A 2 Wait to receive B 3 Send a 4 digit force with appropriate sign Variable Initialization char senda 61 int ij ant p char receiveb 2 char sOp 5 int 1131 xmi x int counter int i1 int m 4 int n p variable indicates the number of values to be written or read Whenever n values are to be written or read assign p i To send Z for the 1st time the control starts else send A if k 0 7 else senda A If successfully written then it will return a non zero value if writeport amp senda p printf write failed n close fd return 1 initport fd 2 Don t block serial read 1 fd F SETFL FNDELAY If successfully read then it will return a non zero value if readport fd receiveb p printf read failed n close fd return 1 This is to check the condition whether the pendulum has fallen if true then it will return 2 if receiveb 0 F return 2 initport fd 5 This section is to convert the numerical value of op to ch
31. 92 n 0 acc 0 m 0 t 0 g 0 char f 6 JR e e x e e e DISPLAY FUNCTION x xk void led display if send theta 0 t0 goto displayed if send_theta 1 t1 goto displayed if send_theta gt l amp amp send_theta lt 5 t5 goto displayed if send_theta gt 5 amp amp send_theta lt 10 t10 goto displayed if send_theta gt 10 amp amp send_theta lt 20 t20 goto displayed if send_theta gt 20 amp amp send_theta lt 89 t40 goto displayed if send theta 1 t 1 goto displayed if send_theta lt l amp amp send theta 5 t 5 goto displayed if send theta 5 amp amp send theta 10 t 10 goto displayed if send_theta lt 10 amp amp send theta 20 t 20 goto displayed if send_theta lt 20 amp amp send theta 89 t_40 goto displayed 67 displayed Timer 1 overflow interrupt service routine interrupt OVF void timerl_ovf_isr void o e e e e e e e e e e e e x START OF TSR e koe ke ke ke e e e ke e e e e e ke e e e e e ke e e e e e 11 VALUE OF ACCELERATION FROM ARM BEGIN if UCSRA 7 BEGIN scanf c amp 0 if f 0 2 7 send theta 0 send d theta 0 RE INITIALISE THE SYSTEM i 0 R cg accn 0 fail 0 put 0 theta initial
32. Applications window 7 Execute make dep 8 Now create a new document named Makefile using Gedit or VI under the uClinux dist user sample directory Write the following script into the file 20 EXEC sample OBJS sample o CFLAGS I all S EXEC S OBJS CC S LDFLAGS o OBJS LDLIBS romfs ROMFSINST bin EXEC clean rm f EXEC elf gdb o 9 Now under the uClinux dist user sample directory write a C program named sample c 10 Execute the make all command in the uClinux dist directory This should result in an object file sample in the uClinux dist romfs bin directory 11 Copy the linux image created in uClinux dist linux 2 4 x directory to the uClinux dist images dirctory Note that this images directory should contain 3 files for proper operation of the program skyeye conf boot rom linux 12 Now execute the command skyeye e linux in the uClinux dist images directory You will get the Sash gt command prompt You can see if sample exists in the bin directory 13 The program is executed by typing sample at the command prompt 5 8 mand shell version 1 1 1 e This is ASAP s 1st application 15 88 Fig 3 8 Screenshot the simulation of the sample program 21 4 ARM ARCHITECTURE AN OVERVIEW 4 1 Introduction ARM is a 32 bit RISC processor architecture developed by the ARM corporation ARM processors possess a unique
33. PERFORMANCE EVALUATION OF EMBEDDED LINUX AN ARM PROCESSOR Project submitted in partial fulfillment of requirements For the Degree of BACHELOR OF ENGINEERING BY AMIT KARANDE ANKIT BANSAL PRASHANT NAIR SHANTANU KULKARNI Under the guidance of Prof Y SS RAO ge PON gt A e A ek ER gt gt a aes 4 i v z i NC YS CSN 4 Department of Electronics Engineering Sardar Patel Institute of Technology University of Mumbai 2008 2009 BHARTIYA BHAVAN S SARDAR PATEL INSTITUTE OF TECHNOLOGY MUNSHI NAGAR ANDHERI W MUMBAI 400 058 2008 09 CERTIFICATE OF APPROVAL This is to certify that the following students AMIT KARANDE ANKIT BANSAL PRASHANT NAIR SHANTANU KULKARNI have successfully completed and submitted the project entitled PERFORMANCE EVALUATION OF EMBEDDED LINUX ON AN ARM PROCESSOR towards the fulfillment of Bachelor of Engineering course in Electronics of the Mumbai University Internal Examiner External Examiner Internal Guide Head of Department Principal ACKNOWLEDGEMENTS It is with great pleasure that we present the report on our project work We take this opportunity to share a few words of gratitude to all those who have supported us in making it Success Our heartfelt gratitude to our project guide Prof Y S Rao for his able and expert guidance We are also indebted to our college for provi
34. able 9 2 Asynchronous Communication For the computer to understand the serial data coming into it it needs some way to determine where one character ends and the next begins In asynchronous mode the serial data line stays in the mark 1 state until a character is transmitted A start bit precedes each character and is followed immediately by each bit in the character an optional parity bit and one or more stop bits The start bit is always a space 0 and tells the computer that new serial data is available Data can be sent or received at any time thus the name asynchronous 41 5 12V MARK 12 Fig 9 1 Timing diagram of asynchronous mode The optional parity bit is a simple sum of the data bits indicating whether or not the data contains an even odd number of 1 bits With even parity the parity bit is 0 if there is an even number of 1 s in the character With odd parity the parity bit is 0 if there is an odd number of 1 s in the data The remaining bits are called stop bits There can be 1 1 5 or 2 stop bits between characters and they always have a value of 1 Stop bits traditionally were used to give the computer time to process the previous character but now only serve to synchronize the receiving computer to the incoming characters Asynchronous data formats are usually expressed as 8 1 7EI and so forth These stand for 8 data bits no parity 1 stop bit and 7 data bits even parity 1 stop
35. able target block number 0674095 Input target block number Fig 5 1 Screenshot of bootloader download to NAND Flash 5 2 2 Installation of kernel and filesystem using TFTP server To download images of kernel and file systems from the host machine to the target board a network interface is setup using a TFTP server at the host end 5 2 2 1 Configuring a TFTP server on the host 1 Download and install a TFTP server using the command lt root localhost gt yum install tfipd server 2 Create a directory tftpboot in the directory 3 Place the zImage and the image of the root file system in the tftpboot folder This is because the TFTP server will let the target access files that are present only in the tftpboot 4 Start the TFTP server by using the following commands lt root localhost gt iptables F lt root localhost gt service xinetd start 28 iptables F command flushes the current firewall settings and allows all the IP addresses to use the TFTP service on the host machine Note For doing the above operations you must be the root user Now the host is ready to transfer the images to the target board The next step is the installation of Linux Linux installation 1 divided into three steps 1 Flash memory partition and format usually a Nand Flash 2 Download the Linux kernel 3 Download the file system 5 2 2 2 Partition and format Flash memory The flash memory can be partitioned usin
36. ag 15 pidfile T Specifies the character set to use with text MIME types The default is 150 8859 1 The config file option name for this flag is charset and the config h option is DEFAULT CHARSET V Shows the current version info D This was originally just a debugging flag however it s worth mentioning because one of the things it does is prevent thttpd from making itself a background daemon Instead it runs in the foreground like a regular program This is necessary when you want to run thttpd wrapped in a little shell script that restarts it if it exits If using a config file to set the settings its syntax is series of option or option value separated by a whitespace in between 17 51 10 1 6 Installation steps of Thttpd SS oe SP YS Download the latest version of thttpd thttpd 2 25b tar gz from the website WWNW acme com Untar the package graphically or at the command line as tar xvf thttpd 2 25b tar gz You get a single folder named thttpd 2 25b cd to the folder at the command line Run the command CC arm linux gec configure Then run the command A binary by the name of thttpd is generated Copy the binary to the target board through the USB interface in the usr sbin directory Execute the binary with the appropriate flags at the command line p Port No d Document Root c Files that should be executed as CGI scripts u The user by
37. ake menuconfig xconfig It helps us to customize the configuration 4 make image It is used to make the binary image of the complied kernel 5 make dep It helps us to make dependencies 75 6 The usual execution of a binary would require you to access the binary by writing its absolute path Instead the whole process is converted into a command that acts as a shortcut to run the binary 7 sh Bash is an sh compatible command language interpreter that executes commands read from the standard input or from a file Bash also incorporates useful features from the Korn and C shells ksh and csh Bash is intended to be a conformant implementation of the Shell and Utilities portion of the IEEE POSIX specification IEEE Standard 1003 1 Bash can be configured to be POSIX conformant by default 18 76 APPENDIX SCHEMATICS FOR ARM TARGET BOARD tic 1 ARM Microcontroller Schema 94595 GN9S BLOOA ISSA TidW ISSA ISSA ISSA ISSA ISSA ISSA 20 vss dOSSA 4055 4055 dOSSA dOSSA 4055 dOWSSA dOWSSA dOWSSA dOWSSA dOWSSA dOWSSA dOWSSA dOWSSA dOWSSA uuelSSA uuelSsA uueilSsA 55 55 WEISSA 55 uo OlPZOES WHY ee oav YOGA AE E 00L AS Z G8 A8 L ZHIN99 X19S dOWQQA IAE 00L AS Z S8 A8 L ZHIN99 X19S dOWOGA AE E 00L AS 2 58
38. and building the Linux kernel and installing toolchains We understood the preponderance of the ARM processors in the field of embedded systems and the features of ARM processors from the document ARM Architecture by Leonid Ryzhyk The ARM architecture is a confluence of many useful features that makes it better than other peer processors Being small in size and requiring less power they prove useful in providing an efficient performance in embedded applications Linux development tools being available through the GPL license are available online from sources such as FTP servers mailing lists and discussion portals These online helpdesks have been the source for all the toolchains that we have downloaded and the subsequent development Modeling of a system is an integral part of any embedded control system development The documentation provided by Atmel and Code Vision AVR helped us to develop a mathematical model of an Inverted Pendulum on an Atmega 8 bit controller The aim of the application is to control this pendulum using a Proportional plus Derivative PD controller which was implemented on ARM Embedded Linux System The theory of controllers from Mechatronics by W Bolton helped us to develop the controlling algorithm test the real time performance of the system it was subjected to varying process loads through the implementation of the web server The thttpd source and documentation at w
39. aracter string This facilitates in sending data via serial port in 8 bit format i e 8N1 0 0 10 10 m 1 op 10 10 m 2 op 10 m 3 op 10 for 1 lt 5 62 if m n 1 0 sOp 5 n 0 if m n 1 1 sOp 5 nj 1 sOp 5 n 2 if m n 1 3 sOp 5 n 3 if m n 1 4 sOp 5 nj 4 5 sOp 5 n 5 if m n 1 6 sOp 5 nj 6 18 m n 1 7 sOp 5 nj 7 if m n 1 8 sOp 5 n 8 if m n 1 9 sOp 5 n 9 1 1 lt 0 50 0 1 50 0 if writeport fd sOp p printf write failed n close fd return 1 This provides synchronization in communication between ARM processor and Inverted Pendulum model implemented in Atmega 8535 for 1 0 1 lt 5 1 return 0 J OK e e e Protocol implementation of Read ek ok ek e ke int read ser char sResult The Protocol for reading data from the serial port is l Wait for an array of 7 characters 2 The 1st three digits will indicate theta 3 The last 4 characters will indicate deri theta int ij ant p 63 int 3171 initport fd 8 fcntl fd F SETFL FNDELAY if readport fd sResult p printf read failed n close fd return 1 This provides synchronization in communication between ARM processor and Inverted Pendulum model implemented in Atmega 8535 for i
40. ation of the inverted pendulum is on huge lifting cranes in shipyards When moving the shipping containers back and forth the cranes move the box accordingly so that it never swings or sways It always stays perfectly positioned under the operator even when moving or stopping quickly 11 7 1 Working Fig 7 1 Schematic for Inverted Pendulum An inverted pendulum is a physical device consisting of a cylindrical bar free to oscillate around a fixed pivot The pivot is mounted on a carriage cart which in turn can move in the horizontal direction The cart is driven by a motor which can exert on it a variable force depending on the dynamics of the pendulum The bar would tend to fall down from the top vertical position which is a position ofunstable equilibrium The goal of the inverted pendulum controller is to stabilize the bar in the top vertical position Thisis possible by exerting on the carriage a force which tends to contrast the free pendulum dynamics The correct force has to be calculated measuring the instant values of the horizontal position and the pendulum angle The system pendulum cart motor can be modelled as a linear system if all the parameters are known in order to find a controller to stabilize it If all the parameters are not known we try to reconstruct the system parameters 29 using measured data on the dynamics of the pendulum 12 7 2 Approximate Model of the Inverted Pendulum For develop
41. bit respectively 9 3 Accessing the Serial Port Like all devices UNIX provides access to serial ports via device files To access a serial port the corresponding device file has to be opened 9 3 1 Opening a Serial Port Each serial port on a UNIX system has one or more device files files in the dev directory associated with it Since a serial port is a file the open function is used to access it The following command is used to open the serial port fd open dev ttyS0 RDWR O NDELAY The device file is opened with two other flags along with the read write mode OCTTY flag tells UNIX that this program does not want to be the controlling terminal for that port If this is not specified then any input such as keyboard abort signals and so forth will affect the process The NDELAY flag tells UNIX that this program does not care what state the DCD signal line is in whether the other end of the port is up and running If this flag is not specified the process will be put to sleep until the DCD signal line 15 the space voltage 42 9 3 2 Writing Data to the Port Writing data to the port is done using the write2 system call to send data it n write fd ATZ r 4 if n 0 fputs write of 4 bytes failed n stderr The write function returns the number of bytes sent or 1 if an error occurred 9 3 3 Reading Data from the Port When the port is operated in raw data mode each read
42. consumption of the system 4 4 Pipeline Design in ARM instruction 3 fetch decode decode instr Instr address address execute 21 data a ARM7TDMI b ARM9TDMI Fig 4 1 Pipeline architecture in ARM7 and ARM9 cores 29 4 41 The 3 stage pipeline It is a classical fetch decode execute pipeline which in the absence of pipeline hazards and memory accesses completes one instruction per cycle The first pipeline stage reads an instruction from memory and increments the value of the instruction address register which stores the value of the next instruction to be fetched This value is also stored in the PC register The next stage decodes the instruction and prepares control signals required to execute it on The third stage does all the actual work it reads operands from the register file performs ALU operations reads or writes memory if necessary and finally writes back modified register values In case the instruction being executed is a data processing instruction the result generated by the ALU is written directly to the register file and the execution stage completes in one cycle If it is a load or store instruction the memory address computed by the ALU is placed on the address bus and the actual memory access is performed during the second cycle of the execute stage
43. d Linux Distribution Online Available http www snapgear org snapgear documentation htm 8 2008 Aug Jeff Dionne and Michael Durrant Manual Online Available http www uclinux org 9 ARM Architecture Reference Manual 2nd edition Leonid Ryzhyk Australia June 2006 10 Emblitz S3C2410 development board user manual Everest Infocomm India 2009 11 Danbing Seto and Lui 5 Case Study on Analytical Analysis of the Inverted Pendulum Real Time Control System Technical Report Software Engineering Institute Carnegie Mellon University Pittsburg USA November 1999 12 2004 Sept Brian Korte and Brian Halaburka Inverted Pendulum Online Availiable http lims mech northwestern edu design mechatronics 2004 Team1 1 13 Herbert Charles Corben and Philip Stehle Inverted Pendulum in Classical Mechanics 2nd Edition Courier Dover Publications 1994 pp 67 69 14 W Bolton Mechatronics A Multidisciplinary Approach 2nd edition Prentice Hall 2008 15 Michael Sweet Serial Programming Guide for POSIX Operating Systems 5th Edition 6th Revision Copyright 1994 2009 16 Porting Guide and Unit Test for UART S3C2410 Linux manual Samsung Electronics Co Korea 2004 86 17 2003 Dec Acme Laboratories thttpd server Online Available http www acme com software thttpd notes html 18 Linux Manual Pages for Linux Kernel in Fedora Core linux Linus Torvalds 2008 87
44. d to record force theta and deri theta It is opened in w write mode if fpl fopen usr theta txt w NULL printf Cannot open file n cur theta txt is file used for displaying current value of force theta and deri theta on the web page if fp2 fopen usr local www cgi bin cur theta txt w NULL printf Cannot open file n while loop for PD COntro l x kkk kk oe ok while k 2000 w write ser op if the pendulum ha fallen i e if a F is received then get out of the main program if w 2 goto fail r read ser result Convert the received character array into integer array for 1 0 1 lt 7 1 if result 1 0 9 11 0 if result 1 1 if result 1 2 if result i 3 if result 1 4 if result i 5 if result i 6 if result i 7 if result i 38 65 jlil28 if result i 3111 94 Calculate the values of theta deri theta theta j 1 10 3 2 deri theta j 4 100 j 5 10 j3 6 0 gt 0 theta theta 7 1 if j 3 gt 0 deri theta deri theta 1 PD controller calculations op kpl theta ckdl theta prev theta op kp2 deri theta kd2 deri theta prev deri theta op prev theta theta prev deri theta deri theta Write the contents to the file fprintf fpl d t d n k op t
45. dering rotational motion of the rod about the pivot I Ia Where Torque mgh sin 0 Fhcos 0 I Moment of Inertia about pivot mL 3 Angular acceleration a 3 AL sin 0 F m cos 0 3 13 put equations 2 and 3 in 1 the discrete mathematical model is 40 h V 2gh 1 cos0 dt 1 2 3 4L g sin 0 F m cos 0 dt 7 3 Communication protocol between the model and the controller The model first checks 1f the pendulum is initially fallen or not by examining the fail flag as long as it is found 0 the steps 2 to 6 are executed sequentially Controller sends character A to indicate it is ready to send Force values to the model or it sends character Z to re initialize the pendulum to original position On receipt of either or Z the model sends character as an acknowledgement and becomes ready to receive the Fore from the Controller 35 The controller sends the 4 digit force character by character preceded by the character or to indicate the sign of the force The model then sends the current value of 0 and 40 to the controller character by character preceded by character 0 for positive and 1 for negative Model then calculates the values of 40 and 0 as per the derived mechanical equation If 0 becomes 90 i e 090 or 90 i e 190 then the model sends a character F to the controller to indicate
46. ding us with all the resources we required for the successful completion of the project We are grateful to Mr S G Mistry without whose support and advice our project would not have shaped up as it has Lastly we would like to thank the Open Source Community whose contributions have helped us through the various phases of our project iii TABLE CONTENTS FIGURES EE vii ABSTRACT T viii INTRODUCTION ciel ute LL 1 11 Embedded Systems ness nde rete ho dot e nerit 1 2 151 2 Systems ivt erecti 2 2 LITERATURE 6 BL S 7 9 9 3 2 Skyeye Simmulator yn iat eA OI 11 3 3 Host Speciticatioris 1 donee tette ee eee Mat eerie 12 3 4 Installing uClinux on the host Linux platform 15 34 1 Bali ova telo d Qus 15 25402 gt 15 3 4 4 uClinux Distribution 18 20070130 22 000000000000000041 16 3 3 5 Running a Sample Program on uClinux nennen 19 4 ARM ARCHITECTURE AN 22 e SIM rire d DIVIDI 22 AARM BISU 22 4 3 Thumb instruction
47. e locations by the paging or segmentation mechanism So even though the process sees the virtual memory as contiguous the physical memory it occupies can be scattered around Because arbitrarily located memory can be mapped to anywhere in the process address space it is possible to add memory to an already running process Without VM each process must be located at a place in memory where it can be run In the simplest case this area of memory must be contiguous Generally it cannot be expanded as there may be other processes above and below it This means that a process in uClinux cannot increase the size of its available memory at runtime as a traditional Linux process would The effect of the absence of VM concept is that no memory protection of any kind is offered So it is possible for any application or the kernel to corrupt any part of the system because the user applications and the kernel share the same memory area The corruption causes the system to crash and tracking down random inter process corruption can be extremely difficult Without VM swap is effectively impossible but this limitation is rarely an issue on the kinds of systems that run uClinux Embedded Systems applications often do not require hard drives or large external memory Hence uClinux is the ideal option for these applications uClinux is only slightly different from Linux with respect to its kernel Due to absence of VM tmpfs temporary file system d
48. et It can be minimized by a larger gain kp but larger the gain the proportional band decreases Hence the PD controller cannot eliminate the offset of the proportional controller but it can handle fast process load changes as long as the offset error is acceptable 14 8 4 Controller Algorithm The controller algorithm runs on the ARM processor It is interfaced to the Atmega8535 through a serial port The model of the inverted pendulum runs on the Atmega board There is a fixed protocol followed to enable synchronization between the model and the controller The following is the protocol 1 The controller sends a character Z for the first time to the inverted pendulum 2 In response the pendulum model sends a character to the controller 3 Now the controller sends the acceleration which it has computed for the pendulum to return to its equilibrium position For the first time the acceleration 15 zero 39 The controller waits for the Atmega to send the current angular displacement 0 and the change in the angular displacement 40 The controller now calculates the new value of acceleration using the values of 0 40 kp and kd The controller sends a character to the Atmega board for synchronization Steps 2 to 6 are repeated for the number of times the code is run 40 9 SERIAL COMMUNICATION Computers transfer information data in the form of one or more bits at a time Serial refers to
49. for ARM with varying load with 2 sec refresh 56 1 Analysis of performance of desktop and ARM processor The first plot Fig 11 1 is Force v s time and the second plot Fig 11 2 is Angular displacement v s time The green plot is indicating the ARM performance whereas the red plot is for the desktop From the plot it can be inferred that the performance of ARM and the desktop is comparable however the controlling algorithm running on the desktop loses synchronization after a while However the ARM processor controls the inverted pendulum for any amount of time Hence it 15 preferred over the desktop for real time applications 2 Analysis of performance of ARM processor with varying loads Plots 3 Fig 11 3 and 4 Fig 11 4 are plotted when there are two clients accessing the webpage red plot and it is compared with no load condition green plot It can be observed that the pendulum settles down to its equilibrium condition quickly as compared to the case when two clients are present It can be seen that when there is load on the ARM processor the overshoot increases and it takes much longer for the pendulum to settle down Plots 5 Fig 11 5 and 6 Fig 11 6 are plotted when there are two clients accessing the webpage and one of them 15 refreshing the page every two seconds red plot and it is compared with no load condition green plot Here it be demonstrated that the settling time of the pendulum is much higher in case
50. fra red IR transmit receive one or two stop bit insertion 5 bit 6 bit 7 bit or 8 bit data width and parity checking UARTO is used to send serial data to the host machine which can be viewed via minicom Minicom then displays the boot up sequence the command prompt of vivi and shell prompt of embedded linux Peripheral BUS Transmitter gt FIFO Regeter FIFO mode Transmit Buffer Register 18 Byta Transe Hoking Register Nan F mode Cock Source Receiver Sher Recewe Hoiting Regste Non F FO mode ory Buffer Regester 18 Byte FIFO Regeter FIFO mode n mode af 16 Byte of Buffer register weed as FIFO register n non F FO mode only 1 Byte of Buffer register is used as Holding regeter Fig 9 2 Serial port architecture S3C2410 44 9 5 Minicom Minicom is an application which is used to view the contents of the serial port receive buffer when it acts as a receiver and send data to the transmit buffer when acting as a transmitter The following are the steps to start Minicom and edit its settings 1 froot a localhost root minicom s This command starts Minicom in Setup mode One can select the serial port to be interfaced baud rate and other settings of the serial port 2 Press key for setting the Serial Device then give the complete path of the serial port w
51. ftware Flow Control to NO The default value is NO Once the setup is done press the Enter key And select Save setup as dfl item then press Enter for saving the values Press the Exit key to exit from the setting mode Currently the set points are stored to the file etc minirc dfl To quit from Minicom please press Ctrl A and then Z at last press Q key Then Selecting Yes the Minicom is quit 16 46 10 EMBEDDED WEB SERVER thttpd Web servers play an important role in industry If a system is to be accessed and controlled remotely and if the data is to be presented in a user friendly manner then it is very important to have web servers Embedded systems that are hosting control applications should have web services enabled so that the status of the system can be checked from a distant place At the same time one can also keep an option of controlling the system remotely if sufficient security of control is ensured Examples of prominent embedded web servers are Boa thttpd mini thttpd micro thttpd In our project we have used the thttpd web server 10 1 Thttpd Tiny Turbo Throttling HTTP server An Overview It is a simple small portable fast and secure HTTP server It is not a feature rich web server but its features suffice most of the applications and has a very important feature called URL traffic based throttling Some important concepts before s
52. g the following steps 1 Hold down the spacebar while starting up the target board in Minicom to see vivi command line 2 Enter the command bon part 0 192k 2m bon is the partition command this means that the Nand Flash is divided into three zones 0 192k size of 192k 192k 2M size 1 8Mbyte 2M flash terminal Please Note After partition and format please do not turn off the target board s power supply Otherwise we need to re use of JTAG line to download VIVI This is because the target of the on board flash memory is now being cleared 29 5 2 2 3 Download the Kernel and File System Images Before downloading the kernel image and file system we must first ensure proper network settings 1 As we enter to command line vivi Type the command net IVI bootloader 0 1 4 chris yangchu com gcc version 2 95 3 20010315 release7 MU table base address 0x33DFC000 53C2410 flash probing 32 bit flash bus called with unsupported buswidth 4 FI Found no 53 2410 flash device at location zero device Manufacture ID Oxec Chip ID 0x76 Samsung K9D1208V0M ound saved vivi parameters ga initialize error ress Return to start the 05 now other key for vivi shell ype help for help iivi net urrent Network Configuration thernet Address 00 01 5D 68 7A 0F Address 192 168 1 22 Net Mask 255 255 255 0 192 168 1 1 Server IP 192 168 1 206 sage ping ipaddr
53. he config file option names this flag are chroot and nochroot and the config h option is ALWAYS CHROOT Specifies a directory to chdir to after chrooting If you re not chrooting you might as well do a single chdir with the d flag If you are chrooting this lets you put the web files in a subdirectory of the chroot tree instead of in the top level mixed in with the chroot files The config file option name for this flag is data dir Don t do explicit symbolic link checking Normally thttpd explicitly expands any symbolic links in filenames to check that the resulting path stays within the original document tree If you want to turn off this check and save some CPU time you can use the nos flag however this is not recommended Note though that if you are using the chroot option the symlink checking is unnecessary and is turned off so the safe way to save those CPU cycles is to use chroot The config file option names for this flag symlinkcheck and nosymlinkcheck It enables virtual hosting nov disables it The config file option names for this flag are vhost and novhost and the config h option is ALWAYS VHOST Use a global password file This means that every file in the entire document tree is protected by the single htpasswd file at the top of the tree Otherwise the semantics of the htpasswd file are the same If this option is set but there is no htpasswd file in the top level directory then
54. heta deri theta fprintf fp2 d 54 54 op theta deri theta frewind returns the control to the begining of the file rewind fp2 k while loop ends 11 fclose fpl fclose fp2 close fd return 0 66 p code c Mathematical model for inverted pendulum running on Atmega8535 JC eoo eee KK KKK A PENDULUM SOFTWARE MODEL ATMEGA8 535 8 x xx KE COMO 1 ded using Codevison AVR Compiler W WWW k o WOO EAR ER 7 include lt mega8535 h gt include lt math h gt include lt delay h gt Standard Input Output functions include lt stdio h gt include lt stdlib h gt define cg 1 define initial 0 176 PORT VALUES FOR LED DISPLAY OF PARTICULAR ANGLES 0 led glows 1 led off define t90 PORTC 0x7F PORTB OxFF define t40 PORTC 0xBF PORTB OxFF define t20 PORTC 0xDF PORTB OxFF define t10 PORTC 0xEF PORTB OxFF define t5 PORTC 0xF7 PORTB OxFF define t1 PORTC 0xFB PORTB OxFF define t0 PORTC 0xFD PORTB OxFF define t 1 PORTC 0xFE PORTB OxFF define t 5 PORTC 0xFF PORTB 0x7F define t 10 PORTC OxFF PORTB OxBF define t 20 PORTC OxFF PORTB OxDF define t 40 PORTC OxFF PORTB OxEF define t 90 PORTC OxFF PORTB OxF7 int send theta 0 send d theta 0 i 0 R 2cg accn 0 fail 0 put 0 float theta initial d_theta 0 dt 0 0081
55. hich is connected to target board For COMI write 4 50 for 2 write dev ttyS1 x Ele Ede Jemal Qo Serial Device Lockfile Location Callim Program n Callout Frogram E Bps Par Bits 1 115200 N F G Flow Control Software Flow Control Change which setting 1 Screen and keyboard Save setup 411 Save setup as Exit Exit from Minicon Fig 9 3 Minicom setup screenshot 3 Press key for setting up bps Par Bits Press to set up bps to 115200 Press to set up Data bits to 8 Press to set up Stop bits to 1 and V to set up parity to NONE 45 EM View Jemma Go 2 Comm ja Serial Current 113200 b Lockfile 1 Callin Speed Parity Data D Callout E Bps Par 300 Li None 1 F Hardware F B 1200 Ever 6 G Software f 2400 7 D 4800 2 Mark 8 Change whic 2000 Space 19200 Stophite Screen 0 38400 wi 1 Save H 57600 x 2 Save 1 115200 0 amp N 1 Exit J 230400 7 1 Exit f Choice or Enter to exit L 4 Fig 9 4 Screenshot Baud rate setting in Minicom Press F key for setting up Hardware Flow Control to NO Press G key for setting up So
56. ilding Linux image on the host 5 2 3 1 Installing cross compiler toolchain 1 Create a directory usr local arm 2 Change the directory to usr local arm 3 Untar the cross 2 95 3 tar bz2 file downloaded from www handhelds org in this directory 4 Type this command to export path PATH PATH usr local arm 2 95 3 bin 5 2 3 2 Compiling Linux source Untar the file 2410Linuxsrc tar gz from the CD This will generate a directory named linux 2 Change directory to linux by command cd We can type the command make menuconfig if desired for customizing 3 Type the following command to make dependencies make dep 4 zlmage This will create the image in arch arm boot directory 2 31 6 OVERVIEW OF THE PROJECT It is evident that uClinux and Embedded Linux can work as a reliably on time system The project now aims to explore the possibilities of an ARM processor S3C2410 using Embedded Linux for a real time control application The problem statement chosen is to control an Inverted Pendulum Since development of a mechanical inverted pendulum is tedious and most industry development processes recommend the use of a mathematical model for simulating the hardware we have chosen to model the Inverted Pendulum on an 8 bit microcontroller Atmega8535 This model helps in saving development time and also gives comparable results which can be used to evaluate the real time control system A Proportional
57. ing the approximate mathematical model of the inverted pendulum it is necessary to mimic the mechanics of the free falling rod This is done through the dynamic analysis of the Free Body Diagram of the system For our mathematical model the following are the principle assumptions with respect to the entire system Length of rod L 2mts Entire mass of the rod is assumed to be concentrated at its centre of mass 1 at half of its length Centre of mass h 1mt Centre of mass of the cart and motor are at ground level Contributing mass of the rod cart and motor m 1kg mgsine Fig 7 2 Free Body Diagram Consider a pendulum falling freely under gravity about the pivot as shown in the diagram alongside At an instant of time it is at a displacement of angle 0 from its mean position 0 degrees with a linear velocity of v In the next time interval dt it displaces by angle 40 such that the change in the force due to gravity remains constant 1 sin 0 is approximately equal to 0 40 Applying fundamental law of mechanics to the rod 40 o dt 1 2 a dt 1 By applying law of Conservation of Energy between initial position A 0 0 and current position 0 0 P E b K E b mgh mghcos 0 1 2 34 NDgh 1 cos0 since where v linear velocity r radius of circular motion o angular velocity o N 2gh 1 cos0 h h V 2gh 1 cos0 2 By consi
58. introduction will help in understanding the remainder of the report The report begins with the details of installation steps of uClinux OS It further outlines how to use Skyeye as a simulator for running operating systems mimicking the behaviour of a target board It then describes the features and configuration of the ARM target board followed by the explanation of the process of installing Embedded Linux and developing an application on it Once the embedded system setup 15 ready the report points towards the development of a software model of an Inverted Pendulum that needs to be controlled in real time by the ARM Embedded Linux system Finally the report details a comparison of the results of performance of the system under various conditions during the execution of the project 2 11 50 With embedded systems fast expanding its reach subject matter related to this field is available in abundance While working on this project we have studied matter from various sources such as books online articles and reference manuals The knowledge gained from this activity has been of great help to us in understanding the basic concepts related to our project and has ignited further interest in this topic Linux for Embedded and Real time Applications by Doug Abbott has been of great help in providing an introduction to the process of building embedded systems in Linux It has helped us understand the process of configuring
59. inux 1 Create a folder named sample under the uClinux dist user directory 2 Open the Makefile document under the uClinux dist user directory using VI or GEdit 3 Add the following line between the folder list and save the changes dir CONFIG USER SAMPLE SAMPLE sample 4 Now open the config in under uClinux dist config directory After the line mainmenu option next comment comment Miscellaneous Applications add bool Sample program CONFIG USER SAMPLE SAMPLE Save the changes 5 After doing the above changes execute make menuconfig 6 A new window opens that has the following option in the menu Kernel Library Defaults Selection gt Select the option by pressing Enter key Now select the Customise Vendor User settings 19 under the new menu that occurs This selection is done by pressing the Spacebar key sign indicates that the option is selected Save and exit the menu uClinux Distribution v4 0 Configuration c 0 Customize Application Librs Fig 3 6 Screenshot of Kernel and Library selections Then a new window named Main Menu appears Select Miscellaneous Applications under this menu Select Sample program under the menu that appears Then save and exit the menu uClinux Distribution v4 0 Configuration Miscellaneous Applications al a i d c c di d E f g g ES Fig 3 7 Screenshot of Miscellaneous
60. it then the server returns a special code saying again later The minimum rates are implemented similarly If too many people are trying to fetch something at the same time throttling may slow down each connection so much that it s not really useable Furthermore all those slow connections clog up the server using up file handles and connection slots Setting a minimum rate says that past a certain point you should 48 not even bother the server returns the try again later code the connection isn t even started 10 1 4 Multihoming Multihoming means using one machine to serve multiple hostnames If we want to have different web addresses say for different users all running on the same physical hardware then this feature is known as multihoming also known as virtual hosting There are 3 steps to set up virtual hosting 1 Make DNS entries for all the hostnames using CNAME aliases according to the HTTP 1 1 rules 2 Make separate directories for each web address 3 Enable the virtual hosting option using v flag or by using the ALWAYS VHOST option in config h 10 1 5 Symlinks and Permissions For any request that comes to the server the path is checked for any symbolic links If they exist then they are expanded to indicate the real path Then when there are no symbolic links in the path it is checked if the path is pointing to a location above the web server directory If it is then an error
61. itectures supported by this kernel with little or no changes The low level interfaces are specific to the hardware configuration on which the kernel runs and provide for the direct control of hardware resources using a hardware independent API Higher level components provide the abstractions common to all UNIX systems including processes files sockets and signals Since the low level APIs provided by the kernel are common among different architectures the code implementing the higher level abstractions is almost constant regardless of the underlying architecture Between these two levels of abstraction the kernel sometimes needs what could be called interpretation components to understand and interact with structured data coming from or going to certain devices Filesystem types and networking protocols are prime examples of sources of structured data the kernel needs to understand and interact with in order to provide access to data going to and coming from these sources Applications and Libraries Applications do not directly operate above the kernel but rely on libraries and special system daemons to provide familiar APIs and abstract services that interact with the kernel on the application s behalf to obtain the desired functionality The main library used by most Linux applications is the GNU C library glibc For Embedded Linux systems substitutes to this library that are much less in size than glibc are preferred 2 This basic
62. lation steps of Thttpd 2 1 21 52 TERESULTSAND ANALYSIS 53 12 CONCLUSION 58 13 FUTURE SCOPE e 59 ARRENDIX F PROJECT 60 APPENDIX HI LINUX COMMANDS virei 75 APPENDIX III SCHEMATICS FOR ARM TARGET BOARD sss 77 APPENDIX IV SCHEMATIC FOR 8535 BOARD sse 83 APPENDIX V WHETSTONE BENCHMARK TOOL eee 84 LIST OF REFERENCES eret ttbi oe o tae tace sc 86 vi LIST FIGURES Fig 1 1 Standard Embedded Linux Architecture eene 4 Fig 3 1 Screenshot showing the menuconfig window eese 16 Fig 3 2 Screenshot for vendor product selection eese 17 Fig 3 3 Screenshot of selection of kernel and library version sss 17 Fig 3 4 Screenshot of completion of make step essen eene 18 Fig 3 5 Screenshot of the Skyeye simulator eese 19 Fig 3 6 Screenshot of Kernel and Library selections esee 20 Fig 3 7 Screenshot of Miscellaneous Applications window essere 20 Fig 3 8 Screenshot of the simulation of the sample program 21 Fig 4 1 Pipeline architecture in ARM7 and ARMS cores sse 23 Fig 5 1 Screenshot of bootloader download to NAND Flash sse 28 Fig
63. ller algorithm i e the used operating system Actually the control algorithm can be implemented from the numerical point of view as a set of mutually co operating tasks which are periodically activated by the kernel and which perform different calculations The way these tasks activated is called scheduling of the tasks A correct scheduling of each task is crucial for a good performance of the controller and hence for an effective pendulum stabilization Thus the inverted pendulum is very useful in determining whether a particular scheduling choice is better than another one The controlling algorithm running on the ARM processor can be used to test its controlling capability on a physical inverted pendulum This project also includes simulation of uClinux OS on Skyeye Actual porting of uClinux OS on an MMU less processor can be carried out For this purpose the entire memory and addressing space of the processor must be known to the user Porting uClinux on the embedded processor will enable the processor to run real time applications 59 APPENDIX I PROJECT CODES finall c Controller Algorithm running on the ARM processor f Listing 11 header files include lt stdio h gt Standard input output definitions include lt string h gt String function definitions include lt unistd h gt UNIX standard function definitions include fcntl h File control definitions include
64. lowing specifications 1 Operating System Fedora Core 9 root localhost uname r 2 6 25 14 fc9 x86_64 2 Processor Specifications root localhost cat proc cpuinfo processor 0 vendor id GenuineIntel cpufamily 15 model 4 model Intel R Pentium R D CPU 2 80GHz stepping A cpu MHz 2792 995 cache size 1024 KB physicalid 0 siblings 2 14 0 cpu cores 2 fpu yes fpu exception yes cpuidlevel 5 wp yes flags fpu vme de pse tsc msr pae mce 8 apic sep pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx Im constant tsc pebs bts pni monitor ds_cpl cid cx16 xtpr lahf Im bogomips 5589 48 12 clflush size 64 cache alignment 128 address sizes 36 bits physical 48 bits virtual power management processor 1 vendor id GenuineIntel cpu family 15 model 4 model Intel R Pentium R D CPU 2 80GHz stepping 7 cpu MHz 2792 995 cache size 1024 physicalid 0 siblings 22 14 51 cpu cores 22 fpu yes fpu_exception yes level 5 wp yes flags fpu vme de pse tsc msr pae mce 8 pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx Im constant tsc pebs bts pni monitor ds cid cx16 xtpr lahf Im bogomips 5585 87 clflush size 64 cache alignment 128 address sizes 36 bits physical 48 bits virtual
65. lt errno h gt Error number definitions include lt termios h gt POSIX terminal control definitions Initialize and Declare Global variables xx x This is the file descriptor used for serial port int fd Number of times the serial port transactions will take place int k 0 This is to initialize the serial port x x x x x int initport int fd struct termios options Get the current attributes for the port assigned to the file descriptor fd in the termios structure named options tcgetattr fd amp options Set the baud rates to 19200 cfsetispeed amp options B38400 cfsetospeed amp options B38400 Enable the receiver and set local mode options c cflag CLOCAL CREAD Raw mode is enabled options c lflag 1 ECHO ECHOE 1516 Set the serial port to 8 1 8 bit data No parity 1 stop bit options c cflag amp options c cflag amp CSTOPB options c_cflag amp CSIZE options c_cflag CS8 Set the new options for the port immediately tcsetattr fd TCSANOW amp options Flush the input serial buffer tcflush fd TCOFLUSH Flush the output serial buffer tcflush fd TCIFLUSH return 1 e write to serial port ok ce x e e e e e int writeport int fd char chars int count Int n write file descriptor char ptr num chars
66. m a quality code are modularity and structure readability extensibility and configurability Reliable code should have features like predictability error recovery and longevity Most programmers agree that the Linux kernel and other projects used in a Linux system fit this description of quality and reliability The reason is the open source development model which invites many parties to contribute to projects identify existing problems debate possible solutions and fix problems effectively 2 Availability of Code Code availability relates to the fact that the Linux source code and all build tools are available without any access restrictions The most important Linux components including the kernel itself are distributed under the GNU General Public License GPL Access to these components source code is therefore compulsory at least to those users who have purchased any system running GPL based software and they have the right to redistribute once they obtain the source in any case Code availability has implications for standardization and commoditization of components too Since it is possible to build Linux systems based entirely upon software for which source is available there is a lot to be gained from adopting standardized embedded software platforms 3 Hardware Support Broad hardware support means that Linux supports different types of hardware platforms and devices Although a number of vendors still do no
67. number of clients goes on increasing Simultaneously we have also tested the control program on Desktop Linux and documented the result The various conditions for which the program has been tested and for which the results are provided here are 1 Running the code on Desktop Linux v s running the code on ARM Embedded Linux 2 Running the code on the ARM without starting the web server v s running the code on ARM board with server started and 2 clients accessing the webpage 3 Running the code on the ARM without starting the web server v s running the code on ARM board with server started and 2 clients accessing the webpage with 1 client refreshing the status page every 2 sec 53 plications Places System 4 lt 2 root 21 5 06 PM 4 Gnuplot 500 desk th10 kp17 kd 10 txt using 1 2 farm no load txt using 1 2 30 06 84 8 E untitled fol root localh 2 INVERTED _ _ Fig 11 1 Gnuplot of force v s time for desktop and ARM e Applications Places System 4 lt lt root Tue Apr 21 510 PM Gnuplot 500_desk_th10_kp1 _kd_10 txt using 1 3 farm no load txt using 1 3 EB 8 untitled folder 88 rootGlocalhost laxzcjpeg INVERTED PEN 8 desk arm nol Fig 11 2 Gnuplot of theta v s time for desktop and ARM 54
68. oes not work on uClinux The uClinux kernel is highly stripped modular and totally customizable as per the user requirements All of the standard executable formats are not supported on uClinux because they make use of VM features such as stacks and segments However uClinux works on the flat memory format It is a condensed executable format that stores only executable code and data in the same space as the kernel and the file system along with the relocations needed to load the executable into any location in memory The elf2flt Executable Linux Format to Flat Format is a tool used to make the applications compatible with uClinux 3 The implementation of Memory Map mmap within the kernel is also very different Though it is transparent to the user it needs to be understood so that it is not used inefficiently on uClinux systems The only filesystem that currently guarantees that files are stored contiguously i e flat memory model is romfs Secondly only read only mappings can be shared which means a mapping must be read only in order to avoid the allocation of memory The kernel also must consider the filesystem to be in ROM which means a nominally read only area within the CPU s address space This is possible if the filesystem is present somewhere in RAM or ROM both of which are addressable directly by the CPU Also when developing the uClinux OS customized for a target board it is essential to know the actual hardware
69. of two clients who are periodically refreshing the web page Thus it can be inferred that though the time required for the pendulum to settle down to its equilibrium position varies depending on the load conditions the ARM processor can control the inverted pendulum successfully 57 12 CONCLUSION In light of the result analysis presented earlier we empirically conclude that processor S3C2410 has performed extraordinarily well while running the Real Time Control Application when compared to Desktop Linux Desktop Linux underperformed severely by losing synchronization when the number of control transactions was increased beyond the count of five hundred Addition of a web server also made the Desktop Linux a highly unreliable system From the previous results it can be viewed that the ARM Linux controller performance is satisfactory even when it hosts web pages and services multiple client requests Hence it can be concluded that the overhead involved in running an application on an ARM processor is much less than that on a Desktop Linux which is why a Desktop Linux cannot be a reliable platform for running time critical applications Therefore the features of ARM architecture combined with Embedded Linux helps us in building a reliably on time platform 58 13 FUTURE SCOPE The Inverted Pendulum may be used as a benchmark to test the validity and the performance of the software underlying the state space contro
70. ot the case First the parent is suspended and cannot continue executing until the child exits The child directly after returning from vfork is running on the parent s stack and is using the parent s memory and data This means the child can corrupt the data structures or the stack in the parent resulting in failure This is avoided by ensuring that the child never returns from the current stack frame once vfork has been called and that it calls exit when finishing The child also must avoid changing any information in global data structures or variables 3 3 2 Skyeye Simulator Skyeye is an Open Source Software Project GPL Licence that has originated from GDB Armulator The goal of Skyeye is to provide an integrated simulation environment in Linux Skyeye is a simulation tool that is used to mimic the behavior of the embedded platform on the standard desktop Linux It is extremely useful as it enables the developer to analyse the behaviour of the system before actually implementing it on the hardware Latest developments in China have made Skyeye support the ARM architecture based microprocessors and Blackfin DSP Processors By using Skyeye it is possible to run Embedded Operating Systems such as ARM Linux uCos ii etc and analyse or debug them at source level 5 11 3 3 Host Specifications Throughout this report the user is assumed to be root and the host machine has atleast one serial port The host machine has the fol
71. plus Derivative PD control system is implemented as an application on the ARM Embedded linux and communication is established between the ARM board and the model using serial communication By doing this one can determine how well the ARM processor will implement the control system Data such as force angle etc are also logged into the database which could be used for plotting and analysis Since a single user process is being run on the Embedded ARM Linux one cannot evaluate the critical conditions for the control system in which it would fail to control The project accomplishes this task by running a thttpd web server in parallel with the PD control application Various features such as remote control are also introduced for ease of use The process load on Embedded Linux is increased by using multiple clients which access the web page that is hosted on the ARM processor The database results are now compared and statistics are evaluated between Desktop and Embedded Linux It is expected that the ARM processor which runs Embedded Linux will show superior results 32 7 MODEL OF AN INVERTED PENDULUM The inverted pendulum is a classic problem in dynamics and control theory and widely used as a benchmark for testing control algorithms PID controllers neural networks fuzzy control genetic algorithms etc This concept is best implemented in the technology of Segway a self balancing transportation device The largest implement
72. power management 3 The network configuration of the host machine is root g localhost ifconfig ethO Link encap Ethernet HWaddr 00 14 85 9 6 62 inet addr 192 168 1 217 Bcast 192 168 1 255 Mask 255 255 255 0 inet6 addr 80 214 85 9 6 62 64 Scope Link 13 UP BROADCAST RUNNING MULTICAST MTU 1500 Metric 1 RX packets 1311808 errors 0 dropped 0 overruns 0 frame 0 TX packets 1070 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 1000 RX bytes 89497811 85 3 MiB TX bytes 221766 216 5 KiB Interrupt 21 lo Link encap Local Loopback inet addr 127 0 0 1 Mask 255 0 0 0 inet6 addr 1 128 Scope Host UP LOOPBACK RUNNING MTU 16436 Metric 1 packets 3344 errors 0 dropped 0 overruns 0 frame 0 TX packets 3344 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 0 RX bytes 171307 167 2 KiB TX bytes 171307 167 2 KiB virbrO Link encap Ethernet HWaddr 72 29 C6 B0 6D 16 inet addr 192 168 122 1 Bcast 192 168 122 255 Mask 255 255 255 0 inet6 addr fe80 7029 c6ff feb0 6d16 64 Scope Link UP BROADCAST RUNNING MULTICAST MTU 1500 Metric 1 RX packets 0 errors 0 dropped 0 overruns 0 frame 0 TX packets 29 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 0 RX bytes 0 0 0 b TX bytes 5166 5 0 KiB 14 3 4 Installing uClinux on the host Linux platform Since the ARM board has memory constraints we compile uClinux on a host platform The host processor is primarily Pentium AMD etc
73. r finall c over a webserver bin sh echo Content type text html echo finall status cgi Shell script to view current status hello cgi of the inverted pendulum bin sh echo echo Content type text plain hello cgi 73 hello cgi Source code to read current status file include lt stdio h gt int main void FILE fpl fp2 fp3 char f 6 int i20 printf Hello ASAP printf n n CURRENT STATUS OF INVERTED PENDULUM nn RKKKAKKAKKAKAKARDAT amp PRINT FORCE VALUE x k x x fpl fopen cur force txt r if fpl NULL printf Cannot open force file n else for 1 0 1 lt 5 1 fscanf fpl c amp f i fclose fpl printf n nFORCE for 1 0 1 lt 5 1 printf Sc f i x nEADp amp PRINT THETA VALUE x k x x fp2 fopen cur theta txt r if fp2 NULL printf Cannot open theta file n else for 1 0 1 lt 3 1 fscanf fp2 c amp f i fclose fp2 printf XnXnTHETA for i 0 i 3 i printf c f i XXXXXXXXXXXXREAD amp PRINT D THETA VALUE x fp3 fopen cur d theta txt r if fp3 NULL printf Cannot open d theta file n else for 1 0 1 lt 4 1 fscanf fp3 c amp f i fclose fp3 printf NnMnD THETA for 1 0 1 lt 4 1 printi set ELIN return 0 74 APPENDIX II LINUX COMMANDS 1
74. rupt s initialization TIMSK 0x05 USART initialization Communication Parameters 8 Data 1 Stop No Parity USART Receiver On USART Transmitter On USART Mode Asynchronous USART Baud Rate 38400 UCSRA 0x00 UCSRB 0x18 UCSRC 0x86 UBRRH 0x00 UBRRL 0x0C Analog Comparator initialization Analog Comparator Off Analog Comparator Input Capture by Timer Counter 1 Off ACSR 0x80 SFIOR 0x00 Global disable interrupts asm sei while 1 while fail 1 IF PENDULUM FAILED THEN CHECK IF THERE IS REQUEST FOR RESET CHAR 2 if UCSRA 7 IF CHAR RECEIVED THEN SET INTERRUPTS dasm sei 72 index cgi Index page for thttpd server bin sh asap_hopel cgi Environment Variable echo echo echo echo echo echo echo echo Content type text html gt etitlo ASAP BE PROJECT lt title gt lt head gt lt font size 5 color burgundy face Latin sXx INVERTED PENDULUM STATUS Ion eoe rompen run lt head gt lt gt lt br gt lt br gt lt a href run_init cgi gt START THE PROCESS lt a gt lt br gt lt br gt lt a href status cgi gt CHECK CURRENT STATUS lt a gt lt body gt lt html gt init cgi Shell script to start the controlle
75. simulator The procedure to install skyeye is as follows 1 skyeye 1 2 2 Rel tar bz2 in root uclinux directory 2 untar skyeye 1 2 2 Rel tar bz2 in root uclinux directory 3 cd root uclinux skyeye 1 2 2 Rel 4 make 5 Addskyeye to PATH as PATH PATH root uclinux skyeye 1 2 2 Rel binary 5 3 4 4 uClinux Distribution uClinux dist 20070130 The procedure to install uClinux distribution is as follows 1 untar uClinux dist 20070130 tar gz in root uclinux directory 2 cd root uclinux uClinux dist 3 make menuconfig or make xconfig Fig 3 1 Screenshot showing the menuconfig window 16 4 Select vendor product here select GDB armulator uClinux Distribution v4 0 Configuration Vendor Product Selection DB Products ARMulator gt lt Select gt Fig 3 2 Screenshot for vendor product selection 5 Select kernel and library version 2 6 x and uClibc uClinux Distribution v4 0 Configuration kernel Version limx 6 x gt D E Fig 3 3 Screenshot of selection of kernel and library version 6 optionally select application explained in detail later 7 save and exit 8 for linux 2 4 x make dep 9 make 17 m OxSecf9 console 0 ptypc lib telnetd mtdm bcdm init boa 0020620 0020644 0100744 0100744 0100744 0100744 0100744 0100744 0040755 85344 50492 78860 102940 45024 105756 0 106300 35144 102124 0
76. system call will return the number of characters that are actually available in the serial input buffers If no characters are available the call will block wait until characters come in an interval timer expires or an error occurs The read function can be made to return immediately by doing the following fcntl fd F SETFL FNDELAY The FNDELAY option causes the read function to return 0 if no characters are available on the port To restore normal blocking behavior call fentl without the FNDELAY option fentl fd F SETFL 0 This is also used after opening a serial port with the O NDELAY option 9 3 4 Closing a Serial Port To close the serial port just use the close system call close fd Closing a serial port will also usually set the signal low which causes most MODEMs to hang up 15 43 9 4 Serial Communication S3C2410 The S3C2410X UART Universal Asynchronous Receiver and Transmitter provides three independent asynchronous serial I O SIO ports each of which can operate in Interrupt based or DMA based mode In other words the UART can generate an interrupt or a DMA request to transfer data between CPU and the UART The UART can support bit rates of up to 115 2K bps using system clock If an external device provides the UART with UCLK then the UART can operate at higher speed Each UART channel contains two 16 byte FIFOs for receive and transmit The S3C2410X UART includes programmable baud rates in
77. t provide Linux drivers considerable progress has been made and more is expected Because a large number of drivers are maintained by the Linux community itself you can confidently use hardware components without fear that the vendor may one day discontinue driver support for that product line Linux also provides support for dozens of hardware architectures No other OS provides this level of portability Typical architecture of an Embedded Linux System x Applications Linux kernel High level abstractions 4 4 ue temon systems protocols Low level interfaces Hardware y Fig 1 1 Standard Embedded Linux Architecture 1 Hardware Linux normally requires at least a 32 bit CPU containing a memory management unit MMU A sufficient amount of RAM must be available to accommodate the system Minimal I O capabilities are required if any development is to be carried out on the target with reasonable debugging facilities The kernel must be able to load a root filesystem through some form of permanent storage or access it over a network Linux Kernel Immediately above the hardware sits the kernel the core component of the operating system Its purpose is to manage the hardware in a coherent manner while providing familiar high level abstractions to user level software It is expected that applications using the APIs provided by a kernel will be portable among the various arch
78. tarting with thttpd are 10 1 1 Chroot chroot is a system call that restricts the program s view of the filesystem to the current directory and directories below it It becomes impossible for remote users to access any file outside of the initial directory The restriction is inherited by child processes so CGI programs get it too This is a very strong security measure and is recommended The only downside is that only root can call chroot so this means the program must be started as root However the last thing it does during initialization is to give up root access by becoming another user so this is safe The program can also be compile time configured to always do a chroot without needing the r flag One has to make sure that any shells utilities and config files used by your CGI programs and scripts are available If you have CGI disabled or if you make a policy that all CGI programs must be written in a compiled language such as C and statically linked then you probably don t have to do any setup at all 47 10 1 2 CGI Common Gateway Interface thttpd supports the CGI 1 1 spec In order for a CGI program to be run its name must match the pattern specified either at compile time or on the command line with the c flag This is a simple shell style filename pattern You can use to match any string not including a slash or to match any string including slashes or to match any single character You can also use
79. tate7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTC OXFF DDRC OXFF Port D initialization Func7 Out Func6 Out Func5 Out Func4 Out Func3 Out Func2 Out Funci Out Func0 Out State7 0 State6 0 State5 0 State4 0 State3 0 State2 0 Statel 0 State0 0 PORTD 0x00 DDRD 0x00 Timer Counter 0 initialization Clock source System Clock Clock value 125 000 kHz Mode Normal top FFh output Disconnected TCCRO 0x00 0 0 00 OCRO 0x00 Timer Counter 1 initialization Clock source System Clock Clock value 8000 000 kHz Mode Normal top FFFFh output Discon OCIB output Discon Noise Canceler Off Input Capture on Falling Edge Timer 1 Overflow Interrupt On Input Capture Interrupt Off Compare A Match Interrupt Off Compare B Match Interrupt Off TCCR1A 0x00 TCCR1B 0x01 CNT1H 0x00 CNT1L 0x00 1 0 00 ICR1L 0x00 OCR1AH 0x00 OCR1AL 0x00 1 0 00 OCRIBL 0x00 Timer Counter 2 initialization Clock source System Clock Clock value Timer 2 Stopped Mode Normal top FFh OC2 output Disconnected ASSR 0x00 TCCR2 0x00 2 0 00 OCR2 0x00 External Interrupt s initialization INTO On INTO Mode Low level INT1 Off INT2 Off 71 0 40 MCUCR 0x00 MCUCSR 0x00 GIFR 0x40 Timer s Counter s Inter
80. the controller has failed and that the pendulum has fallen Now the flag for fail is set to 1 36 CLEAR INTERRUPTS SCAN FOR SYNC CHAR Aoz CONFIRM Z AND INITIALIZE PENDULUM CONFIRM A REPORT F SET INTERRUPTS AND RETURN TO MAIN SEND ACKNOWLEDGEMENT RECEIVE FORCE IN THE FORM OF 5 CHARACTERS CONVERT CHAR FORCE INTO INT PRINT CURRENT VALUES OF 0 AND d0 IN DEGREES TO THE CONTROLLER WITH PROPER SIGN AND APPENDEDED ZERO CHARACTERS COMPUTE THE MATHEMATICAL MODEL SET INTERRUPTS HAS THE AND RETURN PENDULUM FALLEN Fig 7 3 Flowchart for inverted pendulum model 37 8 PD CONTROLLER APPLICATION ON ARM The PD controller is a combination of proportional and derivative controller 8 1 Proportional mode In this mode a linear relation exists between the controller output and the error signal when the error increases the controller output increases and vice versa In the application the deviation of angle from 0 degree is the error The range of error over 0 100 of controller output is called proportional band PB The expression for proportional mode output is p t kp e t PO where kp proportional gain p t controller output e t error input P0 controller output at the start of the error Proportional band 100 kp The characteristics of Proportional controller are 1 When error is zero the controller output is equal to PO 1 e
81. the transfer of data one bit at a time Serial communication is used by most network devices keyboards mice MODEMs and terminals When doing serial communications each word i e byte or character of data that is sent or received is sent one bit at a time Each bit is either on or off The terms mark for the on state and space for the off state are generally used The speed of the serial data is most often expressed as bits per second bps or Baudot rate baud This just represents the number of ones and zeroes that can be sent in one second When referring to serial devices or ports they are either labelled as Data Communications Equipment DCE or Data Terminal Equipment DTE The difference between them is that every signal pair like transmit and receive is swapped When connecting two DTE or two DCE interfaces together a serial null MODEM cable or adapter is used that swaps the signal pairs 9 1 RS 232 Standard RS 232 15 a standard electrical interface for serial communications defined by the Electronic Industries Association EIA RS 232 actually comes in 3 different flavours A B and C with each one defining a different voltage range for the on and off levels The most commonly used variety is RS 232C which defines a mark on bit as a voltage between 3V and 12V and a space off bit as a voltage between 3V and 12V The RS 232C specification states that these signals can go about 25 feet 8m before they become unus
82. ulation of uClinux OS on Skyeye uClinux is the microcontroller version of the desktop Linux aimed to work with MMU less processors or with architectures that use it for memory protection only The report details the results observed during the running of the controlling algorithm for various load conditions The process load on the ARM board is increased by running a thttpd web server and varying the number of clients The controlling algorithm is also run on desktop for performance comparison Finally the result analysis of the controller algorithm is carried out and the future scope of the project is discussed viii 1 INTRODUCTION The project is aimed at evaluating the performance of an operating system on an embedded system Before delving into its implementation an introduction is needed to the parts involved in the project The whole report is centered around the field of embedded systems and the use of Linux to run applications on them Hence an introduction to Embedded Systems and using Linux as an OS in them is provided 1 1 Embedded Systems An embedded system is a special purpose computer system that is designed to perform very small sets of designated activities Embedded systems date back as early as the late 1960s where they used to control electromechanical telephone switches The first recognizable embedded system was the Apollo Guidance Computer developed by Charles Draper and his team Later they found their way into the
83. ures such as RISC where the large number of processor registers enhance the handling of local variables e Whetstone contains a number of very tight loops and the use of even small instruction caches will enhance performance considerably 84 Results For Desktop Linux the output 18 Loops 10000 Iterations 1 Duration 1 sec C Converted Double Precision Whetstones 1000 0 MIPS For ARM Embedded Linux the output 15 Loops 1000 Iterations 1 Duration 36 sec C Converted Double Precision Whetstones 2 5 MIPS 85 115 P Raghavan Amol Lad and Sriram Neelakandan Embedded linux System Design Development 1st Indian reprint New York Auerbach publications 2007 2 Karim YaghmourJon Masters Gilad Ben Yossef and Philippe Gerum Building Embedded Linux Systems 2nd ed Beijing O Reilly August 2008 3 2004 July David MaCullough Embedded 2nd Ed Online Available http www linuxjournal com article 7221 4 2008 Aug Ryan McDonald and Edo Lui uClinx FAQ Online Available http www uclinux org pub uClinux F AQ shtml 5 2007 June ChenYu Department of Computer Science and Technology Tsinghua University Skyeye Project Online Available http skyeye sourceforge net index shtml 6 2004 July David MaCullough Embedded 2nd Ed Online Available http www linuxjournal com article 7221 7 2001 July Cyber Guard Corporation Snap Gear Embedde
84. ww acme com have enabled us to implement this web server on our system POSIX compliant systems always have a detailed documentation that helps in accessing the hardware with fewer restraints The Serial Programming Guide for POSIX Operating Systems by Michael R Sweet is an excellent guide to using serial ports of POSIX compliant systems It has helped us in developing an interface between the ARM board and microcontroller model The implications of this control system are vast and brings into effect an intelligent and user friendly control system which is easily reconfigurable 3 UCLINUX uClinux stands for Microcontroller uC Linux It is a popular embedded system OS used traditionally for deeply embedded applications 3 1 Features of uClinux The following points detail the characteristic features of uClinux and how they make it different from the standard desktop Linux OS l The defining and most prevalent difference between the uClinux operating system and other Linux systems is the lack of memory management Under Linux memory management is achieved through the use of Virtual Memory VM uClinux was created for systems that do not support VM Since VM is implemented using a processing unit called Memory Management Unit MMU uClinux is usually preferred for MMU less processors With VM all processes run at the same address although a virtual one and the MMU takes care of what physical memory is mapped to thes

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