Introduction to the Coldfire 5272 - J.-M Friedt
Contents
1. include lt sys stat h gt fd open dev uc_int 0_RDONLY while 1 read fd i 16 include lt fcnt1 h gt for n 0 n lt 16 n print x char iln amp 0xff include lt asm coldfire h gt defines MCF_MBAR printf n include lt asm m68knommu m5272sim h gt defines PADDR return 0 int main int argce char argv char i 16 int fd char n The steps for compiling this module are described in a document available in linux 2 4 x Documentation kbuild in the uClinux directory structure most importantly config language txt and makefiles txt which describe the modifications to be brought to Config in and the Makefile in order to include the new module in the compilation sequence In summary we create a direc tory named uc_int in the linux 2 4 x drivers char directory of uClinux in which we place the source code of our module and a Makefile including the lines obj CONFIG_UC_INT uc_int o and include TOPDIR Rules make Then in the Makefile of the char directory we add ifeq CONFIG_UC_INT m subdir CONFIG_UC_INT uc_int obj CONFIG_UC_INT uc_int uc_int o endif and finally in linux 2 4 x drivers char Config inweaddtristate uc_int driver CONFIG_UC_INT to add a new entry in the kernel configuration menu A make to build the kernel then creates the module uc_int o which is appended to the kernel by executing an insmod as would be done classically under linux 10 Results We have attach2. contacts bouncing against each other upon switch closure debounce we add a 7414 Schmitt trigger with a low RC time constant in order not to slow down the response time of the circuit in order to trigger only one and not several interrupts when the switch is closed The circuit using a component supplied with 3 3 V LVC type is connected directly to pin 77 of the uCdimm In case a 3 3 V compatible component is not readily available it should be possible to use any TTL compatible 5 V component connected to the hardware interrupt related pin by a resistor fig 3 Similarly to the activation of hardware interrupts on IBM compatible PCs the initialization and acknowledgement sequence after interrupt processing is strongly dependant on the hardware In the case of interest here namely the management of IRQ0 in the Arcturus naming convention which is INT2 in the Motorola naming convention the register with which we must interract is ICR1 located at address MBAR 0x20 Initializing interrupt i is done by setting INT IPL to 0x111 Acknowledging of this interrupt after management of the event is completed by setting to 1 the bit INTzPI One must rember during the management servicing function uc_int_irqhandler to deactivate the interrupt before acknowledging then to perform the actions associated with this interrupt before finally re activating the interrupt at the end of the service routine All the other functionalities are standard modul
3. of electrical mishandling are quite reduced thanks to the simple connections The first test is to check whether when powered up the uCdimm 5272 transmits a message The default protocol used is to communicate through the first serial port 9600 bauds and N81 The following messages obtained either by cat lt dev ttySO or cu 1 dev ttySO s 9600 appear upon power up uCbootloader 1 7 7r1 c Copyright 2001 2004 Arcturus Networks Inc All Rights Reserved CACHE on BOOT FLASH type 00c8 AT49BV32XA 0x10c00000 DP 002000 DP 004000 DP 006000 DP 008000 DP 00a000 DP 00c000 DP 00e000 DP 010000 DP 020000 D 030000 D 040000 D 050000 D 060000 D 1070000 D 080000 D 090000 D 0a0000 D 0b0000 D 0c0000 D 0d0000 D 0e0000 D 0 0000 D 100000 D 110000 D 120000 D 130000 D 140000 D 150000 D 160000 D 170000 D 180000 D 190000 D 1a0000 D 1b0000 D 1c0000 D 140000 D 1e0000 D 1 0000 D 200000 D 210000 D 220000 D 230000 D 240000 D 250000 D 260000 D 270000 D 280000 D 290000 D 2a0000 D 2b0000 D 2c0000 D 240000 D 2e0000 D 2 0000 D 400000 BS The command go then launches the operating system stored in non volatile flash memory The uCdimm 5272 is provided with a functional uClinux system A classical linux bootsequence is observed until a login prompt appears the only account is root with the password uClinux Discovering the available tools is straighforward all executable binaries are located in bin We will se
4. unsigned long MCF_MBAR MCFSIM_ICR1 tmp if retval request_irq uc_int_irq uc_int_irqhandler SA_INTERRUPT uc_int dev dbg unable to assign irq d uc_int_irq goto exit_sem static ssize_t uc_int_read struct file file char buffer size_t count loff_t ppos unsigned long tmp 4 besa interruptible_sleep_on amp dev gt uc_int_queue sleep until a interrupt occurs memcpy void tmp void MCF_MBAR MCFSIM_ICR1 sizeof tmp the realease method is call when user want close the device static int uc_int_release struct inode inode struct file file C tmp 0x0f000000 volatile unsigned long MCF_MBAR MCFSIM_ICR1 tmp free_irgq dev gt uc_int_irq NULL eee This module registers the interrupt service routine for INT2 in the Motorola naming conven tion thanks to the function request_irq A user space client then listens through an interface dev uc_int defined with a major number of 6 by running the command mknod uc_int c 6 0 in romfs dev of the uClinux directory the function read being blocking the execution of the client only continues when a hardware interrupt is triggered The module then transfers to the client the 16 bytes displaying the values to which registers INTiPL i 1 4 are set i e most significant word of the ICR1 register include lt stdio h gt include lt stdlib h gt include lt sys types h gt
5. Introduction to the Coldfire 5272 J M Friedt S Guinot Carry Association Projet Aurore 16 route de Gray 25030 Besan on http projetaurore assos univ fcomte fr 7 juin 2005 We here aim at a step by step introduction to the use of embedded systems based on uClinux The objective is to allow one to get familiar with linux running embedded systems on a limited budget We will first tackle the hardware aspects including the printed circuit board PCB to be developed for running a test circuit We will then present the development environment and most interstingly the cross compiler for generating a Motorola compatible binary in a computer based on an Intel processor Finally we will show how to access hardware peripherals of the processor and the programming method somewhat unusual on embedded devices 1 Hardware aspects The uClinux kernel 1 2 3 has been ported to a wide range of microcontrollers and processors Its main contribution is to run on systems with no Memory Management Unit MMU and hence to run on relatively simple embedded devices only including a microcontroller and a few additional necessary peripherals We impose two requirements in choosing the hardware price and weight The latter requirement is defined by our objective the final system should fit in a flying object hence the necessity for a lightweight low volume and simple power supply circuitry to be used with our processor board Our choice is the Arcturus Net
6. _PWCRi 3 the relative width of the pulses is defined by the value stored in MCFSIM_PWWDi located at address MBAR 0xd0 4 7 We thus generate with a division factor of 0x0c pulses on PWMO every 15 8 ms with widths ranging from 1 5 to 2 5 ms when the delays range from 13 to 37 as required for the angular control of servo motors We see in this example the complementarity of the programming methods under uClinux simultaneously programming on a high level operating system for example when accessing the RS232 ports on the uCdimm exactly as would be done on a PC and low level programming as more usually performed on microcontrollers when directly writing to Coldfire 5272 hardware configuration registers 9 Interrupts management Hardware interrupts which trigger a software event upon a hardware event generated on one of the pins of the processor are an unusual case in this presentation since only the kernel can access these functionalities We must thus in order to be able to use these functions of the Coldfire processor write a module to be appended to the kernel There again we will find programming structures familiar to linux developpers with methods usual for module programming 13 as well as hardware specific calls which require an extensive reading of the datasheet of the processor 6 chapter 7 As a first step an additional hardware circuit is needed to trigger a hardware interrupt by a push button while avoiding the effect of the
7. dist http www seattlerobotics org encoder 200009 qcam html http projets sequanux org membres sim uclinux webcam J Corbet A Rubini amp G Kroah Hartman Linux Device Drivers 3rd Edition O Reilly Ed 2005 http photopc sourceforge net protocol html http projetaurore assos univ fcomte fr ballon http friedtj free fr aduc816 pdf W R Newcott Return to Mars et J B MacInnis E Kristof Titanic Tragedy in Three Dimensions National Geographic Aout 1998 http www dilnetpc com dnp0038 htm 11
8. e later section 6 how to use minicom to communicate and transfer new binary images Having checked that the communication through the serial port is working we still have to test the ethernet connexion The default IP address of the uCdimm is 192 168 1 200 which is initialized if and only if an ethernet connexion is detected during the boot sequence The common network configuration tools ifconfig and route are available to chage these parameters and a ping command towards the host used as the serial terminal allows us to check that the ethernet communication is functional The system is shipped with a telnet daemon login root passwd uClinux waiting for a connexion as well as mount The filesystem of the host can thus be exported by NFS using the following command mount o nolock moutvers 2 IP_hote r pertoire mnt where the options are necessary for a proper communication between the NFS server provided in a linux 2 4 22 kernel and the uCdimm 3 Cross compiling Having checked that the basic system is functional we must now learn how to cross compile our own application in order to optimize the kernel to our application add new applications for exampe web server text editor etc develop our own applications We have recompiled the toolchain targetted towards the m68k elf i e binary for Motorola 68k processors in ELF format which will then be converted to a flat binary format to be directly executed under uClinu
9. e programming as presented in the following example in which we have only kept the parts which are specific to our interrupt management module for the version T ucdinms 272 N 1 6 74LVC14 74ers 5 1 kQ 3 3 V IRQO 4 7uF Fic 3 Schematic left and implementation right of the debounce circuit used to trigger a single hardware interrupt when a push button is pressed of the kernel ported to the Coldfire processor as well as the communication with user space A fully functional version of the module is available at 12 define IRQ_DEFAULT 66 static int uc_int_major 6 static struct file_operations uc_int_fops owner THIS_MODULE read uc_int_read open uc_int_open release uc_int_release static void uc_int_irgqhandler int irq void dev_id struct pt_regs regs unsigned long tmp Lave tmp volatile unsigned long MCF_MBAR MCFSIM_ICR1 disable interrupts tmp amp Oxf8ffffff volatile unsigned long MCF_MBAR MCFSIM_ICR1 tmp we ack this interruption to the hardware tmp 0x08000000 volatile unsigned long MCF_MBAR MCFSIM_ICR1 tmp and wake up user application waiting for a read wake_up_interruptible amp dev gt uc_int_queue restore interrupts static int uc_int_open struct inode inode struct file file C tmp volatile unsigned long MCF_MBAR MCFSIM_ICR1 tmp 0x0 000000 volatile
10. ed our circuits including the uCdimm5272 board two black and white webcams as presented previously motorized by a servo motor controled by the PWM an Olympus C 860L digital camera remote contolled through an RS232 link 14 and a wifi module DLink DWL 810 to a gondola attached to a 2 60 m diameter tethered gas balloon inflated with helium European Balloon Corporation Belgique 15 The wifi link used to transmit images to the ground station and to control the digital camera works when no obstacle is present in the path at a distance of more than 150 m Fig 4 The lack of analog to digital converter to monitor the environment is compensated for by connecting to the second RS232 port of the wCdimm a microcontroler ADuC814 16 used to read an analog value in our case the temperature of the gondola and store the result in a file mounted by NFS from a server located on the ground All these devices are powered by a 2000 mA h Lithium polymer battery T2M Powerhouse providing an autonomy of about 1 h The whole gondola weights about 1 kg Fic 4 Top aerial photography of the parc of the Besancon observatory left and sunset on the Ecole Nationale Sup rieure de M canique et des Microtechiques ENSMM the new Maison des Microtechniques under construction and the buildings of the CROUS right Bottom snapshot of the Laboratoire de Physique et M trologie des Oscillateurs FEMTO ST LPMO Besancon France and resulting stereoscopic
11. g way volatile unsigned char MCF_MBAR MCFSIM_PADAT 1 value to write on port C and volatile unsigned char MCF_MBAR MCFSIM_PCDAT 1 value to write on port A notice that the names of the port and of the register are inverted due to the differences in the naming conventions of Arcturus Networks and Motorola Reading from port B is done with value volatile unsigned char MCF_MBAR MCFSIM_PCDAT Once familiar with these basic concepts both hardware and software we just have to imple ment the communication protocols to grab an image as shown on figure 2 right The images are acquired in a loop and first stored on an NFS mounted directory for later viewing on a PC with a graphical interface Quickcam control software The program as described here 12 periodically grabs an image on the uCdimm and transfers it on the network to clients running on PCs for display and storage Thus we have selected to run a multithreaded server on the uCdimm using the pthread library optimized for embedded applications and provided with uClinux in order to allow multiple remote PCs to connect directly to the image server with the aim of disseminating stereoscopic images grabbed by the uCdimm on a balloon or an unmanned autonomous vehicle for example while multiple clients watch simultaneously the result of these acquisitions The ethernet connexion was replaced by a wireless Wifi connexion thanks to a DLink DWL810 ethernet to wif
12. i converter compatible in terms of supply voltage with an embedded application 5 V voltage regulated by an 7805 600 mA current We have completed the interfacing electronics by doubling all bus management components 75245 and 74573 so that two cameras could be connected in order to be able to measure the distance of target objects by means of stereoscopy the computational power of the Coldfire 5272 being enough for calculating the cross correlation between a few lines of the acquired images Furthermore we have implemented jpeg image compression either before image transmission in order to save bandwidth and hence increase the wifi range or after reception of the images for a direct display on a web interface 8 Using the PWM The Pulse Width Modulation PWM generators are useful peripherals for controlling the speed of DC motors to make simple digital to analog converters after low pass filtering or in our case for the angular control of servo motors as used in remote controlled models Two of the PWMs integrated in the Coldfire 5272 are available to the uCdimm user Their use is consistent with their description provided in the 5272 datasheet 6 chapter 18 1 PWM i is activated by setting the most significant bit of the control register MCFSIM_PWCRi located at address MBAR Oxc0 4 i i 0 2 2 the repetition rate of the pulses is defined by the division factor set by the least significant bits of this same register MCFSIM
13. image to be watched with red blue glasses 17 11 Conclusion We have presented the successive steps during the development of our embedded application image acquisition and transfer from a tethered balloon based on uClinux We have first be come familiar with the development tools bootloader cross compilation transfer of the resulting programs by NFS before approaching the hardware interfacing issues and software access to the input output ports The main point of using the Arcturus Networks uCdimm 5272 board is the availability at minimal cost and power consumption of a decent computational power and the availability of all the development tools and libraries provided by linux Several manufacturers are now providing new boards with new functionalities and smaller dimensions proving new application opportunities we have just bought an SSV DIL NetPC DNP 5280 18 whose presentation will be the subject of another article this board is based on the Coldfire 5282 which provides several useful peripherals which were not available of the 5272 for example analog to digital converters an I C bus or a CAN bus as well as a connector much more convenient to use DIL64 Despite their naming similarities the programming model is very different than that of the 5272 since like on other processors with an MMU we must go to kernel space to access registers controling hardware functionalities on the 5282 10 Acknowledgements We ac
14. ire a heat sink since the power consumption is so low The RS232 ports are directly usable the TTL to RS232 voltage converters are included on the board The same is true of the ethernet ports the transformers converting the output signals to differential pairs are mounted on the board and use a large volume over the PCB The connector is a SODIMM 144 pins as found for connecting RAM on laptops bought from Digikey in the US since we were unable to locate such connectors in France 7 One must expect though to compensate for the expensive daughter board sold by Arcturus the access to a mandatory SMD compatible soldering iron and a binocular microscope for soldering the connector as well as the ability to etch a single sided PCB with tracks separated by 0 8 mm lcross compilation compiling a binary for a given target architecture Motorola Coldfire on a processor of another architecture here Intel x86 or SPARC uCdimm5272 war a oe l E regul 3 3 V bus ports camera2 Fic 1 Test board including the emulation of a TTL compatible PC parallel port for interfa cing the webcam The board holding the uCdimm including the voltage regulator and ethernet connector and an RS232 connector is visible to the left while the A B and C busses are trans ported to a daughter board dedicated to the CMOS TTL levels conversion and multiplexing these busses to the two webcams 2 First time startup The chances
15. is working on in our case Arcturus 5272 and selects whether he wants to modify the default parameters of the kernel for this hardware in our case we must change the processor frequency from 48 to 66 MHz and the amount of RAM from 2 to 4 MB and or the applications compiled in the disc image to be loaded to RAM We always use the compact C library uClibc AFter leaving this first menu the following menus kernel configuration and utilities appear The compilation is then completed by running make dep and make which end up by putting in the images directory an image of the disc image bin ready to be transferred to the RAM of the embedded device and in the romfs directory the individual files included in this image By mounting via NFS this latter directory one can execute these new programs without having to transfer the whole image to RAM through the RS232 link rx from the bootloader a lengthy operation detailed in the next paragraph Notice that the kernel always executes from RAM due to excessive memory access times to the other kinds of memories even a kernel to be stored in flash memory must be defined in the Processor type and features menu of the kernel configuration with Kernel executes from RAM 6 Transferring an image of the filesystem We have seen that cat or cu can be used for monitoring the behaviour of the uCdimm A more complete tool is minicom which however requires a few initial configurations to be usable 1 lancer
16. knowledge the support of F Vernotte director of the Besancon observatory for kindly hosting the student association Projet Aurore and the help of H Bassmann The Imaging Source http www theimagingsource com for offering two identical webcam lenses ref Ado gon L12mf3 6f so that we could achieve stereoscopic imaging Vincent Giordanno and the os cillator metrology team of the FEMTO ST LPMO laboratory have provided the helium for the tethered balloon The association for the promotion of opensource software in Franche Comt Sequanux www sequanux org is acknowledged for its logistics support R f rences 1 2 3 10 11 12 13 14 15 16 17 18 Linux embarqu le projet uClinux Linux Magazine pp 16 22 F vrier 2002 in French Linux et le syst me sur silicium Linux Magazine pp 50 59 Avril 2005 in French M Opdenacker Embedded Linux kernel and driver development disponible http free electrons com http www arcturusnetworks com coldfire5272 shtml http friedtj free fr h8eng pdf MCF5272 ColdFire Integrated Microprocessor User Manual MCF5272UM disponible http www freescale com webapp sps site prod_summary jsp code MCF5272 http www digikey com reference 54697 1440 http www uclinux org pub uClinux uclinux elf tools m68k elf tools 20030314 sh http www uclinux org pub uClinux uclinux elf tools gcc 3 http www uclinux org pub uClinux
17. launch the configuration pannel of minicom by CTRL A O Serial port setup Serial Device gt dev ttyS0 Serial port setup Bps Par Bits 9600 8N1 Serial port setup Hardware Flow Control No OL a cn Serial port setup Software Flow Control No and check that under File transfer protocols we have xmodem usr bin sx vv There is no use attempting an image transfer at 115200 bauds while all our transfers succeeded at 57600 they always failed at 115200 Once an image has been transferred remember to set the terminal speed back to 9600 bauds before launching the goram command since linux will open a terminal on the serial port expecting communication at this speed After observing that the image stored in RAM behaves as expected it can be permanently transferred to flash memory by running the instruction program from the bootloader after the transfer rx In our case a satisfying result was obtained after having edited etc inittab and removing the execution of agetty in order to free the serial ports this is done in the vendor Arcturus uC5272 directory otherwise this file would be replaced by the default one during the next kernel compilation having added in etc a file passwd including an entry for root with no password in the directory romfs etc since this file is not replaced during the compilation of a new kernel having added in the user applications fundamental tools such as 1s mkdir a
18. mming ports A to C of the Arcturus hardware seemed not to match the programming rules given by Motorola It appeared in fact that the port called B on the uCdimm5272 is in fact the least significant byte of port C of the Coldfire 5272 port A of the uCdimm is the most significant byte of port C of the Coldfire 5272 and finally port C of the uCdimm is the most significant byte of port A of the Coldfire This surprising result is confirmed by the manipulation of the port direction registers the most significant byte of PCDDR must be modified for port B of the uCdimm to become an output port In summary ports are configured as GPIO by volatile unsigned long MCF_MBAR MCFSIM_PACNT 0x40000000 to use ports A and B as general purpose input outputs There is no use in modifying MCFSIM PBCNT fol lowing the naming conventions we just described ethernet and serial interfaces are always available PADDR and PCDDR direction registers define whether a port is set for intput or output the most significant byte of PC Coldfire naming convention setting the direction of port B Arcturus Networks naming convention Hence to configure ports A and C as outputs and the 5 least significant bits of port B as inputs with the 3 most significant bits as outputs we use volatile unsigned short MCF_MBAR MCFSIM_PADDR Ox0Off volatile unsigned short MCF_MBAR MCFSIM_PCDDR OxeOff writing on a port is done in the followin
19. n the PC parallel port and the Quickcam is not freely available but several opensource software Linux DOS and 68HC11 11 provide the successive steps needed to configure the camera and grab images We observe that 8 bits aree needed for the communication from the uCdimm to the camera sending commands through port A 5 bits from the camera to the uCdimm reading pixels as nibbles and handshake through port B and 2 control signals from the uCdimm to the camera port C We will later use an additional 2 output bits on port B to multiplex the ports and hence connect simultaneously two cameras Interfacing the 3 3 V logic to TTL is done by resistors pull up resistors from 3 3 V to TTL and current limiting resistors in series from TTL to 3 3 V 2 We have observed that all pins whether as inputs or outputs require such an interface without which proper communication with the camera could not be achieved Port A is thus connected to the camera via a 74LS245 bus interface while ports B and C are connected throught a 74HCT573 latch the selection of the components being only defined by their availability and any other TTL compatible bus interfacing chip could be suitable The advantage of using a 74245 to interface port A is that we will later be able to use this port in both directions and hence speed up the image transfer from the camera to the uCdimm The uClinux operating system provides the address of some of the useful registers the base add
20. nd in order to activate NFS access portmap and mount Notice that for the latter the default uClibc confi guration must be edited to activate RPC deactivated by default modify UCLIBC_HAS_RPC y by editing the file config uClibc having added our own programs either in the romfs bin directory following manual com pilation or after having appropriately modified the Makefile as described in section 3 7 Development of a practical application image transfers The practical application we wish to develop in order to be able to transfer images from a captive balloon are 1 capture images and eventually compress them 2 replace the ethernet connexion by a wireless connexion 3 transfer images in real time through this netwoek connexion The first point will be achieved by using old black and white Connectix Quickcam webcams which used to be connected to the PC parallel port This first part will get us used to programming ports A B and C as inputs and outputs as well as with the electronics aspects of converting CMOS 3 3 V logic levels uCdimm to TTL level 5 V webcam The second point is simplified by using a commercial product an ethernet wifi converter is used as wireless communication interface The last point is achieved by modifying the program controlling the camera so that it conti nuously transfers images through the network rather than saves them in files 7 1 Webcam programming The communication protocol betwee
21. omewhat unusual commands in which the pointer addresses are defined to reach a predefined memory location A first simple example is to have LEDs connected to ports A and C pins 53 60 and 71 74 of the uCdimm 5272 blink Reading the Coldfire 5272 datasheet teaches us that these ports are accessed by reading and writing to a base register MBAR incremented by 0x86 and 0x96 respectively The choice of ports A and C is dictated by the fact that the functions of port B are multiplexed between a digital general purpose input output GPIO port and the first serial port ttyS0 which want to keep running We will see though later that due to naming conventions differences between Motorola and Arcturus all ports will finally become usable We will see 6 chapter 17 that 3 registers control the behaviour of each port PiCNT i A B defines the mulitplexed mode of each port for example port B is multiplexed with the first ethernet serial ports PiDDR i A B C defines the direction of each pin PiDAT i A B C defines the level of each pin read if the pin is configured as an input 5 Compiling a new kernel The uClinux distribution includes linux kernels 2 4 and 2 6 adapted to systems which lack MMU The configuration is done as would be done with a classical linux make menuconfig The difference then comes with the menu that appears instead of directly getting to the kernel configuration menu the user selects which hardware he
22. ress register MBAR is defined in asm coldfire h in a constant called MCF_MBAR while the hardware configuration registers are defined in asm m68knommu m5272sim h uClinux 3 3V portB_ portC portA av 8 b gt Hob sv H sy 74HCT573 ENFDIR ENDR i TALS245 74LS245 status contro data status control data parallel port 5V parallel port 5V Connectix Quickcam B amp W Connectix Quickcam B amp W Fic 2 Left interface circuitry between the uCdimm 3 3 V CMOS and TTL level electronics compatible with the PC parallel port for connecting a webcam The TTL components are used as buffers and eventually for the multiplexing of the ports of the processor between the peripherals Port A is used as a bidirectional data bus commands from the uCdimm to the camera pixel values in the other direction the 5 least significant bits of port B are used for reading the data from the camera port C is used for sending control signals to the camera and finally 2 most significant bits of port B are used for multiplexing the digital circuits between the two cameras Right example of stereoscopic images obtained with the cameras connected to the uCdimm 6 bits pixel After observing that the adresses of the registers as defined in the uClinux header files indeed match the values provided in the Motorola Coldfire 5272 datasheet we were surprised to see that progra
23. works uCdimm 5272 4 which answers our price criteron 275 US dollars including shipment and most importantly as being the smallest system we could find for such a computational power for example a Renesas H8 microcontroller 5 based board smaller and cheaper was eliminated for lack of sufficient memory and processing power The hardware we selected includes 4 MB of non volatile flash memory 8 MB RAM a Motorola Coldfire 5272 processor clocked at 66 MHz and a second 100 Mb s ethernet port additional to the one includeed on the processor The uCdimm 5272 is provided with no documentation other than the few web pages available on the Arcturus web page mainly the connector pinout and the commands of the proprietary bootloader provided for hardware initialization A much more expensive development daughter board is available but was not within our available budget uCevolution board The datasheet of the embedded processor Motorola Coldfire 5272 6 quickly becomes a fundamental reading in order to understand the capabilities of this system as will be described later Getting the Arcturus uCdimm 5272 to run is surprisingly simple the only requirement is a 3 3 V power supply which is provided in our case by a LM317 voltage regulator compatible with a wide input voltage range 5 37 V including the slowly decreasing voltage of a battery pack properly decoupled to ground by a 440 nF capacitor The voltage regulator does not even requ
24. x on Intel based PCs and SPARC The simplest method on PCs is to unarchive an image of the directory including all the precompiled binaries for intel processors gcc 1d as and associated libraries 8 Under SPARC the compilation of all these tools is necessary binutils v 2 10 gcc v 2 95 3 genromfs v 0 5 1 and STLport v 4 5 3 with the option TARGET m68k elf the whole procedure being automated by the script build uclinux tools sh 9 Once the toolchain available we must fetch an uClinux source archive 10 configure it for our hardware and compile a new kernel see section 5 Our application to be included in the embedded system will also be compiled during this step as described in Documentation Adding User Apps HOTO in the uClinux distribution 4 Programming under uClinux The development environment on a uClinux system is closer to that commonly found on mi crocontrollers or under MS DOS than that found usually on a multiuser multitasking operating system The fact that our program can freely access the whole memory range is possible thanks to the lack of MMU which thus cannot generate a segmentation fault when our process attempts an access to a memory zone out of its allocated range This major difference provides us with the ability to access hardware peripherals by writing and reading to pre defined memory locations since on Motorola architectures input output peripherals are reached as memory accesses Hence we will use s
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