OSs-Micrium-Learning Centre-Application Notes
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1. bus Vectors that are accidentally placed into banked memory will have a 24 bit address 8 bit page number 16 bit address and will overflow the slot in the interrupt vector table The interrupt handler written in C may be placed in banked memory A label for the PPAGE register memory address is defined This label is used in place of hard coding the PPAGE register address multiple times within the source code XDEF is a Codewarrior assembly directive for prototyping assembly routines thereby making them visible from C files such as vectors c This directive is not necessarily portable to other assemblers 4 5 6 and 7 are external references to variables and or functions defined in C These variables are referenced from the context of the assembly ISR and must therefore be declared external such that they are visible to the assembler and ISR file This directive is not necessarily portable to other assemblers MyISR is the name of the interrupt service routine and must match the name specified in L3 4 3 This ISR name is also external from within vectors c Store the H register on the stack of the task that was interrupted This register is not automatically stored and restored by the processor interrupt mechanism and must be pushed and pulled from the stack separately Load the value of the PPAGE register into the A register Store the current value of PPAGE on to the stack of the task that was interrupted T2. system variables on various user definable graphical elements such as simulated mechanical counters graphs on screen LEDs and so on In order for uC Probe to display information about your application an ELF file must be generated by the user s compiler The ELF file contains the names and addresses of all the global symbols referenced within the users embedded application Only symbols that have been allocated memory e g not allocated on the stack are able to be monitored by uC Probe Global and static variables are examples of variables that may be monitored The user places components such as gauges labels and charts into a Data Screen in a uC Probe workspace Each one of these controls is then assigned to one or more of the variables from the Symbol Browser The Symbol Browser lists all symbols referenced from within the ELF file Symbols associated with components placed on an open Data Screen will be updated after the user presses the start button assuming the user s PC is connected to the target and the target is running uC Probe currently interfaces with a target processor via JTAG RS 232 UDP and USB A small section of code resident on the target receives commands from the Windows application and responds to those commands The commands ask for a certain number of bytes located at a certain address for example Send 16 bytes beginning at 0x0040102C The Windows application upon receiving the response updates the a
3. Micrium Empowering Embedded Systems ucC OsS II uC Probe and The Freescale MC9S08 Using the P amp E DEMOQE Evaluation Board Application Note AN 1208 www Micrium com Micripm uC OS II and pC Probe on the Freescale MC9S08 Table Of Contents 1 00 Introduction 3 1 01 Port Specific Details 4 1 03 Directories and Files 5 1 04 Codewarrior IDE 9 2 00 Example Code 10 2 01 Example Code app c 10 2 02 Example Code app_cfg h 13 2 03 Example Code includes h 13 2 04 Example Code os_cfg h 13 3 00 Board Support Package BSP 14 3 02 Board Support Package bsp 16 3 03 Configuring the FLL 20 3 04 Vectors c 20 3 05 Creating Interrupt Service Routines 21 Licensing 28 References 28 Contacts 28 Micripm yC OS II and yC Probe on the Freescale MC9S08 1 00 Introduction This document shows example code for using pC OS II on a Freescale MC9S08 processor To demonstrate the MC9S08 we used a P amp E DEMOQE evaluation board as shown in Figure 1 1 We used the Freescale Codewarrior for Microcontrollers IDE version 6 0 to demonstrate this application However other tool chains could be used Figure 1 1 P amp E DEMOQE EVB The application code is downloaded into Flash using a P amp E Micro BDM Multilink While the application is running the 4 onboard LEDs sequentially illuminate and blink uC Probe may be used to view various graphs depicting data read from the on board accelerometer To use uC Probe with the DEMOQE128 do
4. NON banked and the banked memory model from an assembly ISR perspective is the use of JSR vs the CALL instruction CALL uses a 24 bit address to jump to and return from the called function JSR only uses 16 bit addresses and is only suitable for calling functions in non banked memory Since one can never be sure of a functions linked address ahead of time it becomes necessary to substitute JSR for CALL in the banked version of the uC OS II port and associated user interrupt service routines Likewise RTS return from sub routine must be substituted with RTC return from call Lastly the NON banked port does not need to save or restore the PPAGE register before or after context switches This is however necessary in order to resume execution from within a function that was interrupted from a banked page in memory 23 Micripm yC OS II and yC Probe on the Freescale MC9S08 For more information one may compare the non banked and banked versions of os_cpu_a s Specifically one should examine Tmr_TickISR which is the pC OS II time tick ISR All interrupts should be modeled exactly as shown with the exception of the labels used to identify the sub routine Additional examples are available upon request 3 05 Context Switching on the MC9S08 When a new task is created a stack frame for that task is initialized from within os_cpu_c c OSTaskStkInit The values placed on the initial stack frame represent the desired values of the processor reg
5. OS_TASK_OPT_STK_CHK OS_TASK_OPT_STK_CLR if OS_TASK_NAME_SIZE gt 11 OSTaskNameSet APP_TASK_START_PRIO Startup Task amp err 5 endif OSStart 6 L2 1 1 As with most C applications the code starts in main L2 1 2 We start off by calling a BSP function see bsp c that will disable all interrupts We do this to ensure that initialization doesn t get interrupted in case we do a warm restart L2 1 3 As with all uC OS II applications you need to call OSInit before creating any task or other kernel objects L2 1 4 L2 1 5 L2 1 6 Listing 2 Micripm yC OS II and yC Probe on the Freescale MC9S08 We then create at least one task in this case we used OSTaskCreateExt to specify additional information about your task to wC OS II It turns out that uwC OS Il creates up to three tasks in OSInit AS a minimum wC OS II creates an idle task OS_TaskIdle which is internal to wC OS II and OS_TaskStat if you set OS_TASK_STAT_EN to 1 in os_cfg h OS_TaskStat is also an internal task in uC OS II The Timer task may be optional enabled or disabled from within os_cfg h As of V2 6x you can now name wC OS II tasks and other kernel objects and be able to display task names at run time or with a debugger In this case we name our first task Start Task We finally start uC OS II by calling oSStart wC OS II will then start executing AppStartTask since tha
6. Probe Target Communication Generic RS 232 OS uCOS II This directory contains OS dependent interface code for the RS 232 specific portion of uC Probe specifically the code necessary to generate an optional Rx packet parse task If you plan to run pC Probe with a different RTOS modifications to the files listed below will have to be made If you are not running an RTOS the following files may be excluded from the build probe_rs232_os c Micripm uC OS II and yC Probe on the Freescale MC9S08 C Micrium Software uC Probe Target Communication Generic RS 232 Ports Freescale MC9S08 This directory contains the pC Probe hardware port files for the MC9S08 processor Care must be taken to ensure that the correct assembly file either probe_rs232_ba s banked assembly or probe_rs232_nba s non banked assembly is compiled into you project Non banked and banked assembly files must never be mixed within the same uC Probe project probe_rs232c c probe_rs232_ba s probe_rs232_nba s C Micrium Software uC Probe Target Communication Generic RS 232 Source This directory contains target independent source code for the pC Probe RS 232 communication layer Specifically this directory contains the following files probe_rs232 c probe_rs232 h C Micrium Software uC Probe Target Communication Generic Source This directory contains target independent source code for the wC Probe communication layer Specifically this directory contains the followin
7. also require modification See the section labeled vectors c for more information All ISRs must be written as specified in the section labeled Creating Interrupt Service Routines 1 03 Directories and Files The code and documentation of the port are placed in a directory structure according to AN 2002 uC OS II Directory Structure Files for both the banked and non banked memory models are provided by Micrium pC OS II Micrium Software uCOS I Source This directory contains the processor independent code for pC OS II The version used was 2 85 Micrium Software uCOS II Ports MCS08 Paged Codewarrior This directory contains the standard processor specific files for a uC OS II port assuming the Freescale Codewarrior IDE These files could easily be modified to work with other tool chains however you would place the modified files in a different directory Only one processor port non paged or paged may be compiled in to a wC OS II project at any given time Specifically this directory contains the following files for the banked memory model os_cpu h OS_cpu_a s OS_cpu_c c yC Probe C Micrium Software uC Probe Target Communication Generic OS uCOS I This directory contains the OS dependent interface for the communication layer of uC Probe If you plan to run wC Probe with a different RTOS or without any RTOS the following files would have to be adjusted accordingly probe_com_os c C Micrium Software uC
8. application As C OS II tasks must either enter an infinite loop waiting for some event to occur or terminate itself In this case we wait for time to expire as the event This is accomplished by calling OSTimeD1lyHMSM 12 Micripm yC OS II and yC Probe on the Freescale MC9S08 2 02 Example Code app_cfg h This file is used to configure Additional wC module enables specifically support for wC LIB and pC Probe The wC OS II task priorities of each of the tasks in your application The stack size for each tasks 2 03 Example Code includes h includes h is a master header file that contains include directives to include other header files This is done to make the code cleaner to read and easier to maintain 2 04 Example Code os_cfg h This file is used to configure uC OS II and defines the maximum number of tasks that your application can have which services will be enabled Semaphores mailboxes queues etc the size of the idle and statistic task and more In all there are about 60 or so define s that you can set in this file Each entry is commented and additional information about the purpose of each define can be found in the pC OS II book os_cfg h assumes you have pC OS II V2 83 or higher but also works with previous versions of uC OS II 13 Micripm yC OS II and yC Probe on the Freescale MC9S08 2 05 yC Probe uC Probe is a Microsoft Windows program that displays the content of
9. as been removed from the stack the new tasks stack looks like that of figure 3 3 and is ready to be restored automatically by the RTI instruction Return from interrupt This instruction automatically pops PC X A and CCR from the current stack pointed to by the stack pointer register The new task is now running from where it left off prior to its last preemption 27 Micripm yC OS II and yC Probe on the Freescale MC9S08 Licensing If you intend to use wC OS II in a commercial product remember that you need to contact Micrium to properly license its use in your product The use of pC OS II in commercial applications is NOT FREE Your honesty is greatly appreciated References MicroC OS Il The Real Time Kernel 2 Edition Jean J Labrosse CMP Technical Books 2002 ISBN 1 5782 0103 9 score Eee CMP Books Inc 6600 Silacci Way Gilroy CA 95020 USA Phone Orders 1 800 500 6875 or 1 408 848 3854 Fax Orders 1 408 848 5784 e mail rushorders cmpbooks com WEB _http Awww cmpbooks com Micrium 949 Crestview Circle Weston FL 33327 USA 954 217 2036 954 217 2037 FAX e mail Jean Labrosse Micrium com WEB www Micrium com Freescale Technology Inc 2355 West Chandler Blvd Chandler Arizona 85224 6199 USA 480 792 7200 WEB www Freescale com 28
10. ating Interrupt Service Routines for more information L3 3 1 L3 3 2 L3 3 3 L3 3 4 If OS_TICK_TPM1_CH is configured to 0 Clear the interrupt source Adjust the timer channel match register so that a new time tick will occur after OSTickCnts additional counts Call OSTimeTick to inform wC OS II of the clock tick 18 Micripm yC OS II and yC Probe on the Freescale MC9S08 The TPM generates a match interrupt when the up counter value reaches the value stored within the timer channel match register After an interrupt occurs the match register is incremented to the next value for which a time tick interrupt is desired The timer is allowed to free run and overflow without error when necessary TPM1CnV Interrupt on TPM1CHn OxFFFF 0x0000 O NL 1 Millisecond with OS_TICKS_PER_SEC set to 1000 see os_cfg h Figure 3 1 OS Tick Timer Operation When the selected TPM issues an interrupt the processor vectors to the associated TPM module and channel interrupt service routine The ISR calls Tmr_TickISR_Handler as described above in Listing 3 3 You should note that ALL of your ISRs should be written in assembly and call an ISR handler function written in C The ISR handler should be prototyped as void MyISR_Handler void The assembly interrupt service routine is necessary in order to maintain a fully preemptive RTOS If the processor is allowed to jump directly to an ISR written in C then any task made r
11. de Micrium Software EvalBoards Freescale MC9S08QE128 DEMOQE Paged Codewarrior OS Probe This directory contains the Codewarrior project file OS Probe mcp for the banked version of AN 1208 Micrium Software EvalBoards Freescale MC9SO8QE128 DEMOQE Paged Codewarrior OS Probe Source This directory contains the sample source code for using pC OS II on the MC9S08 micro controller This directory contains the following files app c app_cfg h probe_com_cfg h derivative h includes h os_cfg h start08 c vectors c Micripm yC OS II and yC Probe on the Freescale MC9S08 app c contains the application code app_cfg h contains application specific configuration information such as task priorities and stack sizes probe_com_cfg h contains pC Probe communication specific configuration includes h contains a master include file used by the application os_cfg h is the wC OS II configuration file derivative h and start08 c are generated files for MCU compatibility and startup vectors c contains the processor interrupt vector table This array of Interrupt Service Routine addresses must be updated whenever a new interrupt is being configured on the system Interrupt vectors that are not in use should be plugged with the appropriate Dummy ISR handler provided Micrium Software EvalBoards Freescale MC9S08QE128 DEMOQE Paged Codewarrior BSP This directory contains the Board Support Package for the DEMOQE128 evaluation board and the MC9S08 MCU Whil
12. e associated with the program counter of the preempted task Push PPAGE on to the preempted tasks stack 26 L3 6 2 L3 6 3 L3 6 4 L3 6 2 L3 6 6 L3 6 7 L3 6 8 L3 6 9 L3 6 10 Micripm uC OS II and C Probe on the Freescale MC9S08 Push the H register on to the preempted tasks stack The stack frame for the preempted task is now complete The next group of instructions loads the preempted tasks stack pointer into the 16 bit HX register The stack pointer is then pushed on to the preempted tasks stack for temporary storage A pointer to the preempted tasks TCB is then loaded into Hx This pointer also points to the storage location for the tasks stack pointer The tasks stack pointer is stored in this location each time the task is swapped out in favor of a higher priority task that is ready to run The next group of instructions pulls the preempted tasks stack pointer off of the preempted tasks stack 1 byte at a time Each byte is stored within the holding place located within the preempted tasks TCB Later when the this preempted task becomes the highest priority task that is ready to run the stack pointer will be recovered from the TCB and used to restore this tasks context Call the wC OS II task switch hook This function is defined within os_cpu_c c and may be used to notify the application of a context switch In newer example applications the task switch hook calls an application defined task switch ho
13. e some of the code in this directory may work on other MC9S08 derivatives routines that are hardware dependent such as LED_On will require modification depending on the hardware design of your EVB This directory contains BSP c BSP h BSP c contains hardware specific source code for LED services FLL initialization uC OS II ticker initialization and so on BSP h contains prototypes for the BSP initialization and LED service functionality provided within BSP c The OS timer TPM1 channel selection and internal and external oscillator frequencies are also configured from within this file You may adjust these settings by changing the macros OS_TICK_TPM1_CH BSP_INT_REF_FREQ and BSP_EXT_REF_FREQ respectively BSP_EXT_REF_FREQ has been intentionally defined to 0 Hz since the DEMOQE128 EVB does not have an external oscillator on board Micrium Software EvalBoards Freescale MC9SO8QE128 DEMOQE Paged Codewarrior OS Probe prm This directory contains the processor linker file The user MUST remove all previously existing vector definitions from within this file in favor of those specified in vectors c Note The linker file must be changed when porting to a different MC9S08 derivative Micripm uC OS II and pC Probe on the Freescale MC9S08 1 04 Codewarrior IDE We used the Freescale Codewarrior for Microcontrollers IDE version 6 0 to compile and run the MC9S08 example You can of course use pC OS II with
14. eady to run as the result of that ISR may have to wait until the interrupted task is resumed and the scheduler runs This is non deterministic and is determined by the application code length Instead the ISR handler returns to the assembly interrupt service routine which immediately calls the scheduler preventing the restoration of a lower priority task context when a higher priority task should run upon completion of the ISR Micripm yC OS II and yC Probe on the Freescale MC9S08 3 03 Configuring the FLL The FLL is an on chip peripheral capable of boosting the processor clock and bus frequencies higher than the frequency provided by either an external or internal oscillator Before attempting to reconfigure the FLL from BSP c you should consult the MC9S08 datasheet and understand the MCU s absolute maximum ratings The absolute maximum ratings must be followed in order to prevent the possibility of damaging the device The MC9S08 has a maximum processor clock of 59 77MHz The bus clock is always 1 2 of the processor clock ICS_OUT and must never exceed 25 16 MHz Therefore when running ICS_OUT at the maximum frequency it becomes necessary to further divide the bus clock to prevent overclocking of the peripheral bus Further bus clock division may be performed within FLL_Init by setting the BDIV bits greater than 0 There is no external oscillator on the DEMOQE128 therefore all clock references are derived from the MC9S08 internal o
15. er Care must be taken to ensure that the correct uC OS II and pC CPU files are compiled when running in either non banked or banked memory model Files from both ports must not be mixed together within any project Separate directories have been created for files belonging to both the non paged and paged wC OS II and wC CPU ports However other modules such as uC Probe group the port files within the same directory and are distinguished by file name Example pC Probe file names for non banked and banked assembly port files are as follows probe_rs232_nba s probe_rs232_ba s This example uses the on chip FLL Once configured the processor clock is set to 48MHz and the bus clock to 24MHz The FLL settings may be changed from within BSP c by adjusting FLL_Init accordingly Note In some cases oscillator trimming may be desired In order to adjust the port for a trimmed oscillator the target oscillator frequency must be known and set within BSP h This may be accomplished by adjusting the macro BSP_INT_REF_FREQ prior to compilation The default value is set to 32768 Hertz Micripm yC OS II and yC Probe on the Freescale MC9S08 Additionally this example assumes the use of TPM1 channel 0 for the uC OS II periodic time tick interrupt If TPM1 channel 0 is not available this you may configure an alternate TPM1 channel by adjusting the macro named OS_TICK_TPM1_CH within BSP h for channel numbers 0 1 or 2 The file vectors c will
16. er increments necessary to generate the desired C OS II time tick period The 8 represents the TPM prescaler that is configured in step 10 17 L3 2 3 L3 2 4 L3 2 5 L3 2 6 L3 2 7 L3 2 8 L3 2 9 Micripm yC OS II and yC Probe on the Freescale MC9S08 Enable the TPM1 module clock Stop and reset the TPM1 counter Set the modulus count to 0x00 allowing the timer to freerun from 0x00 to OxFFFF If OS_TICK_TPM1_CH in BSP h is defined as 0 1 or 2 then configure the corresponding TPM1 channel for use with the wC OS II periodic time tick interrupt Configure the timer channel for output compare and enable TPM1 channel 0 interrupts Write the match register with the current value of the TPM1 counter plus the number of ticks until the next desired match Configure the TPM1 reference clock source set the prescaler and enable the timer Listing 3 3 Tmr_TickISR_Handler void Tmr_TickISR_Handler void if OS_TICK_TPM1_CH 1 TPM1COSC amp TPM1COSC_CHOF_MASK 2 TPM OSTickCnts 3 endif if OS_TICK_TPM1_CH 1 TPMIC1SC amp TPM1C1SC_CH1F_MASK TPM OSTickCnts endif if OS_TICK_TPM1_CH 2 TPM1C2SC amp TPM1C2SC_CH2F_MASK TPM OSTickCnts fendif OSTimeTick 4 This function is called from an assembly interrupt service routine which informs pC OS II of the interrupt and calls the C code interrupt handler See os_cpu_a s and the section labeled Cre
17. for all 32 vectors excluding reset When an interrupt vector is not in use the dummy ISR for that vector should be set In the case of a spurious interrupt the processor will vector to the dummy ISR and loop indefinitely Should this occur you may be able to debug the application and catch the processor in the dummy interrupt service routine thus identifying the source of the spurious interrupt The correct action may then be taken to correct the application to prevent this type of error in the future When plugging the interrupt vector table with a new ISR address a C prototype in the form of 20 Micripm yC OS II and yC Probe on the Freescale MC9S08 extern void near MyISR void Must be provided at the top of the file The name of the ISR may then be plugged into the correct location of the interrupt vector table The following vectors are used by uC OS II and should not be modified e Vector 1 SWI Used to perform the pC OS II context switch e Vector 4 TPM1 channel 0 This may be adjusted to one of the other TPM1 channel vectors if desired The macro named OS_TICK_TPM1_CH in BSP h will also have to be adjusted accordingly 3 05 Creating Interrupt Service Routines All interrupt service routines must contain a short assembly routine The address of the assembly routine is used to plug the interrupt vector table while the content is designed to notify wC OS II of the interrupt and call the user supplied interrupt handler w
18. g files probe_com c probe_com h C Micrium Software uC Probe Target Plugins uCOS II This directory contains the target independent source code for pC Probe Specifically this directory contains the following files os_probe c os_probe h pC CPU Micrium Software uC CPU This directory contains processor independent files for uC CPU uC CPU contains code for entering and existing critical sections as well as macro definitions for the C programming datatypes used in most Micrium products Specifically this directory includes cpu_def h Micripm yC OS II and yC Probe on the Freescale MC9S08 Micrium Software uC CPU Ports MCS08 Paged Codewarrior This directory contains processor port files for wC CPU pC CPU contains code for entering and existing critical sections as well as macro definitions for the C programming datatypes used in most Micrium products Care must be taken to ensure that the correct memory model port files for wC CPU are used when building your project Only one port either non paged or paged may be compiled into a given project at any time The following directory contains the following files cpu h cpu_a s yC LIB Micrium Software uC LIB This directory contains lib_def h which provides defines for useful constants like DE F_TRU E and DEF_DISABLED and macros Micrium Software uC LIB Doc This directory contains the documentation for pC LIB Application Co
19. his register is not automatically stored and restored by the processor interrupt mechanism and must be pushed and pulled from the stack separately Note enabling the PPAGE checkbox within the compiler options in Codewarrior will cause the compiler to add code for storing and restoring PPAGE on and off the stack when an interrupt occurs Since not all compilers support this feature the storing and restoring of PPAGE is manually specified within the port Enabling this feature will cause PPAGE to be pushed twice on to the stack and cause the system to fail 22 L3 4 11 L3 4 12 L3 4 15 L3 4 16 L3 4 17 L3 4 25 L3 4 26 L3 4 27 L3 4 28 L3 4 29 L3 4 30 Micripm yC OS II and yC Probe on the Freescale MC9S08 Store the H register on to the stack of the task that was interrupted This register is not automatically stored and restored by the processor interrupt mechanism and must be pushed and pulled from the stack separately 12 13 and 14 increment OSIntNesting This notifies wC OS II that at least One interrupt is in progress and that the scheduler should not schedule any new tasks to run until all nested interrupts have completed e g OSIntNesting equals 0 It also informs the OS of the interrupt thereby allowing certain pC OS II API calls to return error codes if called from within the context of an ISR Load a copy of OSIntNesting from memory into a register so a comparison may be made Chec
20. ing L3 5 6 Push the initial value for the A register on to the stack We choose OxAA since the value corresponds to the name of the register This value is easy to identify during debugging L3 5 7 Push the initial value for the CCR register on to the stack Interrupts for the tasks context are enabled by means of clearing the l bit for the initial CCR value Since the 24 Micripm yC OS II and yC Probe on the Freescale MC9S08 task has yet to run we initialize the CCR to 0 to indicate that no condition codes have been set and that global interrupts should be enabled when the task is running L3 5 8 Push the PPAGE value of the tasks address on to the stack L3 5 9 Push the initial value for the H register on to the stack We chose 0x11 since H is the first register to be restored This value is easy to identify during debugging L3 5 10 Return a pointer to the new top of stack Note since a task body is in the form of an infinite loop the return address is never utilized and remains on the stack along with p_arg indefinitely When the scheduler switches task context the RTI Return From Interrupt instruction is used to restore all of the system registers from the stack pointer provided Since the RTI instruction does not restore H or PPAGE they must be manually restored before using RTI Again the non banked port does not require the manual saving or restoration of PPAGE After task stack initialization the
21. isters when the task runs for the first time The following code shows stack initialization for a banked memory project Non banked memory projects do not need to push a value for PPAGE on to the tasks stack Listing 3 5 OSTaskStkinit OS_STK OSTaskStkInit void task void pd void p_arg OS_STK ptos INT16U opt INT16U wstk ISTU bstk wstk INT16U ptos 13 wstk INT16U p_arg 2 wstk INT16U task 3 bstk INT8U wstk 4 bstk INT8U 0x22 5 bstk INT8U 0xAA 6 bstk 0x00 7 bstk INT8U INT32U task gt gt 16 8 bstk INT8U 0x11 9 return OS_STK bstk 10 L3 5 1 Cast a pointer to the top of the stack The top of the new tasks stack is known from the call to either OSTaskCreate Of OSTaskCreateExt L3 5 2 Push the argument for the task function on to the stack The argument is an optional argument passed to either OSTaskCreate Of OSTaskCreateExt and is often passed as NULL L3 5 3 Push the tasks function address on to the stack The address is a 16 bit value and does not include the page number that contains the task L3 5 4 Cast the current top of stack pointer to an 8 bit pointer since the remaining values to be pushed are only 8 bits each L3 5 5 Push the initial value for the x register on to the stack We choose 0x22 since it s the second register to be restored This value is easy to identify during debugg
22. ium com products probe probe html 2 Open uC Probe After downloading and installing this program open the example uC Probe workspace for uC OS II named OS Probe wsp which should be located in the AN 1208 Codewarrior project directory You may also open one of the sample workspaces that comes with uC Probe The sample workspaces located in the wC Probe target directory contains generic workspaces for yC OS II as well as other Micrium software modules 3 Connect Target to PC Currently pC Probe can use RS 232 to retrieve information from the target You should connect a RS 232 cable between your target and computer Load Your ELF File The example projects included with this application note are already configured to output an ELF file If you are using your own project please refer 15 Micripm yC OS II and yC Probe on the Freescale MC9S08 to Appendix A of the yC Probe user manual for directions for generating an ELF file with your compiler Codewarrior generates an ELF file with a abs extension This file is located in a directory named BIN within the sample project directory To load this ELF file right click on the symbol browser and choose Add Symbols Navigate to the file directory select the file and choose OK 4 Configure the RS 232 Options In pC Probe choose the Options menu item on the Tools menu A dialog box as shown in Figure 6 2 left should appear Choose the RS 232 radio b
23. k OSIntNesting to see if its value is 1 If so then this is the only interrupt in progress and no nested interrupts are pending completion 17 24 If no interrupts have been nested then the scheduler is free to schedule a new task when the ISR completes Therefore the address of the current task TCB Task Control Block is obtained and the current stack pointer is saved to the current tasks TCB OSTCBCur gt OSTCBStkPtr Stack Pointer If interrupt have been nested skip storing the current tasks stack pointer back into its task control block and jump to MyISR1 Note the name of the ISR and the labels used within it must be changed for each new ISR implemented in the system For convenience the number 1 is added to the end of the ISR name in order to create a unique and convenient label to jump to Call the user defined ISR handler Generally the ISR handler is defined and prototyped in C The ISR handler may be located in banked memory Call OSIntExit This informs pC OS II about the end of the interrupt This is effectively the same as decrementing OSIntNesting and calling the scheduler A context switch to a task different than the one that was running before the interrupt may or may not occur Restore the H register Pull the value of PPAGE of the stack of the task that is to be resumed Restore the PPAGE register Return to the highest priority task that is ready to run The difference between the
24. new tasks stack looks as follows Low Memory OSTCBHighRdy gt OSTCBStkPtr gt ft Top of Stack High Memory Bottom of Stack Stack grows toward low memory Figure 3 2 25 Micripm yC OS II and yC Probe on the Freescale MC9S08 When wC OS II scheduler determines that a context switch is necessary it calls a macro named OS_TASK_SWITCH located within os_cpu h This macro is defined as __asm swi which in turn causes the scheduler to invoke a software interrupt vectors c loads the SWI interrupt vector with the address of OSCtxSw which is located within os_cpu_a s Upon entering OSCtxSw SWI pushes the majority of the interrupted tasks context on to the interrupted tasks stack Notice the absence of the PPAGE and H register as shown in figure 3 3 below These registers must be manually saved and restored by the wC OS II port For non banked projects the PPAGE is exempt from this requirement Stack Pointer Register gt Top of Stack Low Memory PC High Byte Stack grows toward low memory High Memory Bottom of Stack Figure 3 3 Listing 3 6 OSCtxSw OSCtxSw lda psha pshh tsx pshx pshh ldhx pula sta pula sta call lda sta ldhx sthx ldhx txs pulh pula sta PCL L3 6 1 PPAGE 1 2 3 OSTCBCur 4 OSTaskSwHook 5 OSPrioHighRdy 6 OSPrioCur OSTCBHighRdy 7 OSTCBCur x 8 9 PPAGE 10 Obtain the PPAGE register valu
25. o 1 in os_cfg h If uc_pROBE_os_pLuGIN Is defined in app_cfg h then include code to initialize the target independent portion of uC Probe Initialize the target independent portion of uC Probe Configure an optional call back function for uC Probe The callback function is called each time uC Probe is queried to update variable values Set the delay in milliseconds that the pC Probe task should delay before collecting information about task stacks and so forth This task will not be necessary in future versions of pC Probe Initialize the hardware independent portion of the pC Probe communication layer Initialize the hardware dependent communication channel The baud rate for yC Probe RS 232 communication should not be set higher than 38 400 on the MC9S08 Enable receive interrupts This function call enables pC Probe to begin processing requests from the host AppTaskCreate is a user defined function for creating additional 1 C OS II tasks This function is not required and additional tasks could have been created directly within AppStartTask This function has been left empty in this example Shut off all onboard LEDs As with all task managed by pC OS II the task body must be in the form of an infinite loop Tasks managed by C OS II must never be allowed to exit Instead tasks should be deleted using OSTaskDel when they are no longer desired This task performs the LED illumination and scrolling effect used within this
26. ok to avoid modification to files used by the wC OS II port Application hooks may be enabled by defining oS_APP_HOOKS_EN to 1 within os_cfg h Upon doing so several functions will need to be defined within the user application to handle the various hook function made available by pC OS II to the user application Update the current running task priority to reflect the priority of the task that is about to be swapped in Update the currently running task TCB pointer to reflect the address of the TCB that is about to be swapped in store this value in the Hx register As mentioned in L3 6 4 the new task to be swapped in stores the value of its last known stack pointer in the first location of the TCB Therefore the address of the current running task though it is not yet running also points to the stack pointer associated with the task that will run next The pointer is dereferenced and the stack pointer address is also stored in Hx Lastly the stack pointer address is copied into the stack pointer register Restore the new tasks H register Recall that the H register is not automatically restored Before the task may be run the stack frame must be reduced from that of figure of 3 2 to that of 3 3 Obtain and restore the new tasks PPAGE register Recall that the PPAGE register is not automatically restored by the RTI Return from Interrupt instruction In fact for the non banked pC OS II port PPAGE must not be restored Once PPAGE h
27. other tools Figures 1 3 shows the project source tree of the banked example project with all of the files visible in the project file source tree zix 0S Probe mcp D gt Pee Multink Cyclone Po Gk D y g Re Files Link Order Targets EE Sources 5066 xf B Application 608 406 xi M app c 4 amp 5 405 of D app_ciah 0 o mf BB probe_com_cfgh 0 0 z AB includes h 0 o of MB os_cfgh 0 0 of M vectors c 157 0e z BEBSP 672 26a M bep c 601 26a bsp h 0 Oo af M accelerometer c 7 0e z M accelerometer h 0 0 af B uC CPU 5 0e x 2E Potts 5 EGQMc3s08 5 O af HE Paged 5 0 o af BE Codewarrior 5 0 x D cpwas 5 Oem M cpuh 0 o af M cpu_def h 0 o af Gqut UB 2224 0 m AB ib_def h a o ow Bi 788 O af 0 o vf 1436 O a D ib 0 o af B 3uC 05 1 167374131 mi BE Source 16407 4129 zi MB os_time c 443 O x D os_tm c 2155 0e AB ucos_ih 0 o af 2648 4129 zi 2512 0 m 1013 O a a 767 O a D os_mutexc 1730 0 af D osae 2018 0 x M os_semc 920 Oo MB os_task c 2195 0 x B Pots 330 2em Ea Mc3sos 330 20a BE Paged 330 2 x EE Codewarrior 330 2em M 05_CPU h a o af MM os_cpu_as 128 oe MB os_cpu_c c 202 26x EG gul Probe 3984 1327 mi BE Target 3143 S16 zi EE Communication 1137 756 mi a0 100 2em AS uc70s 1 100 2em M probe_com_os c 100 2em 1037 754 xi 153 202 af 153 202 of 240 8e mi MB probe_1s232_bas 120 0 af M probe_1s232c c 120 Bex Ea Source 644 544 o mi MB probe_1s232 c 644 544 e zi BB
28. ppropriate component s on the data screen s with the new values 14 Micripm uC OS II and pC Probe on the Freescale MC9S08 Micrium pC Probe probe_example wsp E 5 x Eile Tools Help lB p p p p a BSB x MC9S08 Demonstration dbx Start Stop button This button switches between Design and Run Time Views During Run Time View when data is collected this will appear as a stop button a blue square Accelerometer Raw Data Accelerometer Raw Data CPU Usage ZJ os_cpu_c c os_probe c os_time c 1 600 1 800 1 400 1 400 1 800 1 800 Hae E os_tmr c probe_com c probe_com_os c 1 200 Te J 3 probe_1s232 c 1 000 1 000 3 E Hawa ic probe_1s232_os c 20 probe_1s232c c Ae x RTSHCO C 600 600 Stat08 c 400 400 10 vectors c a CSREES Data Screen Components are placed onto the data screen and assigned symbols during Design View During Run Time View these components are updated with values of those symbols from the target Symbol Browser Contains all symbols from the ELF files added to the workspace RS 232 38400 COM1 s 315 symbols sec Figure 2 1 uC Probe Windows Program To use uC Probe with the example project or your application do the following 1 Download and Install C Probe A trial version of wC Probe can be downloaded from the Micrium website at http www micr
29. probe 15232 h 0 o af EG Source 2006 160 zi BB probe_com c 2006 160 zi AB probe_comh 0 o of BE Plugin BECSI 8 moeg I os_probe c 81 41 e xi M os_probe h 0 o s E lncludes 0 0 m BB derivative h a o of AB MC9S080E128 h 0 0 of E13 Libs 56513 2229 af AB ansibfm ib 56513 2022 xi AB MC95080E128 C 0 207 x EE Project Settings 133 6 e xi BE Startup Code 133 6e s M Stant08 c 133 6 e mi BE Linker Files 0 o af BB burner bbl na nma m BB Project pm na na S AB Project map na ma af Bs 50 files 80876 8101 Figure 1 3 Codewarrior Source Tree Micripm yC OS II and yC Probe on the Freescale MC9S08 2 00 Example Code As mentioned in the previous section the test code for this board is found in the following directories and will be briefly described Micrium Software EvalBoards Freescale MC9S08QE128 DEMOQE Paged Codewarrior OS Probe It should be noted that processor header files and libraries are not included within the AN 1208 code archive since they are supplied by Freescale via the Codewarrior installation 2 01 Example Code app c app c demonstrate some of the capabilities of wC OS II Listing 2 1 main void main void 1 CPU_INTO8U err BSP_IntDisAl1l 2 OSInit 3 OSTaskCreateExt AppStartTask 4 void 0 OS_STK amp AppStartTaskStk APP_TASK_START_STK_SIZE 1 APP_TASK_START_PRIO APP_TASK_START_PRIO OS_STK amp AppStartTaskStk 0 APP_TASK_START_STK_SIZE void 0
30. ritten in either assembly or C code The prototype specified at the top of Vectors c See section 3 04 above is the C code prototype for the following assembly interrupt service routine It is this prototype that allows you to plug the interrupt vector table with the name address of the ISR from C As a reminder the prototype is written as follows extern void near MyISR void Of course the name of the ISR would change each time a new ISR is declared since two ISR s of the same name cannot exist in the system simultaneously The format of an interrupt service routine for the BANKED memory model is as follows Listing 3 4 MyISR NON_BANKED section 1 PPAGE equ 0078 2 xdef MyISR 3 xref OSIntExit 4 xref OSIntNesting 5 xref OSTCBCur 6 xref MyISR_Handler 7 MyISR 8 lda PPAGE 9 psha 10 pshh 11 lda OSIntNesting 12 add 1 13 sta OSIntNesting 14 cmpa S01 15 bne MyISR1 16 tsx 17 21 psh psh Lah pul sta pul sta MyISR1 cal cal L3 4 2 L3 4 3 L3 4 4 L3 4 8 L3 4 8 L3 4 9 x nh x a a H L3 4 10 Micripm yC OS II and C Probe on the Freescale MC9S08 19 OSTCBCur 20 21 Or xX 22 23 lp X 24 MyISR_Handler 26 OSIntExit 26 27 28 PPAGE 29 30 Force the contents of the assembly file perhaps named myisr_a s into NON_BANKED memory This is critical since the processor only has a 16 bit address
31. scillator and FLL The FLL output frequency is computed as follows 32768Hz Pre selected Multiplier Where the pre selected multiplier has been hard coded within BSP c FLL_Init as 1536 by the setting of the DCO range to high range and the DMX32 bit to 0 Note BSP_CPU_C1kFreq returns a 32 bit unsigned integer representation of ICS_OUT the processor clock frequency Dividing this value by 2 will yield the bus clock frequency during run time It is recommended that users call this function in order to compute peripheral clock dividers as opposed to hard coding them This ensures system integrity should the clock settings require modification at a later time The use of this function is demonstrated in Tmr_TickInit 3 04 vectors c vectors c contains the interrupt vector table for the application The interrupt vector table is necessary so that the processor knows the address of the interrupt service routine to jump to when a specific interrupt occurs Failure to properly plug the interrupt vector table with the address of a valid handler may cause the application to crash If a wrong but valid interrupt handler address is specified for vector number n and the interrupt occurs the interrupt source will not be cleared the processor will execute the same interrupt service routine indefinitely Care should be taken when working with the interrupt vector table For convenience dummy interrupt service routines have been provided
32. t s the highest priority task created oSStart does not return 2 AppStartTask static void AppStartTask void p_arg void p_arg BSP_Init 1 if OS_TASK_STAT_EN gt 0 OSStatInit 2 endif if uC_PROBE_OS_PLUGIN gt 0 3 OSProbe_Init 4 OSProbe_SetCallback AppProbeCallback 5 OSProbe_SetDelay 50 6 endif if uC_PROBE_COM_MODULE gt 0 ProbeCom_Init 7 ProbeRS232_Init 38400 8 ProbeRS232_RxIntEn 9 endif AppTaskCreate 10 LED_Off 0 11 while DEF_TRUE 12 for J 0 J lt 4 J for i 1 i lt 4 i LED_On i OSTimeDlyHMSM 0 0 0 20 13 for LED_Off i OSTimeD1lyHMSM 0 0 0 20 for i 3 i gt 2 i LED_On i OSTimeDlyHMSM 0 0 0 20 LED_Off i OSTimeDlyHMSM 0 0 0 20 i 0 i lt 4 i LED_On 1 LED_On 2 LED_On 3 LED_On 4 OSTimeDlyHMSM 0 0 0 50 11 L2 2 1 L2 2 2 L2 2 3 L2 2 4 L2 2 5 L2 2 6 L2 2 7 L2 2 8 L2 2 9 L2 2 10 L2 2 11 L2 2 12 L2 2 13 Micripm yC OS II and yC Probe on the Freescale MC9S08 LED_Off 1 LED_Off 2 LED_Off 3 LED_Off 4 OSTimeDlyHMSM 0 0 0 50 BSP_Init is called to initialize the Board Support Package the I Os the tick interrupt and so on BSP_Init will be discussed in the next section OSStatInit computes how fast the CPU runs when OS_TASK_STAT_EN is set t
33. ting 3 1 BSP_Init void BSP_Init void SOPT1 amp SOPT1_COPE_MASK FLL_Init Tmr_TickInit LED_Init L3 1 1 Disable the watchdog timer It is enabled automatically after reset L3 1 2 Initialize the FLL set CS_OUT to 50 33MHz using the internal oscillator L3 1 3 Initialize the selected TPM1 channel for use with the C OS II time tick interrupt The code for this function is described below L3 1 4 Initialize the general purpose I O pins used for controlling the onboard LEDs Listing 3 2 Tmr_Ticklnit static void Tmr_TickInit void CPU_INT32U bus_freq bus_freq BSP_CPU_C1kFreq 1 bus_freq 2 OSTickCnts CPU_INT16U bus_freq 8 OS_TICKS_PER_SEC 2 SCGC1 SCGC1_TPM1_MASK 3 TPM1SC 0 4 TPM1MOD 0 5 if OS_TICK_TPM1_CH 6 TPM1COSC TPM1COSC_MSOA_MASK 7 TPM1COSC_CHOIE_MASK TPM1COV TPMICNT OSTickCnts 8 endif if OS_TICK_TPM1_CH TPM1C1SC TPM1C1SC_MS1A_MASK TPM1C1SC_CH1IE_MASK TPMIC1V TPMICNT OSTickCnts fendif if OS_TICK_TPM1_CH TPM1C2SC TPM1C2SC_MS2A_MASK TPM1C2SC_CH2IE_MASK TPM1C2V TPMICNT OSTickCnts endif TPM1SC 1 lt lt TPM1SC_CLKSx_BITNUM 9 3 lt lt TPM1SC_PS_BITNUM L3 2 1 Get the CPU operating frequency ICS_OUT in Hz This number is divided by 2 in order to generate the bus frequency The bus frequency is the reference frequency for the TPM L3 2 2 Compute the number of tim
34. utton Next select the RS 232 item in the options tree and choose the appropriate COM port and baud rate The baud rate for the projects accompanying this application note is 38 400 5 6 Start Running You should now be ready to run wC Probe Just press the run button to see the variables in the open data screens update 3 00 Board Support Package BSP BSP stands for Board Support Package and provides functions to encapsulate common I O access functions in order to make it easier for you to port your application code In fact you should be able to create other applications using the DEMOQE128 evaluation board and reuse these functions thus saving you a lot of time The BSP performs the following functions Determine the MC9S08s CPU clock and bus frequencies Configure the LED I Os for the DEMOQE128 EVB and MC9S08 CPU Configuration and handling of the uC OS II tick timer The BSP for the DEMOQE128 is found in the follow directory Micrium Software EvalBoards Freescale MC9S08QE128 DEMOQE Paged Codewarrior BSP The BSP files are BSP c BSP h 3 02 Board Support Package bsp We will not be discussing every aspect of the BSP but only cover topics that require special attention Your application code must call BSP_Init to initialize the BSP BSP_Init in turn calls other essential functions for initializing the MCU to the desired run time state Micripm yC OS II and yC Probe on the Freescale MC9S08 Lis
35. wnload and install the trial version of the program from the Micrium website as discussed below in the section 2 05 pC Probe After programming your target with one of the included example projects connect a RS 232 cable between your PC and the evaluation board configure the RS 232 options also covered below and start running the program The open data screens should begin to update Please note that the communication baud rate for the MC9S08 should be configured to 38 400 baud and not higher Micripm yC OS II and yC Probe on the Freescale MC9S08 1 01 Setting up the Hardware The following table illustrates the recommended jumper configuration for the DEMOQE EVB Jumper Label Description J3 Set to USB Power J4 Set to 3v J5 User may select J6 Across RXD and PTBO J7 Across TXD and PTB1 J8 COM_EN ON J9 All ON J11 PTCO PTC1 both OFF J12 All ON J13 0 J14 0 J15 1 J16 PTA7 PTC7 and PTA1 only J18 Reset_EN LED_EN both ON J19 ON J20 SDL SDA both ON J21 PTAO only Table 1 1 1 02 Port Specific Details Two pC OS II ports and example projects have been written for the MC9S08 to accommodate both the banked and non banked memory models For both ports the paging option must not be enabled within the Codewarrior project settings This application note uses the terms non banked and non paged interchangeably The terms banked and paged are also used in place of one anoth
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