1. Lab 5 Department of Computer Science and Information Engineering National Taiwan University Lab5 – μC/OS 2016/5/31/ 13 1

2. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Practice real-time programming on μC/OS-II. 2016/5/31/ 13 2

3. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Host System  Windows XP  Build System  IAR Embedded Workbench  Target System  PTK development board (STM32F207)  Software  The source codes of μC/OS-II.  You can find all software on HERE.HERE 2016/5/31/ 13 3

4. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  μC/OS-II is a real-time operating system with the following features:  Highly portable  It is written in ANSI C, with target-specific code written in assembly language.  It support various platforms, such as x86, MIPS, ARM.  ROMable  You can embed μC/OS-II as part of a product with the proper tool chain.  Very scalable  Simply specify which features to use through #define constant.  Preemptive real-time  It always runs the highest priority task that is ready.  Multitasking  It can manage up to 64 tasks, including 8 reserved tasks for μC/OS-II.  The source codes can be downloaded from the official website freely.official website  It is neither freeware nor open source code.  You are required to purchase a license for use in any commercial application. 2016/5/31/ 13 4

5. Lab 5 Department of Computer Science and Information Engineering National Taiwan University 2016/5/31/ 13 5 The definition of features in this application The main kernel The user tasks The functionalities of board support package (BSP) The functions of tick interrupt handler and context switch

6. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  It is a multitasking and preemptive kernel with a priority-driven real-time scheduling.  Nested interrupts could go up to 256 levels.  There are 64 priorities, 0 is the highest, and 63 is the lowest.  Each task must have a unique priority in the application.  μC/OS-III supports more tasks having the same priority with round-robin scheduling, while it is not supported in μC/OS-II. 2016/5/31/ 13 6 Non-preemptive kernelPreemptive kernel

7. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  A task control block (TCB) is a data structure used to maintain the state of a task when it is preempted.  All valid TCB’s are doubly linked.  Free TCB’s are linked in a free list.  The contents of a TCB is saved/restored when a context switch occurs.  The stack, priority, time delay, etc. of a task.  CPU registers are stored in the stack rather than in the TCB. 2016/5/31/ 13 7

8. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  If there is no user task ready, it will start the idle task (the priority is 63).  In os_core.c : void OS_Sched (void) {... OS_ENTER_CRITICAL(); if (OSIntNesting == 0u) { if (OSLockNesting == 0u) { OS_SchedNew(); OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy]; if (OSPrioHighRdy != OSPrioCur) { #if OS_TASK_PROFILE_EN > 0u OSTCBHighRdy->OSTCBCtxSwCtr++; #endif OSCtxSwCtr++; OS_TASK_SW(); } OS_EXIT_CRITICAL(); } 2016/5/31/ 13 8 Find the highest ready task. Perform a context switch.

9. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  app.c : void main(void) { OSInit(); OSTaskCreate( ((void (*)(void *)) App_TaskStart, (void *) 0, (OS_STK *) &App_TaskStartStk[APP_TASK_START_STK_SIZE - 1], (INT8U) APP_TASK_START_PRIO); OSStart(); } void App_TaskStart(void *pdata) { for (;;) { /* do something... */ OSTimeDly(100); } 2016/5/31/ 13 9 Each task performs an infinite loop. Initialize task ready list, priority table, TCBs, and free pool. Use OSTaskCreate() or OSTaskCreateExt() to create a task. Tasks become “ready” after they are created. Start multitasking of μC/OS-II (and never return). function pointer of a user task the pointer to the task's top of stack the task's priority task-specified data Use OSTimeDly() or OSTimeDlyHMSM() to do time delay. It allows other tasks to execute.

10. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Step 1: download the PTK_Examples, provided in Lab4.PTK_Examples  Step 2: download and extract the μC/OS-II source codes.μC/OS-II source codes  Step 3: copy the folder Software in Micrium to PTK_Examples/ePBB/Libraries/OS_uCOS-II/Micrium-V29x.  Step 4: connect the target system STM32F207 to Windows XP. 2016/5/31/ 13 10

11. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Step 1: open the serial console.  Please set baud rate to 115200bps.  Step 2: open the following workspace in IAR Embedded Workbench IDE.  PTK_Examples/ePBB/Applications/Projects/PTK-STM32F207/EWARM- V6/OS_uCOS-II/base_uart/demo.eww  Step 3: compile the project and download the program to the target system.  Step 4: click the button “Go” or press the key “F5” to continue the execution.  You will see the message “Hello World!!!” on the serial console. 2016/5/31/ 13 11

12. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  A counter recording the number of OS-ticks since the system’s startup.  OS_TICKS_PER_SEC ticks per second. Originally configured to be 1000.  typedef unsigned int INT32U  0~4294967295  Other than %d, You may use %u in the format string for printing. 2016/5/31/ 13 12

13. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  1. You are asked to create several tasks in μC/OS-II to complete the followings:  Regularly read the value of temperature.  Regularly read the value of luminous flux.  Set up a key handler to display message to LCD screen when a key button is pressed.  2. Show OSTime on the LCD screen periodically. Alternatively, practice timing using OSTime.  Tips:  You need to initialize the LCD device by invoking “ ili9325_gui_config() ” in the function “ platform_board_init_hook() ”.  OSTimeDly(#OS-tick) / VK_DELAY_MS(#ms) ; OSTimeDlyHMSM(H, M, S, M)  If confronted by the problem of displaying things on LCD screen, try to check the size of stack of a task. 2016/5/31/ 13 13

14. Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Show that you can display the information of current temperature and luminous flux on LCD screen by pressing key buttons and your other ideas.  Timing  Display (change of) luminous flux/temperature regularly, or when key button is pressed, on the LCD screen. In a addition, give the maximum and minimum quantity of time (OS-ticks) so far after which a change of luminous flux/temperature is detected.  Simultaneously, regularly display luminous flux and temperature on LCD screen every single second. Try to make it as accurate as possible. 2016/5/31/ 13 14