版本 b4b50d88d06cc2dbfbd3143a8b8cd65fe0989d6b

embedded/Lab9

Changes from b4b50d88d06cc2dbfbd3143a8b8cd65fe0989d6b to current

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title: Lab9: Multi-tasking programming
toc: no
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預期目標
-------
- 學習 GNU Toolchain 的使用
- 學習 FreeRTOS 程式開發
- 藉由 [coroutine](http://en.wikipedia.org/wiki/Coroutine) 的實做，作為日後 RTOS 學習的準備

預先準備
-------
- 確保 [Lab 8](/embedded/Lab8) 的環境設定一切無誤
- 參閱 [Git 簡易操作](/git) 與 [寫給大家的 Git 教學](http://www.slideshare.net/littlebtc/git-5528339)
- 強者我同事的演講: [MCLinker -- an LLVM Linker for Mobile Computing](http://www.youtube.com/watch?v=nCAlAoXKWVk)

QEMU + GDB 操作
----------------------
- 切換到 [Lab 8](/embedded/Lab8) 所取得的 Labs 目錄，並更新程式碼

.. code-block:: prettyprint

    cd Labs
    git pull

- 切換到 Lab 9 所用的環境

.. code-block:: prettyprint

    cd Lab-9/mtask
    make qemudbg

- 開啟另一個終端機，準備透過 gdb 來追蹤程式。下列 (gdb) 開頭的指令表示在 GDB 內部操作

.. code-block:: prettyprint

    cd Lab-9/mtask
    arm-none-eabi-gdb
    (gdb) file main.elf 
    Reading symbols from Lab-2/demo/main.elf...done.
    (gdb) b main
    Breakpoint 1 at 0x2206: file main.c, line 8.
    (gdb) target remote :3333
    Remote debugging using :3333
    Reset_Handler ()
        at libraries/CMSIS/CM3/DeviceSupport/ST/STM32F10x/startup/gcc_ride7/startup_stm32f10x_md.s:67
    67	  movs	r1, #0
    (gdb) c
    Continuing.
    
    Breakpoint 1, main () at main.c:8
    8		RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
    (gdb) list
    3	
    4	int main(void)
    5	{
    6		int last_button_state, new_button_state;
    7	
    8		RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
    9		RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOA, ENABLE);
    10						
    11		/* Configure PC.12 as output push-pull (LED) */
    12		GPIO_WriteBit(GPIOC,GPIO_Pin_12,Bit_SET);
    (gdb) b 23
    Breakpoint 2 at 0x2264: file main.c, line 23.
    (gdb) c
    Continuing.
    
    Breakpoint 2, main () at main.c:23
    23			new_button_state = GPIOA->IDR & 0x00000001;
    (gdb) n
    24			if(new_button_state ^ last_button_state) {
    (gdb) p new_button_state
    $1 = 0
    (gdb) info breakpoints 
    Num     Type           Disp Enb Address    What
    1       breakpoint     keep y   0x00002206 in main at main.c:8
    breakpoint already hit 1 time
    2       breakpoint     keep y   0x00002264 in main at main.c:23
    breakpoint already hit 1 time
    (gdb) del 2
    (gdb) watch GPIOC->ODR
    Hardware watchpoint 3: GPIOC->ODR
    (gdb) c
    Continuing.

- 在 QEMU 按下 Ctrl-Alt-2，可操作 UART，再按下 Ctrl-Alt-1 則回到 monitor 畫面
- 在 QEMU monitor 內作以下輸入，試圖模擬按鈕的動作

.. code-block:: prettyprint

    sendkey b

- 隨後可發現 GDB 畫面出現變化：
 
.. code-block:: prettyprint

    Hardware watchpoint 3: GPIOC->ODR

    Old value = 4096
    New value = 0
    main () at main.c:29
    29			last_button_state = new_button_state;

- 事實上 GPIOC 是個 macro，可透過 GDB 驗證

.. code-block:: prettyprint

    (gdb) info macro GPIOC
    Defined at libraries/CMSIS/CM3/DeviceSupport/ST/STM32F10x/stm32f10x.h:1410
      included at Lab-2/demo/main.c:2
    #define GPIOC ((GPIO_TypeDef *) GPIOC_BASE)


作業
-------
- 適度修改 Lab-9/mtask 目錄底下的檔案，以 co-routine 改寫原本 task 的操作
  * 注意：有些如 UART 處理 (輸出與輸入)，需要相當謹慎，務求功能一致
  * 只需要繳交「修改過」的檔案即可

繳交作業
-------
- 截止日期：
   * 成大/中正: March 15, 2013 (含) 之前

- 寄件到 <jserv.tw@gmail.com>
  - 標題: "[NCKU/Lab9]" 開頭，後面加學號與姓名
    * 中正: 改為 "[CCU/Lab9]" 開頭
    * 格式不合者，不計分！