作業系統工程-Presentation

Table Of Content

tags: 作業系統工程 Operating System Programming note, 110-1, 2021

• 作業系統工程-Presentation
  • Table Of Content
• IPC application
• PWM application
• timer application
• clock application

---

IPC application

• 若在底部抓球時偵測到卡球的情況，透過增加步進馬達轉力，此時就能從下方推球。
  • By Signal
  • Signal
    • Operation of Signal

      • rt_signal_mask
      • 信號阻塞，也可以理解為屏蔽信號。
        若該信號被阻塞，則該信號將不會遞達給安裝此信號的線程，也不會引發 soft interrupt。

#include <rtthread.h>

#define THREAD_PRIORITY         25
#define THREAD_STACK_SIZE       512
#define THREAD_TIMESLICE        5

static rt_thread_t tid1 = RT_NULL;

// thread 1 的信號處裡函数 
void thread1_signal_handler(int sig)
{
    rt_kprintf("thread1 received signal %d\n", sig);
    return;
}
// kernal 中，在 signal.c 也有預設的 signal_handler
//
//static void _signal_default_handler(int signo)
//{
//    LOG_I("handled signo[%d] with default action.", signo);
//    return ;
//}
//
 
// thread 1 的入口函数
static void thread1_entry(void *parameter)
{
    int cnt = 0;

    // set up signal
    rt_signal_install(SIGUSR1, thread1_signal_handler);
    rt_signal_unmask(SIGUSR1);
    
    while(/*不斷的去偵測卡球的情況有沒有發生*/) 
    {
        rt_thread_kill(tid2, SIGUSR1);
        // 若發現有卡球的情況發生，就發送信號 SIGUSR1 给 thread 2 去處理
    }
    
}
/* thread 2 的入口函数 */
static void thread2_entry(void *parameter)
{
    int cnt = 0;

    // set up signal
    rt_signal_install(SIGUSR1, thread1_signal_handler);
    rt_signal_unmask(SIGUSR1);

    /* 增加底部馬達的轉動力度 */
    /// Code
}

int _sample(void)
{
    // 產生thread 1
    tid1 = rt_thread_create("thread1", thread1_entry, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIO, THREAD_TIMESLICE);

    if (tid1 != RT_NULL)
        rt_thread_startup(tid1);
    
    // 產生thread 2
    tid2 = rt_thread_create("thread2", thread2_entry, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIO, THREAD_TIMESLICE);

    if (tid2 != RT_NULL)
        rt_thread_startup(tid2);

    return 0;
}

// 导出到 msh 命令列表中 
MSH_CMD_EXPORT(signal_sample, signal sample);

• 若偵測到的錯誤訊息不僅限於「在底部抓球時的卡球情況」，可用 mailbox 的 priority 方法將 error 放進 mailbox ，再針對他的 priority 進行各個處理。
  • By Mailbox

#include <rtthread.h>

#define THREAD_PRIORITY      10
#define THREAD_TIMESLICE     5


static struct rt_mailbox mb;
/* 用於放 mail 的 memory pool */
static char mb_pool[128];

static char mb_str1[] = "type 1 error";
static char mb_str2[] = "type 2 error";
static char mb_str3[] = "over";

ALIGN(RT_ALIGN_SIZE)
static char thread1_stack[1024];
static struct rt_thread thread1;

/* thread 1 入口 */
static void thread1_entry(void *parameter)
{
    char *str;

    while (1)
    {
        rt_kprintf("thread1: try to recv a mail\n");

        // 從 mailbox 中收 mail 
        if (rt_mb_recv(&mb, (rt_uint32_t *)&str, RT_WAITING_FOREVER) == RT_EOK)
        {
            rt_kprintf("thread1: get a mail from mailbox, the content:%s\n", str);
            if (str == mb_str1)
            {
                // call 對應得 function 處理對應的 error
            }
            else if (str == mb_str2)
            {
                // call 對應得 function 處理對應的 error
            }
            else if (str == mb_str3)
                break;

            // delay 100ms 
            rt_thread_mdelay(100);
        }
    }
    // 讓 mailbox 上的 object 脫離
    rt_mb_detach(&mb);
}

ALIGN(RT_ALIGN_SIZE)
static char thread2_stack[1024];
static struct rt_thread thread2;

// thread 2 入口 
// 負責發送 mail (各種 error type)到 mailbox
rt_uint8_t _error_type;
static void thread2_entry(void *parameter)
{
    while (_error_type < 10)
    {
        _error_type ++;
        if (_error_type & 0x1)
        {
            /* 發送 mb_str1 地址到 mailbox 中 */
            rt_mb_send(&mb, (rt_uint32_t)&mb_str1);
        }
        else
        {
            /* 發送 mb_str2 地址到 mailbox 中 */
            rt_mb_send(&mb, (rt_uint32_t)&mb_str2);
        }

        /* delay 200ms */
        rt_thread_mdelay(200);
    }

    // thread 3 代表運行結束的字串
    // 發送 mail 告诉 thread 1，thread 2 已经運行结束 
    rt_mb_send(&mb, (rt_uint32_t)&mb_str3);
}

int mailbox_sample(void)
{
    rt_err_t result;

    // 初始化 mailbox
    // 名稱是 mbt, mailbox 用到的 memory pool 是 mb_pool, mailbox 中的郵件數目，因为一封 mail 為 4 bytes, 用 PRIORITY 的方式做 processes waiting
    result = rt_mb_init(&mb, "mbt", &mb_pool[0], sizeof(mb_pool)/4, RT_IPC_FLAG_PRIO);          
    if (result != RT_EOK)
    {
        rt_kprintf("init mailbox failed.\n");
        return -1;
    }
    //初始化 thread　１，並啟動他
    rt_thread_init(&thread1, "thread1", thread1_entry, RT_NULL, &thread1_stack[0], sizeof(thread1_stack), THREAD_PRIORITY, THREAD_TIMESLICE);
    rt_thread_startup(&thread1);

    //初始化 thread　２，並啟動他
    rt_thread_init(&thread2, "thread2", thread2_entry, RT_NULL, &thread2_stack[0], sizeof(thread2_stack), THREAD_PRIORITY, THREAD_TIMESLICE);
    rt_thread_startup(&thread2);
    return 0;
}

PWM application

int main(void)
{
    /*int count = 1;

     while (count++)
     {
     LOG_D("Hello RT-Thread!");
     rt_thread_mdelay(1000);
     }*/

    rt_uint32_t period, pulse, dir;

    period = 500000;    // 周期为0.5ms，单位为纳秒ns
    dir = 1;            // PWM脉冲宽度值的增减方向
    pulse = 0;          // PWM脉冲宽度值，单位为纳秒ns

    // 找 device
    pwm_dev = (struct rt_device_pwm *) rt_device_find(PWM_DEV_NAME);
    if (pwm_dev == RT_NULL)
    {
        rt_kprintf("pwm sample run failed! can't find %s device!\n", PWM_DEV_NAME);
        return RT_ERROR;
    }

    // 设置PWM周期和脉冲宽度默认值
    rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
    // 使能设备
    rt_pwm_enable(pwm_dev, PWM_DEV_CHANNEL);

    int count = 0;
    while (count < 10)
    {
        rt_thread_mdelay(1000);
        if (dir)
        {
            pulse += 5000;      // 从0值开始每次增加5000ns
        }
        else
        {
            pulse -= 5000;      // 从最大值开始每次减少5000ns
        }
        if (pulse >= period)
        {
            dir = 0;
        }
        if (0 == pulse)
        {
            dir = 1;
        }

        // 设置PWM周期和脉冲宽度
        rt_pwm_set(pwm_dev, PWM_DEV_CHANNEL, period, pulse);
        count++;
    }

    return RT_EOK;
}

timer application

​​​​> RT-Thread 中，時鐘節拍的長度可以根據RT_TICK_PER_SECOND 的定義來調整，等於1/RT_TICK_PER_SECOND 秒。

clock application

​​​​> # Semaphone/ mutex application