前面先準備三個檔案:
1. Makefile

TARGET = periodic_task  
SRCS = periodic_task.c 
prefix := $(shell rtai-config --prefix)
ifeq ($(prefix),)
$(error Please add <rtai-install>/bin to your PATH variable)
endif
OBJECTS = $(SRCS:.c=.o)
CC = $(shell rtai-config --cc)
LXRT_CFLAGS = $(shell rtai-config --lxrt-cflags)
LXRT_LDFLAGS = $(
 
shell rtai-config --lxrt-ldflags
all: $(TARGET)
%.o: %.c
    $(CC) -c  $(LXRT_CFLAGS) $<
$(TARGET) :  $(OBJECTS)
    $(CC)  -o $(TARGET) $(LXRT_LDFLAGS) -llxrt $(OBJECTS)
clean:
    rm -f *.o  *~ core.* $(TARGET)
.PHONY: clean

2. run
實際上是呼叫rtai-load來執行的.

${DESTDIR}/usr/realtime/bin/rtai-load
 

3. .runinfo
隱藏檔案rtai-load根據這個來執行

prog_name:lxrt+sem+mbx+msg+fifos:!./prog_name; popall:control_c

（2 、3步驟可以簡化成另一種方式，直接進入RTAI安裝目錄，然後insmod rtai_hal.ko insmod rtai_sched.ko insmod rtai_lxrt.ko……，然後執行程式./prog_name 就行了）

4. 程式碼框架

• 單觸發模式

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
 

#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
//#include <sys/time.h>
//#include <signal.h>
#include <fcntl.h>
#include <sched.h>
#include <rtai_lxrt.h>
//#include <rtai_sem.h>
//#include <rtai_msg.h>

static int thread0;
static void *fun0(void *arg)
{
    RT_TASK *task;
    task = rt_task_init_schmod(nam2num("TASK0"), 0, 0, 0, SCHED_FIFO, 0xF);
     mlockall(MCL_CURRENT | MCL_FUTURE); 
    //設定優先順序和排程演算法 這裡他用SCHED_FIFO，而SCHED_OTHER（基於時間片）優先會低些,這個Name就是實時任務的標識  nam2num 是把名字轉為name id 以免命名衝突

    // 進入硬實時模式，無此語句時，預設的是軟實時
    //rt_make_hard_real_time();

    //此處新增程式碼，如下語句
    //rt_printk("Hello World!\n");

    //將實時任務或者執行緒返回到標準linux的狀態
    rt_make_soft_real_time();

    //刪除任務
    rt_task_delete(task);
    return 0;
}

int main(void)
{
    RT_TASK *task;

    // make main thread LXRT soft realtime
    task = rt_task_init_schmod(nam2num("MYTASK"), 9, 0, 0, SCHED_FIFO, 0xF);
    mlockall(MCL_CURRENT | MCL_FUTURE);

    // start realtime timer and scheduler
    rt_set_oneshot_mode();
    start_rt_timer(0);

    // create a linux thread 
    thread0 = rt_thread_create(fun0, NULL, 10000);

    // wait for end of program
    printf("TYPE <ENTER> TO TERMINATE\n");
    getchar();

    // cleanup stuff
    stop_rt_timer();
    return 0;
}

- 週期模式

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <rtai_lxrt.h>
#include <sys/io.h>

#define TICK_TIME 1000000
#define CPUMAP 0x1

static RT_TASK *main_Task;
static RT_TASK *loop_Task;
int keep_on_running = 1;
static pthread_t main_thread;
static RTIME expected;
static RTIME sampling_interval;

static void *main_loop()
{
    if (!(loop_Task = rt_task_init_schmod(nam2num("RTAI01"), 2, 0, 0, SCHED_FIFO, CPUMAP))) 
    {
        printf("CANNOT INIT PERIODIC TASK\n");
        exit(1); 
    } 

    //mlockall(MCL_CURRENT | MCL_FUTURE);(原始碼沒有，…？)
    expected = rt_get_time() + 100*sampling_interval;
    rt_task_make_periodic(loop_Task, expected, sampling_interval); 

    rt_make_hard_real_time();

    while (keep_on_running)
    {
        //insert your main periodic loop here
        rt_task_wait_period();//
        //set keep_on_running to 0 if you want to exit
    } 

    rt_task_delete(loop_Task);
    return 0;
}

int main(void)
{
    RT_TASK *Main_Task;
    if (!(Main_Task = rt_task_init_schmod(nam2num("MNTSK"), 0, 0, 0, SCHED_FIFO, 0xF))) 
    {
        printf("CANNOT INIT MAIN TASK\n");
        exit(1);
    } 

    //mlockall(MCL_CURRENT | MCL_FUTURE); 
    if ((hard_timer_running = rt_is_hard_timer_running()))
    {
        printf("Skip hard real_timer setting...\n");
        sampling_interval = nano2count(TICK_TIME);
    }
    else
    {
        printf("Starting real time timer...\n");
        rt_set_oneshot_mode();
        start_rt_timer(0);// 啟動計時器 記得用完要關掉
    } 

    sampling_interval = nano2count(TICK_TIME);
    pthread_create(&main_thread, NULL, main_loop, NULL);
    while (keep_on_running)
        sampling_interval = sampling_interval; //do nothing!

    rt_task_delete(Main_Task);
    return 0;
}