5 线程问题，线程已经创建成功了，为啥线程调用的函数不会运行呢？

void airun_thread()
{
    /* 创建 serial 线程 */
    rt_thread_t thread = rt_thread_create("ai", ai_thread_entry, RT_NULL, 1024, 28, 30);
    /* 创建成功则启动线程 */
    if (thread != RT_NULL)
    {
        rt_pin_write(LED2,PIN_LOW);
        rt_thread_startup(thread);
    }
}
void ai_thread_entry(void *param)
{
    while(1)
    {
        PT1=getaibyChanel(ADC_DEV_NAME0,0);
        PT2=getaibyChanel(ADC_DEV_NAME0,1);
        PT3=getaibyChanel(ADC_DEV_NAME0,2);
        PT4=getaibyChanel(ADC_DEV_NAME0,3);
        //临时方案，关闭AD通道，设置为普通输入通道
        rt_pin_mode(GET_PIN(A, 0), PIN_MODE_INPUT);
        rt_pin_mode(GET_PIN(A, 1), PIN_MODE_INPUT);
        rt_pin_mode(GET_PIN(A, 2), PIN_MODE_INPUT);
        rt_pin_mode(GET_PIN(A, 3), PIN_MODE_INPUT);
        AI1=getaibyChanel(ADC_DEV_NAME1,4);
        AI2=getaibyChanel(ADC_DEV_NAME1,5);
        AI3=getaibyChanel(ADC_DEV_NAME1,6);
        //AI4=getaibyChanel(ADC_DEV_NAME0,7);
        PT1old=getPToldValue(PT1);//2.8432875
        PT2old=getPToldValue(PT2);
        PT3old=getPToldValue(PT3);
        PT4old=getPToldValue(PT4);
        rt_uint16_t u1=0.254767386299465*PT1old-55.8156683028539;
        rt_uint16_t u2=0.254767386299465*PT2old-55.8156683028539;
        AI1old=AI1/4;
        AI2old=AI2/4;
        AI3old=AI3/4;
        rt_pin_write(LED3,PIN_LOW);
        rt_thread_mdelay(500);
    }
}