信号量同步闪烁LED出现卡死

发布于 2019-10-26 12:50:56 浏览：1164 订阅该版

LED只闪烁了1次，然后就不动了。断点调试下发现，led_inform线程中，在rt_sem_release之后，信号量的value依然是0，不知道为什么出现了这种情况。新手才接触，非常奇怪这种现象，是我对信号量的理解出现了偏差吗:'(

```#include <rtthread.h>
#include <rtdevice.h>
#include "led_ctrl.h"

rt_thread_t th_led ;
rt_thread_t th_led_inform ;
rt_uint8_t led_state = 0 ;
struct rt_semaphore sem_led ;

void led_on(rt_base_t pin){
    rt_pin_write(pin, PIN_HIGH);
}

void led_off(rt_base_t pin){
    rt_pin_write(pin, PIN_LOW);
}

void led_init(rt_base_t pin){
    rt_pin_mode(pin, PIN_MODE_OUTPUT);
}

void th_led_entry(void * para){
    rt_err_t result ;
    while(1){
        result = rt_sem_take(&sem_led, RT_WAITING_FOREVER);
        if(result == RT_EOK)
        {
            if(led_state)
                led_on(LED0_PIN);
            else
                led_off(LED0_PIN);
        }
    }
}

void th_led_inform_entry(void * para){
    rt_err_t result ;
    while(1){
        led_state = ~led_state ;
        result = rt_sem_release(&sem_led);
        if(result == RT_EOK){
            rt_thread_mdelay(500);
        }
    }
}

void th_led_ctrl_init(void){
    th_led = rt_thread_create("led_on", th_led_entry, RT_NULL, 128, 15, 100);
    th_led_inform = rt_thread_create("led_off", th_led_inform_entry, RT_NULL, 128, 14, 10);

led_init(LED0_PIN);
    rt_sem_init(&sem_led, "led", 1, RT_IPC_FLAG_FIFO);

rt_thread_startup(th_led);
    rt_thread_startup(th_led_inform);
}```