[RTT例程练习] 2.3 信号量-检测按键(同步) -(信号量互斥)

来源：互联网发布：鹰眼数据编辑：程序博客网时间：2024/06/05 14:14

这里，使用信号量来同步两个线程。

简单来说，线程每隔一定的时间扫描按键。一旦其检测到有效的按键，便release 信号量，使得线程2 从挂起进入运行态，向串口打印按键信息。

这样，便实现了两个线程的同步。

程序：

#include <rtthread.h>#include "stm32f10x.h"#define KEY_PORT    GPIOB#define KEY_PIN     (GPIO_Pin_0 | GPIO_Pin_1)#define KEY_CLOCK   RCC_AHB1Periph_GPIOBvoid rt_init_thread_entry(void *parameter){GPIO_InitTypeDef GPIO_InitStructure;//开启PB0时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;GPIO_Init(GPIOB,&GPIO_InitStructure);}   static rt_uint8_t thread1_stack[1024];struct rt_thread thread1;static int key;static struct rt_semaphore sem;static void rt_thread_entry1(void *parameter){    int temp;        while (1)    {        key = GPIO_ReadInputData(KEY_PORT);                if (key & KEY_PIN)        {            temp = key;            rt_thread_delay(RT_TICK_PER_SECOND / 50);            key = GPIO_ReadInputData(KEY_PORT);            if (key == temp);                rt_sem_release(&sem);        }                rt_thread_delay(RT_TICK_PER_SECOND / 10);    }}static rt_uint8_t thread2_stack[1024];struct rt_thread thread2;//static int key;static void rt_thread_entry2(void *parameter){    while (1)    {        rt_sem_take(&sem, RT_WAITING_FOREVER);                if (key & KEY_PIN)        {            rt_kprintf("some keys has been pressed: %x\n", key);        }    }}int rt_application_init(){    rt_thread_t init_thread;    rt_err_t result;        result = rt_sem_init(&sem, "sem",        0, RT_IPC_FLAG_FIFO);    if (result != RT_EOK)    {        rt_kprintf("error, init sem failed!\n");        return 0;    }        init_thread = rt_thread_create("init",         rt_init_thread_entry,        RT_NULL,        2048, 8, 20);    if (init_thread != RT_NULL)        rt_thread_startup(init_thread);        /* init thread1 */    rt_thread_init(&thread1,         "keyp", // producer        rt_thread_entry1,         RT_NULL,         &thread1_stack[0], sizeof(thread1_stack),        11, 25);    rt_thread_startup(&thread1);    rt_thread_init(&thread2,        "keyc", // consumer        rt_thread_entry2,         RT_NULL,        &thread2_stack[0], sizeof(thread2_stack),        11, 24);    rt_thread_startup(&thread2);        return 0;}

结果为：

some keys has been pressed : 40some keys has been pressed : 80