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[经验分享] 【一起来玩RTOS系列】之RT-Thread 信号量用于中断与线程的同步

发表于 2017-12-2 13:04:26 | 显示全部楼层 |阅读模式
校园创客福利

信号量也能够方便的应用于中断与线程间的同步,例如一个中断触发,中断服务例程需要通知线程进行相应的数据处理。这个时候可以设置信号量的初始值是0,线程在试图持有这个信号量时,由于信号量的初始值是0,线程直接在这个信号量上挂起直到信号量被释放。 当中断触发时,先进行与硬件相关的动作,例如从硬件的I/O口中读取相应的数据,并确认中断以清除中断源,而后释放一个信号量来唤醒相应的线程以做后续的数据处理。例如finsh shell线程的处理方式,如图 finsh shell的中断、线程间同步 所示:
sem_shell.png
semaphore先初始为0,而后shell线程试图取得信号量,因为信号量值是0,所以它会被挂起。当console设备有数据输入时,将产生中断而进入中断服务例程。在中断服务例程中,它会读取console设备的数据,并把读得的数据放入uart buffer中进行缓冲,而后释放信号量,释放信号量的操作将唤醒shell线程。在中断服务例程运行完毕后,如果系统中没有比shell线程优先级更高的就绪线程存在时,shell线程将持有信号量并运行,从uart buffer缓冲区中获取输入的数据。

警告: 中断与线程间的互斥不能采用信号量(锁)的方式,而应采用中断锁。


接下来在机智云gokit开发板上演示如何创建并使用信号量进行中断与任务的同步,程序中初始化信号量的初始值是0,在systick中断回调中间隔1000ms释放信号量,线程等待信号量后翻转LED。

注意:要在systick中调用HAL库函数
搜狗截图20171202125955.png

  1. /**
  2.   ****************************************************
  3.   * File Name          : main.c
  4.   * Description        : Main program body
  5.   ****************************************************
  6.   ** This notice applies to any and all portions of this file
  7.   * that are not between comment pairs USER CODE BEGIN and
  8.   * USER CODE END. Other portions of this file, whether
  9.   * inserted by the user or by software development tools
  10.   * are owned by their respective copyright owners.
  11.   *
  12.   * COPYRIGHT(c) 2017 STMicroelectronics
  13.   *
  14.   * Redistribution and use in source and binary forms, with or without modification,
  15.   * are permitted provided that the following conditions are met:
  16.   *   1. Redistributions of source code must retain the above copyright notice,
  17.   *      this list of conditions and the following disclaimer.
  18.   *   2. Redistributions in binary form must reproduce the above copyright notice,
  19.   *      this list of conditions and the following disclaimer in the documentation
  20.   *      and/or other materials provided with the distribution.
  21.   *   3. Neither the name of STMicroelectronics nor the names of its contributors
  22.   *      may be used to endorse or promote products derived from this software
  23.   *      without specific prior written permission.
  24.   *
  25.   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  26.   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27.   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  28.   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  29.   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30.   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  31.   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  32.   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  33.   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  34.   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35.   *
  36.   ****************************************************
  37.   */
  38. /* Includes ------------------------------------------------------------------*/
  39. #include "main.h"
  40. #include "STM32f1xx_hal.h"
  41. #include "usart.h"
  42. #include "gpio.h"

  43. /* USER CODE BEGIN Includes */
  44. #include "rtthread.h"
  45. #include "string.h"
  46. /* USER CODE END Includes */

  47. /* Private variables ---------------------------------------------------------*/

  48. /* USER CODE BEGIN PV */
  49. /* Private variables ---------------------------------------------------------*/

  50. /* USER CODE END PV */

  51. /* Private function prototypes -----------------------------------------------*/
  52. void SystemClock_Config(void);

  53. /* USER CODE BEGIN PFP */
  54. /* Private function prototypes -----------------------------------------------*/

  55. /* USER CODE END PFP */

  56. /* USER CODE BEGIN 0 */
  57. //重映射串口1到rt_kprintf
  58. void rt_hw_console_output(const char *str)
  59. {
  60.     /* empty console output */
  61.         char aa='\r';
  62.           rt_enter_critical();

  63.                 while(*str!='\0')
  64.                 {
  65.                         if(*str=='\n')
  66.                         {
  67.                                 HAL_UART_Transmit(&huart1, (uint8_t *)&aa, 1, 10);
  68.                         }
  69.                                 HAL_UART_Transmit(&huart1, (uint8_t *)(str++), 1, 10);
  70.                 }
  71.                
  72.                 rt_exit_critical();
  73. }

  74. void rt_hw_us_delay(int us)
  75. {
  76.     rt_uint32_t delta;

  77.     /* 获得延时经过的tick数 */
  78.     us = us * (SysTick->LOAD/(1000000/RT_TICK_PER_SECOND));

  79.     /* 获得当前时间 */
  80.     delta = SysTick->VAL;

  81.     /* 循环获得当前时间,直到达到指定的时间后退出循环 */
  82.     while (delta - SysTick->VAL< us);
  83. }

  84. void rt_hw_ms_delay(int ms)
  85. {
  86.         int i=0,j=0;
  87.         for(j=0;j<ms;j++)
  88.         {
  89.                 for (i=0;i<2;i++)
  90.                 rt_hw_us_delay(500);
  91.         }
  92. }

  93. /*
  94. * 程序清单:信号量用于中断和线程的同步,在systick中断中释放信号量,用户线程中等待信号量并翻转LED。
  95. *
  96. * 这个例子中将创建两个线程用于实现生产者消费者问题
  97. */

  98. /* 指向线程控制块的指针 */
  99. static rt_thread_t tid = RT_NULL;

  100. struct rt_semaphore sem;

  101. /* 线程入口 */
  102. void thread_entry(void* parameter)
  103. {

  104.     while(1)
  105.     {
  106.                         rt_sem_take(&sem, RT_WAITING_FOREVER);
  107.                         rt_kprintf("thread take a sem.\n");
  108.                         LED1_Toggle();
  109.                         LED2_Toggle();
  110.                         LED3_Toggle();
  111.                         LED4_Toggle();
  112.                        
  113.     }

  114. }

  115. uint32_t cnt=0;
  116. void HAL_SYSTICK_Callback(void)
  117. {
  118.   /* NOTE : This function Should not be modified, when the callback is needed,
  119.             the HAL_SYSTICK_Callback could be implemented in the user file
  120.    */
  121.         cnt++;
  122.         if(cnt==1000)
  123.         {
  124.                 rt_sem_release(&sem);       
  125.                 cnt=0;
  126.         }
  127. }
  128. /* USER CODE END 0 */

  129. int main(void)
  130. {

  131.   /* USER CODE BEGIN 1 */

  132.   /* USER CODE END 1 */

  133.   /* MCU Configuration----------------------------------------------------------*/

  134. //  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  135. //  HAL_Init();

  136. //  /* USER CODE BEGIN Init */

  137. //  /* USER CODE END Init */

  138. //  /* Configure the system clock */
  139. //  SystemClock_Config();

  140. //  /* USER CODE BEGIN SysInit */

  141. //  /* USER CODE END SysInit */

  142. //  /* Initialize all configured peripherals */
  143. //  MX_GPIO_Init();
  144. //  MX_USART1_UART_Init();

  145.   /* USER CODE BEGIN 2 */
  146.        
  147.         rt_sem_init(&sem, "sem",   0,    RT_IPC_FLAG_FIFO);//初始化信号量

  148. /* 创建线程1 */
  149.     tid = rt_thread_create("thread",
  150.         thread_entry, /* 线程入口是thread_entry */
  151.         RT_NULL, /* 入口参数是RT_NULL */
  152.         512, //堆栈大小
  153.                                 2, //优先级
  154.                                 20);//时间片
  155.     if (tid != RT_NULL)
  156.         rt_thread_startup(tid);
  157.                
  158.         printf("\r\n机智云  只为智能硬件而生\r\n");
  159.         printf("Gizwits Smart Cloud for Smart Products\r\n");
  160.         printf("链接|增值|开放|中立|安全|自有|自由|生态\r\n");
  161.         printf("www.gizwits.com\r\n");
  162.         printf("\r\nGokit RT-Thread Demo\r\n\r\n");
  163.        
  164.         return 0;
  165.        
  166.        


  167.   /* USER CODE END 2 */

  168.   /* Infinite loop */
  169.   /* USER CODE BEGIN WHILE */
  170. //  while (1)
  171. //  {
  172.   /* USER CODE END WHILE */

  173.   /* USER CODE BEGIN 3 */
  174. //               
  175. //  }
  176.   /* USER CODE END 3 */

  177. }

  178. /** System Clock Configuration
  179. */
  180. void SystemClock_Config(void)
  181. {

  182.   RCC_OscInitTypeDef RCC_OscInitStruct;
  183.   RCC_ClkInitTypeDef RCC_ClkInitStruct;

  184.     /**Initializes the CPU, AHB and APB busses clocks
  185.     */
  186.   RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  187.   RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  188.   RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  189.   RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  190.   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  191.   RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  192.   RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  193.   if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  194.   {
  195.     _Error_Handler(__FILE__, __LINE__);
  196.   }

  197.     /**Initializes the CPU, AHB and APB busses clocks
  198.     */
  199.   RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
  200.                               |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  201.   RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  202.   RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  203.   RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  204.   RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  205.   if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  206.   {
  207.     _Error_Handler(__FILE__, __LINE__);
  208.   }

  209.     /**Configure the Systick interrupt time
  210.     */
  211.   HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

  212.     /**Configure the Systick
  213.     */
  214.   HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

  215.   /* SysTick_IRQn interrupt configuration */
  216.   HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
  217. }

  218. /* USER CODE BEGIN 4 */

  219. /* USER CODE END 4 */

  220. /**
  221.   * @brief  This function is executed in case of error occurrence.
  222.   * @param  None
  223.   * @retval None
  224.   */
  225. void _Error_Handler(char * file, int line)
  226. {
  227.   /* USER CODE BEGIN Error_Handler_Debug */
  228.   /* User can add his own implementation to report the HAL error return state */
  229.   while(1)
  230.   {
  231.   }
  232.   /* USER CODE END Error_Handler_Debug */
  233. }

  234. #ifdef USE_FULL_ASSERT

  235. /**
  236.    * @brief Reports the name of the source file and the source line number
  237.    * where the assert_param error has occurred.
  238.    * @param file: pointer to the source file name
  239.    * @param line: assert_param error line source number
  240.    * @retval None
  241.    */
  242. void assert_failed(uint8_t* file, uint32_t line)
  243. {
  244.   /* USER CODE BEGIN 6 */
  245.   /* User can add his own implementation to report the file name and line number,
  246.     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  247.   /* USER CODE END 6 */

  248. }

  249. #endif

  250. /**
  251.   * @}
  252.   */

  253. /**
  254.   * @}
  255. */

  256. /**************** (C) COPYRIGHT STMicroelectronics ****END OF FILE***/
复制代码


串口打印信息如下:
搜狗截图20171202125907.png

于此同时可以看到LED每隔1s翻转状态。

源码下载:

Gokit_RT-Thread.zip (8.7 MB, 下载次数: 7, 售价: 1 金钱)
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发表于 2018-8-31 12:12:23 | 显示全部楼层
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