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標(biāo)題: STM32之SYSCLK滴答精確延時(shí)程序 寄存器實(shí)現(xiàn) [打印本頁]
作者: xuwei    時(shí)間: 2015-6-14 03:17
標(biāo)題: STM32之SYSCLK滴答精確延時(shí)程序 寄存器實(shí)現(xiàn)
要知道時(shí)間對(duì)程序來說也是生命！該延時(shí)的要延時(shí)，不該延時(shí)的不能延時(shí)，操作器件不也就是操作時(shí)序嗎？，所以延時(shí)是非常重要的，但是ARM的運(yùn)算速度非常快，用普通單片機(jī)似的延時(shí)恐怕。。。，很難算得很精確，這就出來了滴答時(shí)鐘，他和內(nèi)核在一塊，方便的時(shí)鐘選擇，簡單的寄存器，就搞定。
本程是查詢程序，下一步亞用中斷實(shí)現(xiàn)！
值得注意的是我沒找到庫函數(shù)！所以采用的是操作寄存器實(shí)現(xiàn)的！

SYSCLK=72mhz

  1. #include "main.h"
  2. GPIO_InitTypeDef GPIO_InitStructure;
  3. void mysysint()//系統(tǒng)初始化程序
  4. {
  5. ErrorStatus HSEStartUpStatus;//說明標(biāo)志位
  6. RCC_DeInit();//所有外設(shè)全部缺省設(shè)置

  8. /* Enable HSE */
  9. RCC_HSEConfig(RCC_HSE_ON);
  10. /* Wait till HSE is ready and if Time out is reached exit */
  11. HSEStartUpStatus = RCC_WaitForHSEStartUp();
  12. if(HSEStartUpStatus == SUCCESS)//啟動(dòng)成功
  13. {
  14. /*這兩條FLASH指令必須加上，不知為啥？不加上就運(yùn)行幾秒后出錯(cuò)，參照系統(tǒng)初始化*/
  15. /* Enable The Prefetch Buffer */
  16. FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);//FLASH緩存開啟
  17. /* Configure the Latency cycle: Set 2 Latency cycles */
  18.   FLASH_SetLatency(FLASH_Latency_2);  //設(shè)置FLASH這些位表示SYSCLK(系統(tǒng)時(shí)鐘)周期與閃存訪問時(shí)間的比例,為010：兩個(gè)等待狀態(tài)，當(dāng) 48MHz < SYSCLK ≤ 72MHz
  19. /* Set PLL clock output to 72MHz using HSE (8MHz) as entry clock */
  20. RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);//外部時(shí)鐘為8M，PLL的輸入時(shí)鐘=8MHZ，倍頻系數(shù)9，

  22. /* Configure HCLK such as HCLK = SYSCLK */
  23. RCC_HCLKConfig(RCC_SYSCLK_Div1);//設(shè)置了啦AHB分頻器的分頻系數(shù)=1，即HCLK=SYSCLK=72MHZ
  24. /* Configure PCLK1 such as PCLK1 = HCLK/2 */
  25. RCC_PCLK1Config(RCC_HCLK_Div2);//設(shè)置了APB1外設(shè)的時(shí)鐘頻率最大是36M這里是APB1的分頻器設(shè)為2,PCLK1=HCLK/2=72/2=36MHZ正好是最大值
  26. /* Configure PCLK2 such as PCLK2 = HCLK */
  27. RCC_PCLK2Config(RCC_HCLK_Div1);//設(shè)置PLCK2=HCLK=72MHZ，的APB2分頻器=1
  28. /* Select the PLL as system clock source */
  29. RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);//設(shè)置了SYSCLK的提供者為PLL，頻率由上面算出=72MHZ
  30. /* disable PLL Ready interrupt */
  31. RCC_ITConfig(RCC_IT_PLLRDY, DISABLE);//PLL中斷關(guān)閉
  32. /* disable PLL Ready interrupt */
  33. RCC_ITConfig(RCC_IT_HSERDY,DISABLE);//HSE中斷關(guān)閉
  34. /* disable PLL Ready interrupt */
  35. RCC_ITConfig(RCC_IT_HSIRDY, DISABLE); //HSI中斷關(guān)閉
  36. /* disable PLL Ready interrupt */
  37. RCC_ITConfig(RCC_IT_LSERDY, DISABLE); //LSE中斷關(guān)閉
  38. /* disable PLL Ready interrupt */
  39. RCC_ITConfig(RCC_IT_LSIRDY, DISABLE); //LSI中斷關(guān)閉

  41. /* PLL clock divided by 1.5 used as USB clock source */
  42. RCC_USBCLKConfig(RCC_USBCLKSource_PLLCLK_1Div5);//設(shè)置USB的時(shí)鐘為=72、1.5=48mhz
  43. /* Configure ADCCLK such as ADCCLK = PCLK2/2 */
  44. RCC_ADCCLKConfig(RCC_PCLK2_Div2);//設(shè)置ADC時(shí)鐘=PCLK2/2= 36MHZ
  45. /* disable the LSE */
  46. RCC_LSEConfig(RCC_LSE_OFF);//外部低速晶振關(guān)閉

  48. /*DISable the RTC clock */
  49. RCC_RTCCLKCmd(DISABLE);
  50. /* DISable the Clock Security System */
  51. RCC_ClockSecuritySystemCmd(DISABLE);
  52. /* Enable the PLL */
  53. RCC_PLLCmd(ENABLE);//使能PLL







  61. /* PLL ans system clock config */
  62. }
  63. else
  64. {
  65. /* Add here some code to deal with this error */
  66. }





  72. }

  74. /** @addtogroup STM32F10x_StdPeriph_Examples
  75.   * @{
  76.   */

  78. /** @addtogroup SysTick_TimeBase
  79.   * @{
  80.   */

  82. /* Private typedef -----------------------------------------------------------*/
  83. /* Private define ------------------------------------------------------------*/
  84. /* Private macro -------------------------------------------------------------*/
  85. /* Private variables ---------------------------------------------------------*/
  86. static __IO uint32_t TimingDelay;

  88. /* Private function prototypes -----------------------------------------------*/
  89. void Delay(__IO uint32_t nTime);

  91. /* Private functions ---------------------------------------------------------*/

  93. /**
  94.   * @brief  Main program.
  95.   * @param  None
  96.   * @retval None
  97.   */


  100. void wang_mySYStick_init()
  101. {

  103. //SysTick->LOAD=72000; //53MHZ下定時(shí)1ms
  104. SysTick->LOAD  = 72000;

  106. SysTick->CTRL=0x00000005;//表示HCLK=SYStick時(shí)鐘，開啟滴答，關(guān)閉中斷


  109. }

  111. /*
  112. *此函數(shù)為滴答時(shí)鐘的查詢函數(shù)，不斷地在查詢標(biāo)志位！！！！
  113. *
  114. *  王均偉
  115. *
  116. * 形參為時(shí)間值，延時(shí)時(shí)間=TIME*1毫秒

  118. */
  119. void mydelay(unsigned int time) //20110725他媽的我沒找到關(guān)于這個(gè)版本的庫函數(shù)，直接對(duì)寄存器操作了、反而感覺更親切了。很想51
  120. {
  121. unsigned long a,b;
  122.    while(time)
  123.    {
  124.      a=SysTick->CTRL;
  125.   b=a&0x00010000;
  126.    if(b==0x00010000)
  127.    {
  128.     SysTick->LOAD  = 72000-1;  //用的72MHZ時(shí)鐘，一直使用的話要減一！！！！
  129.   time--;
  130.    }



  134.    }

  136. }
  137. int main(void)
  138. {

  140. mysysint();//系統(tǒng)初始化程序

  142. /* GPIOD Periph clock enable */
  143.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);//使能時(shí)鐘
  144. /* Configure PD0 and PD2 in output pushpull mode */
  145.   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9| GPIO_Pin_10| GPIO_Pin_11;
  146.   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  147.   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  148.   GPIO_Init(GPIOD, &GPIO_InitStructure);


  151. wang_mySYStick_init();//滴答初始化！

  153.   while(1)
  154.   {
  155.       /* Set the GPIOA port pin 10 and pin 15 */
  156.   GPIO_SetBits(GPIOD,  GPIO_Pin_8);//GPIOD->BSRR = 0x00000f00;//置為PD8-PD11
  157. mydelay(100);

  159.    /* Clears the GPIOA port pin 10 and pin 15 */
  160.     GPIO_ResetBits(GPIOD,  GPIO_Pin_8);//GPIOD->BRR  = 0x00000f00;

  162. mydelay(100);
  163.   /* Set the GPIOA port pin 10 and pin 15 */
  164.   GPIO_SetBits(GPIOD, GPIO_Pin_9);//GPIOD->BSRR = 0x00000f00;//置為PD8-PD11
  165. mydelay(100);

  167.    /* Clears the GPIOA port pin 10 and pin 15 */
  168.     GPIO_ResetBits(GPIOD,  GPIO_Pin_9);//GPIOD->BRR  = 0x00000f00;

  170. mydelay(100);

  172.   /* Set the GPIOA port pin 10 and pin 15 */
  173.   GPIO_SetBits(GPIOD, GPIO_Pin_10);//GPIOD->BSRR = 0x00000f00;//置為PD8-PD11
  174. mydelay(100);

  176.    /* Clears the GPIOA port pin 10 and pin 15 */
  177.     GPIO_ResetBits(GPIOD,  GPIO_Pin_10);//GPIOD->BRR  = 0x00000f00;


  180.   mydelay(100);
  181.   /* Set the GPIOA port pin 10 and pin 15 */
  182.   GPIO_SetBits(GPIOD, GPIO_Pin_11);//GPIOD->BSRR = 0x00000f00;//置為PD8-PD11
  183. mydelay(100);

  185.    /* Clears the GPIOA port pin 10 and pin 15 */
  186.     GPIO_ResetBits(GPIOD,  GPIO_Pin_11);//GPIOD->BRR  = 0x00000f00;

  188. mydelay(100);


  191.   }
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