【转】串口生成的32Bit随机数

只看该作者 · 2017-8-22 17:00

/**
  * @file Timer.c
  * @author  WB R&D Team - openmcu666
  * @version V0.1
  * @date 2015.7.9
  * @brief Timer
  */
#include "Timer.h"

__IO uint32_t TimingDelay = 0;
__IO uint32_t CaptureNumber = 0;
__IO uint32_t PeriodValue = 0;

/**
  * @brief  Configures TIM5 to measure the LSI oscillator frequency.
  * @param  None
  * @retval LSI Frequency
  */
uint32_t GetLSIFrequency(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  TIM_ICInitTypeDef  TIM_ICInitStructure;
  RCC_ClocksTypeDef  RCC_ClockFreq;

  RCC_LSICmd(ENABLE);                                           //使能LSI

  while (RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET)             //等待LSI稳定
  {
  }

  /* TIM5 configuration *******************************************************/

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);          //使能TIM5时钟

  TIM_RemapConfig(TIM5, TIM5_LSI);                               //内部TIM5_CH4输入捕获连接到LSI时钟输出

  TIM_PrescalerConfig(TIM5, 0, TIM_PSCReloadMode_Immediate);    //设置预分频

  /* TIM5 configuration: Input Capture mode ---------------------
   The LSI oscillator is connected to TIM5 CH4
   The Rising edge is used as active edge,
   The TIM5 CCR4 is used to compute the frequency value
  ------------------------------------------------------------ */
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV8;
  TIM_ICInitStructure.TIM_ICFilter = 0;
  TIM_ICInit(TIM5, &TIM_ICInitStructure);

  /* Enable TIM5 Interrupt channel */
  NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

  TIM_Cmd(TIM5, ENABLE);                                  //启动计数器

  TIM5->SR = 0;                                           //Reset the flags

  TIM_ITConfig(TIM5, TIM_IT_CC4, ENABLE);                //启动CC4中断请求

  /* Wait until the TIM5 get 2 LSI edges (refer to TIM5_IRQHandler() in
stm32f4xx_it.c file) ******************************************************/
  while(CaptureNumber != 2)
  {
  }

  TIM_DeInit(TIM5);                                           //设置为复位后的默认值

  RCC_GetClocksFreq(&RCC_ClockFreq);                         //获取系统时钟,HCLK 和 PCLKx 频率

  if ((RCC->CFGR & RCC_CFGR_PPRE1) == 0)                      //获取PCLK1预分频器
  {
return ((RCC_ClockFreq.PCLK1_Frequency / PeriodValue) * 8);//PCLK1预分频器
  }
  else
  {
return (((2 * RCC_ClockFreq.PCLK1_Frequency) / PeriodValue) * 8) ;
  }
}
** 实验名：旺宝-红龙429-RNG实验
** KEIL MDK-ARM Standard Version：V5.10
** 软件库(keil) Version: unused
** 固件库(ST) Version: 1.5.0

** 实验说明：
实验原理：
硬件连接：

实验现象：程序运行后,串口打印RNG生成的32Bit随机数.
**********************************/