140 lines
3.3 KiB
C
140 lines
3.3 KiB
C
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#include "main.h"
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#include "core_delay.h"
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//获取系统主频
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uint32_t GetSysClocksFreq (void)
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{
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RCC_ClocksTypeDef t={0};
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RCC_GetClocksFreq (&t);
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return t.SYSCLK_Frequency;
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}
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/*
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**********************************************************************
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* 时间戳相关寄存器定义
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**********************************************************************
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*/
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/*
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在Cortex-M 里面有一个外设叫DWT(Data Watchpoint and Trace)，
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该外设有一个32 位的寄存器叫CYCCNT，它是一个向上的计数器，
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记录的是内核时钟运行的个数，最长能记录的时间为：
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10.74s=2 的32 次方/400000000
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(假设内核频率为400M，内核跳一次的时间大概为1/400M=2.5ns)
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当CYCCNT 溢出之后，会清0 重新开始向上计数。
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使能CYCCNT 计数的操作步骤：
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1、先使能DWT 外设，这个由另外内核调试寄存器DEMCR 的位24 控制，写1 使能
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2、使能CYCCNT 寄存器之前，先清0
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3、使能CYCCNT 寄存器，这个由DWT_CTRL(代码上宏定义为DWT_CR)的位0 控制，写1 使能
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*/
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#define DWT_CR *(__IO uint32_t *)0xE0001000
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#define DWT_CYCCNT *(__IO uint32_t *)0xE0001004
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#define DEM_CR *(__IO uint32_t *)0xE000EDFC
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#define DEM_CR_TRCENA (1 << 24)
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#define DWT_CR_CYCCNTENA (1 << 0)
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/**
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* @brief 初始化时间戳
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* @param 无
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* @retval 无
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* @note 使用延时函数前，必须调用本函数
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*/
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HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)
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{
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/* 使能DWT 外设 */
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DEM_CR |= (uint32_t)DEM_CR_TRCENA;
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/* DWT CYCCNT 寄存器计数清0 */
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DWT_CYCCNT = (uint32_t)0u;
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/* 使能Cortex-M DWT CYCCNT 寄存器 */
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DWT_CR |= (uint32_t)DWT_CR_CYCCNTENA;
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return HAL_OK;
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}
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/**
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* @brief 读取当前时间戳
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* @param 无
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* @retval 当前时间戳，即DWT_CYCCNT 寄存器的值
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*/
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uint32_t CPU_TS_TmrRd(void)
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{
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return ((uint32_t)DWT_CYCCNT);
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}
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/**
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* @brief 读取当前时间戳
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* @param 无
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* @retval 当前时间戳，即DWT_CYCCNT 寄存器的值
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*/
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uint32_t HAL_GetTick(void)
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{
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return ((uint32_t)DWT_CYCCNT*1000/SysClockFreq);
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}
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/**
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* @brief 采用CPU 的内部计数实现精确延时，32 位计数器
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* @param us : 延迟长度，单位1 us
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* @retval 无
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* @note 使用本函数前必须先调用CPU_TS_TmrInit 函数使能计数器，
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* 或使能宏CPU_TS_INIT_IN_DELAY_FUNCTION
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*最大延时值为8 秒，即8*1000*1000
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*/
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void CPU_TS_Tmr_Delay_US(uint32_t us)
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{
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uint32_t ticks;
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uint32_t told, tnow, tcnt=0;
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/* 在函数内部初始化时间戳寄存器， */
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#if (CPU_TS_INIT_IN_DELAY_FUNCTION)
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/* 初始化时间戳并清零 */
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HAL_InitTick(5);
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#endif
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ticks = us * (GET_CPU_ClkFreq() / 1000000); /* 需要的节拍数 */
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tcnt = 0;
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told = (uint32_t)CPU_TS_TmrRd(); /* 刚进入时的计数器值 */
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while (1)
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{
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tnow = (uint32_t)CPU_TS_TmrRd();
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if (tnow != told)
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{
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/* 32 位计数器是递增计数器 */
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if (tnow > told)
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{
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tcnt += tnow - told;
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}
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/* 重新装载 */
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else
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{
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tcnt += UINT32_MAX - told + tnow;
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}
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told = tnow;
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/*时间超过/等于要延迟的时间,则退出 */
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if (tcnt >= ticks)break;
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}
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}
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}
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/*****************************END OF FILE**********************/
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