bsp_DWT_delay-FreeRTOS下us延时

进行初始化 DWT_Delay_Init();
可以直接使用 DWT_Delay_us(1000);
需要大量使用ms延时，可自己写一个 DWT_Delay_ms(1);

bsp_DWT_delay.c

#include "bsp_DWT_delay.h"
 
/**
 * @brief  Initializes DWT_Clock_Cycle_Count for DWT_Delay_us function
 * @return Error DWT counter
 *         1: clock cycle counter not started
 *         0: clock cycle counter works
 */
uint32_t DWT_Delay_Init(void) {
  /* Disable TRC */
  CoreDebug->DEMCR &= ~CoreDebug_DEMCR_TRCENA_Msk; // ~0x01000000;
  /* Enable TRC */
  CoreDebug->DEMCR |=  CoreDebug_DEMCR_TRCENA_Msk; // 0x01000000;
 
  /* Disable clock cycle counter */
  DWT->CTRL &= ~DWT_CTRL_CYCCNTENA_Msk; //~0x00000001;
  /* Enable  clock cycle counter */
  DWT->CTRL |=  DWT_CTRL_CYCCNTENA_Msk; //0x00000001;
 
  /* Reset the clock cycle counter value */
  DWT->CYCCNT = 0;
 
     /* 3 NO OPERATION instructions */
	__ASM volatile ("NOP");
	__ASM volatile ("NOP");
 	__ASM volatile ("NOP");
 
  /* Check if clock cycle counter has started */
     if(DWT->CYCCNT)
     {
       return 0; /*clock cycle counter started*/
     }
     else
  {
    return 1; /*clock cycle counter not started*/
  }
}

bsp_DWT_delay.h

#ifndef _BSP_DWT_DELAY_H_
#define _BSP_DWT_DELAY_H_
 
#ifdef __cplusplus
extern "C" {
#endif
 
#include "main.h"
 
 //系统时钟频率
#define SystemCLK  400000000

/**
 * @brief  Initializes DWT_Cycle_Count for DWT_Delay_us function
 * @return Error DWT counter
 *         1: DWT counter Error
 *         0: DWT counter works
 */
uint32_t DWT_Delay_Init(void);
 
/**
 * @brief  This function provides a delay (in microseconds)
 * @param  microseconds: delay in microseconds
 */
__STATIC_INLINE void DWT_Delay_us(volatile uint32_t microseconds)
{
  uint32_t clk_cycle_start = DWT->CYCCNT;
 
  /* Go to number of cycles for system */
  //microseconds *= (HAL_RCC_GetHCLKFreq() / 1000000);
	microseconds *= (SystemCLK / 1000000);
	
  /* Delay till end */
  while ((DWT->CYCCNT - clk_cycle_start) < microseconds);
}
 
#ifdef __cplusplus
}
#endif
 
#endif