因为时间片的原因freeRTOS自身貌似无法进行微秒级的延时,实测通过以下函数可以进行微秒级的消息

dwt_stm32_delay.h

#ifndef DWT_STM32_DELAY_H

#define DWT_STM32_DELAY_H

#ifdef __cplusplus

extern "C" {

#endif

#include "stm32f4xx_hal.h"

/**

 * @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);

  /* Delay till end */

  while ((DWT->CYCCNT - clk_cycle_start) < microseconds);

}

#ifdef __cplusplus

}

#endif

#endif

dwt_stm32_delay.c

#include "dwt_stm32_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*/

  }

}

main.c

/* Includes ------------------------------------------------------------------*/

#include "stm32f4xx_hal.h"

#include "dwt_stm32_delay.h"

int main(void)

{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration----------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */

  HAL_Init();

  /* Configure the system clock */

  SystemClock_Config();

  /* Initialize all configured peripherals */

  MX_GPIO_Init();

  /* USER CODE BEGIN 2 */

  if(DWT_Delay_Init())

  {

    Error_Handler(); /* Call Error Handler */

  }

  while(1)

  {

    /* 10s Delay */

    DWT_Delay_us(10000000);

    HAL_GPIO_TogglePin(LD2_GPIO_Port, LD2_Pin);

  }

}

亲测,通过修改stm32f4xx_hal.h头文件为stm32f1xx_hal.h, 

f1系列也适应