在stm32的freeRTOS上进行微秒级延时(HAL库)

秒速五厘米 2024-04-17 19:40 73阅读 0赞

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  
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原文链接：https://blog.csdn.net/keysking/article/details/78768720