不占用定时器和Systick的us级延时函数

bigfanofloT

来自国外TM大神的函数库，不占用定时器和Systick的延时函数，利用了DWT：

uint32_t TM_DELAY_Init(void) {
#if !defined(STM32F0xx)
        uint32_t c;
       
    /* Enable TRC */
    CoreDebug->DEMCR &= ~0x01000000;
    CoreDebug->DEMCR |=  0x01000000;
       
    /* Enable counter */
    DWT->CTRL &= ~0x00000001;
    DWT->CTRL |=  0x00000001;
       
    /* Reset counter */
    DWT->CYCCNT = 0;
       
        /* Check if DWT has started */
        c = DWT->CYCCNT;
       
        /* 2 dummys */
        __ASM volatile ("NOP");
        __ASM volatile ("NOP");
       
        /* Return difference, if result is zero, DWT has not started */
        return (DWT->CYCCNT - c);
#else
        /* Return OK */
        return 1;
#endif
}
__STATIC_INLINE void Delay(__IO uint32_t micros) {
#if !defined(STM32F0xx)
        uint32_t start = DWT->CYCCNT;
       
        /* Go to number of cycles for system */
        micros *= (HAL_RCC_GetHCLKFreq() / 1000000);
       
        /* Delay till end */
        while ((DWT->CYCCNT - start) < micros);
#else
        /* Go to clock cycles */
        micros *= (SystemCoreClock / 1000000) / 5;
       
        /* Wait till done */
        while (micros--);
#endif
}

jipin

国外人学艺精，值得学习