AT32F421xx外设驱动2-delay（寄存器）

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

#include "BspPhy.h"   static uint32_t fac_us; static uint32_t fac_ms;   void PhyDelayInit() {   SysTick->CTRL |= SYSTICK_CLOCK_SOURCE_AHBCLK_NODIV;   fac_us = system_core_clock / (1000000U);   fac_ms = fac_us * (1000U); }   void PhyDelayUs(uint32_t nus) {   uint32_t temp = 0;   SysTick->LOAD = (uint32_t)(nus * fac_us);   SysTick->VAL = 0x00;   SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk ;   do   {     temp = SysTick->CTRL;   }while((temp & 0x01) && !(temp & (1 << 16)));     SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;   SysTick->VAL = 0x00; }   void PhyDelayMs(uint16_t nms) {     uint32_t i;     for (i = 0; i < nms; i++)         PhyDelayUs(1000); }   void PhyDelaySec(uint16_t sec) {   uint16_t index;   for(index = 0; index < sec; index++)   {     PhyDelayMs(500);     PhyDelayMs(500);   } }   /******************************delay****************************************/ void PhyDelayInit(void); void PhyDelayUs(uint32_t nus); void PhyDelayMs(uint16_t nms); void PhyDelaySec(uint16_t sec); /*************************************************************************/