116 lines
3.3 KiB
C
116 lines
3.3 KiB
C
#include "Delay.h"
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#if MODE == USE_SYS_TICK
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//初始化延迟函数
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//SYSTICK的时钟固定为AHB时钟的1/8
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//SYSCLK:系统时钟频率
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void vDelayInit(void)
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{
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uint8_t ucSYSCLK;
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SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8);
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xUcFacInit.ucFacUs=ucSYSCLK/8;
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xUcFacInit.usFacMs=(uint16_t)xUcFacInit.ucFacUs*1000;
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}
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//延时nus
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//nus为要延时的us数.
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void vDelayUs(uint32_t ulNus)
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{
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uint32_t ulTemp;
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SysTick->LOAD=ulNus*xUcFacInit.ucFacUs; //时间加载
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SysTick->VAL=0x00; //清空计数器
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SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ; //开始倒数
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do
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{
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ulTemp=SysTick->CTRL;
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} while((ulTemp&0x01)&&!(ulTemp&(1<<16))); //等待时间到达
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SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk; //关闭计数器
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SysTick->VAL =0x00; //清空计数器
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}
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/**
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* @brief 毫秒级延时函数
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* @note 由于Systick定时器为24位定时器，其装载的最大值为0xFFFFFF，也就是16777215，如果加载的值超过0xFFFFFF，则实际加载的值是取模后的值，导致延时时间缩短，
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* usNms<=0xFFFFFF*8*1000/SYSCLK。所以在72M条件下，超过1.864s的延时会导致计数器溢出，从而导致定时为xms-16777215的结果。
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* @note 如下函数会判断延时是否超过最大延时，若超过则分成多次1000ms处理。
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* @param None
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* @retval None
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*/
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void vDelayMs(uint16_t usNms)
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{
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uint32_t ulTemp;
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while (usNms)
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{
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uint16_t current = (usNms > 1000) ? 1000 : usNms;
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usNms -= current;
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SysTick->LOAD = (uint32_t)current * xUcFacInit.usFacMs;
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SysTick->VAL = 0x00;
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SysTick->CTRL |= SysTick_CTRL_ENABLE_Msk;
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do
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{
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ulTemp = SysTick->CTRL;
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} while ((ulTemp & 0x01) && !(ulTemp & (1 << 16)));
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SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
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SysTick->VAL = 0x00;
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}
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}
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#elif MODE == USE_DWT
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void vDelayInit(void)
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{
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DEMCR |= (uint32_t)TRCENA; // 使能DWT外设
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DWT_CYCCNT = (uint32_t)0u; // DWT CYCCNT寄存器计数清0
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DWT_CTRL |= (uint32_t)DWT_CTRL_CYCCNTENA; // 使能Cortex-M3 DWT CYCCNT寄存器
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}
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// 微秒延时
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void vDelayUs(uint32_t ulNus)
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{
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if(ulNus > 10000) ulNus = 10000;
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uint32_t ulTicksStart, ulTicksEnd, ulTicksDelay;
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ulTicksStart = DWT_CYCCNT;
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ulTicksDelay = ( ulNus * ( SystemCoreClock / (1000000) ) ); // 将微秒数换算成滴答数
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ulTicksEnd = ulTicksStart + ulTicksDelay;
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if ( ulTicksEnd >= ulTicksStart ) // ulTicksEnd没有溢出
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{
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if(DWT_CYCCNT > ulTicksStart) // DWT_CYCCNT在上述计算的这段时间中没有溢出
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{
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while( DWT_CYCCNT < ulTicksEnd );
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}
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// DWT_CYCCNT溢出
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else
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{
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return; // 已经超时，直接退出
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}
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}
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else // ulTicksEnd溢出
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{
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// DWT_CYCCNT在上述计算的这段时间中没有溢出
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if(DWT_CYCCNT > ulTicksStart)
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{
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// 等待DWT_CYCCNT的值溢出
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while( DWT_CYCCNT > ulTicksEnd );
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}
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// 等待溢出后的DWT_CYCCNT到达ulTicksEnd
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while( DWT_CYCCNT < ulTicksEnd );
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}
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}
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void vDelayMs(uint16_t usNms)
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{
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for(uint16_t i = 0; i < usNms; i++)
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{
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// delay 1 ms
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vDelayUs(1000);
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}
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}
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#else
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#endif
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