33 lines
601 B
C
33 lines
601 B
C
#include "delay.h"
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#include "rtthread.h"
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#include "stm32f10x.h"
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void rt_hw_us_delay(unsigned int us)
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{
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rt_uint32_t delta, current_delay, tick;
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if(us == 0)
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return;
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//获得延时需要经过的tick数
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tick = us * (SysTick->LOAD/(1000000/RT_TICK_PER_SECOND));
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//获得当前时间
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delta = SysTick->VAL;
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//循环获得当前时间，直到达到指定时间后退出循环
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do
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{
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if(delta > SysTick->VAL)
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{
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current_delay = delta - SysTick->VAL;
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}
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else
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{
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//延时跨越了一次OS tick的边界
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current_delay = SysTick->LOAD + delta - SysTick->VAL;
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}
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}while(current_delay < tick);
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}
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