[stm32f10x-HAL] add function rt_hw_us_delay

实现rt_hw_us_delay函数
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杨连钊 2018-06-11 08:59:30 +08:00 committed by GitHub
parent e1a57f053a
commit 699bb32073
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1 changed files with 20 additions and 0 deletions

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@ -113,3 +113,23 @@ void rt_hw_board_init(void)
rt_console_set_device(RT_CONSOLE_DEVICE_NAME);
#endif
}
/**
* This function will delay for some us.
*
* @param us the delay time of us
*/
void rt_hw_us_delay(rt_uint32_t us)
{
rt_uint32_t delta;
us = us * (SysTick->LOAD / (1000000 / RT_TICK_PER_SECOND));
delta = SysTick->VAL;
if (delta < us)
{
/* wait current OSTick left time gone */
while (SysTick->VAL < us);
us -= delta;
delta = SysTick->LOAD;
}
while (delta - SysTick->VAL < us);
}