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!217 rt_hw_us_delay的实现有问题，针对这一问题进行了修改 

Merge pull request !217 from cyz/cyz
This commit is contained in:
bernard 2021-06-10 08:50:47 +00:00 committed by Gitee
parent 2961b37104 796c8affdd
commit 45b540d334
1 changed files with 24 additions and 8 deletions
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32
bsp/stm32/libraries/HAL_Drivers/drv_common.c
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@ -113,16 +113,32 @@ void _Error_Handler(char *s, int num)
*/
void rt_hw_us_delay(rt_uint32_t us)
{
rt_uint32_t start, now, delta, reload, us_tick;
start = SysTick->VAL;
reload = SysTick->LOAD;
us_tick = SystemCoreClock / 1000000UL;
do
rt_uint32_t ticks;
rt_uint32_t told, tnow, tcnt = 0;
rt_uint32_t reload = SysTick->LOAD;
ticks = us * reload / (1000000 / RT_TICK_PER_SECOND);
told = SysTick->VAL;
while (1)
{
now = SysTick->VAL;
delta = start >= now ? start - now : reload + start - now;
tnow = SysTick->VAL;
if (tnow != told)
{
if (tnow < told)
{
tcnt += told - tnow;
}
else
{
tcnt += reload - tnow + told;
}
told = tnow;
if (tcnt >= ticks)
{
break;
}
}
}
while (delta < us_tick * us);
}
/**