我一般使用這個：
void delay_us(__IO uint32_t nTime)
{
int old_val,new_val,val;
if(nTime > 900)
{
for(old_val = 0; old_val < nTime/900; old_val++)
{
delay_us(900);
}
nTime = nTime%900;
}
old_val = SysTick->VAL;
new_val = old_val - CPU_FREQUENCY_MHZ*nTime;
if(new_val >= 0)
{
do
{
val = SysTick->VAL;
}
while((val < old_val)&&(val >= new_val));
}
else
{
new_val += CPU_FREQUENCY_MHZ*1000;
do
{
val = SysTick->VAL;
}
while((val <= old_val)||(val > new_val));
}
} |
![{LHF5VH]6T@1UA3@8`GTT]6.png](http://c.51hei.com/d/forum/201904/25/162046svsc5ustiu0so2lf.png "{LHF5VH]6T@1UA3@8`GTT]6.png")
