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Merge branch 'master' of https://github.com/cleanflight/cleanflight

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Larry (TBS) 2015-09-05 12:03:42 +08:00
commit 1026dbde0b
1 changed files with 6 additions and 0 deletions
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6
src/main/drivers/system.c
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@ -99,6 +99,12 @@ uint32_t micros(void)
do { do {
ms = sysTickUptime; ms = sysTickUptime;
cycle_cnt = SysTick->VAL; cycle_cnt = SysTick->VAL;
/*
* If the SysTick timer expired during the previous instruction, we need to give it a little time for that
* interrupt to be delivered before we can recheck sysTickUptime:
*/
asm volatile("\tnop\n");
} while (ms != sysTickUptime); } while (ms != sysTickUptime);
return (ms * 1000) + (usTicks * 1000 - cycle_cnt) / usTicks; return (ms * 1000) + (usTicks * 1000 - cycle_cnt) / usTicks;
} }