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The PIT timer is counting downward, so we need to subtract the count from the period value

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Kristian Sloth Lauszus
2018-06-22 21:50:14 +02:00
parent d449123fab
commit 9a8b1ef8b9
1 changed files with 2 additions and 1 deletions
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3
right/src/timer.c
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@@ -37,7 +37,8 @@ uint32_t Timer_GetCurrentTimeMicros() {
ms = CurrentTime; // Read the overflow counter
EnableGlobalIRQ(primask); // Enable interrupts again if they where enabled before - this should make it interrupt safe
uint32_t us = COUNT_TO_USEC(count, timerClockFrequency);
// Calculate the counter value in microseconds - note that the PIT timer is counting downward, so we need to subtract the count from the period value
uint32_t us = 1000U * TIMER_INTERVAL_MSEC - COUNT_TO_USEC(count, timerClockFrequency);
return ms * 1000U * TIMER_INTERVAL_MSEC + us;
}