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Only disable timer interrupt instead of all interrutps in millis()/micros() #1442

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Only disable timer interrupt instead of all interrutps in millis()/micros() #1442

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15 changes: 7 additions & 8 deletions hardware/arduino/cores/arduino/wiring.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,22 +67,21 @@ ISR(TIMER0_OVF_vect)
unsigned long millis()
{
unsigned long m;
uint8_t oldSREG = SREG;

// disable interrupts while we read timer0_millis or we might get an
// disable overflow interrupt while we read timer0_millis or we might get an
// inconsistent value (e.g. in the middle of a write to timer0_millis)
cli();
// See: http://forum.arduino.cc/index.php?topic=168864.0
TIMSK0 &= ~(1 << TOIE0); // Clear Overflow Interrupt Enable
m = timer0_millis;
SREG = oldSREG;

TIMSK0 |= 1 << TOIE0; // Sets Overflow Interrupt Enable
return m;
}

unsigned long micros() {
unsigned long m;
uint8_t oldSREG = SREG, t;
uint8_t t;

cli();
TIMSK0 &= ~(1 << TOIE0); // Clear Overflow Interrupt Enable
m = timer0_overflow_count;
#if defined(TCNT0)
t = TCNT0;
Expand All @@ -101,7 +100,7 @@ unsigned long micros() {
m++;
#endif

SREG = oldSREG;
TIMSK0 |= 1 << TOIE0; // Sets Overflow Interrupt Enable

return ((m << 8) + t) * (64 / clockCyclesPerMicrosecond());
}
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