Created
September 14, 2015 22:40
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Timing drift when interrupts disabled
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void setup() { | |
pinMode(D4, OUTPUT); | |
Serial.begin(9600); | |
delay(5000); | |
uint32_t t0_m = millis(); | |
uint32_t t0_u = micros(); | |
Serial.print(micros() - t0_u); // Relative time 0. | |
Serial.print(", "); | |
Serial.println(millis() - t0_m); // Relative time 0. | |
digitalWrite(D4, HIGH); | |
delayMicroseconds(5000); | |
digitalWrite(D4, LOW); | |
Serial.print(micros() - t0_u); // Relative time 5000. | |
Serial.print(", "); | |
Serial.println(millis() - t0_m); // Relative time 5000. | |
__disable_irq(); | |
digitalWrite(D4, HIGH); | |
delayMicroseconds(5000); | |
digitalWrite(D4, LOW); | |
__enable_irq(); | |
Serial.print(micros() - t0_u); // Relative time 10000. | |
Serial.print(", "); | |
Serial.println(millis() - t0_m); // Relative time 10000. | |
digitalWrite(D4, HIGH); | |
delayMicroseconds(5000); | |
digitalWrite(D4, LOW); | |
Serial.print(micros() - t0_u); // Relative time 15000. | |
Serial.print(", "); | |
Serial.println(millis() - t0_m); // Relative time 15000. | |
} |
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