Returns the number of milliseconds passed since the Arduino board began running the current program. This number will overflow (go back to zero), after approximately 50 days.
time = millis()
None
Number of milliseconds passed since the program started. Data type: unsigned long.
This example code prints on the serial port the number of milliseconds passed since the Arduino board started running the code itself.
unsigned long myTime;
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.print("Time: ");
myTime = millis();
Serial.println(myTime); // prints time since program started
delay(1000); // wait a second so as not to send massive amounts of data
}The return value for millis() is of type unsigned long, logic errors may occur if a programmer tries to do arithmetic with smaller data types such as int. Even signed long may encounter errors as its maximum value is half that of its unsigned counterpart.
millis() is incremented (for 16 MHz AVR chips and some others) every 1.024 milliseconds, then incrementing by 2 (rather than 1) every 41 or 42 ticks, to pull it back into synch; thus some millis() values are skipped. For accurate timing over short intervals, consider using micros().
millis() will wrap around to 0 after about 49 days (micros in about 71 minutes).
Reconfiguration of the microcontroller’s timers may result in inaccurate millis() readings. The "Arduino AVR Boards" and "Arduino megaAVR Boards" cores use Timer0 to generate millis(). The "Arduino ARM (32-bits) Boards" and "Arduino SAMD (32-bits ARM Cortex-M0+) Boards" cores use the SysTick timer.
EXAMPLE Blink Without Delay