Arduino IDE - Time Function

Time Function millis()

millis() - is a time function that measures time since the microcontroller starts. It reads the time lapse every time the function was executed.

For example, the statement  timeNow=millis(); will read the time lapse since microcontroller start in milliseconds and store it in the variable timeNow.

void setup()
{Serial.begin(9600);}

void loop()
{
int timeNow=millis();

Serial.println(timeNow);
}

Another example, we want to measure how fast a microcontroller could loop.


int timeNow=0, timePrevious=0, timeLapse=0;

void setup()
{Serial.begin(9600);}
 
void loop()
{
    timeNow=millis();
    timeLapse=timeNow-timePrevious;
 
   Serial.print(timePrevious);Serial.print("\t");Serial.print(timeNow); Serial.print("\t");Serial.println(timeLapse);
   timePrevious=timeNow;
}

Here's how it works......

On first loop,   
                              statement 1: timeNow is read and recorded  timeNow=millis(); say timeNow=5;
                              statement 2: Time lapse is computed i.e. timeLapse=timeNow - timePrevious ;
                                                   where initially declared timePrevious =0. then  timeLapse=5-0=5ms
                              statement 3: Print or display the time for viewing.
                              statement 4: value of timeNow  is passed on to timePrevious by timePrevious=timeNow;
                                                   This is to record the time a loop was last executed.