How to get the time between 2 events

Projects Programming
1

How to get the time between 2 events please

long startTime ;                    // start time for stop watch
long elapsedTime ;

 

float prevtension;// global variables are retained on each iteration of loop()

int valeurLue;

int analogPin = A0;
const int led =  13; 
float tension; //variable pour stocker la valeur lue après conversion


void setup() {
pinMode(analogPin, INPUT);
  pinMode( led, OUTPUT ); 
  digitalWrite(led, HIGH); 
       delay (1000);
       digitalWrite(led, LOW); // 2.5cm
       Serial.begin(38400);

}



void loop() {
prevtension = tension;
  
  valeurLue = analogRead(analogPin);

	//on traduit la valeur brute en tension (produit en croix)
	tension = valeurLue * 5.0 / 1024;
  
  
 if (tension < 2.55)
  {if (tension < (prevtension - 0.005)) {  // compare them
        
       digitalWrite(led, HIGH); 
       delay (20);
       digitalWrite(led, LOW); // do something, they are different
{if (tension > 2.54 && tension < (prevtension - 0.005)) {digitalWrite(led, LOW);}
  } }
    }
 
 
   
   
   Serial.print("elapsedTime = ");
	Serial.println(elapsedTime);

   Serial.print("previoust= ");
	Serial.println(prevtension);
	
  
  Serial.print("current= ");
	Serial.println(tension);
	



Serial.println();
     Serial.println();
      
}

I want to get the time from HIGH to next HIGH please

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2

Use millis(). Should use unsigned long)

unsigned long startTime ;                    // start time for stop watch
unsigned long elapsedTime ;

// then start clock with:

startTime = millis();

// and later on:

elapsedTime = millis() - startTime;
3

but on the code wrotten before how to take the time from the HIGH to next High like wher shoud I insert these lines.
thanks

4

Perhaps something like this. See the lines marked //<<<<<<<<<<<<<<<<<<<<<

void setup() {
pinMode(analogPin, INPUT);
  pinMode( led, OUTPUT ); 
  digitalWrite(led, HIGH); 
startTime = millis(); //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
  
       delay (1000);
       digitalWrite(led, LOW); // 2.5cm
       Serial.begin(38400);

}



void loop() {
prevtension = tension;
  
  valeurLue = analogRead(analogPin);

	//on traduit la valeur brute en tension (produit en croix)
	tension = valeurLue * 5.0 / 1024;
  
  
 if (tension < 2.55)
  {if (tension < (prevtension - 0.005)) {  // compare them
        
       digitalWrite(led, HIGH); 

elapsedTime = millis() - startTime;   //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
// perhaps display it here with a Serial.print.... <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
startTime = millis();       //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< reset for next one

       delay (20);
       digitalWrite(led, LOW); // do something, they are different
{if (tension > 2.54 && tension < (prevtension - 0.005)) {digitalWrite(led, LOW);}
  } }
    }
5

how you tell to reset it?
thanks

6

Jhjh:
how you tell to reset it?
thanks

Don't forget that millis() is changing all the time.... so

startTime = millis();       //<<<<<<<<<<<<< reset for next one

... puts a "new" millis value into startTime, effectively resetting it. It now comtains the new "high time"