Multiple Ultrasonic Sensor Millis instead of Delay

Other Hardware Sensors
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#define valvePin 11
#define trigPin 3 
#define echoPin 4

int period = 5000;
unsigned long time_now = 0;
float duration, distance;
bool TurnOn = false;

void setup() { 
 pinMode(trigPin, OUTPUT); 
 pinMode(echoPin, INPUT); 
 pinMode(valvePin, OUTPUT);
 Serial.begin(9600); 
} 

void loop() { 
 digitalWrite(trigPin, LOW); 
 delayMicroseconds(2); 
 digitalWrite(trigPin, HIGH); 
 delayMicroseconds(10); 
 digitalWrite(trigPin, LOW);

 duration = pulseIn(echoPin, HIGH); 

 distance = (duration*.0343)/2;

 Serial.print("Distance: "); 
 Serial.println(distance); 

 time_now = 0;
 TurnOn = false;
  
 while ((distance >=10) && (distance<= 50))
 {
 digitalWrite(valvePin, LOW);
 digitalWrite(trigPin, LOW); 
 delayMicroseconds(2); 
 digitalWrite(trigPin, HIGH); 
 delayMicroseconds(10); 
 digitalWrite(trigPin, LOW);

 duration = pulseIn(echoPin, HIGH); 

 distance = (duration*.0343)/2;

 Serial.print("Inside zone :"); 
 Serial.println(distance);

 time_now ++;
 delay(1000);
 if(time_now == 5){
  Serial.print("5 sec");
  delay(1000);
  TurnOn = true; 
  } 
 }

 if(TurnOn){
  Serial.print("Turn On");
  digitalWrite(valvePin, HIGH);
  delay(5000);
  digitalWrite(valvePin, LOW);
  }
}

I would like to use millis instead of delay function, anybody can help me?

In future I would like to use multiple Ultrasonic Sensor with arduino nono will it work?

Can they work independently without freezing nano?

2

I would like to use millis instead of delay function, anybody can help me?

That won't help as the pulseIn() function is the one the consumes most of the time.

In future I would like to use multiple Ultrasonic Sensor with arduino nono will it work?

If you can request the value of one after the other: yes. Otherwise you might have to use ultrasonic sensors that measure the distance by itself and return the value digitally. They cost a bit more than the ones you probably know.

3

For pinging multiple sensors cleanly, you can use the NewPing library: teckel12 / Arduino New Ping / wiki / Home — Bitbucket