Hi. I am creating a traffic light with a speed checker. What i want to know is that my arduino led traffic light works fine but it gives a delay to the speed checker ( ultrasonic distance sensor ). How to Reamove that delay and still create a traffic light Code as below :- const int trigPin = 5; const int echoPin = 6; const int greenled = 2; const int yellowled = 4; const int redled = 3; long duration; int FirstDistance = 0; int SecondDistance = 0; double speed = 0; int distance = 1; float Time = 2.0; float delayedtime = 100; void setup() { pinMode(trigPin, OUTPUT); pinMode(echoPin, INPUT); pinMode(redled,OUTPUT); pinMode(greenled,OUTPUT); pinMode(yellowled,OUTPUT); Serial.begin(9600); } void loop() { GetSpeed(); Traffic(); } float GetDistance() { // Clears the trigPin digitalWrite(trigPin, LOW); delayMicroseconds(2); // Sets the trigPin on HIGH state for 10 micro seconds digitalWrite(trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW); // Reads the echoPin, returns the sound wave travel time in microseconds duration = pulseIn(echoPin, HIGH); //calculating distance distance = duration * 0.034 / 2; // Prints the distance on the Serial Monitor Serial.print("Distance in cm : "); Serial.println(distance); return distance; } void GetSpeed() { FirstDistance = GetDistance(); //get the first distance delay(delayedtime); //waits 2 seconds depending on the time declared above ,, feel free to change the value dependng on the resolution of your sensor SecondDistance = GetDistance(); //gets the second distance speed = (FirstDistance - SecondDistance) / Time; // now calculating the difference //printing the speed on the serial monitor Serial.print("the speed (cm/s) is : "); Serial.println(speed); delay (200); } void Traffic() { digitalWrite(redled,LOW); digitalWrite(greenled,HIGH); delay(500); // 10000 digitalWrite(yellowled,HIGH); digitalWrite(greenled,LOW); delay(500); digitalWrite(yellowled,LOW); digitalWrite(redled,HIGH); delay(500); }

Don't use delay() but a millis() based approach. You will also need to read up on a finite state machine. In your Traffic() function you have three states; you have to keep track in which state you are and switch to the next state when it is time. Lastly there is a non-blocking ping library (search for NewPing) that might help to get rid of delays due to your GetDistance() function.

Pls can you share the code @sterretje as i couldnt understand it. what is millis() ?

[image] Abeer_goel: what is millis() ? millis() - Arduino Reference The Arduino programming language Reference, organized into Functions, Variable and Constant, and Structure keywords.

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sterretje June 27, 2021, 6:00pm 7

And here another one: Using millis() for timing. A beginners guide

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