How can I stop my circuit from repeating when a new distance has been detected?

Projects Programming
1

I have an Arduino project that uses a 7-segment display, an ultrasonic sensor, a LED, and a buzzer to display a countdown based on the measured distance. My problem is it keeps repeating when the distance changes, even though it's still greater than 100 cm. Please help! Here's my code:

unsigned const int A = 13;
unsigned const int B = 12;
unsigned const int C = 11;
unsigned const int D = 10;
unsigned const int E = 9;
unsigned const int F = 8;
unsigned const int G = 7;
unsigned const int H = 6;
unsigned const int DP = 3;
int buzzer = 4;
int trig = 6;
int echo = 5;
const int ledPin = 2;

void setup(void)
{
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);
  pinMode(H, OUTPUT);
  pinMode(DP,OUTPUT);
  Serial.begin(9600);
  pinMode(buzzer, OUTPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  none(); 
  digitalWrite(ledPin, LOW);
}


void none(void) {
  digitalWrite(A, LOW);
  digitalWrite(B, LOW);
  digitalWrite(C, LOW);
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(H, LOW);
  digitalWrite(DP, LOW);
}

void one(void) {
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void two(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, LOW);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void three(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void four(void) {
  digitalWrite(A, LOW);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void five(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, LOW);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void six(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, LOW);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void seven(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, LOW);
  digitalWrite(E, LOW);
  digitalWrite(F, LOW);
  digitalWrite(G, LOW);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void eight(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void nine(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, LOW);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void zero(void) {
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, LOW);
  digitalWrite(H, HIGH);
  digitalWrite(DP, HIGH);
}

void loop() {
  // Trigger the ultrasonic sensor
  digitalWrite(trig, LOW);
  delayMicroseconds(5);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  // Measure the pulse duration and calculate distance in cm
  int a = pulseIn(echo, HIGH);
  float d = a * 0.034 / 2; // Distance in cm
  float distanceInInches = d * 0.3937; // Convert cm to inches

  // Print distances to the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(d, 2); // Print cm with 2 decimal places
  Serial.print(" cm, ");
  Serial.print(distanceInInches, 2); // Print inches with 2 decimal places
  Serial.println(" inches");

  if (d >= 100) { 
    digitalWrite(ledPin, HIGH); // Turn on LED
    // Countdown sequence
    for (int i = 9; i >= 0; i--) { // Use a for loop for the countdown
      switch (i) {
        case 9: nine(); break;
        case 8: eight(); break;
        case 7: seven(); break;
        case 6: six(); break;
        case 5: five(); break;
        case 4: four(); break;
        case 3: three(); break;
        case 2: two(); break;
        case 1: one(); break;
        case 0: zero();  break;
      }
      delay(1000); // 1-second delay for the countdown

      // Check distance during each delay
      digitalWrite(trig, LOW);
      delayMicroseconds(5);
      digitalWrite(trig, HIGH);
      delayMicroseconds(10);
      digitalWrite(trig, LOW);
      a = pulseIn(echo, HIGH);
      d = a * 0.034 / 2; // Update distance in cm
      distanceInInches = d * 0.3937; // Update distance in inches

      if (d < 100) { 
        none(); // Clear the 7-segment display
        digitalWrite(ledPin, LOW); // Turn off LED
        break; // Break out of the for loop
      }

      // Insert buzzer sound for each count
      digitalWrite(buzzer, HIGH);
      delay(500); // Short buzzer duration
      digitalWrite(buzzer, LOW);
    }

  } else {
    none(); // Clear the 7-segment display
    digitalWrite(ledPin, LOW); // Turn off LED
    
    
  }

  delay(200); // Short delay before next loop iteration
}
2

Welcome to the forum

You need to detect when the distance becomes greater than 100 rather than when it is greater than 100

See the StateChangeDetection example in the IDE

3

After a quick look thru, your code would seem to be detecting the state of being > 100 cm.

But what you seem to be saying is that you want it to do it detect the event of changing from <= 100 cm to > 100 cm.

They're two completely different things.

I don't see anywhere in your code where you do anything like:

  static float lastDistance = 0;
   .
   .
   .
   if( lastDistance <= 100 && distance > 100 ) {
      // so something
   } else if( lastDistance > 100 && distance <= 100 ) {
      // do something else
   }
   lastDistance = distance;

The above is purely off the top of my head after a single quick read thru. No warranty of fitness for purpose is expressed or implied. :slight_smile:

4

You have used pin 6 twice.

5

by "repeat" i assume you mean the count-down. But isn't the code written to do that count-down as long as the d, distance > 100?

or do you want it to only do it once when the distance > 100? If so, do you need to keep track of what the distance was previously and only do a count-down when d > 100 but was previously < 100?