I wrote this sketch along with an HC - SR 04 Ultrasonic transducer and a DC motor. Whenever the HC-SR 04 reads any distance less than 15 cm, the motor stops, otherwise it keeps running.

The problem is whenever I upload the sketch, the motor runs for a short while and stops. Then when I open my serial monitor, the motor runs until an object crosses the 15 cm threshold and stops right after the limit is crossed. But when I again put the object outside of the 15 cm range, the motor should start running again, but it doesn't.

I am using a this motor driver and a simple DC motor(12V).
Here's the code-

int trigPin1 = A0;
int echoPin1 = A1;
int distance1 = 0;
int E1 = 10;
int brake1 = 7;

void setup() {
  pinMode(trigPin1, OUTPUT);
  pinMode(echoPin1, INPUT);
  pinMode(brake1, OUTPUT);
  pinMode (E1, OUTPUT);

void loop() {
  analogWrite(E1, 153);
  distance1 = getDistance(trigPin1, echoPin1);
  printDistance(1, distance1);
  if(distance1 <=15){
    digitalWrite(brake1, HIGH);
    analogWrite(E1, 153);


int getDistance (int initPin, int echoPin) {
  digitalWrite(initPin, HIGH);
  digitalWrite(initPin, LOW);
  long pulseTime = pulseIn(echoPin, HIGH);
  int distance = pulseTime / 58.2;
  return distance;

void printDistance(int id, int dist) {

  if (dist >= 120 || dist <= 0 ) {
  Serial.println(" Out of range");
   Serial.println(" cm");

What mistake am I doing? Moreover I am currently running it with one motor, I'll add another later on along with more sensors, so the motors are controlled by the left or right sensor. How do I make my code work with them?



It was too damn simple...

I just had to add a line inside the else block in the loop function.

digitalWrite(brake1, LOW);

This was happening because the first time the threshold limit was crossed the brake1 pin was left HIGH and was never set to LOW again, which caused a permanent brake in the motor.

I'm too damn stupid. But I still don't have any idea how will I use this code with multiple sensors and motors.


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