Arduino pulseIn Returns 0 Unexpectedly

In this tutorial, you'll learn about Arduino pulseIn Returns 0 Unexpectedly. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

The Problem

pulseIn() returns 0 even though a pulse is present on the pin.

Quick Fix

Wrong

unsigned long duration = pulseIn(7, HIGH);  // Returns 0 if no pulse within 1 sec

duration = 0 even with a valid pulse.

Right

int sensorPin = 7;

void setup() {
  Serial.begin(9600);
  pinMode(sensorPin, INPUT);
}

void loop() {
  unsigned long duration = pulseIn(sensorPin, HIGH, 5000000);  // 5 sec timeout
  if (duration > 0) {
    float distance = duration / 58.0;  // HC-SR04 ultrasonic
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");
  } else {
    Serial.println("Pulse timeout");
  }
  delay(100);
}

Distance: 10.34 cm  (or "Pulse timeout" if no echo).

Prevention

pulseIn() has a default 1-second timeout. Set a custom timeout (in microseconds) as the third argument. Ensure the pin mode is INPUT (not INPUT_PULLUP). pulseIn() blocks until the pulse starts or timeout. For non-blocking operation, use interrupts or hardware timer capture.

DodaTech engineers apply these same patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro for production IoT reliability.

FAQ