Arduino Alternative to delay() Not Working

In this tutorial, you'll learn about Arduino Alternative to delay() Not Working. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

The Problem

Replacing delay() with millis() timing does not produce the expected behavior.

Quick Fix

Wrong

unsigned long prev = millis();
void loop() {
  if (millis() - prev == 1000) {  // Rarely exactly equal
    action();
  }
}

action() rarely or never executes.

Right

unsigned long prev = 0;
const unsigned long interval = 1000;

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
}

void loop() {
  unsigned long now = millis();
  if (now - prev >= interval) {
    prev = now;
    digitalWrite(13, !digitalRead(13));
    Serial.println("Toggled");
  }
}

LED toggles every second. "Toggled" prints each time.

Prevention

Use >= (greater-or-equal) not == for millis() comparisons. millis() increments by ~1 and may skip the exact target value. Initialize prev = 0 (not millis()) so the first interval starts immediately. The substraction pattern handles overflow correctly.

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

FAQ