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Multitasking with millis() | NexaLearn IoT Lab | NexaLearn

Advanced Skills35 دقيقة

Multitasking with millis()

Get rid of the delay() function and make Arduino do more than one thing at the same time.

Lesson Content

The delay() function is a 'blocking function'. When you run delay(5000), the processor stops reading sensors or buttons for 5 full seconds. For real projects, we use the millis() function which acts like a stopwatch — we read it in every loop() cycle and check if the required time has elapsed to execute a specific task, leaving the code free to continue.

Components Needed

Arduino Uno2 LED

Wiring Notes

Two separate LEDs.

Code Example

unsigned long lastBlink = 0;
const int ledPin = 13;
int ledState = LOW;

void setup() { pinMode(ledPin, OUTPUT); }
void loop() {
  unsigned long currentMillis = millis();
  // يومض كل 500 مللي ثانية بدون إيقاف الـ loop
  if (currentMillis - lastBlink >= 500) {
    lastBlink = currentMillis;
    ledState = !ledState;
    digitalWrite(ledPin, ledState);
  }
  // هنا يمكنك قراءة حساسات أخرى براحة
}

Common Mistakes

Using an int data type to store the millis() value. millis() reaches large numbers and will overflow the variable size within just 32 seconds if using int. Must use unsigned long.

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