Making three LED's blink at given times I have a breadboard connected to an Arduino Uno, 220k resistors connected to an led, of course it has a common ground and a pin connected to 5v. All pins are digital.

Now, I want led 1 to turn on for one second, the next led for two seconds and the next for three seconds, but that means, when the second led which has to be on for two seconds then the first led will come back on after one second has past on the second led, the third led would be on for three seconds, so the second led will also be on when two seconds pass and the first would be on when one second passes. So basically, all leds are on for their given duration.

How do I do this? I have been trying to do this since three days. It would be a pleasure if someone helps me out. Thanks.

int ledPin1= 2;
int ledPin2 = 4;
int ledPin3 = 7;

void setup(){
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
  }

  void loop(){
  digitalWrite(ledPin1, HIGH);
  delay(500);
  digitalWrite(ledPin1, LOW);
  delay(500);

  digitalWrite(ledPin2, HIGH);
  delay(1000);
  digitalWrite(ledPin2, LOW);
  delay(1000);

  digitalWrite(ledPin3, HIGH);
  delay(1500);
  digitalWrite(ledPin3, LOW);
  delay(1500);
    }


So far this is the code. But it delays the whole program. Need leds on at given times.
You could start by drawing a time graph, like this:

LED 1   # # # # # # # # # # # # # # # # # # 
LED 2    ##  ##  ##  ##  ##  ##  ##  ##  ## 
LED 3      ###   ###   ###   ###   ###   ###
        &lt;-period 1-&gt;&lt;-period 2-&gt;&lt;-period 3-&gt;


As you see on the graph, the whole sequence repeats itself every
12&nbsp;seconds. Then, you can just write down all the pin toggles for
12&nbsp;seconds and let the loop repeat itself:

void loop() {
    digitalWrite(ledPin1, HIGH);
    digitalWrite(ledPin3, LOW);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, HIGH);
    delay(1000);
    digitalWrite(ledPin1, HIGH);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, HIGH);
    delay(1000);
    digitalWrite(ledPin1, HIGH);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, HIGH);
    delay(1000);
    digitalWrite(ledPin1, HIGH);
    digitalWrite(ledPin3, LOW);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    delay(1000);
    digitalWrite(ledPin1, HIGH);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, HIGH);
    digitalWrite(ledPin3, HIGH);
    delay(1000);
    digitalWrite(ledPin1, HIGH);
    delay(1000);
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    delay(1000);
}


This was the simple, albeit tedious solution.

The smart solution is to go through the Blink Without Delay Arduino
tutorial. You will see that, once you start using millis() instead of
delay() for managing your timings, blinking three LEDs instead of one
is completely trivial.