Blink Without Delay

Sometimes you need to do two things at once. For example you might want to blink an LED while reading a button press. In this case, you can't use delay(), because Arduino pauses your program during the delay(). If the button is pressed while Arduino is paused waiting for the delay() to pass, your program will miss the button press.

This sketch demonstrates how to blink an LED without using delay(). It turns on the LED on and then makes note of the time. Then, each time through loop(), it checks to see if the desired blink time has passed. If it has, it toggles the LED on or off and makes note of the new time. In this way the LED blinks continuously while the sketch execution never lags on a single instruction.

An analogy would be warming up a pizza in your microwave, and also waiting some important email. You put the pizza in the microwave and set it for 10 minutes. The analogy to using delay() would be to sit in front of the microwave watching the timer count down from 10 minutes until the timer reaches zero. If the important email arrives during this time you will miss it.

What you would do in real life would be to turn on the pizza, and then check your email, and then maybe do something else (that doesn't take too long!) and every so often you will come back to the microwave to see if the timer has reached zero, indicating that your pizza is done.

In this tutorial you will learn how to set up a similar timer.

Step 1: What You Need?

1 x Arduino Board (Arduino UNO used in this tutorial)
1 x LED(Red)
1 x 220 ohm resistor

Optional:

1 x Breadboard

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

To build the circuit, connect one end of the resistor to Arduino pin 13. Connect the long leg of the LED (the positive leg, called the anode) to the other end of the resistor. Connect the short leg of the LED (the negative leg, called the cathode) to the Arduino GND, as shown in the diagram and the schematic below.

Most Arduino boards already have an LED attached to pin 13 on the board itself. If you run this example with no hardware attached, you should see that LED blink.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used. 

2.  Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3. 

Select the right port: Tools >> Port >> Select the port number.

3. The code below uses the millis() function, a command that returns the number of milliseconds since the board started running its current sketch, to blink an LED.

Select File >> Examples >> 02.Digital >> BlinkWithoutDelay
Click upload to upload the code to Arduino board. 

Download: 

Arduino software

Sources:[https://www.arduino.cc/en/Tutorial/BlinkWithoutDelay]

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Author & Editor

My Robot Education Sdn. Bhd. (Robotedu.my) was founded in 2015 as the first robotics education centre in Malaysia to provide Arduino-based robotics courses for youths. Our vision is to be able to provide robotics education to every youth in Malaysia.