LED Blinking using Microcontroller

In this project we will start our journey with microcontroller based control. we are going to build a simple setup to make an LED blink on and off with time period defined by us. let us look at the components we need to use.

We need a microcontroller block which houses a Arduino Nano microcontroller. We also need an LED block which we will make blink. You can select any color LED block for this project. In order to power the microcontroller an an LED, we will need a battery block. We need connectors to connect power and ground pins of the microcontroller and the battery block. Lastly we need USB to USB-C cable to upload a program from computer to the microcontroller block.

Microcontroller block has multiple pins. The pins labelled starting with D like D2, D3, D4 etc. are digital input output pins. These pins can read or supply electrical signal only on 2 levels which is 0V or 5V. We will use one of the digital I/O pins to drive an LED block, say pin D2. Connect the red terminal of the LED block to the pin D2. Connect the black terminal of the LED block to black pin on the microcontroller block which is labelled “-“. Connect USB-C cable to the microcontroller block and connect the other end to USB port of a computer.

Now let’s program the microcontroller block with Arduino IDE on a computer. Open Arduino IDE and start a new sketch. At the start, we need to select the microcontroller we have connected. Type Nano in the search bar and select Arduino Nano with appropriate USB port.

Once the board is selected, we can start writing the sketch in the sketch editor section. Firstly, we will need to declare the Arduino pin we are going to use to drive LED. In our case, we have used pin D2 so we will need to declare the same in the program. We will create a variable called ledPin and assign it as Arduino pin D2. Since the pin name is an integer we declare it as int. Also since the value of this variable will not change during execution, we will declare it as const int. We can add comments in the code to help us identify later on what is the purpose of that specific command. These comments are put after double forward slash like //. Anything after // is ignored by the compiler so it is not part of the executable steps.

The setup section is under the void setup section. In this section we will declare the pin ledPin as an output. This means the pin assigned to ledPin will supply signal and not read the signal. We declare this by using command called pinMode() as below.

The execution happens in the void loop section. In this section, we will turn the LED on by providing high signal, wait for a second then turn the LED off by providing low signal and wait for another one second. These instructions will happen continuously in a loop, as long as the microcontroller is powered on. We will use command digitalWrite() to provide high or low signal to LED. We will keep the LED state as it is for a second using delay() command. The delay command stops the execution of the program for number of milliseconds as mentioned in delay command. Since we want to wait 1 second after we turn the LED on and off, we will put delay(1000) which is 1000mS = 1S.

You can copy entire program from below in to the Arduino IDE sketch editor.

/*
 First microcontroller program to blink LED. Connect LED block red terminal to pin D2
 Makernova Robotics @2025
*/
const int ledPin = 2;  // declare ledPin as variable assigned to arduino pin D2

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);  // we have declared ledPin as output only
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(ledPin, OUTPUT);  // provide high level to ledPin which turns it on.
  delay(1000);                   // wait for 1000mS to keep LED on. You can change the number to adjust blinking period
  digitalWrite(ledPin, OUTPUT);  // provide high level to ledPin which turns it on.
  delay(1000);                   // wait for 1000mS to keep LED off. You can change the number to adjust blinking period
}

Once the entire sketch is ready, press upload button on top left portion of the IDE window. If there are any errors, it will show it in the output window. If there are no errors and the program is uploaded successfully, it shows message on bottom right accordingly.