My Ardunio Hello world - 3 LED's and a Potentiometer

This morning I jumped out of bed at 7am (like at 9 year old boy), brewed a coffee (like a middle-aged man) and set about playing with my new Arduino (like a 9 year old boy). After flying through a few basic tutorials, I was ready to go it alone and try building something off my own back.

This isn't strictly an Internet of Things project but just 2 hours into learning about electronics I have made something work, and I'm proud of myself so thought I'd knock out a quick blog post.

What does it do?

I decided I wanted to make a series of LED's represent the resistance across a potentiometer - not exactly groundbreaking but it was a challenge I felt I could achieve before my pot of coffee went cold.

Kit I used on this project:

  • 1 x Arduino UNO r3
  • 1 x Breadboard
  • 1 x Potentiometer
  • 3 x coloured LED's
  • 3 x 220 Ohm resistors
  • A load of hook-up wires
  • USB cable (for power and data)
  • Laptop
  • Offical Arduino IDE
  • Limited imagination
  • Programing knowledge

Project video

How does it work

I wrote a simple script that does the following:

  • Initiates serial comms on startup
  • Runs a continuous loop that reads analog input from the Potentiometer sensor
  • Checks the sensor value on each pass of the loop
  • Turns on the correct LED based on sensor value
  • If high value (>1000) run another loop to make the red LED flash

I also created a simple method called clearLEDs() that is called whenever I want all LED's to be switched off.

In pictures

The code

This is a thrown-together script to get something working but hey it works so serves its purpose.

int redPin = 9;  
int greenPin = 10;  
int bluePin = 11;  
int fadeValue = 250;

void setup() {  

void loop() {

  int sensorValue = analogRead(A0);  

  if (sensorValue < 5){
  else if (sensorValue < 500){
    analogWrite(bluePin, fadeValue);
  else if (sensorValue < 900){
    analogWrite(greenPin, fadeValue);          
    for (int fadeValue = 0 ; fadeValue <= 255; fadeValue += 5) {   
      analogWrite(redPin, fadeValue);   
    for (int fadeValue = 255 ; fadeValue >= 0; fadeValue -= 5) {   
      analogWrite(redPin, fadeValue);   

void clearLEDs() {  
  for (int thisPin = 9; thisPin < 12; thisPin++) {
    analogWrite(thisPin, 0);

This is a very simple "Hello World" project but I'm happy with my first ever Arduino project. The best part is I managed to not blow anything up!

Next up is my first real IoT project!