Introduction: Flicker Up to 6 LEDs With Arduino

Hi there.
Christmas is coming closer, and I was wondering if I could put some candles in my room to get in the "christmas mood".
But after a friends house burned down of christmas tree candles, I don't want to burn real candles into my room.
So why don't let the Arduino light for you?!

This Instructable will show you, how to flicker up to 6 LEDs using an Arduino Microcontroller.
For more information about Arduino visit

Step 1: What You Need...

Here are the things you will need:

-Arduino Microcontroller (or similar)
-USB cable
-LEDs (up to 6 LEDs are possible)
-Resistors (equal to the number of used LEDs)

LED resistor calculator

if you don't want to solder the circuit:
-Jumper wires

-DC power source

-Arduino IDE
Get it here!

-TrueRandom Library
Get it here! (Instructions included)
Unzip it to your "Libraries" folder.

Step 2: Wire It Up!

Connect the resistor to the PWM pins (e.g. 6, 9...) on the Arduino board.
Now connect the second "leg" of the resistor to the anode of the LED (long "leg")
Then connect the cathode (short "leg") of the LED to ground (GND) on the Arduino board.

Repeat this step for each LED you want to use.

When the wiring is done, continue to the next step!

Step 3: Code It!

Copy this code to the Arduino IDE:

//Multiple LED flicker by gotcha (2010)
<TrueRandom.h>//Include the TrueRandom Library

int ledPin1 = 9; //Set the number of LEDs you use.
int ledPin2 = 10;
int ledPin3 = 11;
int ledPin4 = 6;
//You can use up to 6 LED pins

void setup()
pinMode(ledPin1, OUTPUT); //Sets the LED pins as output pins.
pinMode(ledPin2, OUTPUT); //Use the same pins used above
pinMode(ledPin3, OUTPUT);
pinMode(ledPin4, OUTPUT);

void loop()
{ //Sets a random value of LED voltage in the range of 0V - 5V with PWM
analogWrite(ledPin1, TrueRandom.random(0,255)); //Use the same pins used above
analogWrite(ledPin2, TrueRandom.random(0,255));
analogWrite(ledPin3, TrueRandom.random(0,255));
analogWrite(ledPin4, TrueRandom.random(0,255));
delay(TrueRandom.random(40,70)); //Limits the speed.

Step 4: Test It!

Now connect the Arduino to the PC (or MAC) with the USB cable.
Left click on the compile button at the top of the coding field.
Now wait for the compiling to be done.

Now click on "Upload" and wait for the upload.

A few moments later, the Arduino should start flickering the LEDs!

I hope you liked my Instructable.
Don't mind grammar and speech, I'm from Germany :)
Merry Christmas!

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