Arudino: Realistic Flickering Flame Effect

Mike from London posted a project on Instructables involving LED's and an Arduino, along with the required code to get the project to flicker like a flame. It looked simple enough to try as a good next project after going through the Spark Fun experiments and it turned out to work very well.

Mike from London's video on how he accomplished his flicker effect with an Arduino.

I used "Circuit 02" from the Spark Fun kit which uses 8 LED's - while the Instructable project used only 3. I adapted the code* to accommodate the extra LED's and it worked perfectly. Next I constructed a prototype shade to diffuse the light using a piece of paper, reflective material taken from a drink box, and some metal wire to form the top of the shade. Luckily, the wires and resisters hold the shade in place at its base perfectly - at least as perfectly as you'd want in a prototype.

The next step is to develop a process to make Arduino experiments into finished products - fully functional, permanent prototypes. Of course, unless it was absolutely necessary, you wouldn't want to encase your Arduino into a finished product unless it was something like a robot or large automated system. In the case of an electric candle light, it would be practical to use a smaller and much cheaper microcontroller. Make Magazine recently did a video and article where they explained the process of using an Arduino and its development environment to program an ATtiny45 or 85 chip - this was in turn based on an MIT tutorial which can be found here. 

This  Make Magazine video is quite interesting and I thought I would include it here. The number of pins might limit my design down to a certain number of LED's - this all remains to be seen.

I've chosen a coconut to serve as my light fixture - they are omnipresent in Thailand, sturdy, interesting to look at, and easy to work with. Until I can source an ATtiny chip and do a test run on a breadboard, I'll just have to settle with this conceptualization I did in SketchUp to show readers where this project will go next.

A conceptualization of the next step. The base used for the ATtiny chip will be a coconut, though the shade and other features to best distribute the light have yet to be determined. Luckily coconuts are a dime a dozen in Thailand and experimenting with different designs will be very easy to do.

Here's what the prototype looked like after adapting the Instructable's design by Mike (Earthshine) to use 8 inline LED's and a paper shade. The flickering effect is very subtle which is exactly why it is so effective. It actually looks like the light cast by a flame - not blinking lights.

While this project is not very advanced - it is the process of prototyping and developing an idea with an Arduino and then adapting it to a more permanent platform for everyday use. The lessons learned here can then be used for other, more advanced projects in the future.

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* Here is the code I used with the SparkFun Circuit02 setup:

// LED Fire Effect

int ledPin1 = 6;
int ledPin2 = 7;
int ledPin3 = 8;
int ledPin4 = 9;
int ledPin5 = 2;
int ledPin6 = 3;
int ledPin7 = 4;
int ledPin8 = 5;

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

void loop() {
analogWrite(ledPin1, random(120)+135);
analogWrite(ledPin2, random(120)+135);
analogWrite(ledPin3, random(120)+135);
analogWrite(ledPin4, random(120)+135);
analogWrite(ledPin5, random(120)+135);
analogWrite(ledPin6, random(120)+135);
analogWrite(ledPin7, random(120)+135);
analogWrite(ledPin8, random(120)+135);
delay(random(100));
}