Producing Flicker With Software

We define "flickering lights", as turning on and off with a random or irregular timing, which does not seem to repeat. We have a page that details the theory of flicker, and one dedicated to practical techniques.

This page showcases examples of using software in a micro controller to generate flicker.

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Ching and Land

Philip Ching & Bruce Land published an article about a LED-based candle in October of 2002.

The citation is:

Ching, P. and Land B. (2002) Light the way: An LED-based alternative to a candle, Circuit Cellar Magazine #147, pp30-35, Oct 2002
The article is available for download for a small price at "www.circuitcellar.com". The source code is available free at
ftp://ftp.circuitcellar.com/pub/Circuit_Cellar/2002/147/ching-127.ZIP

Note: This originated as a student project. Additional details are available at:

http://instruct1.cit.cornell.edu/courses/eceprojectsland/STUDENTPROJ/2001to2002/pc59/index.htm 

 

Phredog

In October 2004, Wolfstone reader "Phredog" sent some e-mail describing his software flicker implementation.

The project uses:

If you don't have a clean power supply, add:

Here is a breadboarded version of Phredog's circuit.

This is the schematic. 

 

Tim Doggett

In April 2005, Tim (The Enchanter) Doggett posted a message to Halloween-L describing a software flicker system that he had built for the McLaurin Floating Lantern at the Hallowed Haunting Grounds.

Tim's system uses:

Here is the schematic for Tim's circuit.

Tim's comments on the design:

For additional technical details, please see the original materials at:

Thanks for sharing, Tim! 

 

Sheets And Graf

Sheets and Graf contributed an article to Nuts & Volts, Sept 2003, "Lamp Controllers For Special Effects", pg 52. The article includes a simulated candle flicker based on a microcontroller.

The project is available as a kit from North Country Radio (commercial electronic flicker circuits).
[photo] This is the published schematic.

[photo] This is a photo of the three-channel model. 

 

Based On BASIC Stamp

These software flicker implementations are based on controllers from the BASIC Stamp series by Parallax. 

 

Parallax Application Note AN0001 - Faux Candles

This flicker implementation comes from the nice folks at Parallax EFX, (a division of Parallax, manufacturer of the BASIC Stamp). It was designed for use with their Prop-1 controller. The application note is dated 5/2005.

This schematic drives the LEDs straight off the stamp output pins. Six output bits are driven with independent flicker - you can use as many of them as you need.

In this configuration, the LEDs are driven high to light up.

The Prop-1 also has outputs buffered by an inverting high-current sink driver (ULN2803). This partial schematic shows one of the output channels driven from the ULN2803.

In this configuration, the LEDs are pulled low to light up. The capacitor smoothes out the transitions

The app note is available at http://www.parallaxefx.com/dl/AppNotes/AppNoteFX00001.zip.

Source code: flksof_Faux_Candles.BS1

Notes: 

 

Wolfstone Binary

Dennis wrote this flicker program in response to deficiencies in Parallax Application Note AN0001 - Faux Candles. The goals were:

Source code: flksof_Faux_CandlesD4.BS1

Notes: 

 

Related Pages

You may be interested in these related pages: