1. ECE 492 - Computer Engineering Design Project
Poor Man’s Light Show
Torrin Swanson, Andrew Ovens
2013
How it Works
Our project consists of three major components. Reading an audio source, analyzing this raw audio data, and producing an algorithm for generating a lighting sequence based off this audio input.
We read the audio signal through the on-board Line-In port. We then convert this signal to a digital signal. Once the audio has been converted to a digital signal, we have designed our hardware to pull this data from the ADC and input this into our Fast Fourier Transform supplied by Altera’s Megacore.
Our 1024 point FFT transforms the digital audio signal and outputs the audio into the corresponding bins. With our sampling frequency of kHz, we receive a bin width of Hz per bin. With this critical information, we were then able to generate our algorithm for approximating the frequency ranges of each bin. (i.e Red is bin 4 between Hz, Yellow is bin 9 between Hz , Green is bin 11 between Hz, Blue is bin 14 between Hz). Auto gain control and threshold detection control whether the light is on or off for a given audio sample.
Each LED is controlled by a specific pin from the use of our on-board GPIO bank 0. The ribbon cable attached to the GPIO pins, merely only controls the activation of each LED. The LEDs are powered by an external 3.3V, 1A power supply.
Project Outline
Our implementation of a Poor Man’s Light Show consists of an input from any audio source through the ‘Line In’ port on the Altera DE2 board. With this audio signal we separate the signal into its various frequency components and use these specific frequency ranges to turn on corresponding Light Emitting Diodes. This can then be scaled up at a later time to include actual stage lightning equipment.
Our algorithm is one that tries to mimic the visually intense lighting sequences, which typically are designed by a sound engineer, that you would normally see at a concert. The Light Show was designed to be fully portable as for one to be able to take the Altera DE2 and the LED external circuit to any environment which could supply a ‘Line Out’ audio source which could be tapped into our system.
Fig 1. Altera DE2 and LED external circuit. Audio Input into ‘Line In’ and Speakers attached to ‘Line Out’. Power supply connected to LED circuit. Above.
For colour ideas, University Visual Identity Guidelines can be found here:
Fig 3. Fast Fourier Transform in action. Showing the original audio data, and displaying the frequency ranges of the respective transformed signal. To the left.
Fig 2. A descriptive flow chart of the data flow of the audio signal as it gets transformed into its frequency components and finally sent through our algorithm for generating a lighting sequence. To the right.
Department of Electrical & Computer Engineering