Category Archives: Arduino

Audio Spectrum Analyzer

There is a great tutorial on how to setup and use a 2×16 LCD on the Arduino website:
http://arduino.cc/en/Tutorial/LiquidCrystal

Here’s a good explanation of FFT theory:
http://www.arduinoos.com/2010/10/fast-fourier-transform-fft/

My pinout is a little different because I wanted to save as many PWM pins to add servo control for the next stage of this project.  I’ve been tinkering with the idea of moving physical objects around based on audio input, instead of just showing levels on a display.

To visualize the frequency levels of the incoming audio signal I use the 8-bit Fast Fourier transform code which is discussed here:
http://forum.arduino.cc/index.php/topic,38153.0.html

Honestly, I’m not convinced that what I’m seeing on the display is an accurate representation of the audio spectrum that I’m listening to, but it looks pretty cool and that’s all I really care about at this point.  There is hardware available that would produce much more accurate results than this software.  There is a “Color Organ” project on the Make website that I’d like to build someday:
http://blog.makezine.com/2010/10/18/circuit-skills-led-color-organ-spon/

Additional Reading:
http://forum.arduino.cc/index.php?topic=38153.0
http://forum.arduino.cc/index.php?topic=182169.0

Code and libraries on GitHub

Arduino to TV Adapter

You can send all kinds of fun stuff to a TV from an Arduino using the TVout Library. All you need is an RCA cable and two resistors (470 & 1k).

TV Ground to Arduino Ground
TV Signal to 470 to pin 7
TV Signal to 1k to pin 9
(Audio to pin 11)

http://code.google.com/p/arduino-tvout/
http://www.instructables.com/id/TV-Out-with-Arduino/

Here is the one I built to experiment with:

P1020845P1020846  P1020847

It works!  When I get another long RCA I’ll add audio support.

Here’s some code that makes this using a Line In Adapter:

or use this code for this result:

audio is Trash 80

or use this code for this result:

audio is B.L. Underwood (no relation)

and you can do what with what!!!