Tag Archives: arduino

Audio Spectrum Analyzer

There is a great tutorial on how to setup and use a 2×16 LCD on the Arduino website:

Here’s a good explanation of FFT theory:

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:

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:

Additional Reading:

Code and libraries on GitHub

NFC (RFID) Tag Reader


I get the feeling that NFC and RFID will play a larger part in our lives in the years to come.  I decided that I wanted to find out more about the technology and its uses.  I acquired a Seeed Studios NFC Shield V2.0b for Arduino to experiment with.  It comes in a cool looking box.

The board and example code work great so I decided to put it all in an enclosure to make it less vulnerable, and a little more useful.  I added an RGB LED, a Piezo buzzer, and hardwired a 9 Volt adapter through a switch to an Arduino Uno.


You can see where I accidentally melted the plastic case near the power switch.  It looks like I did it with the hot glue gun, but it was actually from the Heaterizer.  You can’t see in these photos but there is a 220k Ohm resistor under the heat shrink connecting the LED to ground.  The antenna is taped to the top of the case and it’s wire clips on/off easily.

P1020851  P1020855 P1020853 P1020857


NFC Shield:

NFC Tags:

Code on GitHub.