Spectrum Analyser

I found an old, unused 16x32 RGB led matrix which I bought on a whim years ago and had completely forgotten about.

After a little googling I found the Sparkfun Spectrum Shield which seemed to do most of the heavy lifting of a 7-band audio spectrum analyser.

assembling the shield

I soldered headers onto the shield before reading the spec sheet and later realised that in order to get the comparatively low-powered arduino to handle the refresh rate on the matrix, certain liberties were taken in the Matrix library; the matrix is required to use specific ports for it to work.

The Spectrum Shield also uses specific ports for its functionality, and these ports conflict - I would be unable simply to plug the shield into the arduino, as I’d soldered it.

So I decided to use coloured ribbon cables so I could redirect the 4 pins (2 analogue, 2 digital) that the Shield required to ports that were avalaible (essentially moving the Shield digital ports 4 & 5 to 12 & 13, and Analogue ports A0 & A1 to A4 & A5).


The Matrix wants 5v but needs up to 4 Amps, averaging about 2A of current, so I split the output of a 5v 4A supply between the Matrix and the current-limiting Arduino barrel plug.

And went the easy route of simply super-glueing non-solder wires into the ribbon cable of the Matrix

Sadly, that was most of it

At this point it was all about software. Creating a basic visualiser was quite simple.

The finished product

It’s not finished yet, but I like it. I’m adding visualisations and some controls. At some point there might need to be a containing structure. I’m leaving that decision for later.

The code

is here

Written on April 8, 2019