Ambitious 3D spectrum analyzer holds 1280 LEDs

We have seen many LED cube projects that can generate lots of great effects. Sometimes the problem is that in too large cubes inner layers are hardly visible. So what if to build a LED based rectangle with less layers of LEDs. Dooievriend have found great combination of 3D effect and visibility.

He has built 16x16x5 rectangle configuration of blue LEDs that displays spectrum of music being played. The heart of this spectrum analyzer is PIC32 microcontroller running at 80MHz. It has enough power to sample sound and calculate DFT of the signal. It samples input signal at 14kHz and then calculates spectrum frequencies from range 20 – 7000Hz. It refreshes the spectrum graph at 80 FPS so it looks really live.

Playing stereo audio with PIC32

PIC32 microcontroller has enough power to many great things. One of these is playing stereo audio. Tahmid thought it would cool to make one of these an a minimal board without audio amps and fancy interfaces. He interfaced microSD card to microcontroller which is accessed with Microchip Memory Disk Drive File System (MDDFS) library. Audio is sampled by using external dual channel MCP4822 12-bid DAC.

With this setup he is able to play 16-bit 44.1kHz WAV files. Playback program has an automatic period configuration which enables automatic playback of different resolution and rates like 8-bit, 16-bit mono and stereo.

Low budget DIY oscilloscope in a matchbox

It seems that less money you have, more creative you are. Not many dear to start a DIY oscilloscope project since these tools already aren’t that expensive as they were earlier. Anyway there are always hobbyists somewhere in the world that would rather build a tool rather saving to buy. In my opinion, oscilloscope is must have tool on a bench and if possible good one. So if your budget is short to buy one, ajoyraman offers his plans on $15 scope.


Oscilloscope doesn’t come with display, so it has to be connected to PC. He made sure that software is a multi-platform where Visual basic was used to to build windows compatible part, while Python for Linux. Scope has two channels with sampling frequency from 1Mbps to 20Mbps. Other features are like on common scopes including triggering on both edges, selectable gains, different capturing modes including single, repeat and store. Most of work is done on PC software where you can select various parameters and see graphs. Here you can zoom, copy, save images as you would like. Scope is built around dsPIC30F2020 microcontroller that talks to PC through USB interface made of FT232R USB to serial converter. The front end of each channel is build by using MCP6S22 programmable gain amplifier controlled over SPI bus from microcontroller. The PCB is also home made and fits in to larger matchbox.

Compiling Arduino code for PIC32

Programming PIC microcontrollers using Arduino code style isn’t something new. We are already familiar with ChipKit development boards from Digilent and their Arduino like development environment called mpide. Tom Kibalo suggests using MPLAB IDE to develop and use Arduino code for PIC32 microcontrollers. He has been developing Arduino library code for PIC32.


Most agree that Arduino IDE environment sucks for making more serious projects, so different options are always welcome. For instance by using MPLAB X IDE you can be way more productive with all tools it provides. Arduino library for PIC provides most of Arduino specific functions and there fore most of Arduino code can be executed on PIC same way using simple wrapper code.