Octagon Display Construction

Neo-pixels have red, green. and blue LEDs and an integrated circuit. They are intended to be used in strings in a cascaded fashion. They all have common negative and +5 volt power strips and a single signal strip which goes into the chip, is regenerated, and emitted for the next neo-pixel inline. 

The string is fed a continuous NRZ signal with 24 bits per neo-pixel. The neo-pixel’s IC selects its own 24 bits, stores them, decodes and drives the LEDs. After all pixels are set, a common trigger activates all simultaneously. 

The string purchased for this project was 1 meter long and contained 144 neo-pixels. They are packed close together except for a break in the centre. Therefor the project has 72 neo-pixels, which dictated the diameter of the groove containing the 50-cm string.

The groove was made by my router in 4 passes with the octagon rotated around a fixed shaft in its center.

The octagon is supported by a metal casting which was a base for a pole. It has enough space inside for the electronics, but the controls had to be outside it for accessibility. 

The control assembly includes a board with sets of 5-plated-through connected holes, plus 2 busses. The controls are soldered into it and are then connected to male headers. This enables all connections to the processor to use pre-made jumper wires. The neo-pixel string also plugs into this board with the pigtail which came with it.

Octagon Display System Diagram

Init and Main

Octagon Display Underneath