LED Xmas tree

Ina soldered today 16 leds in matrix and then we connected it to “LED Decoration” hardware. The basic idea was:

4x4 LED matrix Xmas tree

4×4 LED matrix Xmas tree

There are four layers of LEDs with 4 LEDs on each layer, together 16 LEDs. First step was bending the LED pins:

LEDs Preparation

LEDs Preparation

Next step was soldering 4 LEDs together:


Not an easy task without this tool:



The tree finlay start growing. Here are three layers finished:


And the final task was to add wires, which will connect LED matrix with the controller electronics:


LED matrix pinout

LED matrix pinout


Rows form R0 to R3 connects anodes of the LEDs and columns C0 to C3 connects cathodes. Individual LED at the juction of the row and column will be energized when Rn + 1 and Cn=0:

LED matrix

LED matrix

The software for this tree is really small. Code is “bare metal”, without STM32 Cube, just the startup assembly and direct adressing of the registers. Complete code is in the GitHub  repository.

The final result is something like this:

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