Elektor Circular Christmas Tree Kit

Das als Weihnachts-Gimmick gedachte WS2812 Arrangement funktioniert gut - auch mit einem nano AVR Board. Bei uns ist der Baum über ein am nano USB angeschlossenes Steckerladegerät gelaufen.
Der empfohlene ESP32 ist hier `etwas oversized` es sei denn, man möchte das Teil über einen Web-Server bedienen, für den es aber (noch) kein passendes Programm gibt.
Schade auch, dass keine Erweiterungsmöglichkeit berücksichtigt wurde, wie Stiftleisten für Mikrofon- oder Lautsprecheranschluss.
Wer seinen nano nicht einlöten möchte, benötigt noch 2 Stck. 15-polige Buchsenleisten extra dazu.
Ein Lob an den Super Service, der mein Problem mit einer defekten LED ruckzuck gelöst hat - Nochmal Danke auf diesem Weg.

In the end it was a fun project, however I had troubles soldering the RGB leds. These were more difficult then the SMD parts. Funny enough what worked for me in the end was using the biggest soldering tip I have, a 5.2mm chisel point with flux and a little bit of solder. With a kind of drag soldering technique I was able to solder all 4 connections in one go without too much solder to form a bridge. I used a Arduino nano clone which I had laying around. It fits the board and with some adjustments to the demo code it worked. I recommend to test all the other rings with 3 wires to PA1, PA3 and PA5 of the base board before putting the tree together and measure for shorts on the powertraces before putting any power on them. Then use the test program to make sure all the LED`s work before continuing. Luckily the LEDS can endure some abuse. Mine survived reversed polarity and several shortcuts of both input / output to ground or 5 volts.

After spending several hours meticulously examining my soldering work for flaws ? using a magnifying glass and ample lighting ? I addressed a few minor issues, yet the main problem persisted. It was only thanks to Ben Schueler`s insightful review, which highlighted an incorrect PIN connection, that I could resolve the issue successfully. I`m grateful for his keen observation.

The fun start with building the Christmas Tree. It took me like 1,5 hour to cut the wires in length, cut the legs of LEDs, breaking the PCB in pieces (be careful, I had to use a cutter to not break the PCB itself) and of-course the soldering. Before I soldered the wires between the PCBs, I checked with a programmed Nano ESP32 if the LEDs worked before I connected the next layer.
When using the Nano ESP32 there are some links for microPython but I was not able to get it to work.
I used Arduino 1.8.x with the Adafruit Neopixels library. But to be able to program the example `strandtest` I had to do 2 things. First, install via boardmanager the Arduino Nano ESP32. There was already one installed but it cannot program the Nano ESP32. After installing the Arduino Nano ESP32 this issue was fixed.
Second one is to set Tolols->Pin numbering->By GPIO Number (legacy) and change the define for LED_PIN to 9.
#define LED_PIN 9 // GPIO9.
When done, select the correct com port and program the Nano ESP32 processor.
The example is a good starting point for your own program. I added the potmeter for speed and the dip switches tor select wich pattern to show.
I am going to add an LDR to adjust the brightness of the LEDs (make sure the LDR has no (in)direct light path with the LEDs).