Code to run different LED patterns using the fantastic 3D RGB Xmas Tree for Raspberry Pi on a Raspberry Pi
This project is to use a Raspberry Pi to run on an attached 3D RGB Xmas Tree for Raspberry Pi, and for it to run unattended (no attached keyboard/mouse), changing the LED lights on the Xmas Tree on an attached headless Raspberry Pi.
The project uses a Raspberry Pi (we used a Pi Zero, although any model Pi would do), and based on the Pi Hut example source code.
The script tree.py supplied by Pi Hut is used, and must be present in the same directory/folder as the Python scripts here. The reason is that the class 'RGBXmasTree' is imported from it:
The following hardware is used:
This hardware is all well designed - having removed the tree parts carefully from the circuit board and without twisting them (clippers will do this, we used a small dremmel fine circular saw). The parts then all just push fit together - no soldering is required.
A variety of code samples are given:
- XmasTree_Colours.py Set all LEDs to same but random colours cycling through using a list of colours, setting the top LED to white
- XmasTree_Sparkle.py Set random LEDs to random colours, setting the top LED to white (this was the preferred Xmas code!)
- XmasTree_Swirl.py run through three separate patterns - spiral, layers, rotate
- XmasTree_WhichLEDIsWhich.py Helps identify which LED is which number - to aid development of patterns. Running this code produces a grid window with 25 buttons - click each number to light up the corresponding LED.
Colours in XmasTree_Colours.py can be added to the list, with the colour names as described at (https://www.rapidtables.com/web/color/RGB_Color.html#color-table).
Colours in the XmasTree_Sparkle.py are generated randomly and can use either the HSV model, or the RGB model (comment out one of these).
There are 25 APA102 RGB LEDs on the board, numbered 0-24, one of these is the LED on the top of the tree. Experimentation with XmasTree_WhichLEDIsWhich.py revealed this to be LED number 3. A variable was set up to represent this to allow it to be coloured separately (set as number 3 in code to refer to the list element holding the number 21).
The Xmas Tree is fitted to the Raspberry Pi, via the GPIO bus. The orientation of the GPIO plug is critical and MUST be fitted correctly or else voltage will be applied to the data line due to the PCB design (not a good idea!)
The Pi was set up to run in 'headless' mode (no monitor/keyboard/mouse) - to do this see our GeoThread blog, allowing a remote laptop to ssh in to the Pi, and using FileZilla to copy files over to it.
To test the Xmas Tree board, in the same folder as the script tree.py supplied by Pi Hut, run the Python shell:
Python 3.7.3
>>> from tree import RGBXmasTree
>>> tree = RGBXmasTree()
>>> tree[3].color = (0, 1, 0)
>>> tree.off()
Respectively, this sets up the tree, turns on the top LED (3) green, then turns all the LEDs off.
Next, to test the code, it was run remotely via ssh from a laptop running the python script, the code was located in the home folder '/home/pi', e.g.:
> python3 XmasTree_Sparkle.py
To make the code run unattended on the Pi, there needed to be a means to start the programme automatically on boot. The best means to do this was found to be to use an autostart desktop file. A file was therefore created thus:
> touch /home/pi/.config/autostart/XmasTree.desktop
> nano /home/pi/.config/autostart/XmasTree.desktop
[Desktop Entry]
Type=Application
Name=3D Xmas Tree
Exec=/usr/bin/python3 /home/pi/XmasTree_Sparkle.py
The code here gives some interesting display options, adding to the existing example code. There is huge scope now for further improvements to have different displays. One interesting development would be to link the display to various sensors and events that the Pi can handle - so a PIR detector used to display lights according to proximity of people for example.
A final note is that the Pi has no graceful way to be shut down when done. Simply turning off the Pi at the mains is not a great idea. One solution is to use a crontab entry to simply close the Pi down at say 23:30 each day (of course it needs to be turned on each day).
sudo crontab -e
[add a root user crontab]
30 23 * * * /sbin/shutdown -h now
Now the Pi can be rebooted.