Mini Christmas Tree Based on WS2812

Project Description:
This mini Christmas tree achieves a harmonious overall look and better viewing angle by using WS2812 LEDs in a 1010 package. It adopts a battery-powered + touch power on/off + mobile phone remote control solution, emphasizing an elegant
 
design. Key Features:
1. Light Board (Christmas Tree Body)
: Utilizes WS2812 LEDs in a 1010 package, resulting in a smaller, more harmonious appearance and better viewing angle. The unified light board design allows for a single free sample (5 PCBs) to be sufficient, simplifying the LED silkscreen printing and preventing it from affecting the Christmas tree's appearance. Curved signal traces are used to integrate the traces into the design without appearing obtrusive.
2. Control Unit (Christmas Tree Base)
: A Bluetooth controller enables rich color... The lighting effect also reduces the development cycle.
Front-facing wiring is avoided as much as possible to improve the overall look.
The charging port, switch button, and indicator lights are all rear- or bottom-mounted.
 
Results
demonstration video: [Bilibili] Plant a Cyber ​​Christmas Tree.
You are also welcome to follow my Bilibili account @何电工.
If you plan to replicate this project, welcome to join my technical exchange QQ group: 1016193632.
 
Circuit Design:
The circuit adopts a modular design.
First, there is a Type-C interface and a charge/discharge management chip, which realizes battery power supply and one-button
power You can refer to my other open-source project:
Mini Charge/Discharge Management Module Based on LY3205. The JLCPCB EDA open-source hardware platform (oshwhub.com)
features a design flawed by my somewhat obsessive-compulsive tendencies. Therefore, I opted for a rear-mounted design for the charging port, power button, and indicator lights. Since the main control board also places all components on the back (to improve the front aesthetics), I designed a unique layered structure.
This structural design is somewhat unusual, hence the soldering method described at the end of the open-source project.
 
For a more elegant power-on/off operation, this project uses a touch switch.
The touch sensor chip is a common 223 chip,
with a pull-up resistor setting OLH to a low level output, thus simulating a button press by pulling down the KEY pin to control the LY3205 charging... It's important to note that the touch chip
requires direct battery power (BAT + network) to function when the device is off.
Therefore, a wide-voltage, low-power touch chip is necessary. You can refer to the datasheet for relevant information.
Additionally, I added a pad on the back of the touch sensor for easy routing of the touch sensor wiring to different casings.
 
The boost converter circuit uses the commonly used 3608, which I won't elaborate on here
. Since this project has low ripple requirements and strict size constraints, I removed the voltage feedforward capacitor C7 from the PCB.
 
Each "leaf" has 8 LEDs on each side, for a total of 16 2812 LEDs.
Four "leaf" sections have a total of 16 * 4 = 64 LEDs.
Soldering is highly recommended. R12-16 is used for series wiring of the LEDs. If any LED is damaged and cannot be repaired, the spare R17-21 is used for parallel wiring of the four "leaves"
. When connected in series, the LEDs of the entire Christmas tree can achieve continuous changing effects. When connected in parallel, the lighting effect of the four "leaves" is the same.
 
The light board adopts a design with fixed pins and multiplexed electrical connections. The light board is fixed by soldering and connected to the main board at the same time, as shown in the figure below.
Therefore, when soldering, it is necessary to ensure that the solder joints are reliably connected.
The four light boards required are the same (of course, you can draw four different ones). One free sample (5 PCBs) is sufficient. If batch soldering is required, a "4-panel" can be used, so that
one board is "one tree".
The LEDs use a 1010 small package, which presents a higher soldering difficulty. Beginners should consider their soldering skills before attempting to solder.
 
The outer shell (base) is designed using Fusion360 modeling, as shown in the image below.
The STL file for the base is included in the project attachments and can be downloaded and printed (it has a beveled surface, but can be printed without support).
The small hole in the center of the base is used to secure the microphone on the light controller.
 
I chose an 8.5cm diameter outer glass cover, which is smaller than the standard 10cm or larger diameter glass cover, making it more suitable as a desktop decoration.
The miniature size of this Christmas tree is also to match this small lampshade, making it look more delicate.
Of course, you can also choose a larger lampshade and modify the base accordingly.
 
Software:
Software download address:
https://faqsys.magichue.net:4489/download/zgble_download.html?tpn=1703399124066
Common software issues:
https://faqsys.magichue.net:4489/content.html?tpn=1703399157750&contentUniID=245f92c3c7f941f7b4fc1451e3e5d524
In the software, set the number of points to 64 and the number of segments to 1. If connecting in parallel, set the number of points to 16 and the number of segments to 4.
On the control interface's homepage, you can display the LEDs in a single color and check if the RGB values ​​are correct. If the LED color is different from the software setting, you need to modify the LED strip sorting (the default is RGB, but my corresponding setting is GRB; different manufacturers' LEDs may require different settings).
 
Production notes:
All boards in this project are 1mm thick!
1. First, solder the charging/discharging management and boost circuits. Confirm that the charging and boost output are working correctly before soldering the LED boards.
2. After soldering the LED boards, ensure that each board lights up normally before assembling and soldering.
3. When soldering the LED boards, solder the interconnecting pads between the boards first, then solder the connection between the LED boards and the main control board.
4. You can use foam tape to attach the battery to the back of the main control board, and then use metal pins to connect the WS2812 expansion board
 
charging interface. Soldering method:
First, bend the two front support pieces of the Type-C interface, then use solder to connect the bent support pieces to the interface itself. When fixing the body
during soldering, first solder the buttons and LEDs. After soldering, it is recommended to use a soldering iron to add more solder to ensure the buttons are securely fixed.
Then, use a soldering iron to apply solder to the Type-C signal pins, and then use a hot air gun to heat and solder the Type-C interface from the back.
After completing the above steps, first ensure that the charging function is normal
before soldering the four fixed pins of the Type-C interface.
 
Control board soldering method:
First, solder the main control board and the LED board, connect the main control board with a jumper wire, and test the lighting function with a battery or power supply. If it is normal,
then use foam tape (thick double-sided tape) to fix the battery in the center of the bottom of the Christmas tree.
Find some rigid component leads, bend them into a C-shape
to match the battery thickness, and solder the bent leads to the control board. Trim them as needed.
Finally, solder the light Bluetooth control board to the Christmas tree main control board.
After all connections are complete, it is recommended to test again. After testing, you can install it into the casing for assembly.
During installation, adjust the light Bluetooth control board so that its microphone is aligned with the bottom hole.
 
Purchase link:
Main components can be purchased according to the circuit diagram.
WS2812 controller: I used the "USB RGB Controller" module from the following link:
WS2811 full-color LED strip 2812B flowing light, running light, dimming, USB. 5V Mini Music Bluetooth Colorful Controller - Taobao.com.
For bulk purchases of WS2812-1010 LED beads, choose
the 0404 Breathing LED Beads Programmable Built-in IC LED 1010 Colorful RGB Minimum Size - Taobao.com.
The glass lampshade diameter is 8.5cm; purchase the lampshade separately for
promotional purposes. Creative Strawberry Bowl Round Glass Doll, Spherical Fondant Cake Doll, Baking Ornaments, Crystal Ball Doll Decoration - Taobao.com.
The battery uses a finished soft-pack lithium battery with a protection board, size 602030.
3.7V Polymer Lithium Battery 602030 Universal Rechargeable Battery for Reading Pens, Recorders, Card Slots, and Speakers - Taobao.com
 
Special Thanks:
Thank you @Trista for your continued support and encouragement.
Thank you @活动酱 for proposing the built-in speaker design. Considering the current tight schedule of this project (to release before Christmas), and my lack of experience in audio circuit design, I am releasing this version first. An improved version will be released later (sound of a procrastinator).
 
Other:
2024/05/21 Update Notes: Fixed the connection problem of signal link 2 (backup line).
If you have any questions or suggestions about the project, please leave a message for discussion.
You are also welcome to join my technical exchange QQ group: 1016193632