UB10MD Open Source Locator

PDF_UB10MD Open Source Locator.zip

Altium_UB10MD Open Source Locator.zip

PADS_UB10MD Open Source Locator.zip

96198

Rhythmic LED strip (color silkscreen printing & modified casing)

The project uses the ESP8266 module as the main controller and the WS2812B 2020 music rhythm LED strip as the LED beads. The peripheral circuit is simple; the casing is complete and can be programmed and modified, making it highly playable.

 I. Project Introduction
    This project cloned and modified the workshop director's rhythmic light strip. The first version was made a year and a half ago. It was relatively small, and the circuitry was working and verified to be usable. However, due to some issues with the casing design, the circuitry was not convenient for programming. Therefore, a second version was recently designed based on available materials. The biggest difference from the first version is the redesigned casing, which can be 3D printed directly. The snap-fit ​​design makes assembly and disassembly easy, eliminating the need for screw posts, reducing size and cost.
 
Comparison of the two versions
: First version: The CH340 download circuit was omitted, making downloading and debugging slightly more complicated, requiring an external programmer, but the cost was relatively reduced; due to being a beginner, automatic wiring was used, resulting in messy wiring, but it was usable; calculation errors occurred during casing design, so the casing is barely usable but not ideal; a power switching circuit was missing, leading to situations where the battery is charged and discharged simultaneously, which is not very battery-friendly.
 
Second version: The second version specifically addressed the issues of the first version.
               1. Added Automatic Download Circuit: An automatic download circuit for the CH340C was added, which has been tested and confirmed to be working. The original integrated MOSFETs were replaced with two NMOS transistors, simplifying soldering and eliminating the need for orientation identification. The program can be burned simply by connecting the automatic download circuit to the computer via a data cable; no download module or button operation is required, facilitating program debugging.
               2. Optimized Layout and Routing: Layout and routing were completed in-house, resulting in a simpler layout and routing compared to the first version.
               3. Housing Structure Design: The housing design was completed using JLCPCB EDA, achieving higher precision. The snap-fit ​​structure was drawn using other housing software, and a grating was used to fix the PCB in place to prevent movement within the housing.
               4. Added Power Switching Circuit: This circuit prevents the battery from using its own power during charging while allowing external power supply during charging, improving battery life and circuit safety.
               5. Added Color Silkscreen Printing: Compared to the monochrome of the first version, the second version incorporates color silkscreen printing, making the PCB more visually appealing.
               6. Complete Project Information: The information is organized, and the purchase of all materials (except the casing, which is included in the accessories and can be printed at JLCPCB) is listed in a convenient inventory list.
 
Advantages and Disadvantages: Disadvantages: The total cost of materials is approximately 90 (including capacitors and resistors; if you have your own capacitors and resistors, it will be about 10 yuan cheaper; this is the cost of one set, and the average cost will be lower if you make several sets). The cost per set is relatively high, and the cost-effectiveness is lower compared to prices on Taobao. The WS2812 package is small and not easy to solder.
                     Advantages: Complete information allows for DIY and enjoying the entire production process; the circuit is simple and easy to understand, and can be added to or modified; the code is publicly available, simple and easy to learn, and you can also learn about the ESP8266 module; there is an automatic program download circuit, which can be used to burn programs at any time with just a data cable.
 
 
II. Circuit Section
    The circuit section mainly consists of a charging circuit, a power switching circuit, an audio source acquisition circuit, an automatic download circuit, a main control circuit, an LDO step-down circuit, and the WS2812 circuit.
 
1. Main Control
  Circuit: The main control circuit uses the ESP8266 module. This module is small in size, has simple peripheral circuitry, can be programmed using Arduino, and is easy to learn. It is also easy to solder, inexpensive (around 5 RMB on Taobao), and offers multiple functions, making it an ideal choice for DIY beginners and suitable for many projects.
     10K pull-up resistors are connected in series on the TX, RX, and IO0 networks. The pull-up resistors on TX and RX ensure more stable data transmission. IO0 is equivalent to the chip's BOOT pin; a low level enters the programming mode, and a high level enters the working mode, hence the need for a pull-up level. The right side of the diagram shows the reset and filtering circuits. The filtering circuit ensures stable operating voltage for the module, and the reset circuit ensures stable operation. The 100NF capacitor connected in series determines the pin power-on sequence. Since the capacitor charges upon initial power-on, these two pins will power on slightly later than other pins. This not only ensures module stability but also serves in the subsequent automatic program download process.
 
2. The automatic download circuit
    uses the CH340C's driver circuit, powered by 3.3V. The external circuitry is simple; compared to the CH340G, it eliminates the need for a crystal oscillator and start-up capacitor. Compared to the CH340N, it adds RTS and DTR pins, enabling automatic downloading. Downloading the program via serial port primarily involves first putting the chip into program burning mode, then downloading the program via serial port. Therefore, manual downloading typically includes a reset button and a BOOT button; while automatic downloading uses two resistors and two NMOS transistors (as shown in the diagram below) to replace the manual downloading operation. Principle: Based on the conduction characteristics of NMOS, we know that when RTS is high and DTS is low, Q13 conducts while Q12 does not, resulting in IO0 being low and EN being high. Conversely, when RTS is low and DTS is high, Q12 conducts while Q13 does not, resulting in IO0 being high and EN being low. Following this principle, during download, the CH340C chip first sets RTS low and DTS high, resulting in EN being low and the main control chip circuit resetting. Then, it sets RTS high and DTS low, resulting in IO0 being low. While EN should be high, due to the charging of the 100NF capacitor in the reset circuit, EN remains low for a very short time (reset state). When EN returns to high, IO0 remains low, thus entering program download mode. (Regarding whether to use the RST or EN pin for reset, theoretically either is fine, but the official recommendation is to use the EN pin, so the EN pin is used here.)
 
3. Power Switching Circuit:
    Due to the limited battery life (a few hours), but sometimes you still want to use the battery when it's empty, you have to charge and use it simultaneously. This causes the battery to heat up, accelerates battery aging, and is also unsafe. To avoid these problems, a power switching circuit is added to the design. When charging, an external power supply is used, and the battery is not used. Charging and use can be done simultaneously. The battery has a battery protection chip, so there is no need to worry about overcharging in the short term. Principle: A PMOS transistor is used here, connected to a resistor pulled down to ground. When there is no external power supply, the MOS transistor is turned on, and the battery powers the battery. When an external power supply is connected, the resistor pulls up, the MOS transistor is turned off, and the external power supply powers the battery.
 
 
4. 3.3V Buck Circuit:
    Used to step down the voltage to 3.3V. The voltage drop is small, suitable for 3.7V lithium batteries. The external components are simple, and it can provide a maximum current of 600mA, which is sufficient to power the main control module and the audio source acquisition module.
 
 
5. The charging circuit
    uses the TP4059 charging chip, which is compact and has a simple peripheral circuit.
 
 
 
6. The audio acquisition circuit uses
    an external MAX9814 module, ensuring stable signal acquisition and easy soldering. R40 is a pull-down resistor for more stable signal transmission, and R39 protects the pins of the main control module chip and also provides some impedance.
 
 
7. The WS2812 LED circuit
   uses bus control; one I/O port can control the color of all LEDs. It has a wide power supply range (3.3-5.5V) and can use battery power or 5V power. Three filter capacitors ensure circuit stability.
 
 
 
III. Program Section
: Library File References and Data Definitions.
 
Program initialization
 
outputs LED color gradient data.
 
Based on the audio acquisition value, it converts the maximum height of the LED strip display
 
and switches the display mode.
 
Develop an HTML webpage interface for
 
switching the LED strip color to a webpage-based color modification mode and automatically connecting to Wi-Fi.
 
 
 
IV. Soldering and Structural Assembly Instructions
    : Soldering: Due to the small package size of the WS2812 LED, although an electric arc soldering iron can be used, it is recommended to use a hot air gun or heating table if possible, as it is faster and more convenient (of course, experienced users can disregard this). If using a heating table, you need to solder the front side first. After soldering, you need to check if the LED has solder joints or obvious cold solder joints (these are subtle and can only be detected upon power-up). This is crucial; otherwise, the LED may smoke upon power-up. I didn't check when soldering the second piece, and as a result, one diode lit up immediately upon power-up. Using a multimeter, I found several LED pins had solder joints. After cleaning the solder joints, the LED returned to normal.
   On the PCB front side, after soldering, first check if the positive and negative terminals of the LED are short-circuited, and then test continuity. Normally, the four pins of each LED should not be connected. If two pins have zero resistance, it indicates solder joints and needs to be addressed.
 
  The back of the PCB contains the main circuitry. Compared to the front, this side is much easier to solder, but there are two details to note. It's best to solder the Type-C connector first, as soldering the 16-pin Type-C connector is prone to solder bridging, requiring drag soldering. If components have already been placed on the back, drag soldering the Type-C connector might be inconvenient. Also, when soldering the MAX9814 module, try to solder the header pins first (vertically). After soldering, solder the module onto the header pins. This makes it easier to adjust the header pin length; any excess pins need to be trimmed. Solder the module close to the PCB to accommodate the battery.
If you are confident in your skills, you can leave a section of solder on the pad, straighten it, and then use this to fix the MAX9814 module. This method is more difficult and may result in cold solder joints if not done correctly. For
 
structural assembly
  , first place the acrylic light-blocking plate, then place the grating, with the flat side facing the acrylic and the side with the studs facing the PCB. Due to printing precision errors, the grating may tilt after placement. You can lightly sand the sides, but it can also be used without sanding.
 
 
V. PCB and Housing Ordering
     PCB Ordering:
     The PCB for this project can be ordered with or without color silkscreen printing. If color silkscreen printing is not required, simply place the order directly. If color silkscreen printing is required, please note the following options:
change the solder mask color to white, change the solder pad tin spraying to immersion gold, and change the character printing process to JLCPCB EDA color silkscreen printing.
 
  Housing printing
  will be done at JLCPCB's 3D Monkey factory; the price is inexpensive and the quality is quite good. The housing file is attached; download, unzip, and upload the file for printing.
 
 
 
 
A high-definition demo video is available on Bilibili: https://b23.tv/YmpKcLm
 
 
Original author: Rhythm Light Strips - JLCPCB EDA Open Source Hardware Platform (oshwhub.com)
 

Materials list and purchase instructions.xlsx

3D Shell and Raster.zip

code.zip

Demo.mp4

Tutorial on changing the color of LED strips on a webpage.mp4

PDF_Rhythmic Light Strips (Color Silkscreen & Modified Case Version).zip

Altium Rhythmic Light Strip (Color Silkscreen & Modified Case) .zip

PADS_Rhythmic Light Strip (Color Silkscreen & Modified Case) .zip

BOM_Rhythmic LED Strip (Color Silkscreen & Modified Shell Version).xlsx

96200

Old Wang ST7796 320*360 IPS screen adapter board

The display looks good, but unfortunately it's out of stock.