WLED 8x32 LED Matrix

This project demonstrates how to create a flexible 8x32 LED matrix panel powered by the free WLED firmware.

This panel has more real-estate than a simple 8x8 panel so in addition to colorful LED animations, it is also suited for displaying scrolling or static text.

The Project

Before starting, ensure your ESP microcontroller is provisioned:

1. Upload the WLED firmware directly from your browser.
2. Configure the WLED settings to match your microcontroller and GPIO(s).

Parts List

The total cost of this project is under €15:

• Microcontroller: I used an ESP32 C3 SuperMini, which is very affordable (<€2) and has a small footprint. You can also use any ESP32 microcontroller or even an old ESP8266.

  

• 8x32 Flexible RGB Matrix Panel: This project uses a WS2812 8x32 Matrix on a flexible (bendable) PCB.

  

• USB Connector: A separate USB adapter PCB is recommended, as most microcontroller boards cannot handle the high current demands (1.8A or more) of the LED matrix. Use a USB adapter PCB with traces rated for at least 2A.

  

Ensure the USB adapter PCB includes two resistors to support USB-C-to-USB-C cables. Adapters without these resistors may only work with USB-A cables and older power supplies.

• 6 Cables:
  • 3 wires (26AWG) to connect the microcontroller.
  • 2 two-wire cables (15cm, 20AWG) for the LED matrix power rail.
  • 1 two-wire cable (5cm, 20-18AWG) for the external USB plug.

  

• Housing: if you have access to a 3D printer, I also provide you with ready-to-use STL files to print a neat housing and cover.

  

Wiring

Below is the schematic for wiring the components:

You can vary this simple schematic and connect microcontroller and USB-C connector to the power rail at any place. Just make sure:

• DIN, not DOUT: connect the control wire (yellow) to DIN on the panel, not DOUT!
• Configure GPIO: connect the other end of the control wire to the GPIO you designated in WLED settings. By default, this is GPIO2 (as seen in the schematics). Frequently, GPIO4 is used instead (I did this in this project, too) since GPIO4 is located closer to the power pins which I liked. If you want to use GPIO4 (or any other GPIO other than GPIO2), you must change the GPIO number in WLED settings.

Next Steps

Follow these detailed steps to assemble the LED Matrix Panel:

1. Firmware Configuration: Fine-tune the WLED firmware settings to match your microcontroller GPIO, and your LED panel.
2. LED Matrix Panel Preparation: Remove any existing wiring from the panel and solder new wires according to the schematic above.
3. Assembly: Connect the microcontroller and external USB plug to the matrix.
4. Housing: Mount all components into a 3D-printed housing for a clean and sturdy build.

1. Firmware Configuration

First, let’s finalize the basic microcontroller configuration to account for the microcontroller you are using, and the kind of LEDs you are going to control with it:

Make sure you have uploaded the WLED firmware successfully to your microcontroller, connected to its web interface, and performed the basic initial configuration.

Connect to your microcontroller, for example using your smart phone or PC, and navigate to its settings. Then click LED Preferences.

LED Preferences

1. Check Enable automatic brightness limiter, and limit the maximum PSU current to 1800mA (850mA by default). USB connections can safely provide at least 2A, and with a large matrix like the one we are using here, 850mA would limit the maximum brightness considerably.

   

2. Tell WLED the number of LEDs you want to control (field Length). For a 8x32 LED Matrix, that’s 256 LEDs:

   

3. Adjust Data GPIO to match the pin that you later want to use to control the LED Matrix. By default, this is set to GPIO 2. If you are using an ESP32 C3 SuperMini, you may want to change it to GPIO 4 because this pin is closer to the power supply pin, making assembly easier.

Click Save at the top or bottom of the page to store your settings. You’ll then return to the main settings menu. Then, back in the main menu, click 2D Configuration to proceed with the final step.

2D Configuration

WLED controls any number of programmable LEDs, whether they are laid out as a single strip or wrapped as a matrix. In order for the light effects to look right, you need to tell WLED the layout of your matrix:

1. Change the 2D Configuration settings: under Strip or panel, select 2D Matrix.

   

2. Scroll down to the section LED panel layout. Since the matrix we are using is not symmetrical (width and height are different), in Orientation choose Vertical. Check Serpentine. In the section below, you now see how the LEDs are expected to be connected. The serpentine style matches most commercially available LED matrix panels.

3. In Dimensions, specify the size of your panel: 32x8. Then click Save.

   

Make sure the panel layout in the picture below the settings matches your panel. On the backside of your panel, you can typically see the traces and how they are oriented. Each panel really is just a LED strip placed on the PCB, and WLED needs to know how the strip is layed out to correctly show light effects, especially Scrolling Text.

LED Matrix Panel Preparation

Most 8x32 LED Matrix Panels come with some wires and plugs preassembled:

These cables need to be desoldered first.

Desoldering works best when you use some flux. Set your soldering iron to a high temperature (such as 430°C), but only touch the pads for a few seconds so you don’t damage the panel.

Once the old cables are removed, generously apply fresh solder to the pads. The matrix panel now should look similar to this:

Some sellers offer “water-proof” panels. Do not buy these, and save the considerably higher cost! They are using the very same LED panels and only add silicone to the soldering pads, making desoldering a lot harder.

Adding New Wires

Now, add the new wiring to your matrix panel according to the schematics above, and connect all 5V pads with one wire, and all GND pads with another.

Do not forget to add the cables to connect the microcontroller and external USB plug.

Twisting together the wire ends before tinning them makes assembly a lot easier.

If you have a cutter knive, you can also use just one long cable and remove the insulation mid-span:

Data Cable

Solder one data cable to DIN (do not confuse it with DOUT). This is the control wire that later controls the LED (color, brightness).

3. Assembly

Now add the microcontroller and external USB plug:

1. Connect the smaller spare power wires that you soldered to the LED matrix panel to the 5V and G pins of your microcontroller.

   

2. Connect the data cable that you soldered to DIN (not DOUT!) to the pin labeled 2 on your microcontroller board (unless you changed the GPIO number in the WLED settings).

3. Connect the larger spare power wires that you soldered to the LED matrix panel to the pins VBUS and GND.

   

Here is a picture of the complete wiring:

Test Run

Once you connect the microcontroller to power by plugging in a USB cable, the LED matrix should start to glow orange. This is the default behavior. If the LED matrix stays dark, something is amiss.

If the LED panel does not light up, measure the voltage at pins 5V and G, and verify that you can measure 5V. Ensure the data cable is connecting pin 2 on the microcontroller to the DIN pin on the LED panel. Double-check that you did not accidentally connect to DOUT. Finally, connect to the device and access the WLED configuration (see the initial section). Ensure you did not change the GPIO assignment, and if you did intentionally, confirm your assigned GPIO matches the GPIO that you connected the data cable to. Keep in mind that pin labels like D2 on some microcontrollers are not identical to GPIO 2.

Refer to the WLED article for more information on how to change colors, effects, etc.

4. Housing

For increased ruggedness and safety, mount your components in a housing.

If you have a 3D printer, you can print the housing I used below. Since the matrix dimensions are too large to print with most 3D printers, I split the housing into two parts that later snap together. You may want to use some glue to secure the parts for extra stability:

STL Files

Here are the STL files for the housing and its cover:

• Housing: Part 1 and Part 2
• Cover: Part 1 and Part 2

For the cover, print it with a transparent material—either fully transparent or a translucent white or gray. This ensures the LEDs shine through effectively.

PLA works best for the housing body, while PETG is generally more translucent for covers. Gray PETG worked best as a cover material, while black matte PLA provided an excellent finish for the body.

Combining Both Parts

Since the housing is too large for most 3D printers, it consists of two parts that snap together:

One part can be inserted into the other:

To assemble, place the right part on top of the left part, and apply pressure from the top to snap them together. Secure both parts permanently with an M3 screw:

When screwed together, the housing becomes rock solid. The screw head will sink neatly into the wall of the part:

Adding Components

Insert the USB adapter PCB into the designated recess and secure it with two M2 screws. Then slide the ESP32 C3 SuperMini into its compartment. Secure it with glue or tape:

If you decide to use different components, the housing offers plenty of room for customization. Secure your components with glue, tape, or other fasteners as needed.

Securing LED Panel

Apply double-sided tape to the designated areas inside the housing. Carefully place the LED panel, align it with the housing, and press it firmly onto the tape:

The panel also acts as a cover for the components beneath it, keeping everything secure and protected.

Adding Covers

The cover, like the housing, is split into two parts. Ensure you print it using a transparent material:

Fit the cover onto the housing. It should snap into place easily. Before securing it, perform a test to ensure the cover aligns with the LEDs and provides sufficient transparency. Once satisfied, secure it with glue:

The cover in the picture has a neat carbon-like pattern. You can achieve similar finishes on your 3D-printed parts by using a textured print plate. Affordable print plates with great patterns can be found on AliExpress or similar online stores, compatible with most 3D printers.

Scrolling Text

Large LED panels like the one in this example are perfect not just for light effects but also for displaying text. WLED includes the Scrolling Text effect, which displays the current date and time when selected. (You may want to review the time zone settings in your WLED configuration to ensure accuracy):

The Scrolling Text effect is an excellent test to verify whether your 2D Layout Settings in the WLED settings are configured correctly. If the text does not scroll horizontally or appears distorted, return to the 2D Configuration and double-check your settings. Pay close attention to the schematic display of your panel below the settings, and compare it to the physical wiring layout of your panel.

Customizing Text with Static and Scrolling Options

WLED offers a variety of options for customizing text, accessible through sliders at the bottom of the effect settings. For example, you can adjust scroll speed and font size to suit your display needs:

Displaying Custom Text

You can also display custom text, but the process to set this up is not immediately intuitive. Follow these steps:

1. At the bottom of the WLED settings, click Segments. Then, click the pencil icon and rename the segment to the text you want to display.

2. Remember to click the save icon at the bottom-right of the box to save your changes:

   

3. After saving, WLED will reset. You’ll need to reselect the Scrolling Text effect, and your custom text will now be displayed.

Static Text

If your text fits entirely on the LED panel, it will be shown as static text, and no scrolling will occur. However, when the text exceeds the display area, WLED automatically scrolls it.

There is no separate setting to toggle between static and scrolling text—the length of your text determines the behavior.

Limitations

Unfortunately, WLED does not support variable-width fonts. This limitation leads to wasted space and inconsistent appearance, particularly when displaying numbers or narrow letters.

As a result, an 8x32 display like the one in this project is not ideal for displaying static text. The text would need to be very small to fit completely and avoid scrolling.

For professional or practical use cases requiring static text, such as “DOCTOR,” “EMERGENCY,” or “POLICE,” an 8x32 display often falls just short of the required space or lacks an efficient font. If this is your goal, consider the following options:

• Expand Your Display: Programmable LED panels can be easily daisy-chained to increase size. The flexible panel used in this project is also available as an 8x8 matrix. To extend your display, connect the DIN pin of an additional panel to the DOUT pin of the first panel. This allows you to create configurations like 8x40 or larger. Alternatively, you can start with 8x8 panels on solid PCBs, as seen in this project, and daisy-chain them to achieve your desired dimensions.
• Use Better Firmware: While WLED is an excellent multi-purpose firmware, it is not optimized for displaying static text. If static text in a crisp and space-efficient font is your priority, consider writing your own firmware. The Adafruit NeoMatrix library simplifies rendering custom text and offers complete control over your display. You can use the same hardware presented here and simply upload your custom firmware to the microcontroller.

Materials

STL file for WLED Matrix Mount Part 1 STL file for WLED Matrix Mount Part 2
STL file for Cover (Part1) STL file for Cover (Part2)

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