HowTo: pxlBlck – Build the pxlDigit_clock using the pxlDigit_PCB

I got the idea for the pxlDigit_PCB while building the pxlDigit (article here: https://nerdiy.de/howto-elektronik-seven-segment-digit-pxldigit-aus-ws2812-leds-bauen/).

There the pxlDigit is made up of individual WS2812 LED segments. To do this, the LEDs must first be glued into the 3D printed housing and then soldered together in the housing. This step in particular is not that easy due to the lack of space. :/

That’s why I have the pxlDigit_PCB designed. The LEDs, the ESP8285 and the rest of the electronics can be installed on it. So you can first build, test and program the entire board and then insert it into the 3D printed housing of the pxlDigit or the pxlDigit_clock.

Thanks to the integrated USB-C connection, the pxlDigit can also be supplied with power directly and, if necessary, the firmware can be programmed.

The following (optional) components can also be installed on the PCB:

  • BME280 climate sensor
  • TSL2591 brightness sensor
  • MPR121 touch sensor for up to 12 touch electrodes< /li>

In order for the pxlDigit PCB to work properly, it should be built into the 3D printed case. In this way, the light from the LEDs is better distributed and the individual digits can be easily combined to form a larger display. You can use the numbers to build a follower counter, a score display or a clock, for example.

Four digits are required to build the clock, which are then mounted on a 3D printed base. This is how the current number of hours and minutes can be displayed.

Of course there are other ways to use the pxlDigit_PCB as a display. The pxlDigit_clock shown in the following article is a first example. 🙂

The structure of the clock “pxlBlck_digitClock” is described in the following article.


Safety instructions

I know the following hints are always a bit annoying and seem unnecessary. But unfortunately, many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. In comparison, a loss of data is almost not worth mentioning, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Even the coolest project is worth no injury or other annoyance. https://www.nerdiy.de/en/sicherheitshinweise/

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Requirements

Für den Aufbau müsst ihr SMD Lötaufgaben bewältigen. Die folgenden Artikel enthalten Tipps dazu.

Required tools:

QuantityItemLink
1xsoldering ironBei Amazon kaufen
1xUSB-soldering ironBei Amazon kaufen
1xthird-handBei Amazon kaufen
1xsoldering tip cleanerBei Amazon kaufen
1xhot glue gunBei Amazon kaufen
1xSLA 3D-printerBei Amazon kaufen
1xM2 internal tapBei Amazon kaufen
1xM3 internal tapBei Amazon kaufen
1xM8 internal tapBei Amazon kaufen
1xM8 external tapBei Amazon kaufen
1xTorx screwdriverBei Amazon kaufen

Required material:

QuantityItemLink
1xM2x6 grub screwBei Amazon kaufen
6xM2x6 countersunk screwBei Amazon kaufen
3xM3x6 grub screwBei Amazon kaufen
1xM3x50 countersunk screw Bei Amazon kaufen
6xM2 threaded insert Bei Amazon kaufen
3xM3 threaded insert Bei Amazon kaufen
3xcylinder magnet 5x2mm Bei Amazon kaufen
1xcylinder magnet 10x5mmhttps://www.supermagnete.de/scheibenmagnete-neodym/scheibenmagnet-10mm-5mm_S-10-05-DN
1x623 ball-bearing Bei Amazon kaufen
2x608 ball-bearing Bei Amazon kaufen
1xJST SH connection cable Bei Amazon kaufen
1xELEGOO ABS-Like 3D Resin Bei Amazon kaufen
1xGlue Bei Amazon kaufen
1x10x2mm aluminum tube Bei Amazon kaufen
1xsolder Bei Amazon kaufen
1xUSB power adapter Bei Amazon kaufen
1xUSB-C cable Bei Amazon kaufen

The components required to assemble the pxlDigit PCB can be found in the following file.

If there are more recent versions of the pxlDigit board, you can find the available versions in the Git repository at:


The structure of the pxlDigit board

In the past I have often inserted individual pictures at this point to show which components have to be soldered where on the PCB.

An even better way to get an overview of which components belong where on the PCB is in the following paragraph. Thanks to the work of Open Scope Project You can now generate very helpful HTML files in which you can see directly which components have to be installed where on the PCB.

You can see the overview for the pxlDigit_PCB here: pxlDigit_PCB

You can also find the current file in the GIT repository under the following link:
https://github.com/Nerdiyde/pxlDigit_PCB/blob/main/PCB/pxlDigit_PCB_v1.2_bom.html
(Please note that you have to download the HTML file to view it. This is not possible directly from the GIT repository.)

PCB manufacturing: You can find all the information you need to manufacture the PCBs here:


The materials needed to build the pxlDigit_clock

The required parts are briefly described in the following section.

You can find the required STL files for 3D printing the housing parts in the GIT repository under the following link.

The following article describes how you can download files from a GIT repository.

You will then need the following parts for assembly.

  • 3x assembled “slave” pxlDigit PCB
  • 1x assembled “master” pxlDigit PCB
  • 4x 3D printed housing
  • 3D printed base
  • 28x 3D printed transparent filament diffuser
  • 8x M3x8 cylinder head screw
  • USB breakout board
  • Wifi patch antenna with UFL connection
  • 3x 25cm cable 0.2mm² in (e.g.) red
  • 3x 25cm cable 0.2mm² in (e.g.) black
  • 3x 25cm cable 0.2mm² in (e.g.) green
  • 15cm cable 0.2mm² in (e.g.) red
  • 15cm cable 0.2mm² in (e.g.) black

Below you can see a few close-ups of the required parts.


Prepare the pxlDigit boards for installation

First you should connect the prepared circuit boards with the necessary connections and cables.

For this you need the four assembled pxlDigit boards. (3x slave version, 1x master version)

A circuit board should be equipped with a USB-C connection, ESP and the electronics required for programming. The three remaining circuit boards only have to be equipped with the LEDs or the components required for them.

You also need the prepared lines.

  • 3x 25cm cable 0.2mm² in (e.g.) red
  • 3x 25cm cable 0.2mm² in (e.g.) black
  • 3x 25cm cable 0.2mm² in (e.g.) green
  • 15cm cable 0.2mm² in (e.g.) red
  • 15cm cable 0.2mm² in (e.g.) black

Then tin the connection pads on the pxlDigit PCB…

… with some solder.

You should also prepare the lines by stripping the ends of the lines…

… and tinned with some solder.

Then you can connect the lines as shown…

… solder to the pxlDigit PCB.

Repeat this for all “slave” PCBs (PCBs on which only the LEDs are assembled).

The PCB which is equipped with the LEDs and the electronics (ESP & Co) required for operation (master version) should then be soldered to the other two lines.

These two wires are only connected to the contacts

  • GND
  • 5V


Prepare the housing parts

So that you can install the prepared PCBs in the housing parts, you should now prepare the housing parts.

For this you need

  • 4x 3D printed circuit board holders
  • the 3D printed base
  • 8x M3x8 cylinder head screws

You should first edit one of the circuit board holders. In addition to the USB-C connection, the connecting cables will later fit through the opening shown.

This is what the finished circuit board holder could look like.

Now you should put two M3x8 cylinder head screws each through the base as shown.

To make this easier, you can use the circuit board holder as a shelf.

Then screw the base to the board bracket as shown.

Another view.

Another view.

Repeat this step for all four board holders.

Another view.


Install the prepared circuit boards in the housing

Now you can install the circuit boards in the brackets.

For this you need the prepared pxlDigit PCBs and the prepared bracket.

Place the first (slave) PCB at the number on the far right and thread the lines through the openings in the housing as shown.

Another view.

Another view.

You should then thread the data line which is connected to the LIN pin on the pxlDigit PCB (in this example the pink line) through the opening of the next PCB as shown.

Another view.

Then you can insert the PCB into the case as shown.

Now repeat the previous steps for the next pxlDigit PCB.

Another view.

After threading the wires through the openings as before, you can solder the data wire from the previous PCB to the current PCB’s LOUT pin.

Another view.

Then repeat this again until you have all slave PCBs and the master PCB in position.

With the master PCB, of course, only the LOUT pin is connected to the data line of the previous PCB.

Another view.

Before you insert the master PCB into the holder, you should now connect the WiFi antenna.

To do this, guide the connecting cable of the antenna through the opening in the bracket.

The UFL connection of the antenna should then…

… be connected to the UFL socket on the master PCB.

You can then mount the antenna as shown…

… and glue it into the base.

Now you can already insert all PCBs into the housing.

At this point I recommend testing the setup. So you can already load the firmware and test that all LEDs are controlled correctly.

So that the PCBs are securely fixed in the holder…

… you can fix them with a drop of hot glue if necessary.

The current structure should now look something like this.

At this point you can combine the power supply lines as shown.

Then thread all the wires to the side of the master PCB.

In order to then connect these lines to the USB breakout, you should first tin the contacts

  • GND
  • VBUS

Then you can connect the power supply lines as shown…

… and solder them to the USB breakout board.

Make sure that there are no short circuits to the neighboring contacts.

You can then glue the USB breakout board…

… with some hot glue…

… into the base as shown.

Another view.

Another view.

Another view.

At this point you should also do a small function test. The pxlDigit_clock should now be able to be supplied with energy via the USB port of the breakout board.


Insert the diffuser

The light from the LEDs in the individual segments only works really well when it is evenly distributed. This can be achieved very well by inserting a diffuser into the housing.

For this you need the prepared pxlDigit_clock and 28x 3D printed diffuser parts.

Insertion works very easily if you let the base of the housing protrude over the edge of a table as shown.

Then you can insert the diffuser as shown. If these are too loose in the case, you can also glue them to the case with a small drop of glue.

As soon as you have used all diffusers, your structure should look like this.

Another view.

Another view.

In operation, thanks to the diffuser, there should then be an even distribution of light.


Programing the firmware

I’m currently still working on a simple Arduino library to control the pxlDigits. Until this is ready you can also install and configure the pxlBlck Firmware. This already supports the LED matrix form of the pxlDigit and also offers useful functions for automation and control via WiFi or the serial interface. You can also find general information about the pxlBlck plugin here:

You can find information about installing the pxlBlck plugin here:


Configure the pxlBlck plugin

After installing the firmware, you still have to configure the plugin correctly. You can also find information about this in the article pxlBlck – Install and configure the pxlBlck plugin.

As an additional orientation, you can also use the settings from the screenshot shown here.


pxlBlck Usecases

Under the “pxlBlckUsecase” tag, articles are listed in which you can find examples of use. It also explains how you can configure your pxlBlck accordingly.


Animations, icons and commands

You can find more information about the display of animations, icons and the possible commands with which you can configure your pxlBlck in the following articles.


Have fun with the project

I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂

P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate it that I share these information with you, I would be happy about a small donation to the coffee box. 🙂

Buy Me a Coffee at ko-fi.com   

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