BlinkBox – A test tool for addressable LED development

I work with addressable LEDs a lot. For all that they’re great for, they’re kind of hard to debug when you have a lot of them connected up at once. This is especially apparent when you have many small single modules in hard to reach spaces.

Here’s my solution:

This lets me set the color and number of LEDs in a strip, and then displays a color pattern. This way I can tell if an LED has become disconnected in a strip, or if a channel  inside a particular has died.


  • Select LED type with the type switch, 4 positions
  • Can test up to 400 LEDs at a time, if you can find a worthy power supply
  • 3 Test modes
    • RGB – 1 second red, 1 second green, 1 second blue
    • HUE – Lock strip at HSV (x, 255, 255) and x loops from 0-255
    • WHTE – Set the strip to RGB(255, 255, 255)
  • Count and Mode are saved into eeprom, so you don’t have to keep resetting the strip if it powers off
  • Wall mount fittings

Design Explanation

All of the raw code solidworks, and KiCAD have been posted on my github. You can look at the 3D models on thingiverse as well.


Here are a couple of quick renders of the assembly design:

The screw mount behind the pushbuttons is extended to be able to support the pressure without flexing:
I added a ridge so you can grab onto something as you interact with the switches / buttons.


Here’s the circuit:

There really isn’t a lot going on here, the parts are probably the coolest part of the project. The 5V jack is a 6mm DC barrel jack, the pushbuttons are illuminated 16mm pushbuttons from adafruit,  the on/off switch is a locking toggle switch, and the 4 position rotary switch can be found here.

I wired up the circuit on a spare piece of perfboard.


My code is available on my github.

The LED driving part of the code is based on FastLED, a beautiful library for driving these types of addressable LEDs.

The rest of the code is mostly just a hardware UI problem, and isn’t all that interesting. LED count “ramps” as you hold the button down. The longer you hold the button, the faster the

Wrap up

That’s pretty much it! I’ve already gotten some use out of this tool and have found great satisfaction in taking the time to make it look nice as it will be a permanent addition to my lab.

I’ll post any updates I make to this project as edits to the top of this post.

Thanks for reading, and here are a few more photos:

Hey! This post was written by Devon Bray, Co-Founder at Telapush. It was originally posted on his blog which you can check out here.

Why you should use Processes instead of Threads to isolate loads in Python

Key Learning

Python uses a Global Interpreter Lock to make sure that  memory shared between threads isn’t corrupted. This is a design choice of the language that has it’s pros and cons. One of these cons is that in multi-threaded applications where at least one  thread applies a large load to the CPU, all other threads will slow down as well.

For multi-threaded Python applications that are at least somewhat time-sensitive, you should use Processes over Threads.


I wrote a simple python script to show this phenomenon. Let’s take a look.

The core is this increment function. It takes in a Value and then sets it over and over, increment each loop, until the running_flag is set to false. The value of count_value is what is graphed later on, and is the measure of how fast things are going.

The other important bit is the load function:

Like incrementload is the target of a thread or process. The z variable quickly becomes large and computing the loop becomes difficult quickly.

The rest of the code is just a way to have different combinations of increment and load running at the same time for varying amounts of time.


The graph really tells the story. Without the load thread running, the process and thread versions of increment run at essentially the same rate. When the load thread is running, increment  in a thread grinds to a halt compared to the process which is unaffected.

That’s all! I’ve pasted the full source below so you can try the experiment yourself.

Hey! This post was written by Devon Bray, Co-Founder at Telapush. It was originally posted on his blog which you can check out here.