I have an embedded device. During the boot process, the only feedback the user receives comes from a programmable RGB LED. That is, I am able to blink, fade, turn on/off etc. The whole boot process takes up to one minute.

I'd like to achieve the following impression:

  • Everything is fine
  • Please be patient while I am starting
  • Optional: Change pattern to signal end of boot process (not sure if it's a good idea).

Currently I use green (00FF00) color:

  • First, Slow (ca. 2s / cycle) fading from zero to maximum brightness (a triangle signal: /\/\/\/\).
  • Last few cycles use blinks with no fade (a pure rectangle signal ∏_∏_∏_∏).
  • After booting, the LED shines green constantly.

I didn't find research on this topic, but I certainly lack the domain vocabulary. Many devices, e.g. on my desk to do a frantic pattern. I don't like that (purely subjectively though). Another answer, however, suggests slow blinking could instead be interpreted as "low battery".

Is there some best-practice or research on:

  • How to design a "(boot) blink pattern" with UX in mind?
  • Established / well understood blink patterns on boot?

1 Answer 1


I'm not sure there is a universally accepted pattern. I'm just thinking of the devices that I usually have with me:


  • Slow blinking: connecting or doing something
  • Static: done and working
  • No light: something isn't working (not necessarily bad, sometimes it's not needed)

Home alarm (green lights only)

  • Slow blinking: everything is ok
  • Fast blinking: output mode
  • Static: turned on, but alarm disabled
  • No light: device turned off

Printer (assuming only green light):

  • Slow blinking: Waiting for something to finish
  • Static: Good and ready to work

Synthesizer (edition mode)

  • Slow blinking: Active
  • Fast blinking: Saving
  • Static: Done

Guitar looper effect (assuming green lights only)

  • Slow blinking: recording
  • Fast blinking: Saving
  • Static: In use

As you can see, 5 different devices, 5 different patterns. However, the music patterns are most similar to your approach. So if your device is audio oriented, this might be a good pattern.

So again, I really don't know of any accepted pattern. And if there is, no one seems to be using it. But assuming that you can only use one color of light, your pattern seems logical to me. On the other hand, as you might imagine, I work with music technology, and your pattern is quite common in that field.

Now, if your device isn't for music, your pattern is more of a "bomb ticker" pattern, so perhaps I'd try inverting the patterns, starting fast then going slow. Optionally, if you can graduate the speed so that it gets slower and slower until it's static, you'll get the same cognitive recognition as with a bar being filled.

  • Good hints, thanks. Indeed, inverting the "bomb timer" made it feel better to me at least. Changing colors is possible, but makes the code more complex. So I'd only do it, when there is a major improvement expected.
    – Mo_
    Jul 11, 2023 at 7:26

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