Improving the micro:bit LED display

The BBC micro:bit has a 5x5 array of surface mount LEDs that allow it to display one character at a time or rudimentary graphics.

I find the LEDs to be a bit too far apart to easily read the characters displayed - the dots(pixels) don't look connected when displaying a line as a row of dots.

Also the LEDs that are not illuminated are quite visible which tends to confuse what is being displayed.

I also find the LEDs to be painfully bright.

I have been experimenting with ways to improve the display to make it more legible.

I have tried many types of diffuser and different bezel arrangements, many of which improve the display.

This blog chronicles some of the work and shows what I ended up with.

It is very hard to show accurately what the micro:bit display looks like with pictures or video because the LEDs are multiplexed, which means the LEDs that are apparently illuminated are not actually on at the same time. They are rapidly sequenced - too fast for the eye to follow, so it looks like many are on at the same time.

The camera is not fooled however and normally will only take a snap shot of what is actually on at the time and it will usually miss most of the illuminated LEDs.

This is especially bad when taking video of a scrolling display - the results can look pretty random.

In the following picture I set the camera to keep its shutter open long enough for all LEDs to be captured so you can get an idea of what it really looks like.

The top row of pictures are a normal micro:bit. The bottom row of pictures show the same "E14" display through the final diffuser assembly.

The fact that the LEDs don't appear to be completely red is because the camera pixels are over saturated from the intensity.

The pixel saturation from the the LEDs in the top row is so severe, it is bleeding into adjacent camera pixels, making the LEDs look bigger than they really are, so the top row of pictures look better in the picture than they do to the eye. Hopefully this comparison still provides some indication of how much better the display looks (to me).

The following video attempts to show what the display looks like, but intelligibility suffers badly due to the frame rate and LED multiplexing effects:

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Improving the micro:bit LED display

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Below are the components that make up the diffusing bezel described in the video.

The whole bezel is 2 mm thick and simply snaps onto the tactile switches.

If you need the 3D STL files, let me know in the comments below.

I am still deciding whether to build the bezel into a full 3D case for the micro:bit.

The bezel and grid .STL files are attached.