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smart 14 segment LED display

Inspired by this did started to think about small alphanumeric displays. Most of them are old and obsolete and because of that quite expensive. But you can get more modern 14 segment LED displays. I decided to use six digit one like this:
(Image by seedstudio)

For controlling this I decided to develop a PCB which does have the same size as the display. For controlling this I will use an ATmega8, a MAX6971 16 channel led driver and some p-channel mosfets. First I will use it as a stand alone thing, but the PCB hast connection for i2c and uart, so this could be also the display for something else.

Here a picture of the PCB design:

I did sent this PCB to osh-park. And got them delivered as you can see in the next picture:

I did also soldered one. I do not know weather they are working, because I did not code any software yet. This and probably some hardware debuggnig will be the next step. More information and progess will come soon.


Eagle Lib for the segment display used

lbr - 9.88 kB - 03/17/2018 at 14:20


  • Serial inout now working

    Alex02/01/2016 at 16:55 1 comment

    So after the basic firmware which I did first for testing, I did now expand that a bit. Now characters received over the the UART interface are shown on the display. The characters a decoded as normal ASCII characters. After some trouble this is also working stable. Thinks that gone wrong:

    • Using the TX line as a digit output was not a good idea. I do have even PINs left over.
    • UART on a AVR does not work good with the internal oscillator. So I had to solder a resonator on the PCB (footprint was available)

    Some ideas for a next revision:

    • Do not use TX for segment.
    • Make TX accessible from the side to chain displays

    So here is a picture showing some test letters. The board in the front is a normal USB to UART converter.

    The characters sent here are:


    One good thing about using the serial interface is that you get a display which is compatible to a huge number of devices.

    I did also add a link to bitbucket repository. There you can find the early firmware version of today.

  • HelloW(orld)

    Alex01/31/2016 at 14:28 3 comments

    Here is a first image of a working display. The software is not ready yet. There is still a lot to do. The test firmware used for this picture can just show this HelloW(orld) example and nothing more.

View all 2 project logs

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deʃhipu wrote 02/01/2016 at 15:31 point

What's the gray thing around the edge of the PCB?

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Alex wrote 02/01/2016 at 15:46 point

I not sure what you mean. But there is white silkscreen frame on top (side with the ICs). This frame is mostly to hide the pruple PCB on top side.

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deʃhipu wrote 02/01/2016 at 15:47 point

Ah, I see. That's it, thanks.

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danjovic wrote 01/31/2016 at 23:34 point

Amazing! Congratulations for the build. Just loved the PCB!

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Alex wrote 02/01/2016 at 14:10 point


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jaromir.sukuba wrote 01/31/2016 at 18:48 point

The display module looks sweet. What is that? I tried to search for JM-S03961BH-001 but no avail.

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jaromir.sukuba wrote 01/31/2016 at 19:35 point

Oh crap, the shipping is way too high and the modules itself aren't cheap either. There aren't much sellers of this display, so I'll probably wait a bit until it gets cheaper.

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Alex wrote 01/31/2016 at 19:48 point


I did pay 2.6US$ each and the same for shipping. I did bought them here:

But they are no more available. This could be because of chinese new year next week.
This should be also the same display:

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jaromir.sukuba wrote 01/31/2016 at 19:49 point

Oh, that's much better, thank you!

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davedarko wrote 02/01/2016 at 09:01 point

Right, seeedstudio was the link... damn. But the picture is exactly the same, maybe that's what confused me! 

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davedarko wrote 12/21/2015 at 18:53 point

woahhhh. By the way I got some more of these displays :) 

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