Berndiboy watch - the smallest homemade Arduboy?

As i am still waiting for some parts to arrive i felt kind of borring and thought i start what i initially wanted to do: An Arduboy watch. :slight_smile:
Well i forgot to build in a timekeeping IC and also would maybe not have had space for it, so it is just the form factor of a watch (size) and not really a watch.

Size of the PCB is 42x36mm so it can compare with a commonly used smart watch at least in size. Screen size will be 0.96". I did not yet order it as i still do not know if my design works but will show pictures when i have them.


If you’re trying to save a bit of space, the FS8205A dual MOSFET is available in a SOT23-6 package, the same size as the DW01A. You could probably also find others in the same package as a substitute, if necessary, such as the DMG6968UDM

And, you could use the QFN44 package version of the ATmega32U4 (as the real Arduboy does), if your soldering equipment and skills are up to it.

Having vias in pads is not recommended if you ever expect to use reflow soldering for production.

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Thanks, i did not know that and will consider it in the future.

I also already thought of using the smaller 32u4 like in the original Arduboy but my solder skills
will not allow me to do so :smiley: I am still learning the “hard stuff” - just did the normal part soldering
till now. So the package i used and the OLED already give enough complexity for me… Getting better so maybe a future version will use a smaller package :wink:

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ArduWatch in the future? :P

Very cool. I like seeing these type of posts, because it keeps the idea of a making a Arduboy clone in the back of my mind.

This PCB board is really handsome. Seems like a lot of hours of learning how to develop these to make it look this clean and functional.

I already asked @bateske about an Arduboy watch but seems no official plans so i decided to take it up. Already working on a version with a DS3231 but the chip is quite big so i need to rework a lot.

Yes these board designs also always looked like “wow” to me and i always thought it must be rocket science. But just took some videos and a good tool to get there. This is my second try now and only took me 3 hours to finish the PCB. So just try it out and i strongly recommend using EasyEDA as it is really easy to use and allows to directly order the PCBs.

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Thanks for the recommendation. Doubt i’ll be ready for something like this within the year, but bookmarked for future sake. Still need to get a handle on arduino first and then bread boards… oh the fun that awaits me.

Whats a board like this go for in your currency?

I ordered 10 and costs are 22.77 dollars. But then shipping of another 20 is added but still worth it i would say. And package arrived 7 days after ordering so i really cannot complain. So at the end one PCB sums up to around 5 Dollars with small quantity.

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So there is another question: why so many?

Is it because you are sharing the board with others or so you have more boards to play with? Does the vendor only provide multiples and not singles?

Well i think the minimum order is 5 and would have cost 19.xx dollars. So it was just a small amount more for double of boards.

No plans to share for the moment, just with my son i always have to share of course :wink: But there is a big risk to restroy some of the boards with the limited skills :smiley: I already destroyed 2 because i lost patience during soldering as things did not run as i wanted it. So if i would have ordered only one i would have been lost already.

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This was really hard… But somehow i was able to put all components including a DS3231 onto the tiny board. This is now the RTC edition. :slight_smile:

I was not able to put a holder for a coin cell on it so i just placed pads and in theory it should be possible to use the lipo directly to keep the time when turned off so i might try this first to save space.

I tried to avoid Vias on pads but was not always able to…


To save space you could use the DS3231MZ in the 8 pin package. And again, switch to the smaller version of the FS8205A dual MOSFET.

There are places where the cost could be lower, especially if you’re willing to wait for a long shipment time. For example PCBway: I got $5 for 10 boards and shipping as low as $9 to the US.

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Cool, thanks for the tip. Will try out next time :slight_smile:
Just realized that the blue surface finish adds another 16 dollars special fee. so at the end 15 of these tiny boards with green surface cost 6.50 dollars plus shipping.

PCBway is $5 for 10 pieces in any colour.

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Can they even make it in corn flower blue?

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I guess I should have said “any of the standard colours they offer”. Purple, matte black and matte white are extra, as well.