Femtoduino: designing an ultrasmall arduino compatible board with the ATMEGA 328P QFN/MLF32

Last updated on Wed, 2011-02-16 12:22. Originally submitted by fabio on 2010-12-29 15:45.

UPDATE 2011-02-16: Femtoduino has now its own project page where you will find all the design sources and all the informations on it.

As a personal learning exercise and challenge to myself, I designed an ultrasmall Arduino compatible board based on the ATMEGA 328P in the QFN/MLF32 package.

Using the smallest 328P uC currently available, very small package components (eg 0402 caps and resistors) and 0.05" headers I've been able to design an Arduino compatible board which is only 20.7x15.2 mm.

Given that the Arduino Pro Mini, currently the smallest Arduino board available, is 34x18 mm and I restricted myself to use a 2 side PCB, I think I accomplished a pretty good result.

I called this board Femtoduino. Have a look at the schematics. Of course this will be a free (as in speech) hardware.

Femtoduino PCB desing

I plan to submit this board to the DorkbotPDX group PCB order of the 3rd January and I'm currently looking for reviews for the project. So, if you have knowledge of this topics please have a look at the Femtoduino designs.

You can get the Kicad sources (as of 30-12-2010) from the attachments below. I'm using a weekly updated version of Kicad, so if you have problems with older versions of Kicad you can try use a recent snapshot for Windows or Ubuntu 10.10.

You can get the most updated sources from my personal repository using bzr with the following command:

bzr co http://repository.varesano.net/Femtoduino

Thanks for your help!

UPDATE 2011-01-28:

I've been able to reflow solder femtoduino and all it's components, including 0402 capacitors! See a picture of Femtoduino!

UPDATE 2011-01-29:

Femtoduino is alive!

AttachmentSize
Femtoduino-20101230_0141.tar_.gz120.24 KB
Femtoduino-20101230_0221.pdf59.07 KB
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question

Submitted by Bryan Burrma (not verified) on Fri, 2011-05-06 00:03.

Hi Fabio,

Can I ask what may appear to be a odd question? I have read a bit of your site and I cant see if these are available to buy yet or not? if so how much money are they selling for?

Id love to know where I can buy some as I have an application that needs small boards like your design.

thanks Bryan

They are for sale

Submitted by Femtoduino Sales (not verified) on Thu, 2012-04-19 19:19.

You can buy them at www.femtoduino.com

Part of the proceeds are donated back to Fabio's site.

- Alex Albino

Hi Bryan, thanks for your

Submitted by fabio on Fri, 2011-05-06 00:18.

Hi Bryan, thanks for your interest in my Femtoduino project!

Even if Femtoduino generated a quite big interest online I'm still not aware of anyone selling it. I have received requests from people who wanted to commercially build the Femtos but I still didn't see any of these people selling them.

Meanwhile I may be able to send you some spare Femtoduino prototypes, get in touch if this interests you.

Thanks!

Probably a newbie question

Submitted by Bob (not verified) on Wed, 2011-04-20 02:33.

Figuring out how to go tiny was a big part of my motivation when I started learning some Arduino stuff a few months back, so this project is hugely interesting. Please forgive me if this is a dumb question, but thus far I've only done stuff with manufactured (Uno) boards. I've read about needing to get chips with the Arduino bootloader preinstalled of you want to move beyond prefabricated Arduino boards. I can't figure it out from the specs I see when I follow your parts list, so does the chip you use in this project come with the bootloader? I.e. once you've built the Femto can you just connect it to a USB-serial board and upload a sketch or is there another step that has to be done to program the chip to be Arduino-ready?

I'm using raw ATMEGA 328p

Submitted by fabio on Wed, 2011-04-20 06:12.

I'm using raw ATMEGA 328p QFN32 chips without any bootloader preloaded. I do load the bootloader by using the ArduinoISP technique which so far has worked great (but only under Windows, not on Linux).

For more details on the Femtoduino project, its schematics and PCB designs, Gerbers and bill of materials please check the Femtoduino project page.

Thanks

Submitted by Bob (not verified) on Wed, 2011-04-20 14:46.

OK. Thanks for clearing that up. I guess it's time to buy some regular chips and see if I can load the bootloader there, and then if all goes well see if I can replicate what you have done. Don't hold your breath, but if I am successful I'll post something here.

Batteries

Submitted by Bob (not verified) on Thu, 2011-04-21 03:48.

I may as well ask: as you're getting things as small as possible, what battery do you use?

The practical usage of

Submitted by fabio on Thu, 2011-04-21 10:56.

The practical usage of Femtoduino has been quite limited and at the moment I don't have any suggestion for small batteries.. I'll let you know when I sort this out.

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