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https://github.com/im-tomu/tomu-hardware

A tiny ARM microprocessor which fits in your USB port.
https://github.com/im-tomu/tomu-hardware

arm hardware hardware-device kicad tomu u2f

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A tiny ARM microprocessor which fits in your USB port.

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README 

        
# Tomu Hardware



[I'm Tomu](tomu.im) a tiny ARM microprocessor which fits in your USB port.

I have two buttons and two LEDs.



![Tomu Front Render](img/tomu-front.png)

![Tomu Back Render](img/tomu-back.png)



## Contact



We're available on mailing lists and IRC:



* [IRC Channel - irc://irc.freenode.net/#tomu](https://webchat.freenode.net/?channels=#tomu) - IRC channel for discussing anything related to the project.

* [Announcement mailing list](https://groups.google.com/forum/#!forum/tomu-announce/join) - Low traffic list for announcements.

* [Discussion mailing list](https://groups.google.com/forum/#!forum/tomu-discuss/join) - List for discussing development / new features / etc.



## About the PCB



Built out of a 3D printed part + 2 layer "thin" PCB.  LCA2018 and Crowd Supply

boards are 0.6mm.



Designs and documentation are available in:



* [`pcb/`](./pcb): [KiCad](http://kicad.org/) design files

* [`docs/`](./docs): PDF schematics, pin-out diagrams, and 3D renders



The board requirements are very lo-fi:



* 6mil traces

* 6mil clearance

* 0.3mm drill / 0.6mm vias



The primary MCU is a Silicon Labs EFM32HG309 ([datasheet](https://www.silabs.com/Support%20Documents/TechnicalDocs/EFM32HG309.pdf), [reference manual](https://www.silabs.com/Support%20Documents/TechnicalDocs/EFM32HG-RM.pdf)).



The important features are:



* [Available on Digikey](http://www.digikey.com/product-detail/en/silicon-labs/EFM32HG309F64G-A-QFN24/336-3207-ND/5142721)

* QFN24 - 5mm x 5mm package

* Inbuilt 5V to 3V3 regulator.

* Crystal-less USB



These make something which is almost hand solder-able fit into the tiny size.



## BOM



All parts are available from Digikey, and are readily available from other suppliers.



* [Kitspace Page](https://kitspace.org/boards/github.com/im-tomu/tomu-hardware/) has links to buy from multiple retailers and download the Gerbers

* [Digikey BOM in CSV format](bom-digikey.csv)

* [Digikey Shared Cart](http://www.digikey.com.au/short/39z1zv)



### Individual Parts



* Resistors

  * 2 x 0402 - 15 Ohm - [Digikey](https://www.digikey.com.au/short/3m8rz5)

  * 2 x 0402 - ~50 Ohm (Depends on LED choice)

* Capacitors - [Digikey Capacitors 0402, >1uF](https://www.digikey.com.au/short/3m8r4z)

  * 2 x Capacitor 1uF 0402

  * 1 x Capacitor 4.7uF 0402

* 2 x LED 0402

  * You choice of two different colors (might require adjustment of R1/R2).

  * 5mA LEDs are better choice.

  * Get highest millicandela rating you can.

  * [Digikey Search of LEDs in 0402 package](https://www.digikey.com.au/short/3m8rz0)

* 1 x EFM32HG309 or EMF32HG308



## Case



The PCB is thinner than a USB socket, and has exposed contacts on the reverse side, so it _needs a case_ in order to make proper contact with the USB pins, and to not short on the shield of the USB port.



Early prototypes used a business card that had been folded over, however the crowd funding campaign made enough to cut steel and make a case.



Designs are available in the [`case/`](./case) directory.  Cases for earlier board versions tend to require higher tolerance on 3D printers.



## FAQ



### Why did you create this?



The aim was to prove that a device which fits in your USB port could be created

**by hobbyists in small quantities** extremely cheaply.



### Where does the name Tomu come from?



TOMU comes from the abbreviation "Tim's Open Micro USB".



### What can I use this for?



What ever you want! If you do create something, please send me the info!



## License



The contents of this repository excluding [`third_party`

directory](./third_party) is released under your choice of the following two

licences:



* the "Creative Commons Attribution-ShareAlike 4.0 International License"

  (CC BY-SA 4.0) full text of this license is included in the

  [LICENSE.CC-BY-SA-4.0](LICENSE.CC-BY-SA-4.0) file and a copy can also be

  found at http://creativecommons.org/licenses/by-sa/4.0/

* the "TAPR Open Hardware License" full text of this license is included

  in the [LICENSE.TAPR](LICENSE.TAPR) file and a copy can also be found at

  http://www.tapr.org/OHL