FreeIMU: free (as in speech) 9DOF/DOM IMU

In the past months I worked a lot on accelerometers, gyroscopes and digital compasses. I'm now pretty intimate with the ADXL345, the ITG3200 and the HMC5843.

I've been able to design and construct homebrew DIY breakout board PCBs for all of them (ADXL345 and ITG3200) and to create a nice library to use them which also implement a great sensor fusion algorithm capable of running on the Arduino without problems.

I'm now making the next step. Let me introduce FreeIMU.

FreeIMU is a 9 DOM/DOF MARG IMU based on the ADXL345, the ITG3200 and the HMC5843. As this is part of my Master of Science Project and that I completely share the openness of projects like Arduino, FreeIMU will be completely open: all the designs will be released under a Creative Commons Attribution-ShareAlike 3.0 Unported while all the software will be release under GNU GPL v3.

As my background is in computer science, I'm quite self-taught in PCB designs and in electronics in general. So, I'm now seeking review for FreeIMU's schematics and PCB designs. If you have experience working with IMUs, designing PCBs or circuits and you would like to contribute to a free project please have a look at the designs and feel free to comment it.

I'm using kicad as schematics and PCB editing software. It's free (as in speech) software and, once you get around its glitches, it works really well. Using non-free software like EAGLE to design a free hardware like FreeIMU would have been simply senseless.

Note: I'm using a nightly updated version of Kicad, so if you have problems opening the files you might need to update your version of Kicad.

So, you'll find the current Kicad based sources of FreeIMU here. You'll also need a library of components which is here. For your convenience there's also a pdf version of the schematics.

I plan to submit FreeIMU to DorkbotPDX PCB Order of the 13th December to have it constructed. I currently don't see this as a commercial project but if someone is interested in FreeIMU I could sell a couple of boards.

Ok, so.. looking forward to hear your comments. Thanks!

Hi Fabio, Great board. I am curious about the method you used to solder the very small components, especially the IC's. I am still considering to use the ITG 3200 in a project but I doubt between a ready-made and a self-made outbreak board. I prefer the diy method but how to do it on the proper way. Please give me some instructions.

FreeIMU is still a work in progress. I sent the PCB designs out for fabrication today and they’ll be here in a couple of weeks… So, I still did not soldered anything to it.

But I do have soldered QFN ICs into homebrew DIY pcbs. You can see some:
http://www.varesano.net/blog/fabio/new-homebrew-diy-breakout-board-pcb-adxl345-accelerometer
http://www.varesano.net/blog/fabio/homebrew-diy-breakout-board-itg3200-gyroscope-tested-arduino-and-processing

On the above links you have my schematics and designs for an homebrew PCB for the ITG3200, in case you decide to build it.

Regarding soldering, I’m using solder past in syringe + “reflow” pizza oven (not to be used for anything else eg cooking).

Alternative ways:
Hot air gun: http://www.youtube.com/watch?v=c_Qt5CtUlqY&feature=related
Skillet: DIY Surface Mount on a Budget – Complete Walkthrough from PCB etching to Reflow – Starlino Electronics

Please open a separate thread if you need more infos (send me the link so I can answer you)

Thank you so much for the info ..... and moreover.... I took your advice :)...
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1292240985/0 /me