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The TWI, Tangible Wireless IMU (Inertial Measurement Unit), is a wireless motion sensor. It is optimized to be ultra low power and tiny, 1 in x 1 in (2.5 cm x 2.5 cm).

TWI is basically composed with an ultra compact 9 axis IMU from Invensense, the MPU-9150 and a BLE cortex M0 from Nordic Semi, the nRF51822.

To make the PCB, you can get the gerbers from the OSHpark widget, or you can get the latest version from upverter.
It's still a prototype but a detailed bill of material is available here:

For a small batch, you might be interested by this awesome german-chinese company:
They charged about $450 to build 10 prototypes, absolutely everything included, even the shipping.

I developed the PCB using Upverter so feel free to fork it and improve it! Similarly, feel free to fork the Github repo and play with the software...
Enjoy ;)

Made in SF - 2013/2014

OSH park rendering

Software design


Testing bluetooth low energy

Just testing that the we can use the soft device with a BLE dongle and hcitool.

Testing the motion sensor

Just testing that we get data from the IMU, here we simply display the value of one accelerometer axis.

Build logs

investigation report
We needed more boards so we ordered 20 more but none of them worked. 

After investigation, we found that the CPU was faulty:


More details can be found in the attached report.

Read previous logs

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by Cedric Honnet

Tangible Wireless IMU (motion sensor) - in progress...

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