Electronic – IMU (ADXL345 & ITG3200). Triple Axis Filter

To decode the number into decimal, convert it to something your processor understands natively, then use the existing binary to decimal conversion capabilities to convert to decimal. To convert to native integer representation, all you have to do is sign extend:

II is native signed integer
II <-- 13 bit signed A/D value  (get the A/D result)
II <-- II & 1FFFh               (make really sure limited to 13 bits)
if II >= 1000h                   (negative value ?)
  then II <-- II - 2000h        (convert to native negative)

Note that this is independent of how wide the native signed integer is, as long as it's more than 13 bits. This means this technique works for both 16 bit and 32 bit signed integers.

Edit: fixed details of sign extending above. I wrote it right on the scribble paper next to my keyboard, then copied it into the post wrong. Also added note about it being independent of the native integer size.

I've worked on a project to implement the Kalman filter on an embedded system that was similar in hardware to the iNemo unit from STMicroelectronics.

Even if you can find these IMU (Inertial Measuring Unit) with 90% chance you will have to implement your algorithm by yourself; or if you're lucky, you can find someone that has the code. The problem is that this filter requires a lot of computation, and in our best experiment (using fixed point variables and trying to optimize the code) we were able to run it 45 times per second, in a STM32 at 72 MHz.

So maybe there is one, but as far as I know requires a good microcontroller or maybe a FPGA\ASIC.