Guide to gyro and accelerometer with Arduino including Kalman filtering

Hallo Lauszus, Thanks so much for this great blog. I need ur help with something. I'm using itg 3200 and bma 180, I applied your code and it works fine but when rotating around roll for exaple with 90 degrees, the output reading is 70 and the same for pitch although before that, i was applying a comp filter (explained by starlino) and it was giving an output of 90 when rotating with 90 degrees. Do you have any idea what might be causing that?