alex8toh

yes, what is the nfc() function ? // do the integral thing ax = (float(aaWorld.x)/16384)*G; // convert to cm / s ay = (float(aaWorld.y)/16384)*G; Serial.print(ax); Serial.print("\t"); Serial.println(ay); vx = prevVx + ((prevAx+ax)/2)*dt; vy = prevVy + ((prevAy+ay)/2)*dt; prevPx = prevPx + ((prevVx+vx)/2)*dt; prevPy = prevPy + ((prevVy+vy)/2)*dt; prevVx = vx; prevVy = vy; prevAx = ax; prevAy = ay; I'm experiencing the drifting problem. Please advise !