title: Sensing acceleration w.r.t. absolute orientation
body: <p>I am trying to make a circuit which can sense acceleration in the X, Y, Z axis. (e.g. movement straight down should be in, say, Z axis - not X and Y)</p>
  
  <p>However, the circuit may not always be mounted straight - so if I want the data to be in line with the axis (i.e. compensate for being wonky), what do I need - can it be done easily? Does it need a magnetometer/gyroscope?</p>
  
  <p>I have also just found inertial measurement units - are these just a combination of gyroscope + accelerometer? Would this do the job?</p>