284 MAKING THINGS TALK Determining Orientation People have an innate ability to determine their orientation relative to the world around them, but objects don't. So orientation sensors are usually used for refining the position of objects rather than of people. In this section, you'll see two types of orientation sensors: a digital compass for determining heading relative to the Earth's magnetic field, and an accelerometer for determining orientation relative to the Earth's gravitational field. Using these two sensors, you can determine which way is north and which way is up. Project 19 Determining Heading Using a Digital Compass Calculating heading can be done using a This example uses a digital compass from Devantech,