The Accelerometer

Most of the inputs provided by the Circuit Playground or micro:bit are relatively simple devices, which give a single value. The accelerometer is a more complex kind of sensor, which measures a number of different things all at once, and therefore provides more complex information to the user.

An accelerometer is commonly used to detect movement and position in devices like laptops, phones, virtual reality controllers, and health trackers. For example, pedometers use the movement from accelerometers to track how many steps you take.

Measuring Orientation

The accelerometer can determine the orientation of the board to figure out how the board is positioned.

Orientation	Type of Motion Being Tracked	Range of Values
Pitch	Forward and back motion	-90 to 90
Roll	Side to side motion	-90 to 90
Inclination	Rotational motion	-180 to 180

Using the accelerometer.getOrientation() block, we write programs that respond to changes in pitch, roll, and inclination. This block returns a number for each of these orientations which indicates which way the board is tilting. For example, pitch is positive when it's being tilted back, and negative when being tilted forward.

Acelerometer Events

Just like the other sensors, the accelerometer has the data and change events. These are particularly useful because they allow you to constantly track the updated values of the accelerometer, like the orientation.

Event	Description
data	Fires every 100ms to check for data from the accelerometer.
change	Fires whenever the accelerometer detects a change in motion. This checks to see if the current data from sensor is the same as it was 100ms ago. If this is the case, the event won't trigger. Otherwise, the event triggers.
shake	Fires whenever the board is shaken.

Sometimes we don't care what the orientation of the board is, we just cared that it moved at all. This is where events like change and shake come in.