Sensing Movement

Sensing Movement using the 3-Axis Accelerometer

• Read: Lesson 10: Sensing Movement

• The "3-Axis-Acceleration" module on the Grove Beginner Kit can be used to determine:

  • tilt/orientation:
    A smartphone uses this type of sensor to switch from portrait to landscape mode display when you rotate the phone, for example.

  • motion:
    steps, free-fall, crashes, taps, drops, etc.
    A fitness watch use this type of sensor to measures steps and other activity.

• The module uses the STMicroelectronics LIS3DH 3-axis MEMS accelerometer.

  • MEMS = Micro Electromechanical System, a nano-scale combination of mechanical moving parts and electronics.

  • This accelerometer senses the gravitational force of the earth in the x, y, and z axis.

• Click the Connect button and select the device for your Grove Board (same as you use to Upload)

• Click the Serial Monitor button

• On the lower right of the Serial Monitor window, change the Baud rate to 19200.

• You should see text like:
  printf(0.01,0.19,0.98,null,null)
  printf(0.01,0.00,1.00,null,null)
  printf(0.01,-0.01,1.00,null,null)
  ...

• Click the Serial Plotter button

• Assuming that your kit is on a level surface, note that the x acceleration value is around 1, while x and y are zero.
  This means that the z axis is experiencing 1 G of force.

• Turn the board upside down and notice that the z value goes to -1.

• Tilt the board slowly to the left and right and notice that the y value moves between -1 and 1. It is 0 when the board is vertical.

• Keeping the board level on the table, rotate it around the vertical (z) axis. Are the x, y, z values changing? Why or why not?

• Tap or shake the board and notice the x, y, and z values.