Z-Axis: Which Way Is Up?

Did you remember that the micro:bit module’s accelerometer also has a z-axis? 

Like the hyp calculation from the previous activity, the accelerometer’s z sensing axis can give your script information about the overall level of tilt. 

The main advantage of using the z-axis is that it can also tell your script whether the accelerometer is facing up or down.  In fact, the hyp calculation is normally only used with two-axis (x-y) accelerometers.  Since the micro:bit has a three-axis (x-y-z) accelerometer, scripts can use a combination of atan2(y, x) and z-axis measurements and calculations to get both rotation and tilt level. 

In other words, the script can know exactly how the micro:bit is oriented in space.  

Example script: test-z-axis-tilt

  • Enter and save test-z-axis-tilt.
  • Flash it into the micro:bit.
# test-z-axis-tilt

from microbit import *


while True:

    z = accelerometer.get_z()
    print("z =", z)

  • Open the terminal and experiment with various levels of tilt and rotation.
  • Try holding the micro:bit level with its LEDs facing the floor.  Were you able to get a z-axis measurement in the neighborhood of 1024?
  • Next, try holding the micro:bit vertical.  Is the z-axis measurement close to zero?
  • Last, try holding the micro:bit level, but with the LEDs facing up.  Verify that the z-axis measurement is in the 1024 neighborhood.