The_Official_Raspberry_Pi_-_Beginner’s_Book_Vol1,_2018 (1)

182 THE OFFICIAL RASPBERRY PI BEGINNER'S GUIDE

Inertial sensing in Python

Start a new program in Thonny and save it as Sense HAT Movement. Fill in the usual starting

lines, remembering to use sense_emu if you’re using the Sense HAT emulator:

from sense_hat import SenseHat

sense = SenseHat()

sense.clear()

To use information from the IMU to work out the current orientation of the Sense HAT on its

three axes, type the following:

orientation = sense.get_orientation()

pitch = orientation["pitch"]

roll = orientation["roll"]

yaw = orientation["yaw"]

print("pitch {0} roll {1} yaw {2} ".format(pitch, roll, yaw))

Click Run and you’ll see readings for the Sense HAT’s orientation split across the three axes

(Figure 7-27). Try rotating the Sense HAT and clicking Run again; you should see the numbers

change to reflect its new orientation.

5 Figure 7-27: Showing the Sense HAT’s pitch, roll, and yaw values

The IMU can do more than measure orientation, though: it can also detect movement. To

get accurate readings for movement, the IMU needs to be read frequently in a loop: unlike

for orientation, taking a single reading won’t get you any useful information when it comes to

detecting movement. Delete everything after sense.clear() then type the following code: