from microbit import *
# simple compass
# compass.heading() measures magnetic field

# taken from page 69 of BBC Micro:bit MicroPython PDF (August 2016)
# from https://media.readthedocs.org/pdf/microbit-micropython/latest/microbit-micropython.pdf

# creates a simple compass - it starts with a calibration 'game' first then goes 
# on to the rest of the program


# start calibration
compass.calibrate()

# tries to keep the needle pointing in the roughly correct direction
while True:
    sleep (100)
    needle = ((15 - compass.heading()) // 30) % 12 
    display.show (Image.ALL_CLOCKS[needle])