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Direction
---------
There is a compass on the BBC micro:bit. If you ever make a weather station
use the device to work out the wind direction.
Compass
+++++++
It can also tell you the direction of North like this::
from microbit import *
compass.calibrate()
while True:
needle = ((15 - compass.heading()) // 30) % 12
display.show(Image.ALL_CLOCKS[needle])
.. note::
**You must calibrate the compass before taking readings.** Failure to do so
will produce garbage results. The ``calibration`` method runs a fun little
game to help the device work out where it is in relation to the Earth's
magnetic field.
To calibrate the compass, tilt the micro:bit around until a circle of pixels is
drawn on the outside edges of the display.
The program takes the ``compass.heading`` and, using some simple yet
cunning maths, `floor division <https://en.wikipedia.org/wiki/Floor_and_ceiling_functions>`_ ``//`` and `modulo <https://en.wikipedia.org/wiki/Modulo_operation>`_ ``%``, works out the number of the clock hand to use to display on the screen
so that it is pointing roughly North.
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