This page (revision-7) was last changed on 2025-07-30 13:21 by Murray Altheim

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Page References

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Micro Python Tutorial Exercise 04
MicroPythonTutorialExercise04

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%%info
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%%
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!motor_controller.py
We can define __classes__ in Python. Classes are defined globally, within the file/module as they begin in column 0.
Within a class its functions are called __methods__. Unlike functions, methods are defined within the scope of the class and are therefore indented within the class's block.
A class has a __constructor__, a special method named {{{__init__}}}. The constructor is called when you create a new object of the class. It can be said that the new object has a type of its class.
%%info
All special methods in Python are surrounded by double underscores. (There are more of these but we'll get to them later.)
%%
%%filename boo.py %%
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# motor controller class
class Boo:
__init__(self):
print('boo!')
}}} %%
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Now let's enter the Python REPL and use our new class:
%%repl {{{
/pyboard> repl
Entering REPL. Use Control-X to exit.
>
MicroPython v1.25.0 on 2025-04-15; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>>
>>> from boo import Boo
>>> b = Boo()
boo!
>>>
>>> print(b)
<Boo object at 20005f50>
>>>
>>> print(type(b))
<class 'Boo'>
>>>
}}} %%
%%info
__What did we do?__
After creating a class named {{Boo}},
# we imported the class ("{{from boo import Boo}}") so the interpreter was aware of it,
# then we ''instantiated'' (created an instance of) an object of the Boo class ("{{b = Boo()}}") and we assigned the object a name "b". Notice that when we created the object, the print line in Boo's constructor was executed ("boo!")
# then we printed the object (the interpreter returned a default result "{{<Boo object at 20005f50>}}"),
# then we printed the type of the object ("{{print(type(b))}}")
%%
%%filename motor_controller.py %%
%%python {{{
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print("motor controller ready.")
def set_speed(self, port_speed, stbd_speed):
self.port_forward_motor.set_speed(port_speed)
self.stbd_forward_motor.set_speed(stbd_speed)
def stop(self):
self.port_forward_motor.stop()
self.stbd_forward_motor.stop()
print('motor controller ready.')
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!motor.py:
%%filename motor.py %%
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# this is the motor class
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print("motor {} ready.".format(self.motor_name))
print('motor {} ready.'.format(self.motor_name))
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print("set motor {} speed to: {}".format(self.motor_name, speed))
print("speed: {}".format(speed))
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def stop(self):
self.motor_speed = 0
print('motor {} stopped.'.format(self.motor_name))
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!main.py:
%%filename main.py %%
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import time
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motor_ctrl = None
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# begin to accelerate in clockwise rotation
for speed in range(0, 101):
motor_ctrl.set_speed(speed,-speed)
time.sleep(3) # wait 3 seconds
# begin to decelerate down to zero (stopped)
for speed in range(100, -1, -1):
motor_ctrl.set_speed(speed,-speed)
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# if motor_ctrl: same thing as:
if motor_ctrl is not None:
motor_ctrl.stop()
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----
__Previous:__ [MicroPython Tutorial Exercise 3|MicroPythonTutorialExercise03]: functions \\
__Next:__ [MicroPython Tutorial Exercise 5|MicroPythonTutorialExercise05]: using classes
This page (revision-7) was last changed on 2025-07-30 13:21 by Murray AltheimTop