_using-microbit-servo-examples.md

title	layout	meta-description	share	author	about	cats	simple-description	date
How to Use Servos on the Microbit	text-width-sidebar	Add the servo Python module to control a servo. Examples using the microbit with servo, potentiometers and LED lights.	true	jez	Examples of using a servo with the microbit for use in physical projects.	component examples	Servo Examples	2016-12-23 10:20:00 UTC

""" Unchecked.

There are a few PWM issues. """

These examples us the The Tower Pro SG90 servo. This is a 180° servo meaning it can turn from 0° to 180°.

See the component article on this website about how to use the servo.

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Microbit Twist

Hardware Required

• 3.3v Servo

Moving the microbit causes the servo to rotate.

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{% highlight python %} from microbit import *

from servo import Servo

def rescale(src_scale, dest_scale, x): src_start, src_end = src_scale proportion = 1.0 * (x - src_start) / (src_end - src_start) dest_start, dest_end = dest_scale return proportion * (dest_end - dest_start) + dest_start

while True: # rescale accelerometer x axis to between 0 and 180 rescaled_angle = rescale( (-1023, 1023), (0, 180), accelerometer.get_x())

Servo(pin0).write_angle(rescaled_angle)
sleep(200)

{% endhighlight %}

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Potentiometer

Hardware Required

• 3.3v Servo
• 10k Potentiometer

Turning the potentiometer causes the servo to rotate.

See the component article for a potentiometer for more.

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{% highlight python %} from microbit import *

from servo import Servo

def rescale(src_scale, dest_scale, x): src_start, src_end = src_scale proportion = 1.0 * (x - src_start) / (src_end - src_start) dest_start, dest_end = dest_scale return proportion * (dest_end - dest_start) + dest_start

servo1 = Servo(pin0) pot_reading = pin1.analog_read()

while True: # rescale pot reading (0 - 1023) to servo angle (0 - 180) rescaled_angle = rescale( (0, 1023), (0, 180), pot_reading)

servo1.write_angle(rescaled_angle)
sleep(200)

{% endhighlight %}

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Buttons

Hardware Required

• 3.3v Servo

button_a and button_b control the rotation of the servo. Be sure to upload the servo class in mu.

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{% highlight python %}

Each time button_a is pressed and the value of angle is less

than or equal to 180, increment the value of the servo's

rotation by 10. Do similar for button_b.

from microbit import *

from servo import Servo

angle to write to the servo.

angle = 0

reset servo to 0 degrees

Servo(pin0).write_angle(angle)

while True: if button_a.was_pressed and (angle <= 180): angle = angle + 10 Servo(pin0).write_angle(angle)

if button_a.was_pressed and (angle >= 0):
    angle = angle - 10
    Servo(pin0).write_angle(angle)

sleep(10)

{% endhighlight %}