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Micro:Bit 180 Servo Rotation Tutorial

Updated

Tutorial Aim:

The aim of this tutorial is to master the skill of controlling a 9g servo using the micro:bit microcontroller and the Kitten Bot Robot:bit extension, achieving continuous 180-degree rotation in both directions. By the end of this tutorial, you will know how to control a servo using the micro:bit microcontroller and the Microsoft Makecode program.

Requirements:

This tutorial makes use of the following components. Note that the Kittenbot robot bit can be substituted for either the micro:bit I/O screw terminal shield or the I/O dupont shield but you will require a power source for the servo. 

  • Microsoft MakeCode for micro:bit
  • Micro:bit V2.2
  • Micro:bit Robot:bit Expansion Shield V2 with and 1850 battery
  • 3 male to female jumper wires
  • A 180 degree 9g servo

Pin Layout:

Micro:Bit Pins:Servo Pins:
GNDGND
3.3VVCC
S1OUT

Setup:

  • Connect the servo to the Robot:bit S1 pin using the Male to Female jumper wires 
  • Open Microsoft Makecode
  • Plug in the Micro:bit to the computer via the USB cable
Click to expand

Code Walk Through:

Adding the Kitten Bot extension

The kitten bot extension allows us to communicate with the servo pins attached to the robot:bit expansion board.

For more information about the extension click the link below: https://makecode.microbit.org/pkg/kittenbot/pxt-robotbit

Adding the extension: In the extensions tab, search & select the robot:bit extension by kittenbot.

Click to expand

Rotating the servo:

We can continuously rotate the servo using the Kitten Bot extension to send signals to pin 0. The code for this section will go inside the ‘forever’ block.

  • Rotating the servo 0 degrees: In the Robotbit tab, select “Servo (servo number) degree (number)”, select S1 for the servo number  & set the degree to 0.

  • Rotating the servo 180 degrees: Select “Servo (servo number) degree (number)” , choose S1 for the servo number  & set the degree to 180.
Click to expand

Pausing the code:

In order for the servo to have enough time to receive the signal & move, the code must be paused before the next command is sent. The code for this section will go inside the ‘forever’ block.

  • Pausing the code: Select “pause (ms)” in the Basic tab & set it to 1000 ms (1 second)

  • Create 2 pause blocks and place them between the servo rotation blocks so that the code alternates between rotation & pause blocks

Flashing the code onto the Micro:Bit:

Make sure the micro:bit is connected to the computer via USB cable
On the bottom left corner, click the “Download” button and follow the prompts

Servo Output:

The servo continuously rotates 180 degrees, pausing for 1 second in between rotations. Please note that the example below uses an 18650 lithium battery to power the Robot:bit shield. 

Click to expand

Block Code:

Entire block code for the tutorial 

Click to expand

Python Code:

Entire python code for the tutorial.

# Continuously rotating the servo
def on_forever():
    robotbit.servo(robotbit.Servos.S1, 0)
    basic.pause(1000)
    robotbit.servo(robotbit.Servos.S1, 180)
    basic.pause(1000)
basic.forever(on_forever)

Downloadable Content:

Please find this tutorial’s python & hex file for microsoft makecode on our GitHub.

Credits:

  • The Microsoft Makecode Community
  • The micro:bit Community
  • The STEM Community
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