Micro:Bit 180 Servo Rotation Tutorial

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:
GND	GND
3.3V	VCC
S1	OUT

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

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.

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

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.

Block Code:

Entire block code for the tutorial

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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