Bluetooth Motor & Servo Control with BBC Micro:bit

Built for UQD10801 – ROBOCON I coursework

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What This Does

This project lets you control DC motors and a servo wirelessly using a BBC Micro:bit. Send commands over Bluetooth ("up", "down", "left", "right") and the Micro:bit converts them to PWM signals that drive the motors. I built this for a robotics course and it works well for small RC vehicles or prototype robots.

Features

• Bluetooth UART for wireless command input
• PWM motor control for variable speed and direction
• Servo positioning for angle control
• Real-time response suitable for mobile platforms

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Hardware Setup

Here's the wiring setup I used. The motor driver connects to the Micro:bit pins and handles the actual current for the DC motors. The servo runs off pin P0.

Motor driver wiring with starter kit components

The assembled prototype

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Parts List

Component	Notes
BBC Micro:bit	Main controller board
DC Motors (2x)	Left and right drive motors
Hobby Servo	For steering or other angle control
Motor Driver Module	H-bridge driver to control motor direction and speed
Bluetooth Device	Phone app or another Micro:bit for sending commands

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Getting Started

To run or modify this code:

1. Go to MakeCode for Micro:bit
2. Click Import → Import URL
3. Paste: https://github.com/alnezar/kart-microbit-motor-control
4. The project opens in the browser editor

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Command Reference

Command	Result
up	Move forward
down	Move backward
left	Turn left
right	Turn right
stop	Stop motors
c	Set servo range

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Code Overview

The main logic listens for UART data over Bluetooth and maps commands to motor control functions. Each direction function sets the appropriate pin states for the motor driver.

let recvievestring = ""

// Motor control functions
function Forward() {
    pins.analogWritePin(AnalogPin.P4, 1023)
    pins.digitalWritePin(AnalogPin.P5, 1)
    pins.digitalWritePin(AnalogPin.P6, 0)
    pins.analogWritePin(AnalogPin.P10, 1023)
    pins.digitalWritePin(AnalogPin.P11, 0)
    pins.digitalWritePin(AnalogPin.P12, 1)
}

function Backword() {
    pins.analogWritePin(AnalogPin.P4, 1023)
    pins.digitalWritePin(AnalogPin.P5, 0)
    pins.digitalWritePin(AnalogPin.P6, 1)
    pins.analogWritePin(AnalogPin.P10, 1023)
    pins.digitalWritePin(AnalogPin.P11, 1)
    pins.digitalWritePin(AnalogPin.P12, 0)
}

// Bluetooth event handlers
bluetooth.onBluetoothConnected(function () {
    music.play(music.builtinPlayableSoundEffect(soundExpression.sad), 
               music.PlaybackMode.UntilDone)
})

bluetooth.onUartDataReceived(serial.delimiters(Delimiters.NewLine), function () {
    recvievestring = bluetooth.uartReadUntil(serial.delimiters(Delimiters.NewLine))
    if (recvievestring == "up") Forward()
    if (recvievestring == "down") Backword()
    if (recvievestring == "right") Right()
    if (recvievestring == "left") Left()
    if (recvievestring.charAt(0) == "c") {
        servos.P0.setRange(0, 180)
    }
})

// Setup
music.play(music.stringPlayable("C D E F G A B C5 ", 120), 
           music.PlaybackMode.UntilDone)
led.enable(false)
bluetooth.startUartService()
servos.P0.setRange(0, 180)
stop()

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Tech Stack

• Platform: Microsoft MakeCode
• Language: TypeScript
• Hardware: BBC Micro:bit, DC motors, hobby servo, motor driver

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