Session 3: Motors and Movement

Goal: Connect a yellow DC motor to the micro:bit using an L298N motor driver and learn to control speed and direction — the first step toward building a moving robot!

📺 Watch First

Before we start wiring, watch this short video that walks through connecting a motor to a micro:bit with an L298N driver:

▶ Motor Driver + micro:bit Tutorial

Follow along — we’ll be doing the same setup in class!

What Are We Building?

By the end of this session you will have one motor wired up and controllable from the micro:bit. You’ll write forward, backward, and stop functions — the building blocks of any robot.

Meet Your Components

Yellow TT DC Motor

The yellow “TT” (transparent tire) gear motor is the workhorse of hobby robotics:

  • Operating voltage: 3 V – 6 V (we’ll use ~5–6 V from a battery pack)
  • Built-in gearbox that trades speed for torque — perfect for driving wheels
  • Two solder tabs for power (no polarity marking — swapping the wires just reverses the direction)

L298N Motor Driver Board

The micro:bit’s pins can only supply a tiny amount of current. A motor can draw 100–200 mA — way too much! The L298N dual H-bridge driver sits between the micro:bit and the motor and does the heavy lifting.

L298N Motor Driver Board

The key parts of the board we’ll use:

  • OUT1 & OUT2 — connect your motor wires here
  • +12V (VMS) — motor power input (battery pack positive)
  • GND — common ground (battery negative and micro:bit GND)
  • ENA — enable / speed control (PWM from micro:bit)
  • IN1, IN2 — direction control pins

Key idea: IN1/IN2 set the direction; ENA sets the speed.

Wiring It Up

Components You’ll Need

  • micro:bit + breakout board (edge connector)
  • L298N motor driver module
  • 1 × yellow TT DC motor (with wheel attached)
  • 4 × AA battery holder (6 V)
  • Jumper wires (male-to-female recommended)
  • Small screwdriver for the L298N screw terminals

Pin Assignments

The micro:bit has three large pins you can easily connect with alligator clips or a breakout board: Pin 0, Pin 1, and Pin 2. We’ll use them like this:

  • Pin 0 → ENA (speed control — PWM)
  • Pin 1 → IN1 (direction control)
  • Pin 2 → IN2 (direction control)

Step-by-Step Wiring

⚠️ Keep the battery pack switched OFF (or disconnected) while wiring!

  1. Remove the ENA jumper cap on the L298N board — we will control speed with PWM from the micro:bit instead of running at full speed.

  2. Connect the motor

    • Loosen the screw terminals on OUT1/OUT2 and insert the two wires from the motor. Tighten.

  3. Connect power

    • Battery pack positive (+) → L298N +12V terminal.
    • Battery pack negative (–) → L298N GND terminal.
    • Run a wire from L298N GND to the micro:bit GND pin (common ground is essential!).

  4. Connect control pins (micro:bit → L298N)

    • Pin 0 → ENA (speed)
    • Pin 1 → IN1 (direction)
    • Pin 2 → IN2 (direction)

  5. Double-check every connection with your partner, then have the teacher verify before powering on.

How Motor Direction Works

The L298N uses two input pins to set direction:

  • IN1 = HIGH, IN2 = LOW → Motor spins forward
  • IN1 = LOW, IN2 = HIGH → Motor spins backward
  • IN1 = LOW, IN2 = LOW → Motor stops (coast)

The ENA pin controls speed using PWM — a value from 0 (stopped) to 1023 (full speed).

Programming the Motor

Activity 1: Make the Motor Spin

In MakeCode — open a new project.

On button A pressed:

  1. From Pins (under Advanced), add digital write pin P1 to 1
  2. Add digital write pin P2 to 0
  3. Add analog write pin P0 to 600

This sets the motor to spin forward at moderate speed.

On button B pressed:

  1. digital write pin P1 to 0
  2. digital write pin P2 to 0
  3. analog write pin P0 to 0

This stops the motor.

Test it! Press A — the motor should spin. Press B — it stops.

Troubleshooting: If the motor doesn’t turn, check:

  • Is the battery pack switched on?
  • Is GND shared between battery, L298N, and micro:bit?
  • Did you remove the ENA jumper cap?
  • Are IN1/IN2 connected to P1/P2 (not swapped)?

Activity 2: Create Forward, Backward, and Stop Functions

In MakeCode, go to Advanced → Functions → Make a Function. We’ll create three functions:

Function: forward

  1. digital write pin P1 to 1
  2. digital write pin P2 to 0
  3. analog write pin P0 to 700
  4. show arrow North (up arrow on LEDs)

Function: backward

  1. digital write pin P1 to 0
  2. digital write pin P2 to 1
  3. analog write pin P0 to 700
  4. show arrow South (down arrow on LEDs)

Function: stop

  1. digital write pin P1 to 0
  2. digital write pin P2 to 0
  3. analog write pin P0 to 0
  4. show icon X (stop symbol on LEDs)

Now call the functions from a forever loop to make the motor run a repeating pattern automatically:

In the forever block:

  1. Call forward
  2. pause 2000 ms (run forward for 2 seconds)
  3. Call stop
  4. pause 1000 ms (pause for 1 second)
  5. Call backward
  6. pause 2000 ms (run backward for 2 seconds)
  7. Call stop
  8. pause 1000 ms (pause for 1 second)

The motor will now repeat the sequence on its own — forward, stop, backward, stop — forever! This is exactly how a real robot would follow a programmed path.

Test it! Watch the LED arrows change as the motor changes direction.

🎯 Challenge: Design Your Own Motor Program

Your Task: Use the forward, backward, and stop functions to create something interesting — you decide what it does!

Here are some ideas to get you thinking, but feel free to come up with your own:

  • Dance pattern — a timed sequence of forward/backward/stop moves set to a beat using the Music blocks
  • Morse code motor — use short and long motor bursts to “spell out” a letter or word
  • Countdown launcher — count down from 5 on the LEDs, then run a sequence
  • Sensor-triggered — combine what you learned in Session 2: use the IR sensor to decide when to run forward or stop
  • Something totally different — surprise us!

There’s no single right answer. Experiment, break things, fix them, and have fun.

Key Concepts You Learned

  • How a DC motor converts electricity into rotation
  • Why we need a motor driver (the micro:bit can’t power motors directly)
  • L298N wiring: direction pins (IN1/IN2 on P1/P2) and speed pin (ENA on P0)
  • PWM (0–1023) to control motor speed like a dimmer switch
  • Using functions to organize your code into reusable blocks

Think About It:

  • What would you need to change to control two motors at once?
  • How could you combine the IR sensor from Session 2 with a motor to make a robot that avoids obstacles?
  • What other sensors could help a robot navigate?

Next Session Preview: We’ll add a second motor and mount everything onto a chassis to build a rolling robot! 🤖

CATALOG