Getting Started

Follow these steps in order. You do not need to write all of the motor-control code from scratch.

Setup - Open Microsoft MakeCode

1. Go to Microsoft MakeCode for micro:bit.
2. Create a new project called RoboMaze.
3. Open Extensions.
4. Search for the Kitronik :MOVE Motor extension and add it.
5. Switch the editor from Blocks to Python.
6. Open the Starter Code, copy it, and paste it into MakeCode.

At the top of the starter code you will find:

speed = 0
turnTime = 0
distanceToWall = 0

You will change these values while testing.

Task 1 - Analyse the Maze

Before changing any code, study the maze.

Work out:

• What route reaches the exit?
• Is it the shortest route?
• How many right turns are needed?
• How many left turns are needed?
• In what order do the turns happen?

Write the order down. You will need it later.

Task 2 - Calibrate the Right Turn

The code for turning right has already been written for you.

Your job is to make it turn approximately 90 degrees.

Change:

speed
turnTime

at the top of the program.

speed controls how fast the motors move.

turnTime controls how long the motors run before stopping.

Test the MicroMouse and keep adjusting the values until turn_right_90() produces a reliable 90 degree turn.

Task 3 - Now Turn Left

Create a new function called:

turn_left_90()

You do not need to write it from scratch.

Copy turn_right_90() and change only what is needed to make the MicroMouse turn the opposite way.

Think about:

• which wheel moves forwards;
• which wheel moves backwards.

Rule: Do not call turn_right_90() three times to turn left!

Task 4 - Test the Ultrasonic Sensor

Temporarily add:

basic.show_number(Kitronik_Move_Motor.measure())

Download the program to the micro:bit and place the MicroMouse different distances from a wall.

Watch the value displayed.

Choose a sensible stopping distance and update:

distanceToWall = 0

at the top of your program.

When you have finished testing, remove or comment out the temporary basic.show_number(...) line.

Task 5 - Move to the Wall

The move_to_wall() function has already been written for you.

The important condition is:

while Kitronik_Move_Motor.measure() > distanceToWall:

This means:

Keep moving while the measured distance is greater than the chosen stopping distance.

Test the function.

If the MicroMouse stops too close or too far away, adjust distanceToWall and try again.

Task 6 - Escape the Maze

You now have:

move_to_wall()
turn_right_90()
turn_left_90()

Complete navigate_maze() by calling those functions in the order you discovered during Task 1.

For example:

def navigate_maze():
    move_to_wall()
    turn_right_90()
    move_to_wall()

Continue until you have programmed the complete route.

If the result is not quite right, check:

• speed;
• turnTime;
• distanceToWall;
• the order of the function calls.

Need Help?

Use the RoboMaze Cheat Sheet whenever you forget what a command does.

If your program becomes badly broken, copy a fresh version from the Starter Code page.