Kitronik BBC Micro Bit move Mini Mk2 User Manual

V1.0

The Kitronik :MOVE mini for the BBC micro:bit provides an introduction
to robotics. The :MOVE mini is a 2 wheeled robot, suitable for both remote
control and autonomous operation. A range of add-on boards can expand
the capabilities to include more advanced functionality. The included :MOVE
Servo:Lite board can also be used in conjunction with a BBC micro:bit to build
other movement based projects.

Kitronik have created custom blocks for the MakeCode coding environment,
these make it ultra simple to code your :MOVE mini. Give it a try by adding
the ‘Servo:Lite’ blocks from the Extensions tab in MakeCode!

CONTENTS

INTRODUCTION TO THE :MOVE MINI

SUPPLIED WITH THIS KIT

GETTING CONNECTED

THE BBC micro:bit SOFTWARE

PROGRAMMING THE BBC micro:bit

2
3
4
5
6

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ASSEMBLING
:MOVE MINI

CODING
:MOVE MINI

SUPPORT FOR
:MOVE MINI

1. ASSEMBLING THE PCB

2. FLASH THE ZIP LEDs

3. BUILDING THE WHEELS

4. TESTING THE SERVOS

5. CALIBRATING THE SERVOS

6. ASSEMBLING THE CHASSIS

7. ATTACHING ELECTRONICS

8. CODE :MOVE MINI TO MOVE

9. DRAW A SHAPE USING JAVASCRIPT

10. GO ONLINE!

:MOVE MINI PIN OUT

TROUBLESHOOTING

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SUPPLIED WITH THIS KIT

ELECTRONICS FIXINGS

CHASSIS PANELS

2x 1x

www.kitronik.co.uk

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GETTING CONNECTED AND FINDING
THE PROGRAMMING ENVIRONMENT

Using a USB to micro-USB type B cable, connect the BBC
micro:bit to a computer.

Code will be created on the BBC micro:bit website.

www.microbit.org

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THE BBC micro:bit SOFTWARE

The BBC micro:bit is programmed using a web based (internet access
required) programming environment which is found at www.microbit.org.

To save programs to access at a later date you will need to save the .hex
files you create (these files will be explained later in this booklet). To reload a
program the relevant file needs to be dragged on to the editor screen. If this
is the first time you have used your BBC micro:bit then please refer to our
getting started guide at www.kitronik.co.uk/microbit.

All of the experiments in this guide are based around the Microsoft
MakeCode and Microsoft MakeCode JavaScript editors. The Microsoft
MakeCode Block Editor is a very easy to use graphical editor. The Microsoft
MakeCode JavaScript editor is a text based programming language which
is ideal for slightly more complex programs. It is possible to convert a Block
program into JavaScript. This offers an easy way of progressing from Block
programming to JavaScript. Other editor options include the Python Editor.
Refer to www.kitronik.co.uk/microbit for tutorials based on this.

www.kitronik.co.uk

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GETTING A PROGRAM ON
TO THE BBC MICRO:BIT

It is very easy to transfer a finished program to the BBC micro:bit.
First of all select ‘download’ . This is where the program
is converted into a program the micro:bit can understand. This
is known as a ‘.hex’ file. If it has compiled successfully, it will
return the message ‘Download completed... Move the .hex file to
the MICROBIT drive to transfer the code to your micro:bit.’ The
message ‘Do you want to open or save microbit-script.hex from
microbit.org’ will appear. Select ‘Save As’ from the ‘Save’ drop
down menu and save the hex file to a folder for BBC micro:bit .hex
files.

Next plug a BBC micro:bit into the computer via USB. The BBC
micro:bit will appear as a removable drive on the computer called
‘MICROBIT’.

To download the .hex file to the BBC micro:bit ‘Drag’ the .hex file
from the folder where it was saved and ‘Drop’ it onto the MICROBIT

removable drive. A message will appear saying ‘ Copying 1 item......

to MICROBIT’. At the same time, the yellow LED on the back of the
BBC micro:bit will flash.

After a few seconds, the download will complete and the BBC
micro:bit should now be running the program.

If it doesn’t you may need to reset the micro:bit, which can be done
by using the switch at the top of the Servo:Lite board to turn it off
and back on again.

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1

STEP 1: Use a small Phillips screwdriver to screw the five M3 machine

screws through the micro:bit and spacer into the nuts mounted on the PCB.

ASSEMBLING THE SERVO:LITE PCB

Micro:bit sold separately

ZIP LEDs

Servo Connections

On/Off Switch

PCB Mounted Nuts

Spacer

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2

STEP 1: Put batteries into the Servo:Lite PCB, and turn it on.
STEP 2: Connect it to a computer using a micro-USB cable.
STEP 3: Bring up MakeCode Blocks Editor (makecode.microbit.org).

NOTE: Kitronik’s ZIP LEDs are compatible with Adafruit’s Neopixels.

STEP 6: In the search bar type

‘neopixel’, then select the ‘neopixel’
box.

FLASH THE ZIP LEDs

STEP 4: In the toolbox towards the left of the

screen, select the ‘Advanced’ section.
Additional packages should appear below.

STEP 5: Select ‘Extensions’.

NOTE: This will load a set of blocks compatible with Kitronik’s ZIP LEDs,

which makes them really easy to code!

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STEP 7: Create a variable and name it ‘Pixel Array’.

New variable name:

Pixel Array

WHAT THIS MEANS

A variable is like a container which can store information.
This could be a number, a word or a piece of information
you want your program to remember.

STEP 8: Create the following code.

WHAT THIS MEANS

This tells the micro:bit that Pin 0 is connected to 5 colour
addressable LEDs.

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WHAT THIS MEANS

When button A is pressed,
light up all the pixels red.

WHAT THIS MEANS

When button B is pressed, clear the
LEDs represented by the variable
‘Pixel Array’. This will turn them off.

STEP 9: Name your program and download!

The program will automatically run on the simulator. Click on the ‘A’ button on
the simulator to see the LED pattern. Click on ‘B’ button to clear the pattern.

Plug the BBC micro:bit into a USB por t then drag and drop the

STEP 10: Press A and get ready for the lights!

STEP 11: Try changing the code to make a different colour.

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As well as addressing all the pixels at once it is possible to set them
individually, or as a group. The first pixel always has an address of 0 (see
diagram below).

0 1 2 3 4

STEP 12: Change the code under ‘On button A pressed’ to the following.
NOTE: To get the ‘range from’ blocks, you may need to disassemble the ‘set

range’ block.

You may also need to click on ‘More’ under the ‘neopixel’ toolset to access
the ‘set pixel colour at’ block.

WHAT THIS MEANS

Set the first two pixels to red,
the middle pixel to white and
the last two to blue.

REMEMBER: To show a change you must use a block with ‘show’ in it.

STEP 13:

UploadDownload

STEP 14: Press A and watch the lights!

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STEP 15: Create the code below.

WHAT THIS MEANS

This code shows a colour changing pattern when button A is
pressed and stops when button B is pressed.

NOTE: The ‘rotate pixels’ block shifts each LED colour onto the next LED.
When it reaches the end of the line, it goes back to the first LED.

STEP 16:

STEP 17: Press A and watch the light show!

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UploadDownload

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BUILDING THE WHEELS

2x

STEP 1: Stretch the O-Ring round the wheel, this will act as a tyre for :MOVE
mini. Press fit the wheel onto the servo shaft and repeat for the opposite
side.

www.kitronik.co.uk

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4

TESTING THE SERVOS

SERVOS

The continuous rotation servos used in the :MOVE mini are controlled in the
same manner as normal remote control servos. These servos are controlled
by a repeating pulse, whose width commands the servo to turn to a position.
For a normal servo, position is measured from the output shaft and used to
determine what angle the servo should stop at.

NORMAL SERVO

0 DEGREES

90 DEGREES

180 DEGREES

CONTINUOS ROTATION SERVO

A continuous rotation servo is slightly different. Instead of the signal telling
the servo how far to move, it tells the servo how fast to move.

SPEED:

DEGREES:

Because of component tolerances, we may need to set the centre point on
the :MOVE mini servos to ensure it will stop when commanded. This is done
with a trimmer, which is explained later on.

STOP

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STEP 1: Plug the servos into the Servo:Lite board.

The board connections are:

BOARD

LOCATION

TOP GROUND BROWN

MIDDLE POWER RED

BOTTOM SIGNAL ORANGE

WHAT IT

DOES

WIRE

COLOUR

STEP 2: With both wheel servos plugged in, it is time to write some test

code. Set out the servos like below. This will allow trimming/calibration of
the servos. This means they will stop and travel at the same speed when
commanded.

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STEP 3: Bring up MakeCode Blocks Editor (makecode.microbit.org).
STEP 4: Create the following code.

When button A is pressed, both servos should turn anti-clockwise
(looking from the wheel side).

When button B is pressed both servos should turn clockwise (looking
from the wheel side).

When buttons A + B are pressed the servos should stop turning.

If they do not then the centre point trimmer will need adjustment. On
the bottom of the servo, there is a small hole. This is used to access the
trimmer.

STEP 5:

UploadDownload

STEP 6: Test out the buttons.

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5

STEP 1: Press buttons A+B,
Then with a small screwdriver (through the hole) gently move the centre
point trimmer until the servo completely stops. There should also be no
sound coming from the servos.

CALIBRATING THE SERVOS

TRIMMER

STEP 2: Once the servos are calibrated unplug them from the board and

detach the wheels from the servos.

NOTE: The diagram below shows how the number of degrees set in the code
relates to the speed of the servo.

SPEED:

DEGREES:

STOP

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6

NOTE: During assembly take care not to overtighten the screws as this can
damage :MOVE mini.

STEP 2: Slot one of the internal side
panels over the top of the servos. Drop
an M3 Nut into the T-Joint and secure in
place with a 16mm bolt. Ensure that the
nut is fully inserted into the joint before
tightening.

ASSEMBLING THE CHASSIS

STEP 1: Slot one of the servos into the base plate

as shown to the left.

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STEP 3: Repeat Step 1 & 2 for the opposite side.

STEP 4: Snap the pen mounting plate

in between the two vertical plates,
just above the servo. The servo cables
should pass out of the rear of the
chassis.

STEP 6: Repeat for opposite side.

STEP 5: Turn the assembly upside down,

align the smaller rectangular holes of the
side panels up with the protruding bars
on the base plate, and slot them together.
Drop M3 nuts into the T-joints, and secure
with the 16mm bolts.

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STEP 7: Add a wheel (built earlier) and screw the smallest servo screw

through the middle to secure it to the servo.

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STEP 8: Repeat for the opposite side. The chassis is now complete.

www.kitronik.co.uk

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7

STEP 2: Clip the Servo:Lite board
under the hooks on the inner side
plates and slide it between the
outer plates.

ATTACHING ELECTRONICS

STEP 1: Plug the servo cables back into the

Servo:Lite board. The left servo should plug
into the left-hand side of the board and vice
versa. The cables should be threaded down the
gaps on either side as shown below.

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STEP 3: Push the Servo:Lite board

fully back inside the :MOVE mini.

STEP 5: Excess wires can then be
fed into the servo compartment at
the rear.

STEP 4: Secure the Servo:Lite board
and micro:bit with the :MOVE T-piece.

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CODE :MOVE MINI TO MOVE

DRIVE IN A STRAIGHT LINE

STEP 1: Create this code.

NOTE: If the move mini does not travel

in a straight line then you can adjust the
values to make the servos run at the
same speed. You may also need to re­adjust the trimmer (see pg.17).

WHAT THIS MEANS

When button A is pressed, drive full speed forwards. When
button B is pressed, drive full speed backwards.

NOTE: Because the servos are mounted on opposite sides of the :MOVE mini,
one has to turn clockwise (Value 0), and one anti-clockwise (Value 180) to
drive the :MOVE mini in a straight line.

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STEP 2:

UploadDownload

DRAW A CIRCLE!

STEP 3: Drop a marker through the designated hole on the pen mounting

plate and create the code below.

WHAT THIS MEANS

Drive one servo at full speed, and the stop the other. This will
cause the :MOVE mini to drive in a circle.

STEP 4:

UploadDownload

ADD SOME LIGHTS!

STEP 5: Create the following code to give :MOVE mini a head-light or

tail-light.

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A square has four equal sides, and four 90 degree corners.
Instead of writing the same code four times for both the sides
and the corners, we can save some time by writing control
functions! This means we can write the code once, and then
tell the program to refer back to it as many times as we want.

STEP 1: Click on the ‘JavaScript’ button towards the top of your browser.
This will activate the JavaScript programming environment, and allow us to
write some code.

STEP 2: Create the following constants. We will use these to store some
information about :MOVE mini.

VARIABLES EXPLAINED

DRAW A SHAPE USING JAVASCRIPT

MICROSEC_IN_A_SEC - The micro:bit’s processor counts

time in ‘micro seconds’. We want to be counting in ‘seconds’
so we will need to convert this. 1sec = 1million microsecs.
DISTANCE_PER_SEC - We will use this to calibrate how far
:MOVE mini travels in one second.
DEGREES_PER_SEC - We will use this to calibrate how far
:MOVE mini turns in one second.

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These will allow us to tune the code to our individual :MOVE mini. For
example, if :MOVE mini turns past 90° when we code ‘turn right’, we can
adjust these values to correct it easily.

Next we will make a function where we can input a chosen number of
degrees and :MOVE mini will output a signal to the servos to turn through
the set number of degrees.
To do this, the function will:

1. Turn on the servos,

2. Wait a period of time,

3. Then turn them off.
The ‘timeToWait’ is calculated by taking the chosen number of degrees,
dividing it by how many degrees :MOVE mini turns per second, and then
converting the answer to microseconds so the micro:bit can understand
it. This value is then output to the servos, resulting in :MOVE mini turning
through the chosen angle.

STEP 3: Add the following code under the previous code.

WHY WE NEED TO DO THIS

Because :MOVE mini can’t tell how far it has turned, we have
to use time and a knowledge of how fast :MOVE mini turns
to make the turn accurately.

Now we have made the function, lets use it!

STEP 4: Program button A to call the function we have just created:

NOTE: There is a pause to allow

you to move your hand before
the :MOVE mini starts turning.

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STEP 6:

Download this code to the micro:bit and press A, the :MOVE mini should wait
half a second (or 500 milliseconds) before turning through 90 degrees.

STEP 7: If :MOVE mini turns too far, or not far enough, you will need to adjust
the ‘DEGREES_PER_SEC’ variable so that the :MOVE mini accurately turns
through 90 degrees.

- If :MOVE mini turns too far, try making the value bigger.

- If :MOVE mini doesn’t turn far enough, try making it smaller.

Now we’ve calibrated the turns, lets code driving forwards! This code is very
similar to the block of code we used for turning, the only differences are:

- Function name - now called “driveForward’, instead of ‘turnLeft’.

- degrees - now called distance.

- timeToWait - now called ‘timeToWait2’.

- The servo output is now Right0 and Left180 instead of Right45 and Left45.

STEP 8: Add the following code under the previous code.

UploadDownload

STEP 9: Program button B to call the ‘DriveForward’ function, like this:

NOTE: The value after ‘driveForward’ is the distance we are telling :MOVE

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mini to drive in mm.

NOTE: Similar to before, if :MOVE mini drives too far/not far enough, adjust
the value of the ‘distancePerSec’ variable.

- If :MOVE mini drives too far, try making the value bigger.

- If :MOVE mini doesn’t turn drive enough, try making it smaller.

STEP 10:

Now we have the building blocks to make the :MOVE mini draw a shape! To
draw a square, we will need to drive forward and turn left four times over.

STEP 11: Under ‘onButtonPressed(Button.A, () ’ change the code to what is
shown below:

UploadDownload

YOUR TURN: Write code to make the MOVE mini turn right, and drive
backwards. Then combine that code to draw other shapes/pictures.

STEP 11:

UploadDownload

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GO ONLINE!

For additional tutorials, add-on packs & resources, scan the QR
Code or visit: kitronik.co.uk/moveminimk2

Kitronik have created custom blocks for the MakeCode coding
environment, these make it ultra simple to code your :MOVE
mini. Give it a try by adding the ‘Servo:Lite’ blocks from the
Extensions tab in MakeCode!

CODE EXAMPLES

- Use your phone as a remote control!

- Use a second micro:bit as a remote control!

- Output to a third servo, such as a bulldozer!

- Personalise the :MOVE mini with extra ZIP LED strips!

:MOVE mini PIN OUT

- GROUND

- 3V

- P2 LEFT SERVO OUTPUT

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- P1 RIGHT SERVO OUTPUT

- P0 ZIP LED OUTPUT

TROUBLESHOOTING

If you are having issues with the :MOVE mini, try the steps below!

THE SERVOS ARE MISBEHAVING

- Is the orange servo wire at the bottom of the connector?

- Check all connections are secure.

- Are the screws holding the electronics together tight?

- Review your code, are you outputting to the correct pin(s)?

:MOVE MINI WON’T DRIVE IN A STRAIGHT LINE

- You may need to recalibrate your servos (see page 17).

- Review your code, are you outputting the correct values?

ZIP LED ISSUES

- Check all screw connections are tight.

- Review your code, are you outputting to the correct pin?

POWER ISSUES

- Is it switched on?

- Are the batteries flat?

- Check all screw connections are tight.

DRAWING ISSUES

- Try a felt tip pen, these tend to work best.

- Try adding some weight to the top of the pen.

- Try using a rubber band to secure the pen.

If this hasn’t solved your issue, visit
kitronik.co.uk/moveminimk2

www.kitronik.co.uk

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The Kitronik :MOVE mini for the BBC micro:bit provides an

introduction to robotics. The mini is a 2 wheeled robot, suitable

for both remote control and autonomous operation. A range

of add on boards can expand the capabilities to include more

advanced functionality.

The :MOVE mini board included in this pack can also be used in

conjunction with a BBC micro:bit to build other movement based

projects.

Visit kitronik.co.uk/moveminimk2 for more details.

Product Code: 5652

( )

RoHS

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THIS IS NOT A TOY.