Building your ChickBot micro:bit

Building your ChickBot micro:bit

These are draft instructions for beta testers who will enjoy a nice game of spot the difference – differences I’ve already spotted are highlighted in red. I’m intending to redo all the photography when this project starts to pay its way.

Please read all the instructions before starting, just in case there is something you do early in the build that has an impact on a later step.

Clear a space on a table and get yourself a chair so you working at the right height.

Unpack the parts, don’t upend the bag, there are small parts that may go astray

Lay the parts out, putting the chassis in the centre:

The Kit

You don’t have stepper motors or their mounts. You have two yellow motors.

You’ll need some glue, a small screwdriver and a pair of scissors

Tools required

First we will attach the motors.

They go under the chassis and are held in position by two cable ties each like so:

LYM from underneath

For this, we use the most right hand red hole and the yellow hole on the picture of the chassis below:

ChickBot chassis

 

 

Thread a cable tie through the long hole in the yellow motor that is in the middle, next to a small screw, through the hole marked in yellow above and around the outside of the chassis edge:

LYM detail

Thread the flat end of the cable tie through the clip at the end of the tie, example below:

Cable tie ready to tighten

And pull the cable tie tight to secure it.

Now thread a cable tie through the front nodule on the yellow motor, around the front of the chassis, through the hole and secure.

LYM front fixing

It is very important to have the cable tie go around the front edge, otherwise the motor is pulled to one side and will be pulled off course when you use it.

Here’s what it looks from the top side once you’ve got both cable ties in place and trimmed them off:

LYM from top

Sticking the caster in place

Use two sticky pads to secure the ping pong ball half on to the square

Ping pong on square

Now use the other two sticky pads it to the end of the chassis

Caster on chassis

Now we will mount the controller board.

Locate the circuit mounts – we call them sticky feet!

Sticky feet

Push the pointy end through the holes on the controller board. On the micro:bit board there are four holes:

Sticky feet in controller borad

Peel off the tape that covers the adhesive pads on the feet:

Sticky foot with tape removed

Position just left of the long motor cable ties so that there is space for the battery at the front and room for the micro:bit at the back:

CB microbit top view

And press in to place

Putting rubber on the wheels.

The new-style wheels have a ribbed edge to them that works great on carpet but can slip on smooth shiny surfaces. If you need to, you can put some rubber tyres on them to give them a bit more grip on other surfaces.

Cut the piece of balloon into three pieces:

Balloon cut up

Turn a piece of balloon inside out and stretch it over the wheel edge:

Rubber stretched over wheel

This can be a bit fiddly, take your time!

And do it for the other wheel:

Both wheels done

Mounting the wheels.

Take the third piece of balloon and cut it in to two small squares like this:

Rubber squares

Taking a square, balance it on the motor shaft: (yes, this is a stepper motor picture, to be changed)

Rubber square on motor shaft

Press a wheel on to it:

Wheel pushed on to motor shaft

Do this for the other motor too.

Wiring up the battery clip

Take the battery clip:

Battery clip

And wire the two leads in to the + and 0V connections like this:

CB mb battery lead

Wiring up the motors

The motor wires go through the two holes in the middle of the board (marked in blue above). With the motors/wheels at the top, the right hand motor wires go in to terminals 8 & 9 (shown here yellow + blue wires), and the left hand motor into 10 & 11 (shown as blue & white wires).

CB microbit motor wiring

Fill the battery pack

You’ll need four AA batteries, take care to put them in the right way round:

Batteries & battery pack

Attach the battery pack to the clip:

Battery pack on chassis

Stick the velcro to the battery box, put the other piece of velcro on to the one on the battery box, peel off and press to the chassis.

Locate the on-off jumper

The on-off jumper

We choose this so that a loop can be attached to it – when your ChickBot is misbehaving, you can tug the loop to turn it off!

Pimp your on-off jumper

We’ve included some stiff nylon cord for you to put a loop on the jumper.

Get ready to fire up your ChickBot for the first time!

Here’s what the finished result should look like:

CB microbit top view

You’ll need to program your micro:bit so that it knows how to drive the motors. Click https://www.microbit.co.uk/txrlsa to load up the starter program which you will need to compile and download to your micro:bit as you would with all other micro:bit programs.

Push your micro:bit in to the socket on the ChickBot – you will have to be quite firm, ensure you push it in line – do not try putting it in at an angle.

Put the jumper across the two pins next to the battery lead and your micro:bit will come on.

Make sure your ChickBot has some room and won’t go off the edge of a table – it’s best to pop it on the floor. Press the A & B button at the same time on the micro:bit and watch as your ChickBot performs a victory dance.

Well done! Don’t forget to give your ChickBot a name!