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:
You don’t have stepper motors or their mounts. You have two yellow motors.
some glue, a small screwdriver and a pair of scissors
First we will attach the motors.
They go under the chassis and are held in position by two cable ties each like so:
For this, we use the most right hand red hole and the yellow hole on the picture of the chassis below:
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:
Thread the flat end of the cable tie through the clip at the end of the tie, example below:
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.
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:
Sticking the caster in place
Use two sticky pads to secure the ping pong ball half on to the square
Now use the other two sticky pads it to the end of the chassis
Now we will mount the controller board.
Locate the circuit mounts – we call them sticky feet!
Push the pointy end through the holes on the controller board. On the micro:bit board there are four holes:
Peel off the tape that covers the adhesive pads on the feet:
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:
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:
Turn a piece of balloon inside out and stretch it over the wheel edge:
This can be a bit fiddly, take your time!
And do it for the other wheel:
Mounting the wheels.
Take the third piece of balloon and cut it in to two small squares like this:
Taking a square, balance it on the motor shaft: (yes, this is a stepper motor picture, to be changed)
Press a wheel on to it:
Do this for the other motor too.
Wiring up the battery clip
Take the battery clip:
And wire the two leads in to the + and 0V connections like this:
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).
Fill the battery pack
You’ll need four AA batteries, take care to put them in the right way round:
Attach the battery pack to the clip:
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
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!
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:
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!