ROBOTICS & CNC PROGRAMMING / MICROPYTHON / CIRCUITPYTHON CRICKIT

Build the Rover

John Park

Here's our collection of parts, let's build it!

Feather to Crickit

First, solder the male header pins onto the Feather as shown here, then connect it to the Crickit.

Standoffs

We'll use four brass standoffs and seven of the provided M3 screws to connect the Crickit to the chassis.

First, fasten one brass standoff to the indicated mounting hole next to the Crickit's reset button. This one won't go through a chassis hole, it will just provide support.

Fasten the remaining three standoffs to the chassis as shown, screwing them in from the bottom. You can leave them a little bit loose for now to get the proper spacing when we connect the Crickit on top, then tighten them.

Roller Bearing

The roller bearing will allow the rover to turn without the need for a complicated differential or steering mechanism.

You will need to remove the bearing from the housing to get to the screw heads.

Screw it into place as shown, using the nuts to secure from the underside.

Motor Wiring

The standard, yellow TT motors come pre-wired, but if you use the blue metal or bi-metal motors for lower speed/higher torque, you'll need to solder on your own wires as shown here.

You don't need to worry too much about which wire is connected to which tab, as everything can be adjusted in software. These motors can be driven in either direction by telling the Crickit motor drivers to flip the polarity in software.

Any of the TT Motors from Adafruit will work well in this project. The blue ones are slower but have more torque, so can deal better with obstacles, the yellow ones are zippier!

NeoPixel Prep

While you've got the soldering iron out, you'll also want to connect three wires to the NeoPixel ring's DATA IN, PWR, and GND pads.

	Motor Mounts It's very easy to mount the motors, as the chassis is designed for their exact dimensions! Place each motor into its spot and secure with one or two of the long screws and nuts.
	Wheels Stretch the tires onto the wheels and then press the wheels on to the motor shafts.

Connect Motor Wires to Crickit

Now, push the motor wires through an opening in the chassis so they can be connected to the Crickit.

The pair of wires from one motor will go into the two positions marked '1' and the pair of wires from the other motor will go into the the two positions marked '2'.

Push each wire into place and then screw down the terminal securely.

We're using the Motor 1 and Motor 2 ports, each can act as bi-polar motor drivers. There is no need to plug a wire into the center position that is marked "GND".

Underbody Lighting Effects

Next we'll connect the NeoPixel ring under the chassis for sweet lighting effects, especially at night, in the rain, on the wet asphalt at an illegal street race!

Push the three NeoPixel wires from the bottom through a hole in the chassis so they emerge up top near the Crickit NeoPixel port.

Use four zip ties to connect the ring to the chassis as shown.

Screw the DATA IN, PWR, and GND wires into their respective ports on the Crickit NeoPixel terminal block.

Battery Power

Now, we'll give the rover a power source!

First, connect the battery pack's jumper wires to the plug adapter. Red to +, Black to -

Feed a zip tie through the two screw holes on the back of the chassis as shown, from out to in and back out.

If your zip tie is too short to make it all the way around the battery pack, extend its length with a second zip tie as shown.

Form a loose ring with the zip ties, then repeat these steps for the second position.

Place four NiMH batteries (not Alkaline, they have too high a voltage and won't work with the Crickit!) into the holder, then slide the plug through one side and secure the pack in place.

Now, tighten the zip ties, but not too tight. You want to still be able to remove the pack to change batteries.

This arrangement works well with the blue TT motors, but may be a bit back heavy for the yellow motors. In this case, you can put the battery pack closer to the wheels by attaching it at the other end of the chassis, or underneath

Plug in the power plug into the Crickit's power jack and now we're ready to program it!