Adafruit My Mini Race Car Users guide

My Mini Race Car

Created by John Park

Last updated on 2021-04-07 06:12:01 PM EDT

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Guide Contents

Guide Contents Introduction Unboxing Your Mini Race Car Kit Kit Contents Feather, USB Cable, & Batteries Car Chassis & Assembly Tools Prototyping Parts and Components Assembling and Wiring Your Mini Race Car

Motors and Wheels and Tires Lower Chassis Turn over the plate Turn over the plate again

Prepare the Battery Box

Middle Chassis Layer

Prepare the Electronics

LiPoly Battery

3D Printed Car Parts Bonus Body Parts How Your Race Car Works: The Basics

Board Support Package and Drivers Libraries DC Motor Test Let's Get Moving

Code for Your Race Car

Libraries The Code

Driving Your Race Car Temperature and Humidity Data

Power Pins: I2C Logic pins:

Download Adafruit_HTU21DF Load Demo Bluetooth Data Streaming

Plotting Sensor Placement

Make Your Race Car Autonomous

Mounting the Sensors The Code

Control Your Race Car's Speed

Using the Controller to Control Speed

Connecting Your Race Car to Adafruit IO

Sign up for Adafruit IO and create your first dashboard. Send data to Adafruit IO

Introduction

Get ready to race down the track with your Feather microcontroller-based Mini Race Car! You'll build this high performance racer, using the Bluetooth LE capable Feather 32u4 Bluefruit LE board, Motor Driver FeatherWing, and TE HTU21D-F temperature & humidity sensor to give you racetrack telemetry data.

All of this is controlled from your mobile device using the free Bluefruit Connect app for iOS and Android.

Let's get started!!

Unboxing Your Mini Race Car Kit

My Mini Race Car is designed to introduce you to the joys of making with electronics. We decided to come up with a fun pack of parts that:

Could introduce a beginner to making Teach electronics and programming skills Does not assume any prior experience Does not require any soldering or special tools

Kit Contents

After a lot of thinking, here's what we came up with:

Feather, USB Cable, & Batteries

Feather 32u4 Bluefruit LE is the brains of your race car! It is Arduino-compatible and has Bluetooth wireless control Motor FeatherWing is the muscle of this car, providing power to the motors -- Lets you drive up to 4 DC or 2 stepper motors- certainly enough motors to power the car kit! TE HTU21D-F is the heart of your race car. Temperature & Humidity sensor breakout board for realtime car/track sensing! 1x USB Cable - Standard A-B - 3 ft/1m (http://adafru.it/62) - use this to install new code onto your Feather (from any computer)

3.7V LiPoly battery - this battery will power your Feather (but not the motors)

4x AA Batteries (http://adafru.it/3349) - Use these to power your the motors of your super awesome little race car

Car Chassis & Assembly Tools

Three layer Robot Chassis Kit in Black (http://adafru.it/3244) - This kit gives you everything you need

to build the shell of a 2-wheel-drive Mobile Platform Robot to help you channel your inner Mario Andretti Pocket Screwdriver with Philips and slotted ends

Prototyping Parts and Components

Half Size Breadboard Perfect fit for your car kit. Your Feather will connect to the breadboard, allowing you to easily plug in other sensor, LEDs, buzzers, potentiometers, switches, and more 1x 4xAA Battery Holder w/ On/Off Switch (https://adafru.it/sfq) - A nice portable battery holder for your car's motor batteries. 1x Shield stacking headers for Arduino (http://adafru.it/85) - Allow optional plugging in of many different boards, sensors, and wiring 1x Rubber Bumper Feet (https://adafru.it/dLG) - Helps keep the battery packs safe and secure Jumper wires for making additional connections

Assembling and Wiring Your Mini Race Car

The wiring and assembly is pretty easy, and there is no soldering required! You'll just need the small screwdriver that came in the kit, and it wouldn't hurt to grab some pliers. (It'll make it faster and easier to put together)

First, you'll assemble the robot chassis. All the parts needed for this are inside the brown box with the 'Custom Black 2WD Robot + extra layer' sticker on it.

Motors and Wheels and Tires

To start, take the two motors, four long screws, four nuts, and two black panels.

Screw the two black panels onto the motors.

The metal panels go on the side with the red and black wires coming out.

Have the hex nuts on the metal panel side so they don't interfere with the wheel!

The metal panels go on the side with the red and black wires coming out.

Have the hex nuts on the metal panel side so they don't interfere with the wheel!

Take the two wheels, rubber treads, and 2x small screws found in the same bag as the wheels.

Put the rubber treads on the wheels. This is a lot of fun!

Fit the wheels onto the white knob on the motors, they will snap nicely onto the oval center.

Lower Chassis

Take one of the black chassis layers. All three layers are identical.

Align it on your table as shown on the left. Note that the panel is not symmetrical - look on the left to see that rectangle cut out? Make sure it's aligned as you see here!

Attach two of the brass standoffs onto the black chassis layer.

The standoffs should be screwed into the second set of

holes from the outer edge - meaning the two interior holes.

Turn over the plate

Attach the white free-wheel into the exterior hole closest to the rectangular opening.

The white free-wheel should be on the opposite side of the chassis of the standoff.

Turn over the plate again

Take your assembled wheels and fit them into the chassis layer.

There are 2 slots on the black panels that you attached to your motor that should fit perfectly into the chassis layer.

The metal front of the motor will be pointing toward the side of the chassis where you placed your white freewheel

Prepare the Battery Box

For this step, you will need the AA battery box, 4 x AA batteries, the screwdriver, and a sheet of 4 rubber bumpers.

First, open each battery box, grab out the screw, insert your batteries, and then screw the boxes shut. Oh, and make sure you have the boxes switched to the off position. Now, take the 4 rubber bumpers and

place them as shown in the picture below. Notice how the one bumper on the left side is not in the upper left corner. Important: don't throw away the leftover piece of bumper material, we are going to use that on the next step.

 Do not discard the leftover piece of bumper material.

Flip the battery box over and place the scrap piece of the bumper material in the middle. This will help hold the battery box nice and tight between the top and middle plate of your robot.

Middle Chassis Layer

Place the middle chassis layer onto robot, making sure to fit the motor tabs into the slots of the layer, then screw in the two brass standoffs.

Take a look at the image below and install the brass stand-offs in the same positions. You can insert the stand-off screws through the middle plate and hand tighten the stand-offs while putting a bit of pressure on the screw with your finger. Or, as a tip, you can screw in the stand-off screws with the flat end of the screwdriver, which can reach through the holes in the bottom plate.

Once you have the stand-offs in place as shown in the image above, let's place the battery box in the correct spot as shown in the image below.

Notice the battery box is lined up on the left side of the middle chassis plate. It should be just in-between the upper left stand-off and the lower left stand-off (not touching either). This will make sure the on-off switch lines up just right in the hole of the top plate. Go ahead and install the top plate now as shown here.

See how the on-off switch is now accessible through the top plate? Now let's take just a minute to route the wires from the motors and the battery box through the chassis like shown in the image below.

We are getting close! Now let's install the breadboard on top of the robot. Peel off the backing from the foam sticker on the bottom of the breadboard. Take a look at the image below and stick it exactly as shown. Be sure to install the breadboard just as shown in the image below and not sideways or the motor wires won't reach the motor driver Feather Wing.

Prepare the Electronics

For this next step, a pair of pliers is handy. First, grab the 6 header pins all attached together and break them into 3 sets of 2 header pins. Then, grab them in the pliers like shown here, and then slightly bend them so they look like the next picture.

If you don't have pliers you can do it with your fingers (carefully!)

With the breadboard in place, go ahead and grab your stacked Bluefruit Feather, and Motor Driver FeatherWing and install it in the breadboard with the USB port facing away from the wires like shown in the image below. Then use your screwdriver and install the bent header pins like shown in the image. Finally, attach the motor wires and power wires as shown in the image. It is important that you have the red and black wires in the correct position. Please reference the image below and triple check that they are installed correctly.

LiPoly Battery

The AA batteries will supply power to the motors through the Motor Driver FeatherWing, but what about power for the Feather itself? For that, you'll use a LiPoly battery. It's small, powerful, and very convenient -- you can charge it simply by plugging the Feather into a USB charger!

Plug the LiPoly battery into the JST battery port on the Feather, and then tuck the battery into the space in the lower level of the robot. If you like, you can secure it with double stick foam tape.

Congratulations, you've built your robot!

Adafruit My Mini Race Car Users guide

Specifications and Main Features

Frequently Asked Questions

User Manual