Rovers: Motor Connections
Python & Building Robots & Rovers - 🤖🚙

Focused on learning Python, using hardware: Adafruit Circuit Playground, Raspberry Pi, Jetson Nano, & other Python-based Microcontrollers & Microprocessors to build Rovers & Robots

Unit Overview, Introduction, Outline

Author: Jim Burnham - TopClown@STEAMClown.org. License: Distributed as Open Source.

In this Unit/Module is focused on Robots & Rovers, primarily Rovers, and features using Python, Raspberry Pi or other Python capable devices/platforms. These labs will focus on building the Rover power infrastucture, implementing drive capability with Python, and adding features, sensors, & Autonoumus and telle Operated driving.

A Cap Stone project will be updating a Robot Rover to run with a Raspberry Pi as it's primary controller. The goal is to be able to control the Rover over the Internet with IoT, and eventually run AI training to let the Rover Autonomously navigate

You'll work on developing programs and implementing them using both a browser interface as well as the Raspberry Pi console-based integrated development environment (IDE), and a graphical user interface (GUI) based interfaces. You'll work primarily with Python, but some other languages and interfaces will also be used.

You will also spend some time learning about and gaining experience in the best practices of software development, such as top-down design, object-oriented design, code debug, code validation, corner case testing, and technical/end-user documentation.

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Let's get started... Its going to be a wild, fun, awesome ride...

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Caution & Safety Considerations:

Primer: "Aaron, I can imagine no way in which this thing could be considered anywhere remotely close to safe. All I know is I spent six hours in there and I'm still alive... You still want to do it?"

As with any activity, please make sure you are using appropriate safety equipment. If you are coding, writing, reading, or working a lab, make sure you stand up and stretch every hour or so, Please consider any safety issues connecting to a Raspberry Pi, Arduino, computers and other electronic equipment.

Connecting Rover Motors:
Lessons, Lectures, & Labs - Robots & Rovers - 🤖🚙

Introduction To Differential Drive Motors On Raspberry Pi

8.n.n.n - Robots & Rovers - Driving A Motor - 📰 Slide Presentation
8.n.n.n - Robots & Rovers - Driving A Motor - 📖 Lesson Tutorial

🧠 Motors

What Is A Connector "Key"

8.n.n.n - Robots & Rovers - Driving A Motor - 📰 Slide Presentation
8.n.n.n - Robots & Rovers - Driving A Motor - 📖 Lesson Tutorial

🔧 What “keyed” means

When a connector is keyed, it has:

A notch, tab, ridge, or missing pin
A matching shape on the mating connector

👉 These features prevent incorrect orientation.

So instead of being able to plug it in:

upside down ❌
backwards ❌
shifted over ❌

…it will only fit:

the one correct way ✅

🧠 Simple mental model

Think of it like a house key:

A key only fits one lock orientation
You can’t insert it upside down or backwards (or it won’t turn)

A keyed connector works the same way mechanically.

🔌 Common examples (you’ve probably seen these)

1. Polarized 2-pin connectors

One side is square, one is rounded
Prevents reversing polarity

2. JST connectors (very common in robotics)

Small plastic latch + slot
Only mates one way

3. IDC ribbon cable connectors

A missing pin + blocked hole acts as the key

4. USB connectors

The shape itself is the key (especially older USB-A)

⚙️ Why keyed connectors matter (especially for your rover)

In your case:

1 = L–

2 = L+

3 = R–

4 = R+

If the connector were not keyed, someone could:

Flip it → left/right swapped ❌
Reverse it → polarity reversed ❌
Offset it → total chaos ❌

👉 Result:

Motors spin wrong direction
Robot drives backward or spins
Possible electrical stress on drivers

✅ What a keyed connector prevents

🔁 Reversed polarity (L+ ↔ L–)
🔄 Swapped channels (Left ↔ Right)
⚡ Misalignment (wrong pins connected)

Connecting From Rover Motor To Motor Controller, To Raspberry Pi

8.n.n.n - Robots & Rovers - Driving A Motor - 📰 Slide Presentation
8.n.n.n - Robots & Rovers - Driving A Motor - NeoPixels - 📖 Lesson Tutorial

🔌 1) Your standardized connector (chassis side)

You defined:

Pin 1 = L–

Pin 2 = L+

Pin 3 = R–

Pin 4 = R+

Encodes function, not color.

⚙️ 2) Connect to the motor outputs on the L298N motor driver module

Use the output terminals (NOT the IN pins):

Left motor → Channel A

Pin 2 (L+) → OUT1
Pin 1 (L–) → OUT2

Right motor → Channel B

Pin 4 (R+) → OUT3
Pin 3 (R–) → OUT4

🧠 3) Now define the control logic (IN1–IN4)

The inputs control polarity of the outputs.

Left motor (OUT1/OUT2 controlled by IN1/IN2)

IN1 IN2 OUT1 OUT2 Motor

1 0 + – Forward ✅

0 1 – + Reverse

0 0 0 0 Coast

1 1 0 0 Brake

👉 Because:

OUT1 → L+ (Pin 2)
OUT2 → L– (Pin 1)

So:

IN1 = HIGH, IN2 = LOW → Left motor forward

Right motor (OUT3/OUT4 controlled by IN3/IN4)

IN3 IN4 OUT3 OUT4 Motor

1 0 + – Forward ✅

0 1 – + Reverse

0 0 0 0 Coast

1 1 0 0 Brake

👉 Because:

OUT3 → R+ (Pin 4)
OUT4 → R– (Pin 3)

So:

IN3 = HIGH, IN4 = LOW → Right motor forward

📦 4) Clean standard (this is what you want for multiple rovers)

Hardware standard

Connector: L298N:

Wire/Pin 1 = L– = Wire/Pin 1 → OUT2 : Forward Controlled with IN1 = 1, IN2 = 0, IN3 = 1, IN4 = 0

Wire/Pin 2 = L+ = Wire/Pin 2 → OUT1

Wire/Pin 3 = R– = Wire/Pin 3 → OUT4

Wire/Pin 4 = R+ = Wire/Pin 4 → OUT3

Software standard

Forward:

IN1 = 1, IN2 = 0

IN3 = 1, IN4 = 0

💡 Why this works so well?

No dependence on motor wire color
No ambiguity about CW/CCW
Every rover behaves identically
You can debug with simple voltage logic:

“When In1=1, In2=0, Is L+ (Wire/Pin 2) actually the VBat+?, Is L- (Wire/Pin 1) actually the VBat-?”

Finally, Let's Drive A Rover

Drive Test Python Code

8.n.n.n - Robots & Rovers - Driving A Motor - 📰 Slide Presentation
8.n.n.n - Robots & Rovers - Driving A Motor - NeoPixels - 📖 Lesson Tutorial

Driving?

Reference, Attribution & Resources:

License - "Be A Hero"... Distribute Your Content As Open Source... That Is What I'm Doing...

The content on this site may have been pulled from other open source sites, but typically the interpretation and presentation is primarily the Intellectual Property of Jim Burnham, - TopClown@STEAMClown.org at www.steamclown.org and the Student curriculum can be found under the specific Mechatronics Engineering Units section of this web site.
If you do use my material, and make changes, I would appreciate getting a copy... because if you are making changes, it means that you think there is a better way to teach this… and I would really appreciate understanding that. Please send me feedback on my Questions or Feedback form. Please don’t hesitate to ask questions or comment.
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Rovers: Motor ConnectionsPython & Building Robots & Rovers - 🤖🚙