Robotics at Home with Raspberry Pi Pico: Build autonomous robots with the versatile low-cost Raspberry Pi Pico controller and Python

401 Pages·2023·35.892 MB·English

by  Danny Staple

Robotics at Home with Raspberry
Pi Pico
Build autonomous robots with the versatile low-cost Raspberry
Pi Pico controller and Python
Danny Staple
BIRMINGHAM—MUMBAI
Robotics at Home with Raspberry Pi Pico
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To my amazing wife, Carol, who has supported all my robotics experiments with love, inspiration, and
tolerance of a living room filled with robots. To my children, Helena and Jonathan, for all their ideas
and enthusiasm and for encouraging me to take a break and play with them sometimes!
– Danny Staple
Contributors
About the author
Danny Staple is a robot builder and programmer. He has been a professional software engineer since
2000, uses Python professionally, and regularly contributes to open source projects.
Danny has been building robots at home since 2004 and has a cupboard full of projects, including
robots with wheels, cameras, tank tracks, legs, and arms, made from plastic, cardboard, metal, kits,
lunchboxes, and modified toys.
Danny authored Learn Robotics Programming, published in 2021 by Packt Publishing, and has written
magazine articles for The MagPi. He runs the robotics YouTube channel Orionrobots and brings his
robots to events such as Pi Wars and Arduino Day. Danny also mentors at CoderDojo KU, where he
shows kids how to program in Python and has run Lego robotics clubs.
I would like to thank the Pi Wars and Adafruit communities for answering my tricky questions,
Mike Moncrieffe for checking diagrams for me, and my review team for the great feedback throughout
this book.
About the reviewer
Leo White is a professional software engineer and a graduate of the University of Kent. His interests
include electronics, 3D printing, and robotics. He first started programming on the Commodore 64
and later wrote several applications for the Acorn Archimedes. He currently programs set-top boxes
for his day job. Utilizing the Raspberry Pi as a foundation, he has mechanized children’s toys and driven
robot arms, blogging about his experiences and processes along the way. He has given presentations
at Raspberry Jams and entered a variety of robots in the Pi Wars competition.

Table of Contents
Preface xv
Part 1: The Basics – Preparing for Robotics
with Raspberry Pi Pico
1
Planning a Robot with Raspberry Pi Pico 3
Technical requirements 3 Test fitting a Raspberry Pi
What is Raspberry Pi Pico, and Pico robot 21
why is it suitable for robotics? 4 Creating your first test-fit part 21
A microcontroller that runs Python 4 Motors 22
Raspberry Pi Pico’s interfaces for Power systems 23
sensors and devices 7 Creating a rough chassis 24
Arranging the test-fit parts 25
What is CircuitPython? 10
A recommended shopping list
Planning a Raspberry Pi Pico
for robot basics 26
robot 11
Robot parts and where to find them 26
An overview of robot planning 12
The robot workshop and makerspaces 28
A note on trade-offs 14
Choosing a robot chassis 15
Summary 30
Choosing the power systems 16
Exercises 30
Pin usage 20
Further reading 30
viii Table of Contents
2
Preparing Raspberry Pi Pico 31
Technical requirements 31 Lighting the Pico LED with CircuitPython 35
Getting CircuitPython onto Blinking the LED with code 36
Raspberry Pi Pico 32
Soldering headers to Raspberry
Preparing the CircuitPython Pi Pico 38
library for Pico 33
Summary 43
Coding on Pico – first steps 33
Exercises 43
Downloading the Mu editor 34
Further reading 44
3
Designing a Robot Chassis in FreeCAD 45
Technical requirements 45 Modeling chassis parts from
Introducing FreeCAD 46 sketches 68
The FreeCAD screen 46 Modeling the chassis plate 68
Selecting workbenches 47 Modeling the other parts 70
FreeCAD settings 48 Troubleshooting the model 72
Modeling the caster in 3D 73
Making robot chassis sketches
in FreeCAD 50 Making FreeCAD technical
drawings 75
Preparing the document 51
Sketching the chassis outline 52 Setting up the page 75
Creating the upper parts main sketch 58 Adding parts to the drawing 76
Sketching the motor holes 63 Preparing the drawing for print 77
Designing the caster placement 67 Summary 79
Exercises 79
Further reading 80
4
Building a Robot around Pico 81
Technical requirements 81 Transferring CAD measurements to a
plastic sheet 83
Cutting styrene parts 83
Cutting the plastic sheet 85
Finishing and sanding the chassis plate 87
Table of Contents ix
Assembling a robot chassis 90 Adding the batteries 96
Attaching the caster and battery box 90 Wiring in the motors and encoders 97
Attaching the motors and wheels 92 Powering the robot up 99
Wiring a Raspberry Pi Pico robot 93 Summary 100
Wiring Pico and the motor controller Exercises 100
into the breadboard 93 Further reading 100
5
Driving Motors with Raspberry Pi Pico 101
Technical requirements 101 Turning while moving 114
Driving forward and back 102
Driving along a planned path 115
Testing each motor with CircuitPython 102
Putting line and turn moves together 115
Driving wheels in a straight line 106
The flaw with driving this way 117
Steering with two motors 108
Summary 118
An introduction to pulse width
Exercises 118
modulation speed control 110
Further reading 118
Driving fast and slow 111
Part 2: Interfacing Raspberry Pi Pico with
Simple Sensors and Outputs
6
Measuring Movement with Encoders on Raspberry
Pi Pico 121
Technical requirements 121 Examining the wiring 125
About encoders and odometry 122
Programming Raspberry Pi
Absolute and relative sensing 122 Pico PIO 126
Types of encoders 122
Introduction to PIO programming 126
Encoder pulse data 123
Introducing PIOASM 128
Wiring in encoders on a Detecting input with PIO 129
Raspberry Pi Pico robot 124 PIO instructions and registers 132
Making a counter with PIO 136
Examining the motors 124