Practical Python Programming for IoT by Gary Smart -- Read -- Imperial Library of Trantor

Index

Title Page Copyright and Credits

Practical Python Programming for IoT

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Preface

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Section 1: Programming with Python and the Raspberry Pi Setting Up your Development Environment

Technical requirements Understanding your Python installation Setting up a Python virtual environment Installing Python GPIO packages with pip

Anatomy of a virtual environment

Alternative methods of executing a Python script

Using sudo within virtual environments Executing Python scripts outside of their virtual environments Running a Python script at boot

Configuring the GPIO interface on our Raspberry Pi

Configuring the PiGPIO daemon

Summary Questions Further reading

Getting Started with Python and IoT

Technical requirements Creating a breadboard prototype circuit

Understanding the breadboard Positioning and connecting the push button Positioning and connecting the LED Positioning and connecting the resistor

Reading an electronic schematic diagram

Reading the push button schematic connection Reading the LED and resistor schematic connection Introducing ground connections and symbols

Exploring two ways to flash an LED in Python

Blinking with GPIOZero

Imports Pin Factory configuration Blinking the LED

Blinking with PiGPIO

Imports PiGPIO and pin configuration Blinking the LED

Comparing the GPIOZero and PiGPIO examples

Exploring two ways to integrate a push button in Python

Responding to a button press with GPIOZero

Imports Button pressed handler Button configuration Preventing the main thread from terminating

Responding to a button press with PiGPIO

Button pin configuration Button pressed handler

Creating your first IoT program

Running and testing the Python server Understanding the server code

Imports Variable definitions The resolve_thing_name() method The get_lastest_dweet() method The poll_dweets_forever() method The process_dweet() method The main program entry point

Extending your IoT program

Implementing a dweeting button PiGPIO LED as a class

Summary Questions Further reading

Networking with RESTful APIs and Web Sockets Using Flask

Technical requirements Introducing the Flask microservices framework Creating a RESTful API service with Flask-RESTful

Running and testing the Python server Understanding the server code

Imports Flask and Flask-RESTful API instance variables Global variables The init_led() method Serving a web page The LEDControl class The get() class method The post() class method LEDController registration and starting the server

Introduction to PWM

Adding a RESTful API client web page

Understanding the client-side code

JavaScript imports The getState() function The postUpdate() function The updateControls() function Registering event handlers with jQuery The web page HTML

Creating a Web Socket service with Flask-SocketIO

Running and testing the Python server Server code walkthrough

Imports Flask and Flask-RESTful API instance variables Serving a web page Connecting and disconnecting handlers LED handler Starting the server

Adding a Web Socket client web page

Understanding the client-side code

Imports Socket.IO connect and disconnect handlers The on LED handler The document ready function The web page HTML

Comparing the RESTful API and Web Socket servers Summary Questions Further reading

Networking with MQTT, Python, and the Mosquitto MQTT Broker

Technical requirements Installing the Mosquitto MQTT broker Learning MQTT by example

Publishing and subscribing MQTT messages Exploring MQTT topics and wildcards Applying Quality of Service to messages Retaining messages for later delivery

Publishing a retained message Creating durable connections

Saying goodbye with a Will Using MQTT broker services

Introducing the Python Paho-MQTT client library Controlling an LED with Python and MQTT

Running the LED MQTT example Understanding the code

Imports Global variables The set_led_level(data) method The on_connect() and on_disconnect() MQTT callback methods The on_message() MQTT callback method The init_mqtt() method Main entry point

Building a web-based MQTT client

Understanding the code

Imports Global variables The Paho JavaScript MQTT client Connecting to the broker The onConnectionLost and onMessageArrived handler methods JQuery document ready function

Summary Questions Further reading

Section 2: Practical Electronics for Interacting with the Physical World Connecting Your Raspberry Pi to the Physical World

Technical requirements Understanding Raspberry Pi pin numbering Exploring popular Python GPIO libraries

Reviewing GPIOZero – simple interfacing for beginners Reviewing RPi.GPIO – a low-level GPIO for beginners Reviewing Circuit Python and Blinka – interfacing for complex devices Reviewing PiGPIO – a low-level GPIO library

Exploring remote GPIO with PiGPIO (and GPIOZero)

Reviewing SPIDev and SMBus – dedicated SPI and I2C libraries Why PiGPIO?

Exploring Raspberry Pi electronic interfacing options

Understanding digital IO Understanding analog IO Understanding Pulse-Width Modulation

Creating PWM signals

Understanding SPI, I2C, and 1-wire interfaces Understanding the serial / UART protocol

Interfacing with an analog-to-digital converter

Building the ADS1115 ADC circuit Making sure the ADS1115 is connected to your Raspberry Pi Reading analog input with the ADS1115

Understanding the code

Imports ADS1115 setup and configuration Global variables Program entry point

Using PWM to control an LED

Understanding the code

Global variables Range mapping function Generating the PWM signal

Visually exploring PWM with PiScope Visualizing software and hardware-timed PWM

Summary Questions Further reading

Electronics 101 for the Software Engineer

Technical requirements Fitting out your workshop

Buying electronic modules and components

Purchasing lose components Purchasing open source hardware modules

Keeping your Raspberry Pi safe Three ways electronic components fail Electronics interfacing principles for GPIO control

Ohm's Law and power Kirchhoff's circuit laws Why are we using a 200 Ohm resistor for the LED circuit?

Calculating the resistor value Factoring in the Raspberry Pi's current limits Calculating the resistor's power dissipation

Exploring digital electronics

Digital output Digital input Using pull-up and pull-down resistors

The resistor solution The code solution

Exploring analog electronics

Analog output Analog input

Voltage dividers

Understanding logic-level conversion

Voltage dividers as logic-level converters Logic-level converter ICs and modules Comparing voltage dividers and logic-level converters

Summary Questions Further reading

Section 3: IoT Playground - Practical Examples to Interact with the Physical World Turning Things On and Off

Technical requirements Exploring a relay driver circuit Determining a load's voltage and current

Measuring the current requirement of a DC motor Measuring the current requirement of a relay and LED

Using an optocoupler as a switch

Building the optocoupler circuit Controlling the optocoupler with Python

Using a transistor as a switch

Building the MOSFET circuit Controlling the MOSFET with Python

Using a relay as a switch

Building the relay driver circuit Controlling the Relay Driver Circuit with Python

Summary Questions Further reading

Lights, Indicators, and Displaying Information

Technical requirements Making color with an RGB LED and PWM

Creating the RGB LED circuit Running and exploring the RGB LED code

Controlling a multi-color APA102 LED strip with SPI

Creating the APA102 circuit

Powering the APA102 circuit Configuring and running the APA102 LED strip code APA102 LED strip code walkthrough Discussion of APA102 and the SPI interface APA102 LED strip troubleshooting tips

Using an OLED display

Connecting the OLED display Verifying whether the OLED display is connected Configuring and running the OLED example

OLED code walkthrough

Making sound with buzzers and PWM

Building the RTTTL circuit Running the RTTTL music example

Summary Questions Further reading

Measuring Temperature, Humidity, and Light Levels

Technical requirements Measuring temperature and humidity

Creating the DHT11/DHT22 circuit Running and exploring the DHT11/DHT22 code

Detecting light

Creating an LDR light-detecting circuit Running the LDR example code LDR code walkthrough LDR configuration summary

Detecting moisture

Comparing detection options

Summary Questions

Movement with Servos, Motors, and Steppers

Technical requirements Using PWM to rotate a servo

Connecting a servo to your Raspberry Pi How a servo is controlled using PWM Running and exploring the servo code Different types of servos

Using an H-Bridge IC to control a motor

Building the motor driver circuit Running the example H-Bridge code to control a motor

motor.py motor_class.py

Introduction to stepper motor control

Connecting the stepper motor to the L293D circuit Running and exploring the stepper motor code

Summary Questions

Measuring Distance and Detecting Movement

Technical requirements Detecting movement with a PIR sensor

Creating the PIR sensor circuit Running and exploring the PIR sensor code

Measuring distance with an ultrasonic sensor

How an ultrasonic distance sensor works HC-SR04 distance measurement process Building the HC-SR04 circuit Running and exploring the HC-SR04 example code

Detecting movement and distance with Hall-effect sensors

Creating a Hall-effect sensor circuit Running and exploring the Hall-effect sensor code

Summary Questions

Advanced IoT Programming Concepts - Threads, AsyncIO, and Event Loops

Technical requirements Building and testing our circuit

Building the reference circuit Running the examples

Exploring the event-loop approach Exploring a threaded approach Exploring the publisher-subscriber alternative Exploring an AsyncIO approach

An asynchronous experiment

Summary Questions Further reading

IoT Visualization and Automation Platforms

Technical requirements Triggering an IFTTT Applet from your Raspberry Pi

Creating the temperature monitoring circuit Creating and configuring an IFTTT Applet Triggering an IFTTT Webhook Triggering an IFTTT Applet in Python

Actioning your Raspberry Pi from an IFTTT Applet

Method 1 – using the dweet.io service as an intermediary Method 2 – creating a Flask-RESTful service Creating the LED circuit Running the IFTTT and LED Python program Creating the IFTTT Applet Controlling the LED from an email IFTTT troubleshooting

Visualizing data with the ThingSpeak platform

Configuring the ThinkSpeak platform Configuring and running the ThinkSpeak Python program

Other IoT and automation platforms for further exploration

Zapier IFTTT platform ThingsBoard IoT platform Home Assistant Amazon Web Services (AWS) Microsoft Azure, IBM Watson, and Google Cloud

Summary Questions

Tying It All Together - An IoT Christmas Tree

Technical requirements Overview of the IoT Christmas tree Building the IoTree circuit

Three IoTree service programs

Configuring, running, and using the Tree API service

Configuring the Tree API service Running the Tree API service

Configuring, running, and using the Tree MQTT service

Configuring the Tree MQTT service Running the Tree MQTT service program

Integrating the IoTree with dweet.io

Configuring the Tree MQTT service Running the dweet integration service program

Integrating with email and Google Assistant via IFTTT

Integration with email Integration with Google Assistant

Ideas and suggestions to extend your IoTree Summary Questions

Assessments

Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14

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