Book Image

Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

By : Steven Lawrence Fernandes, Tim Cox
Book Image

Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

By: Steven Lawrence Fernandes, Tim Cox

Overview of this book

Raspberry Pi 3 Cookbook for Python Programmers – Third Edition begins by guiding you through setting up Raspberry Pi 3, performing tasks using Python 3.6, and introducing the first steps to interface with electronics. As you work through each chapter, you will build your skills and apply them as you progress. You will learn how to build text classifiers, predict sentiments in words, develop applications using the popular Tkinter library, and create games by controlling graphics on your screen. You will harness the power of a built in graphics processor using Pi3D to generate your own high-quality 3D graphics and environments. You will understand how to connect Raspberry Pi’s hardware pins directly to control electronics, from switching on LEDs and responding to push buttons to driving motors and servos. Get to grips with monitoring sensors to gather real-life data, using it to control other devices, and viewing the results over the internet. You will apply what you have learned by creating your own Pi-Rover or Pi-Hexipod robots. You will also learn about sentiment analysis, face recognition techniques, and building neural network modules for optical character recognition. Finally, you will learn to build movie recommendations system on Raspberry Pi 3.
Table of Contents (23 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Extending the Raspberry Pi GPIO with an I/O expander


As we have seen, making use of the higher-level bus protocols allows us to connect to more complex hardware quickly and easily. The I2C can be put to great use by using it to expand the available I/O on the Raspberry Pi, as well as providing additional circuit protection (and, in some cases, additional power to drive more hardware).

There are lots of devices available that provide I/O expansion over the I2C bus (and also SPI), but the most commonly used is a 28-pin device, MCP23017, which provides 16 additional digital input/output pins. Being an I2C device, it only requires the two signals (SCL and SDA connections, plus ground, and power) and will happily function with other I2C devices on the same bus.

We shall see how the Adafruit I2C 16x2 RGB LCD Pi Plate makes use of one of these chips to control an LCD alphanumeric display and keypad over the I2C bus (without the I/O expander, this would normally require up to 15 GPIO pins).

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