Custom Raspberry Pi Interfaces

Transcription

1 Custom Raspberry Pi Interfaces Design and build hardware interfaces for the Raspberry Pi Warren Gay

2 Custom Raspberry Pi Interfaces: Design and build hardware interfaces for the Raspberry Pi Warren Gay St Catharines, Ontario, Canada ISBN-13 (pbk): ISBN-13 (electronic): DOI / Library of Congress Control Number: Copyright 2017 by Warren Gay This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Managing Director: Welmoed Spahr Editorial Director: Todd Green Acquisitions Editor: Aaron Black Development Editor: James Markham Technical Reviewer: Massimo Nardone Coordinating Editor: Jessica Vakili Copy Editor: Kim Wimpsett Compositor: SPi Global Indexer: SPi Global Artist: SPi Global Cover image designed by Freepik Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit Apress titles may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Print and ebook Bulk Sales web page at Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book's product page, located at For more detailed information, please visit Printed on acid-free paper

3 Contents at a Glance About the Author... xiii About the Technical Reviewer... xv Chapter 1: Introduction... 1 Chapter 2: 3V/5V Signal Interfacing... 5 Chapter 3: VGA LCD Monitors Chapter 4: I2C LCD Displays Chapter 5: MC14490 and Software Debouncing Chapter 6: PCF8591 ADC Chapter 7: Potentiometer Input Controls Chapter 8: Rotary Encoders Chapter 9: More Pi Inputs with 74HC Chapter 10: More Pi Outputs with 74HC Chapter 11: MCP23017 I/O Port Extender Chapter 12: MPD/MPC Hardware Controls Chapter 13: Custom Keypads Index iii

4 Contents About the Author... xiii About the Technical Reviewer... xv Chapter 1: Introduction... 1 Raspberry Pi 3 and Zero... 2 Why GPIO Is Important... 2 What to Purchase... 2 Software to Download... 4 Let s Begin... 4 Chapter 2: 3V/5V Signal Interfacing Series (TTL) V Logic... 7 Voltage Dividers Series Derivative Families Unused CMOS Inputs Converting 5V to 3V Input: 74LVC Converting 5V to 3V Input: 74LVC CD4049/CD Input Protection Diodes...16 v

5 vi Converting 3 Volts to 5 Volts with the HCT Family HCT HCT Switching Speed Summary Bibliography Chapter 3: VGA LCD Monitors VGA Converters Resolution and Refresh Rates /boot/config.txt Confirming Resolution Summary Bibliography Chapter 4: I2C LCD Displays LCD Module 1602A I2C Serial Interface I2C Module Configuration I2C Module Output I2C Module Input PCF8574P Chip Volts to 5 Volts Attaching the I2C Serial Module Displaying Data Reading from the LCD Class LCD I2C Baud Rate Profit and Loss Summary... 54

6 Chapter 5: MC14490 and Software Debouncing Hardware: MC Chip Operation Capacitor C Experiment More Inputs Software Debouncing Experiment Summary Chapter 6: PCF8591 ADC The YL-40 PCB Voltage Range I2C Bus I2C Addresses DAC (AOUT) Removing YL-40 LED D Hacking YL-40 I2C Address I2C Bus Setup Reading from PCF Experiment...76 Writing to the DAC Experiment...77 Experiment...78 Limitations Extending Voltage Range Repairing the Temp Sensor Conversion to Celsius vii

7 Reading Temperature Experiment...84 The YL-40 LDR Experiment N914 Experiment Software Potential Experiments Summary Bibliography Chapter 7: Potentiometer Input Controls Potentiometers Voltage Dividers ADC Circuit Pot Resistance Taper Effect of ADC Bits Experiment Applying Potentiometer Controls Selection Resolution Summary Bibliography Chapter 8: Rotary Encoders Keyes KY-040 Rotary Encoder The Switch Operation Voltage viii

8 Evaluation Circuit Interfacing to the Pi Experiment Experiment Sequence Errors Experiment FM Dial FM Dial Class Switch Main Routine Summary Bibliography Chapter 9: More Pi Inputs with 74HC HC165 Pinout Function Table Breadboard Experiment Program Logic Analyzer View Profit and Loss Even More Inputs Other Bit Counts Combining GPIOs Chip Enable CD4012B Summary ix

9 Chapter 10: More Pi Outputs with 74HC HC165 Pinout Function Table Breadboard Experiment Experiment Run Input and Output Additional Outputs Profit and Loss Summary Chapter 11: MCP23017 I/O Port Extender MCP Wiring Output GPIO Experiment Input Experiment Software Operations I2C Header Files Opening the I2C Driver I2C Write I2C Read Configuration Interrupt Capability Interrupt Profit and Loss Summary x

10 Chapter 12: MPD/MPC Hardware Controls Audio Preparation MPD/MPD Hardware Setup Test Volume Control Test Rotary Control Test LCD The mpcctl Program Main Program Rotary Encoder Thread LCD Thread MPC Status Thread Volume Control Thread Program Summary Summary Bibliography Chapter 13: Custom Keypads Breadboard Setup Output Tests Input Tests High-Side Driver Low-Side Driver Driving an LED The Keypad xi

11 Keypad Program The main Program The key_lookup Function The i2c_write Function The i2c_read Function Combination Lock Combination Lock The main Program The get_key_code Function Interrupts Summary Bibliography Index xii

12 About the Author Warren Gay started out in electronics at an early age, dragging discarded TVs and radios home from public school. In high school he developed a fascination for programming the IBM 1130 computer, which resulted in a career plan change to software development. After attending Ryerson Polytechnical Institute, he has enjoyed a software developer career for more than 30 years, programming mainly in C/C++. Warren has been programming Linux since 1994 as an open source contributor and professionally on various Unix platforms since Before attending Ryerson, Warren built an Intel 8008 system from scratch before there were CP/M systems and before computers got personal. In later years, Warren earned an advanced amateur radio license (call sign VE3WWG) and worked the amateur radio satellites. A high point of his ham radio hobby was making digital contact with the Mir space station (U2MIR) in Warren works at Datablocks.net, an enterprise-class ad-serving software services company. There he programs C++ server solutions on Linux back-end systems. xiii

13 About the Technical Reviewer Massimo Nardone has more than 22 years of experience in security, web/mobile development, the cloud, and IT architecture. His true IT passions are security and Android. He has been programming and teaching how to program with Android, Perl, PHP, Java, VB, Python, C/C++, and MySQL for more than 20 years. He has a master s of science degree in computing science from the University of Salerno, Italy. He has worked as a project manager, software engineer, research engineer, chief security architect, information security manager, PCI/SCADA auditor, and senior lead IT security/cloud/scada architect for many years. His technical skills include the following: security, Android, cloud, Java, MySQL, Drupal, Cobol, Perl, web and mobile development, MongoDB, D3, Joomla, Couchbase, C/C++, WebGL, Python, Pro Rails, Django CMS, Jekyll, Scratch, and more. He currently works as chief information security officer (CISO) for Cargotec Oyj. He has worked as a visiting lecturer and supervisor for exercises at the Networking Laboratory of the Helsinki University of Technology (Aalto University). He holds four international patents (PKI, SIP, SAML, and proxy areas). Massimo has reviewed more than 40 IT books for different publishing company and is the coauthor of Pro Android Games (Apress, 2015). xv