reading

● This is an Elektor Publication. Elektor is the media brand of Elektor International Media B.V.78 York StreetLondon W1H 1DP, UKPhone: (+44) (0)20 7692 8344© Elektor International Media BV 2020First published in the United Kingdom 2020

● All rights reserved. No part of this book may be reproduced in any material form, including photocopying, or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication, without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers. The publishers have used their best efforts in ensuring the correctness of the information contained in this book. They do not assume, and hereby disclaim, any liability to any party for any loss or damage caused by errors or omissions in this book, whether such errors or omissions result from negligence, accident or any other cause.

● British Library Cataloguing in Publication DataCatalogue record for this book is available from the British Library

● ISBN 978-1-907920-83-7

● EISBN 978-3-89576-386-1 

● EPUB 978-3-89576-387-8

Prepress production: DMC ¦ dave@daverid.com

Cover Art: Marie Skovgaard MikkelsenPrinted in the Netherlands by Wilco

Table of Contents

Chapter 1 ● Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.1 ● Why this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.2 ● Who the book is designed for. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.3 ● How to use the book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.4 ● Organisation of the book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4.1 ● Section 2: Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4.2 ● Section 3: Arduino IDE Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4.3 ● Section 4: emoncms Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4.4 ● Section 5: MQTT (mosquitto) Installation On A Raspberry Pi. . . . . . . . . . . 11

1.4.5 ● Section 6: ESP8266 Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.4.6 ● Section 7: ESP8266 Watchdogs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.7 ● Section 8: WiFi Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.8 ● Section 9: General Software Design. . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.9 ● Section 10: IKEA Hack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.10 ● Section 11: Door Lock Monitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.11 ● Section 12: Energy Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.12 ● Section 13: Refrigerator Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4.13 ● Section 14: Lamp Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.4.14 ● Section 15: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.4.15 ● Section 16: PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.5 ● Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.6 ● References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.7 ● Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter 2 ● Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.1 ● ESP8266 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.1.1 ● Wemos D1 mini Pro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.1.2 ● Sleep Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2 ● Raspberry Pi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.2.1 ● Raspberry Pi Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.3 ● Neopixel Jewel 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.4 ● IKEA Grönö lamp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.5 ● SSR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.6 ● Maxim DS18B20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.7 ● QRE1113 (Analog). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.8 ● Wemos Shields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Chapter 3 ● Arduino IDE Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.1 ● Standard Arduino IDE Install. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.2 ● ESP8266 support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.3 ● SPI Flash File (SPIFFS) System Install. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Chapter 4 ● emoncms Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.1 ● Update and Upgrade the Raspberry Pi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.2 ● Install Dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2.1 ● MariaDB & apache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2.2 ● phpMyAdmin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.2.3 ● PECL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.3 ● emoncms Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.3.1 ● Configure emoncms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.4 ● emoncms Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.4.1 ● Dashboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.4.2 ● Graph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.4.3 ● Apps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.5 ● Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Chapter 5 ● MQTT (Mosquitto) Installation on a Raspberry Pi . . . . . . . . . . . . . . . . . 63

5.1 ● Installation of the Mosquitto Broker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.2 ● Installation of the Mosquitto Client (Raspberry Pi). . . . . . . . . . . . . . . . . . . . . 69

5.3 ● Verification of Mosquitto Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.4 ● Installation of the Mosquitto Client (Windows PC) . . . . . . . . . . . . . . . . . . . . . 72

Chapter 6 ● ESP8266 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Chapter 7 ● ESP8266 Watchdogs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1 ● Watchdogs in General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.2 ● Loop Watchdog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.2.1 ● Boot Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Chapter 8 ● ESP8266 WiFi Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.1 ● External Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

8.1.1 ● Readymade Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

8.1.2 ● Salvaged Antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

8.1.3 ● DIY Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Chapter 9 ● General Software Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Chapter 10 ● IKEA Hack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.1 ● Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.2 ● Mechanical Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.2.1 ● Grönö Lamp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

10.2.2 ● Wemos Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

10.3 ● Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

10.3.1 ● Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

10.3.2 ● Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

10.3.2.1 ● WEB interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

10.3.2.2 ● Lamp On/Off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

10.3.2.3 ● Set Brightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

10.3.2.4 ● Set Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

10.3.2.5 ● Select Animation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

10.3.2.6 ● Enter static colours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

10.3.2.7 ● Save Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

10.3.3 ● Wemos Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

10.3.3.1 ● setup() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

10.3.3.2 ● loop() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

10.3.4 ● HTTP POST Requests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

10.3.4.1 ● The HTTP POST Request Code in General. . . . . . . . . . . . . . . . . . 114

10.3.4.2 ● PHP-code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

10.3.4.3 ● C-Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

10.3.4.4 ● Python Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

10.3.5 ● Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

10.3.5.1 ● Rainbow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

10.3.5.2 ● Rainbow Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

10.3.5.3 ● Static . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

10.3.5.4 ● Fade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

10.4 ● Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

10.4.1 ● Daily Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

10.4.1.1 ● Power Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

10.4.2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Chapter 11 ● Door Lock Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

11.1 ● Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

11.2 ● Mechanical Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

11.3 ● Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

11.3.1 ● Emoncms Wemos Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

11.3.1.1 ● setup() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

11.3.1.2 ● loop() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

11.3.2 ● Emoncms Dashboard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

11.3.3 ● MQTT Wemos Firmware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

11.3.3.1 ● MQTT Client Publisher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

11.3.3.2 ● MQTT Client Subscriber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

11.3.4 ● MQTT Broker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Chapter 12 ● Energy Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

12.1 ● Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

12.2 ● Mechanical Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

12.3 ● Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

12.3.1 ● Wemos Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

12.3.1.1 ● setup() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

12.3.1.2 ● loop() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

12.3.1.3 ● Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

12.4 ● Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

12.5 ● Dashboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

Chapter 13 ● Refrigerator Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

13.1 ● Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

13.1.1 ● SSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

13.1.2 ● DS18B20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

13.2 ● Mechanical Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

13.3 ● Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

13.3.1 ● Wemos Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

13.3.1.1 ● setup() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

13.3.1.2 ● loop() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

13.3.2 ● Temperature Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

13.3.3 ● Watchdog Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

13.3.4 ● WEB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

13.3.4.1 ● Set Temperature and Hysteresis . . . . . . . . . . . . . . . . . . . . . . . 190

13.3.4.2 ● Open Temperature Logger . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

13.3.4.3 ● Save Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

13.3.5 ● SPI Flash File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

13.3.6 ● Compile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

13.4 ● Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

13.5 ● Dashboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

Chapter 14 ● Lamp Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.1 ● Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.1.1 ● SSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.1.2 ● Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

14.1.3 ● Shield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

14.2 ● Mechanical Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.2.1 ● SSR or Mechanical Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.2.2 ● Relay Shield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.3 ● Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.3.1 ● Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.3.1.1 ● WEB interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210

14.3.2 ● Wemos firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

14.3.2.1 ● setup() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

14.3.2.2 ● loop() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

14.4 ● Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Chapter 15 ● Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

15.1 ● Hardware Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

15.1.1 ● DS18B20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

15.1.2 ● Red/Green LED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

15.1.3 ● Compressor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

15.1.4 ● USB Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

15.2 ● Network issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

15.3 ● Wemos firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

15.3.1 ● Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

15.4 ● emoncms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

15.4.1 ● Graph Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

15.4.2 ● Input / Feeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

Chapter 16 ● PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

16.1 ● IKEA hack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

16.2 ● Door Lock Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

16.3 ● Energy sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

16.4 ● Refrigerator Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

16.4.1 ● Regulator PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

16.4.2 ● DS18B20 PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

16.4.3 ● Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

16.5 ● Lamp Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

Chapter 17 ● Software Listings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

17.1 ● Utility Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

17.1.1 ● formatBytes(size_t bytes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

17.1.2 ● printFloat(float value, int places). . . . . . . . . . . . . . . . . . . . . . . . . . . 235

17.1.3 ● isNumeric(String str). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

17.1.4 ● keypressWait(). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

17.1.5 ● showWiFiStatus(int i) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

17.1.6 ● doWifiConnect(). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

17.2 ● HTTP POST Request Utility Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

17.2.1 ● PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

17.2.2 ● C-Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

17.2.3 ● Python . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248

17.3 ● Loop Watchdog Timer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

Index 252

IoT Home Hacks ● with ESP8266

Chapter 1 ● Introduction

Welcome to the "ESP8266 IoT"-book

Disclaimer: The constructions I describe in this book have been tested as thoroughly as possible. I have not managed to damage any of my equipment (or myself), but I am sure there's a way. In addition, the technology described hereinafter is purely for fun and should not in any circumstances be used for medical, mission-critical or safety-critical applications.

I will not accept any responsibility for damages of any kind due to actions taken by you after reading this book.

Having said that, let's continue.

1.1 ● Why this book

Like many others, when I first laid my eyes on the ESP8266 it captured my imagination immediately, like when the Raspberry Pi came along.

Before the arrival of the ESP8266, I made a lot of Arduino constructions, some with Internet connections. It was therefore obvious that I should have a go with ESP8266.

Some of the constructions and findings are described in this book. It is my hope that you enjoy working with ESP8266 as much as I have.

1.2 ● Who the book is designed for

In order to use this book, I expect some basics from you:

• You have some experience with PC software. That is, you are familiar with operat-ing at least a Windows PC and know how to navigate a file system, edit a file and install/configure software.

• You have experience in surfing the Internet. You need to be able to locate and down-load the files I mention in the book. After download, you should be able to find and install the downloaded files.

• You know how to assemble a PCB. Since many of the constructions need additional hardware compared to the ESP8266, you will need to be able to assemble the required PCBs. They are not complicated and I have avoided using SMD components.

• You have some basic mechanical skills. Most of the constructions need to be incorporated into present mechanical constructions. It shouldn't be difficult it requires that you operate tools which may cause injury.

Please be careful about what you are doing and take care!

Chapter 1 ● Introduction

1.3 ● How to use the book

Even though this book is about the ESP8266 microcontroller, you may need to install and configure an embedded Linux system (a Raspberry Pi).

Some basic skills are required to do so, but everything will be described in details, or through links to additional information on the internet.

When configuring Linux, you will see specific commands listed like this:

pi@raspberrypi: $ cd /var/www/emoncms/Modules

pi@raspberrypi: $ git clone https://github.com/emoncms/app.git

Commands are in bold.

The last command is listed on two lines but you should enter it as one long command like:

“git clone https://github.com/emoncms/app.git”

Throughout the book there will be parts which will be highlighted as shown below:

This is what a warning will look like. This is where you or your surroundings or the equipment may be damaged if not handled with care and attention: Don’t worry there will not be many of these.

This is how a note looks. You should pay attention to these.

This is where I may “side-track” a little and give additional information for further reading on the subject.

Files of interest will be shown like this:

/opt/lamp/htdocs

Finally, I will show file listings in boxes like the following:

I encourage you to go through the entire book before you start your own project. It is always good to be well prepared. You should at the very least read a section in advance.

I also encourage you to make notes about what you are doing, just in case you need to do it all over again...I talk from experience.

#include <stdio.h>

main()

{

printf(“hello world\n”);

}

IoT Home Hacks ● with ESP8266

1.4 ● Organisation of the book

In order to avoid reading the entire book to discover what’s covered, here is a very short description of each section.

1.4.1 ● Section 2: Components

This book is mainly about the Espressif ESP8266 microcontroller. I have chosen the Wemos D1 mini pro, but you will most likely be able to use other variants out there.

Since the ESP8266 and Raspberry Pi complement each other very well, there will also be design ideas which incorporate the Raspberry Pi.

In this section, the following components are briefly described:

• Adafruit Neopixel Jewel 7.

• Raspberry Pi

• Grönö lamp

• SSR

• Maxim DS18B20

• QRE1113 (Analog)

1.4.2 ● Section 3: Arduino IDE Installation

This section will guide you through the installation of the Arduino IDE. In order to compile software for ESP8266, you will need to install additional libraries.

If you are familiar with the Arduino IDE there should be no surprises here.

1.4.3 ● Section 4: emoncms Installation

I have chosen to use emoncms for logging and visualisation.

This section describes how to install emoncms on a Raspberry Pi.

In order to make emoncms work, additional software packages will have to be installed but all will be described here.

1.4.4 ● Section 5: MQTT (mosquitto) Installation On A Raspberry Pi

The installation will cover the basic MQTT broker but also a publisher client and subscriber client.

If in favour of it, a Windows MQTT client will be installed as well.

1.4.5 ● Section 6: ESP8266 Security

A very short walkthrough of why I, so far, have not secured my ESP8266 devices.