This book focuses on communication protocols for the ESP32 microcontroller with illustrative projects ranging from a Bluetooth Low Energy beacon communicating with your smart wristwatch to LoRa (Long Range) communication between microsatellites circling 550km above the Earth and an ESP32 microcontroller in your home. The advantages of each communication protocol correspond to different project types. For example, the I2S (Inter-Integrated circuit Sound) protocol manages digital audio for internet radio, while the WebSocket protocol enables two-way real-time communication between an ESP32 microcontroller and a webpage for control of remote devices.

Just as there are different communication protocols, there are different ESP32 microcontroller formats. The ESP32 microcontroller provides the platform for the ESP32 LoRa module for long-range communication, the ESP32-CAM camera module for image streaming to a webpage on an Android tablet or mobile phone and an ESP32-based programmable watch incorporating a GPS unit for route tracking, a Bluetooth module, an infrared transmitter and Wi-Fi communication to source information over the internet. One ESP32 module incorporates an LCD screen, a microphone and a speaker, which is ideal for an internet radio, as well as an accelerometer and gyroscope to trigger the display of specific information or an action.

Each chapter focuses on a communication protocol and is stand-alone, so they can be read without having to start from the beginning of the book. The chapters are loosely grouped into short- and long-range communication, image management for transmission to a webpage or a remote LCD screen and the required apps and IoT techniques for remote control of an ESP32-CAM robot vehicle.

Although Wi-Fi communication is incorporated in many internet-based applications, knowledge of alternative communication protocols is vital for optimal project development with a microcontroller, such as the ESP32. Information on the features of several ESP32 microcontroller formats enables the optimal combination of communication protocol and ESP32 format to achieve the requirements of a project. Several of the communication protocols and likewise, several of the ESP32 formats have only been available in the last few months or years, making the book very relevant.

What you'll learn

• The ESP32-based internet radio, MP3 player and Bluetooth speaker projects that all use the I2S (Inter-Integrated circuit Sound) communication protocol for transmission of encoded audio data.
• The MESH communication protocol and the ESP-NOW protocol with communication between ESP32 microcontrollers without a Wi-Fi connection.
• Bluetooth Low Energy (BLE) communication with the ESP32 acting as a BLE beacon to transmit information to mobile phones, Android tablets and other devices close to the beacon.
• Email communication projects with an ESP32 and generation of QR (Quick Response) codes to instruct an ESP32 to control a connected device.
• Transmission and storage of image data and the fast display of images in apps.
• The ESP32-CAM module built around a 2M-pixel camera for streaming images with the WebSocket protocol to a remote ESP32 connected to an LCD screen or with Wi-Fi communication to a webpage.
• Control of an ESP32-CAM robot car through remote communication over the internet with image streaming to an Android tablet or mobile phone.

Who This Book Is For

A reader interested in understanding and recognizing the features of available communication protocols to then choose the appropriate protocol for a particular project. A level of C++ programming expertise with the Arduino IDE is assumed, although all sketches are comprehensively described and commented.

¿Neil Cameron is an experienced analyst and programmer with a deep interest in understanding the application of electronics. Neil wrote the books Arduino Applied: Comprehensive Projects for Everyday Electronics and Electronics Projects with the ESP8266 and ESP32: Building Web Pages, Applications, and WiFi Enabled Devices, which are published by Apress. He has previously taught at University of Edinburgh and Cornell University.

PREFACE

CHAPTER 1: ESP32 MICROCONTROLLER

USB to UART driver installation

Arduino IDE Boards Manager esp32 version 2.0.N

ESP32 DEVKIT DOIT

TTGO T-Display V1.1

Pulse width modulation

Analog to digital conversion

TTGO LoRa32 V2.1 1.6

TTGO T-Watch V2

TTGO T-Watch installation

M5Stack Core2

M5Stack Core2 installation

M5Stack Core2 and sound

M5Stack Core2 M5G0 battery base

ESP32-CAM

ESP32-CAM-MB module

ESP32-CAM-CH340 module

Image resolution

Memory

Over The Air (OTA)

Software versions

CHAPTER: 2 I2S AUDIO

Analog to digital

Direct Memory Access

PDM microphone

Fast Fourier Transform

Digital to analog

PCM5102 decoder module

MAX98357 decoder module

Internet radio

Internet radio with ESP32 module

Internet radio with M5Stack Core2

Audio data and Bluetooth

ESP32 to Bluetooth speaker

MP3 player

Play MP3 files from micro-SD card

Play MP3 files with M5Stack Core2

CHAPTER 3 : MESH COMMUNICATION

ESP-MESH

ESP-MESH and one Bluetooth device

ESP-MESH and several Bluetooth devices

CHAPTER 4: TTGO T-WATCH V2

TTGO T-watch functionality

Configuration file

Main sketch

Default display screen

Application menu

Screen brightness

GPS information

GPS satellite map

Bluetooth communication

Infrared signalling

Synchronisation with Network Time Protocol

Source OpenWeatherMap API data

Step counter and distance measure

Timer

Battery voltage and microcontroller temperature

Data storage on micro-SD card

Temperature, current and screen brightness

GPS tracking data

CHAPTER 5: BLE BEACONS

Eddystone beacons

Eddystone URL beacon

Eddystone TLM beacon

Eddystone UID beacon

iBeacon

Beacon raw data

BLE communication

GATT profile

Two-way communication

Notifications

nRF24L01 module as BLE transceiver

CHAPTER 6: LORA AND MICROSATELLITES

ESP32 as LoRa transmitter or receiver

ESP32 and LoRa satellites

Installation and configuration

Test station configuration and test message

Microsatellite tracking

CHAPTER 7: EMAIL AND QR CODES

email

QR codes

XML HTTP request

QR codes and XML HTTP request

QR codes and WebSocket

CHAPTER 8: WEBSOCKET, WEBSERIAL AND WEBDASHBOARD

WebSocket

WebSerial

Web Dashboard

CHAPTER 9: MQTT

Smart meter

MQTT and smart meter

Wi-Fi connection to router

ESP-NOW, MQTT and smart meter

Updating time

Wi-Fi or Wi-Fi and ESP-NOW

CO2 and TVOC

CO2 and TVOC with MQTT

CHAPTER 10: MANAGING IMAGES

Image bitmap

Display black and white image

Display colour image

Bitmap and X bitmap

Send image in email

Store image file in SPIFFS

Image URL in sketch

Display image as Sprite

LCD screen

M5Stack Core2 and accelerometer

Memory requirements

Display time with Sprites

Extension to M5Stack Core2

Compress HTML code

CHAPTER 11: ESP32-CAM CAMERA

Stream images direct to LCD screen

Stream images to remote LCD screen

Stream images over Wi-Fi

Webpage with control functions

WebSocket

esp_http_server

Webpage with image streaming and control functions

ESP32-CAM image resolution

CHAPTER 12: CONTROL APPS

app to display a webpage

app to display streamed images

app to transmit and receive data

app with image streaming and control functions

app sliders

Circular slider

Vertical slider

Horizontal slider touchdown and touchup

app to control WS2812 RGB LED

Bluetooth communication

Wi-Fi communication

CHAPTER 13: REMOTE CONTROL MOTORS

Servo motor

ledc function

ESP32Servo library

app to control servo motor

DC motors

TB6612FNG motor driver board

L298N motor driver board

Motor driver control

app to control DC motors with heading angle

CHAPTER 14: REMOTE CONTROL ESP32-CAM ROBOT CAR

app with direction buttons

app with heading angle control

CHAPTER 15 LIBRARIES

TFT-eSPI library

Libraries used

Create a library

Source file

Header file

Keyword file

Information file