This repository has been created to provide a practical learning experience on how to effectively use the ESP32 microcontroller. The main objective of this project is to establish seamless communication between two or more ESP32s over WiFi using protobuf serialization and display the transmitted data on a web page. To accomplish this, the project is divided into different tasks, with each task organized into folders within this repository. The folders are named using three-letter codes that represent the number of ESP32s involved in the communication process. Each folder contains projects that are sequentially numbered, representing the step-by-step progression towards the final solution.
Now, let's explore the theoretical foundation of the key components we will be using in this project:
The ESP32 is a powerful and versatile microcontroller that combines WiFi and Bluetooth capabilities. It serves as the core hardware component for our project, enabling wireless communication and data processing.
PlatformIO is a popular and user-friendly development ecosystem for embedded systems. It simplifies the development and deployment process by providing a unified platform for code editing, building, and uploading to the ESP32 board.
A PlatformIO project consists of various folders and files that help organize and manage the development process. Let's take a closer look at each of these components:
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.gitignore: The .gitignore file is used to specify which files and folders should be ignored by the version control system (e.g., Git). This ensures that certain files, like build artifacts or sensitive data, are not tracked or uploaded to the remote repository.
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platformio.ini: The platformio.ini file is a configuration file specific to PlatformIO. It defines project settings, board configurations, libraries, and other build-related parameters. It allows developers to tailor the project environment to their specific needs.
Concerning the folders:
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.pio and .vscode: The .pio folder is automatically generated by PlatformIO and contains build-related intermediate files, object files, and the final firmware. The .vscode folder, on the other hand, is used specifically by Visual Studio Code, and it may contain editor-specific settings for the project.
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data: The data folder is utilized to store static files, such as web page documents, images, and other resources. When you upload these files to the flash memory of the ESP32, they become accessible to the web server and can be served to clients.
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include: The include folder is used to store header files (.h) and other code files that need to be included in various parts of the project. It helps in organizing the code and making it more modular.
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**lib:**The lib folder is used to store external libraries that are utilized in the project. PlatformIO simplifies the process of installing and managing libraries, and this folder acts as a centralized location for all the required libraries.
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src: The src folder is the primary location for the project's source code files. The main.cpp file, residing within this folder, is the entry point of the application. It contains the main function that gets executed when the ESP32 is powered on.
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test: The test folder is utilized for writing and running tests related to the project. It allows developers to verify the functionality and behavior of their code through automated tests.
WiFi.h is a library that enables ESP32 to connect to WiFi networks. It allows our ESP32 devices to establish a connection to an existing WiFi network, enabling them to communicate with other devices on the same network.
ESP_WiFiManager is a powerful library that simplifies WiFi configuration and management. It assists in the setup process, allowing the ESP32 to connect to a WiFi network seamlessly, even without prior knowledge of the network credentials.
ESPNOW (ESPNOWW) is a library that facilitates fast and efficient communication between ESP32 devices within a local network without the need for a centralized access point. It is ideal for peer-to-peer communication between ESP32s.
ESPAsyncWebServer is a library that enables the ESP32 to act as a web server. With this library, the ESP32 can serve web pages, handle HTTP requests, and respond to clients with relevant data.
SPIFFS (SPI Flash File System) is a lightweight file system designed for use with flash memory. We can use SPIFFS to store and serve static files, such as HTML, CSS, or JavaScript, for our web server.
Nanopb is a concise and efficient library for encoding and decoding Protocol Buffers (protobuf) data. It streamlines the serialization and deserialization of structured data, making it easier to manage and transmit information between ESP32 devices.
By understanding these theoretical foundations, even those new to ESP32 development will have a solid grasp of the key components and technologies used in this project. The step-by-step organization of the repository will guide you through the learning process.
Let's take a look at the project paths:
- Connecting an ESP32 to WiFi (PC <=> ESP32)
- Processing UART commands (PC <=> ESP32)
- Enabling communication between 2 ESP32 boards (PC <=> ESP32 <=> ESP32)
- The same but with protobuf communication through the Nanopb library (PC <=> ESP32 <=> ESP32)
- Using WiFiManager to connect automatically to WiFi (ESP32)
- Automatically connect all ESP32s through WiFiManager using ESPNOW (ESP32 <=> ESP32)
- Launching and interacting through a web page hosted on the ESP32 (ESP32)
- Project: An ESP server connects to WiFi with WiFiManager, ESP clients ask for the WiFi information, and then connect to the ESP server through it to send information using protobuf.
- The same as Project 8, but the ESP server hosts a web page at the same time.
The first project simply makes the ESP32's built-in LED flash based on the WiFi connection status. This project is a copy of Tomasz Tarnowski's code, which can be found in this video: https://www.youtube.com/watch?v=aAG0bp0Q-y4&t=171s&ab_channel=TomaszTarnowski. We are using the non-blocking approach.
- The LED is ON when the ESP32 is connected to WiFi.
- The LED flashes when waiting for a connection.
This second project causes the ESP32 to blink with a delay set by the user via the serial monitor using the UART. For example, "blink 200" will cause the ESP32 to blink for 200 milliseconds. The ESP32 waits for a WiFi connection to process UART commands.
- The LED works as in the first WiFi connection status project.
- The LED flashes once when a serial signal is received.
- The LED flashes twice when a flashing command is detected.
- The LED flashes three times when a flash command is acknowledged before execution.
These two projects allow communication between two ESP32 boards. It uses a client-server connection over WiFi, where ESPC is the client and ESPS is the server. To simplify the process, you must first connect ESPS and obtain its IP address (using your computer's share point can make it easier to obtain this address). Then enter this IP address in the ESPC code before compiling. Once both ESP32 boards are connected to WiFi, you can issue a blink command to ESPC via the UART and it will be executed by ESP2.
- WiFi connection, same as the first project.
- User enters "blink x", where x is an integer representing the delay.
- The LED blinks three times before sending the UART command over the WiFi connection.
- The serial monitor will indicate when an ACK is received and will wait for it. A "." will appear at the frequency of receiving messages from the server with a newline character ("\n").
- The LED flashes ten times to confirm that it is the ESP32 server after compilation (or when the reset button is pressed).
- WiFi connection, same as the first project.
- If it's a flash command, the LED blinks three times before the flash command is executed.
- The LED will still flash three times to indicate that it has received a signal.
Note: Please be sure to replace the placeholder values in the code with your specific configurations and follow the instructions provided in the respective folders for each project.
Same as project 3 but using nanopb.
A sendCommand will encode the message trough a structure define in message.pb.h (obtained with a message.proto)
A processCommand will decode the message.
Simple use of wifimanager
The ESP32 client needs to have the MAC address of the ESP server to launch communication with ESPNOW. They will request wifi information that the ESP server has (or will obtain with WiFiManager).
First project: ESP server will auto-pair the ESP clients, and they will exchange communication in WiFi using protobuf.
Clients will ask wifi information with ESPNOW. When connected to WiFi, they will send to the server IP a protobuf message containing an analog reading value of a touch port.
Server will connect to WiFi using WiFiManager and then share the information with all the ESPNOW incoming clients. The server will print in the monitor all the value that it received.
Second project: ESP server will host at the same time a web page.
Clients will ask wifi information with ESPNOW. When connected to WiFi, they will
*WARNING SECURITY : the security of your network is engaged because the wifi information are share with all clients comming trough ESPNOW.