![\"ESP-MESH](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-with-ESP32-ESP8266-Getting-Started-f.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nThis article covers the following topics:<\/p>\n\n\n\n
- \n
- Introducing ESP-MESH<\/a><\/li>\n\n\n\n
- ESP-MESH Basic Example (Broadcast messages)<\/a><\/li>\n\n\n\n
- Exchange Sensor Readings using ESP-MESH (broadcast)<\/a><\/li>\n<\/ul>\n\n\n\n
Arduino IDE<\/h2>\n\n\n\n
If you want to program the ESP32<\/a> and ESP8266 <\/a>boards using Arduino IDE, you should have the ESP32 or ESP8266 add-ons installed. Follow the next guides:<\/p>\n\n\n\n
- \n
- Installing ESP32 Board in Arduino IDE (Windows, Mac OS X, and Linux)<\/a><\/li>\n\n\n\n
- Installing ESP8266 Board in Arduino IDE (Windows, Mac OS X, Linux)<\/a><\/li>\n<\/ul>\n\n\n\n
If you want to program the ESP32\/ESP8266 using VS Code + PlatformIO, follow the next tutorial:<\/p>\n\n\n\n
- \n
- Getting Started with VS Code and PlatformIO IDE for ESP32 and ESP8266 (Windows, Mac OS X, Linux Ubuntu)<\/a><\/li>\n<\/ul>\n\n\n\n
Introducing ESP-MESH<\/h2>\n\n\n\n
Accordingly to the Espressif documentation:<\/p>\n\n\n\n
“ESP-MESH is a networking protocol built atop the Wi-Fi protocol. ESP-MESH allows numerous devices (referred to as nodes) spread over a large physical area (both indoors and outdoors) to be interconnected under a single WLAN (Wireless Local-Area Network). <\/p>\n\n\n\n
ESP-MESH is self-organizing and self-healing meaning the network can be built and maintained autonomously.” For more information, visit the ESP-MESH official documentation<\/a>.<\/p>\n\n\n\n
Traditional Wi-Fi Network Architecture<\/h3>\n\n\n\n
In a traditional Wi-Fi network architecture, a single node (access point – usually the router) is connected to all other nodes (stations). Each node can communicate with each other using the access point. However, this is limited to the access point wi-fi coverage. Every station must be in the range to connect directly to the access point. This doesn’t happen with ESP-MESH.<\/p>\n\n\n
\n![\"Traditional](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/Traditional-Wi-Fi-Network-ESP32-ESP8266.png?resize=900%2C500&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nESP-MESH Network Architecture<\/h3>\n\n\n\n
With ESP-MESH, the nodes don’t need to connect to a central node. Nodes are responsible for relaying each others transmissions. This allows multiple devices to spread over a large physical area. The Nodes can self-organize and dynamically talk to each other to ensure that the packet reaches its final node destination. If any node is removed from the network, it is able to self-organize to make sure that the packets reach their destination.<\/p>\n\n\n
\n![\"ESP-MESH](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-Network-ESP32-ESP8266i.png?resize=900%2C500&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\npainlessMesh Library<\/h2>\n\n\n\n
The painlessMesh library<\/a> allows us to create a mesh network with the ESP8266 or\/and ESP32 boards in an easy way.<\/p>\n\n\n\n
“painlessMesh is a true ad-hoc network, meaning that no-planning, central controller, or router is required. Any system of 1 or more nodes will self-organize into fully functional mesh. The maximum size of the mesh is limited (we think) by the amount of memory in the heap that can be allocated to the sub-connections buffer and so should be really quite high.” More information about the painlessMesh library<\/a>.<\/p>\n\n\n\n
Installing painlessMesh Library<\/h3>\n\n\n\n
You can install painlessMesh through the Arduino Library manager. Go to Tools<\/strong> > Manage Libraries<\/strong>. The Library Manager should open.<\/p>\n\n\n\n
Search for “painlessmesh<\/strong>” and install the library. We’re using Version 1.4.5<\/p>\n\n\n
\n![\"Install](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/install-painlessmesh-esp-library-Arduino-IDE.png?resize=786%2C443&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nThis library needs some other library dependencies. A new window should pop up asking you to install any missing dependencies. Select “Install all”.<\/p>\n\n\n
\n![\"Install](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/install-painlessmes-library-dependencies.png?resize=477%2C219&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nIf this window doesn’t show up, you’ll need to install the following library dependencies:<\/p>\n\n\n\n
- \n
- ArduinoJson<\/a> (by bblanchon)<\/li>\n\n\n\n
- TaskScheduler<\/a><\/li>\n\n\n\n
- ESPAsyncTCP<\/a> (ESP8266) <\/li>\n\n\n\n
- AsyncTCP <\/a>(ESP32)<\/li>\n<\/ul>\n\n\n\n
If you’re using PlatformIO<\/a>, add the following lines to the platformio.ini<\/span> file to add the libraries and change the monitor speed.<\/p>\n\n\n\n
For the ESP32:<\/p>\n\n\n\n
monitor_speed = 115200\nlib_deps = painlessmesh\/painlessMesh @ ^1.4.5\n ArduinoJson\n arduinoUnity\n TaskScheduler\n AsyncTCP<\/code><\/pre>\n\n\n\nFor the ESP8266:<\/p>\n\n\n\n
monitor_speed = 115200\nlib_deps = painlessmesh\/painlessMesh @ ^1.4.5\n ArduinoJson\n TaskScheduler\n ESPAsyncTCP<\/code><\/pre>\n\n\n\nESP-MESH Basic Example (Broadcast messages)<\/h2>\n\n\n\n
To get started with ESP-MESH, we’ll first experiment with the library’s basic example. This example creates a mesh network in which all boards broadcast messages to all the other boards. <\/p>\n\n\n\n
We’ve experimented this example with four boards (two ESP32<\/a> and two ESP8266<\/a>). You can add or remove boards. The code is compatible with both the ESP32 and ESP8266 boards.<\/p>\n\n\n
\n![\"ESP-MESH](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-painlessMesh-basic-example-ESP32-ESP8266.png?resize=900%2C500&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode – painlessMesh Library Basic Example<\/h3>\n\n\n\n
Copy the following code to your Arduino IDE (code from the library examples). The code is compatible with both the ESP32 and ESP8266 boards.<\/p>\n\n\n\n
If you’re using an ESP32, you need to downgrade your ESP32 boards’ add-on to version 2.0.X. At the moment, the painlessMesh library is not compatible with version 3.X.<\/p>\n\n\n
\/*\n Rui Santos\n Complete project details at https:\/\/RandomNerdTutorials.com\/esp-mesh-esp32-esp8266-painlessmesh\/\n \n This is a simple example that uses the painlessMesh library: https:\/\/github.com\/gmag11\/painlessMesh\/blob\/master\/examples\/basic\/basic.ino\n*\/\n\n#include "painlessMesh.h"\n\n#define MESH_PREFIX "whateverYouLike"\n#define MESH_PASSWORD "somethingSneaky"\n#define MESH_PORT 5555\n\nScheduler userScheduler; \/\/ to control your personal task\npainlessMesh mesh;\n\n\/\/ User stub\nvoid sendMessage() ; \/\/ Prototype so PlatformIO doesn't complain\n\nTask taskSendMessage( TASK_SECOND * 1 , TASK_FOREVER, &sendMessage );\n\nvoid sendMessage() {\n String msg = "Hi from node1";\n msg += mesh.getNodeId();\n mesh.sendBroadcast( msg );\n taskSendMessage.setInterval( random( TASK_SECOND * 1, TASK_SECOND * 5 ));\n}\n\n\/\/ Needed for painless library\nvoid receivedCallback( uint32_t from, String &msg ) {\n Serial.printf("startHere: Received from %u msg=%s\\n", from, msg.c_str());\n}\n\nvoid newConnectionCallback(uint32_t nodeId) {\n Serial.printf("--> startHere: New Connection, nodeId = %u\\n", nodeId);\n}\n\nvoid changedConnectionCallback() {\n Serial.printf("Changed connections\\n");\n}\n\nvoid nodeTimeAdjustedCallback(int32_t offset) {\n Serial.printf("Adjusted time %u. Offset = %d\\n", mesh.getNodeTime(),offset);\n}\n\nvoid setup() {\n Serial.begin(115200);\n\n\/\/mesh.setDebugMsgTypes( ERROR | MESH_STATUS | CONNECTION | SYNC | COMMUNICATION | GENERAL | MSG_TYPES | REMOTE ); \/\/ all types on\n mesh.setDebugMsgTypes( ERROR | STARTUP ); \/\/ set before init() so that you can see startup messages\n\n mesh.init( MESH_PREFIX, MESH_PASSWORD, &userScheduler, MESH_PORT );\n mesh.onReceive(&receivedCallback);\n mesh.onNewConnection(&newConnectionCallback);\n mesh.onChangedConnections(&changedConnectionCallback);\n mesh.onNodeTimeAdjusted(&nodeTimeAdjustedCallback);\n\n userScheduler.addTask( taskSendMessage );\n taskSendMessage.enable();\n}\n\nvoid loop() {\n \/\/ it will run the user scheduler as well\n mesh.update();\n}\n<\/code><\/pre>\n\tView raw code<\/a><\/p>\n\n\n\n
Before uploading the code, you can set up the MESH_PREFIX<\/span> (it’s like the name of the MESH network) and the MESH_PASSWORD<\/span> variables (you can set it to whatever you like).<\/p>\n\n\n\n
Then, we recommend that you change the following line for each board to easily identify the node that sent the message. For example, for node 1, change the message as follows:<\/p>\n\n\n\n
String msg = \"Hi from node 1 \";<\/code><\/pre>\n\n\n\nHow the Code Works<\/h3>\n\n\n\n
Start by including the painlessMesh<\/span> library.<\/p>\n\n\n\n
#include \"painlessMesh.h\"<\/code><\/pre>\n\n\n\nMESH Details<\/h4>\n\n\n\n
Then, add the mesh details. The MESH_PREFIX<\/span> refers to the name of the mesh. You can change it to whatever you like.<\/p>\n\n\n\n
#define MESH_PREFIX \"whateverYouLike\"<\/code><\/pre>\n\n\n\nThe MESH_PASSWORD<\/span>, as the name suggests is the mesh password. You can change it to whatever you like. <\/p>\n\n\n\n
#define MESH_PASSWORD \"somethingSneaky\"<\/code><\/pre>\n\n\n\nAll nodes in the mesh should use the same MESH_PREFIX<\/span> and MESH_PASSWORD<\/span>.<\/p>\n\n\n\n
The MESH_PORT<\/span> refers to the the TCP port that you want the mesh server to run on. The default is 5555.<\/p>\n\n\n\n
#define MESH_PORT 5555<\/code><\/pre>\n\n\n\nScheduler<\/h4>\n\n\n\n
It is recommended to avoid using delay()<\/span> in the mesh network code. To maintain the mesh, some tasks need to be performed in the background. Using delay()<\/span> will stop these tasks from happening and can cause the mesh to lose stability\/fall apart. <\/p>\n\n\n\n
Instead, it is recommended to use TaskScheduler<\/span> to run your tasks which is used in painlessMesh itself.<\/p>\n\n\n\n
The following line creates a new Scheduler<\/span> called userScheduler<\/span>.<\/p>\n\n\n\n
Scheduler userScheduler; \/\/ to control your personal task<\/code><\/pre>\n\n\n\npainlessMesh<\/h4>\n\n\n\n
Create a painlessMesh<\/span> object called mesh<\/span> to handle the mesh network.<\/p>\n\n\n\n
Create tasks<\/h4>\n\n\n\n
Create a task called taskSendMessage<\/span> responsible for calling the sendMessage()<\/span> function every second as long as the program is running.<\/p>\n\n\n\n
Task taskSendMessage(TASK_SECOND * 1 , TASK_FOREVER, &sendMessage);<\/code><\/pre>\n\n\n\nSend a Message to the Mesh<\/h4>\n\n\n\n
The sendMessage()<\/span> function sends a message to all nodes in the message network (broadcast).<\/p>\n\n\n\n
void sendMessage() {\n String msg = \"Hi from node 1\";\n msg += mesh.getNodeId();\n mesh.sendBroadcast( msg );\n taskSendMessage.setInterval(random(TASK_SECOND * 1, TASK_SECOND * 5));\n}<\/code><\/pre>\n\n\n\nThe message contains the “Hi from node 1<\/span>” text followed by the board chip ID.<\/p>\n\n\n\n
String msg = \"Hi from node 1\";\nmsg += mesh.getNodeId();<\/code><\/pre>\n\n\n\nTo broadcast a message, simply use the sendBroadcast()<\/span> method on the mesh<\/span> object and pass as argument the message (msg<\/span>) you want to send.<\/p>\n\n\n\n
mesh.sendBroadcast(msg);<\/code><\/pre>\n\n\n\nEvery time a new message is sent, the code changes the interval between messages (one to five seconds).<\/p>\n\n\n\n
taskSendMessage.setInterval(random(TASK_SECOND * 1, TASK_SECOND * 5));<\/code><\/pre>\n\n\n\nMesh Callback Functions<\/h4>\n\n\n\n
Next, several callback functions are created that will be called when specific events happen on the mesh.<\/p>\n\n\n\n
The receivedCallback()<\/span> function prints the message sender (from<\/span>) and the content of the message (msg.c_str()<\/span>).<\/p>\n\n\n\n
void receivedCallback( uint32_t from, String &msg ) {\n Serial.printf(\"startHere: Received from %u msg=%s\\n\", from, msg.c_str());\n}<\/code><\/pre>\n\n\n\nThe newConnectionCallback()<\/span> function runs whenever a new node joins the network. This function simply prints the chip ID of the new node. You can modify the function to do any other task.<\/p>\n\n\n\n
void newConnectionCallback(uint32_t nodeId) {\n Serial.printf(\"--> startHere: New Connection, nodeId = %u\\n\", nodeId);\n}<\/code><\/pre>\n\n\n\nThe changedConnectionCallback()<\/span> function runs whenever a connection changes on the network (when a node joins or leaves the network).<\/p>\n\n\n\n
void changedConnectionCallback() {\n Serial.printf(\"Changed connections\\n\");\n}<\/code><\/pre>\n\n\n\nThe nodeTimeAdjustedCallback()<\/span> function runs when the network adjusts the time, so that all nodes are synchronized. It prints the offset.<\/p>\n\n\n\n
void nodeTimeAdjustedCallback(int32_t offset) {\n Serial.printf(\"Adjusted time %u. Offset = %d\\n\", mesh.getNodeTime(),offset);\n}<\/code><\/pre>\n\n\n\nsetup()<\/h4>\n\n\n\n
In the setup()<\/span>, initialize the serial monitor.<\/p>\n\n\n\n
void setup() {\n Serial.begin(115200);<\/code><\/pre>\n\n\n\nChoose the desired debug message types:<\/p>\n\n\n\n
\/\/mesh.setDebugMsgTypes( ERROR | MESH_STATUS | CONNECTION | SYNC | COMMUNICATION | GENERAL | MSG_TYPES | REMOTE ); \/\/ all types on\n\nmesh.setDebugMsgTypes( ERROR | STARTUP ); \/\/ set before init() so that you can see startup messages<\/code><\/pre>\n\n\n\nInitialize the mesh with the details defined earlier.<\/p>\n\n\n\n
mesh.init(MESH_PREFIX, MESH_PASSWORD, &userScheduler, MESH_PORT);<\/code><\/pre>\n\n\n\nAssign all the callback functions to their corresponding events.<\/p>\n\n\n\n
mesh.onReceive(&receivedCallback);\nmesh.onNewConnection(&newConnectionCallback);\nmesh.onChangedConnections(&changedConnectionCallback);\nmesh.onNodeTimeAdjusted(&nodeTimeAdjustedCallback);<\/code><\/pre>\n\n\n\nFinally, add the taskSendMessage<\/span> function to the userScheduler<\/span>. The scheduler is responsible for handling and running the tasks at the right time.<\/p>\n\n\n\n
userScheduler.addTask(taskSendMessage);<\/code><\/pre>\n\n\n\nFinally, enable the taskSendMessage<\/span>, so that the program starts sending the messages to the mesh.<\/p>\n\n\n\n
taskSendMessage.enable();<\/code><\/pre>\n\n\n\nTo keep the mesh running, add mesh.update()<\/span> to the loop()<\/span>.<\/p>\n\n\n\n
void loop() {\n \/\/ it will run the user scheduler as well\n mesh.update();\n}<\/code><\/pre>\n\n\n\nDemonstration<\/h3>\n\n\n\n
Upload the code provided to all your boards. Don’t forget to modify the message to easily identify the sender node<\/p>\n\n\n\n
With the boards connected to your computer, open a serial connection with each board. You can use the Serial Monitor, or you can use a software like PuTTY<\/a> and open multiple windows for all the boards.<\/p>\n\n\n\n
You should see that all boards receive each others messages. For example, these are the messages received by Node 1. It receives the messages from Node 2, 3 and 4.<\/p>\n\n\n
\n![\"ESP-MESH](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-basic-example-4-boards-Serial-Monitor-ESP8266-ESP32.png?resize=760%2C262&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nYou should also see other messages when there are changes on the mesh: when a board leaves or joins the network.<\/p>\n\n\n
\n![\"ESP](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-basic-example-Serial-Monitor-Changed-Connections.png?resize=760%2C252&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nExchange Sensor Readings using ESP-MESH<\/h2>\n\n\n\n
In this next example, we’ll exchange sensor readings between 4 boards (you can use a different number of boards). Every board receives the other boards’ readings.<\/p>\n\n\n
\n![\"ESP-MESH](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/11\/ESP-MESH-Exchnage-BME280-Sensor-Readings-ESP32-ESP8266.png?resize=900%2C540&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nAs an example, we’ll exchange sensor readings from a BME280 sensor<\/a>, but you can use any other sensor.<\/p>\n\n\n\n
Parts Required<\/h3>\n\n\n\n
Here’s the parts required for this example:<\/p>\n\n\n\n
- \n
- 4x ESP boards (ESP32<\/a> or ESP8266<\/a>)<\/li>\n\n\n\n
- 4x BME280<\/a><\/li>\n\n\n\n
- Breadboard<\/a><\/li>\n\n\n\n
- Jumper wires<\/a><\/li>\n<\/ul>\n\n\n\n
Arduino_JSON library<\/h3>\n\n\n\n
In this example, we’ll exchange the sensor readings in JSON format. To make it easier to handle JSON variables, we’ll use the Arduino_JSON library<\/a>. <\/p>\n\n\n\n
You can install this library in the Arduino IDE Library Manager. Just go to Sketch <\/strong>> Include Library<\/strong> > Manage Libraries<\/strong> and search for the library name as follows:<\/p>\n\n\n
\n![\"Install](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/01\/Install-Arduino-JSON-library-Arduino-IDE.png?resize=786%2C443&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nIf you’re using VS Code with PlatformIO, include the libraries in the platformio.ini<\/span> file as follows:<\/p>\n\n\n\n
ESP32<\/strong><\/p>\n\n\n\n
monitor_speed = 115200\nlib_deps = painlessmesh\/painlessMesh @ ^1.4.5\n ArduinoJson\n arduinoUnity\n AsyncTCP\n TaskScheduler\n adafruit\/Adafruit Unified Sensor @ ^1.1.4\n adafruit\/Adafruit BME280 Library @ ^2.1.2\n arduino-libraries\/Arduino_JSON @ ^0.1.0<\/code><\/pre>\n\n\n\nESP8266<\/strong><\/p>\n\n\n\n
monitor_speed = 115200\nlib_deps = painlessmesh\/painlessMesh @ ^1.4.5\n ArduinoJson\n TaskScheduler\n ESPAsyncTCP\n adafruit\/Adafruit Unified Sensor @ ^1.1.4\n adafruit\/Adafruit BME280 Library @ ^2.1.2\n arduino-libraries\/Arduino_JSON @ ^0.1.0<\/code><\/pre>\n\n\n\nCircuit Diagram<\/h2>\n\n\n\n
Wire the BME280 sensor to the ESP32 or ESP8266 default I2C pins as shown in the following schematic diagrams.<\/p>\n\n\n\n
ESP32<\/h3>\n\n\n
\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/10\/ESP32-BME280-Sensor-Temperature-Humidity-Pressure-Wiring-Diagram-Circuit_f.png?resize=675%2C670&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nRecommended reading: ESP32 with BME280 Sensor using Arduino IDE (Pressure, Temperature, Humidity)<\/a><\/p>\n\n\n\n
ESP8266 NodeMCU<\/h3>\n\n\n
- 4x BME280<\/a><\/li>\n\n\n\n
- TaskScheduler<\/a><\/li>\n\n\n\n
- ArduinoJson<\/a> (by bblanchon)<\/li>\n\n\n\n
- Installing ESP8266 Board in Arduino IDE (Windows, Mac OS X, Linux)<\/a><\/li>\n<\/ul>\n\n\n\n
- ESP-MESH Basic Example (Broadcast messages)<\/a><\/li>\n\n\n\n
![\"ESP8266](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/07\/ESP8266-NodeMCU-BME280-Sensor-Temperature-Humidity-Pressure-Wiring-Diagram-Circuit.png?resize=675%2C531&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n