Previously you read about How to send data to multiple ESP32 from one Master Gateway.
Here you learn how to Collect data from many master node’s to a single Gateway and further upload in cloud server.
Component Required
- ESP32 Modules as many you want to connect.
- OLLED Display
Setting up ESP32 environment << click in this link to setup your ESP in Arduino IDE
It is better if you go through previous blog where you learn how to send temperature and humidity data to more than two nodes from a single gateway. through this link —https://elconics.com/connect-multiple-esp32-without-internet/
Every WIFI device has its unique MAC address
By using that Mac address we are going to send data from one ESP32 to other
SO your first question will be how to get MAC address
Copy this code and past in Arduino IDE
This code will give you MAC Address of every node ESP32
#include "WiFi.h"
void setup(){
Serial.begin(115200);
WiFi.mode(WIFI_MODE_STA);
Serial.println(WiFi.macAddress());
}
void loop(){
}Upload this Code in Receiver ESP32 Board to get MAC address of that board
When you get MAC address copy and keep it .
Repeat this step for every node and keep their MAC address for further use.
Now setting up 1st – Master Node
Copy this code below and paste in Arduino IDE >> change MAC address to your receiver’s mac address which is obtain previously .
#include <esp_now.h>
#include <WiFi.h>
int p=1;
// REPLACE WITH THE RECEIVER'S MAC Address
uint8_t broadcastAddress[] = {0xEC,0x62,0x60,0x84,0x36,0xB0};
// Structure example to send data
// Must match the receiver structure
typedef struct struct_message {
int id; // must be unique for each sender board
int x;
int y;
} struct_message;
// Create a struct_message called myData
struct_message myData;
// Create peer interface
esp_now_peer_info_t peerInfo;
// callback when data is sent
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
Serial.print("\r\nLast Packet Send Status:\t");
Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");
}
void setup() {
// Init Serial Monitor
Serial.begin(115200);
// Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
// Init ESP-NOW
if (esp_now_init() != ESP_OK) {
Serial.println("Error initializing ESP-NOW");
return;
}
// Once ESPNow is successfully Init, we will register for Send CB to
// get the status of Trasnmitted packet
esp_now_register_send_cb(OnDataSent);
// Register peer
memcpy(peerInfo.peer_addr, broadcastAddress, 6);
peerInfo.channel = 0;
peerInfo.encrypt = false;
// Add peer
if (esp_now_add_peer(&peerInfo) != ESP_OK){
Serial.println("Failed to add peer");
return;
}
}
void loop() {
myData.id = 1;
myData.x = random(0,100);
myData.y = random(0,100);
// Send message via ESP-NOW
esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &myData, sizeof(myData));
if (result == ESP_OK) {
Serial.println("Sent with success");
}
else {
Serial.println("Error sending the data");
}
delay(10000);
}
Setting Up 2nd Master Node
Copy this code and upload to your receiver node
#include <esp_now.h>
#include <WiFi.h>
int p=1;
// REPLACE WITH THE RECEIVER'S MAC Address
uint8_t broadcastAddress[] = {0xEC,0x62,0x60,0x84,0x36,0xB0};
// Structure example to send data
// Must match the receiver structure
typedef struct struct_message {
int id; // must be unique for each sender board
int x;
int y;
} struct_message;
// Create a struct_message called myData
struct_message myData;
// Create peer interface
esp_now_peer_info_t peerInfo;
// callback when data is sent
void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
Serial.print("\r\nLast Packet Send Status:\t");
Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");
}
void setup() {
// Init Serial Monitor
Serial.begin(115200);
// Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
// Init ESP-NOW
if (esp_now_init() != ESP_OK) {
Serial.println("Error initializing ESP-NOW");
return;
}
// Once ESPNow is successfully Init, we will register for Send CB to
// get the status of Trasnmitted packet
esp_now_register_send_cb(OnDataSent);
// Register peer
memcpy(peerInfo.peer_addr, broadcastAddress, 6);
peerInfo.channel = 0;
peerInfo.encrypt = false;
// Add peer
if (esp_now_add_peer(&peerInfo) != ESP_OK){
Serial.println("Failed to add peer");
return;
}
}
void loop() {
myData.id = 2;
myData.x = random(100,500);
myData.y = random(100,500);
// Send message via ESP-NOW
esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &myData, sizeof(myData));
if (result == ESP_OK) {
Serial.println("Sent with success");
}
else {
Serial.println("Error sending the data");
}
delay(10000);
}
Setting Receiver Slave gateway
If you want to see results in Serial monitor
Copy and upload this code on second receiver and keep connected to your system to see results in serial monitor.
#include <esp_now.h>
#include <WiFi.h>
// Structure example to receive data
// Must match the sender structure
typedef struct struct_message {
int id;
int x;
int y;
}struct_message;
// Create a struct_message called myData
struct_message myData;
// Create a structure to hold the readings from each board
struct_message board1;
struct_message board2;
struct_message board3;
// Create an array with all the structures
struct_message boardsStruct[3] = {board1, board2, board3};
// callback function that will be executed when data is received
void OnDataRecv(const uint8_t * mac_addr, const uint8_t *incomingData, int len) {
char macStr[18];
Serial.print("Packet received from: ");
snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
Serial.println(macStr);
memcpy(&myData, incomingData, sizeof(myData));
Serial.printf("Board ID %u: %u bytes\n", myData.id, len);
// Update the structures with the new incoming data
boardsStruct[myData.id-1].x = myData.x;
boardsStruct[myData.id-1].y = myData.y;
Serial.printf("x value: %d \n", boardsStruct[myData.id-1].x);
Serial.printf("y value: %d \n", boardsStruct[myData.id-1].y);
Serial.println();
}
void setup() {
//Initialize Serial Monitor
Serial.begin(115200);
//Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
//Init ESP-NOW
if (esp_now_init() != ESP_OK) {
Serial.println("Error initializing ESP-NOW");
return;
}
// Once ESPNow is successfully Init, we will register for recv CB to
// get recv packer info
esp_now_register_recv_cb(OnDataRecv);
}
void loop() {
// Acess the variables for each board
int board1X = boardsStruct[0].x;
int board1Y = boardsStruct[0].y;
int board2X = boardsStruct[1].x;
int board2Y = boardsStruct[1].y;
int board3X = boardsStruct[2].x;
int board3Y = boardsStruct[2].y;
delay(10000);
}
If you want to see results in OLED display
Use this code –> connection vcc-5v Gnd-gnd Scl-22 , Sda-21
#include <esp_now.h>
#include <WiFi.h>
//#include <ESP8266WiFi.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
// Structure example to receive data
// Must match the sender structure
typedef struct struct_message {
int id;
int x;
int y;
}struct_message;
// Create a struct_message called myData
struct_message myData;
// Create a structure to hold the readings from each board
struct_message board1;
struct_message board2;
struct_message board3;
// Create an array with all the structures
struct_message boardsStruct[3] = {board1, board2, board3};
// callback function that will be executed when data is received
void OnDataRecv(const uint8_t * mac_addr, const uint8_t *incomingData, int len) {
char macStr[18];
Serial.print("Packet received from: ");
snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
Serial.println(macStr);
memcpy(&myData, incomingData, sizeof(myData));
Serial.printf("Board ID %u: %u bytes\n", myData.id, len);
// Update the structures with the new incoming data
boardsStruct[myData.id-1].x = myData.x;
boardsStruct[myData.id-1].y = myData.y;
Serial.printf("x value: %d \n", boardsStruct[myData.id-1].x);
Serial.printf("y value: %d \n", boardsStruct[myData.id-1].y);
Serial.println();
}
void setup() {
//Initialize Serial Monitor
Serial.begin(115200);
if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
Serial.println(F("SSD1306 allocation failed"));
for(;;);
}
display.clearDisplay();
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0, 10);
// Display static text
display.println("Hello, world!");
display.display();
//Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
//Init ESP-NOW
if (esp_now_init() != ESP_OK) {
Serial.println("Error initializing ESP-NOW");
return;
}
// Once ESPNow is successfully Init, we will register for recv CB to
// get recv packer info
esp_now_register_recv_cb(OnDataRecv);
}
void loop() {
// Acess the variables for each board
int board1X = boardsStruct[0].x;
int board1Y = boardsStruct[0].y;
int board2X = boardsStruct[1].x;
int board2Y = boardsStruct[1].y;
int board3X = boardsStruct[2].x;
int board3Y = boardsStruct[2].y;
display.clearDisplay();
display.setTextSize(2);
display.setTextColor(WHITE);
display.setCursor(0, 0);
display.println("Node" + String(myData.id) );
// Display static text
display.setTextSize(2);
display.setTextColor(WHITE);
display.setCursor(0, 20);
display.println("Random" +String(boardsStruct[myData.id-1].x));
display.setCursor(0, 40);
display.println("Random" +String(boardsStruct[myData.id-1].y));
display.display();
}
Now you are done Give power supply to all Master and Slave node and see result.
