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ESP8266 NodeMCU

NodeMCU is an open source firmware for which open source prototyping board designs are available. The name "NodeMCU" combines "node" and "MCU" (micro-controller unit).

55 ₪

الناشر: متجر القطع الالكترونية

القسم: متحكمات

تاريخ النشر: 2021-02-03


صفحة العنصر الرئيسية

install to arduino IDE

كيفية تثبيت القطعة على برنامج الاردوينو

ESP-NOW communication protocol

establish a two-way communication between two ESP8266 NodeMCU boards




This without using Wi-Fi

This protocol enables multiple devices to talk to each other without using Wi-Fi. This is a fast communication protocol that can be used to exchange small messages (up to 250 bytes) between ESP32 boards. ESP-NOW is very versatile and you can have one-way or two-way communication in different arrangements.







Getting the Boards MAC Address

code
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#include <ESP8266WiFi.h>
String mac;
void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  mac = WiFi.macAddress();
  Serial.println(mac);
}

void loop() {
  Serial.println(mac);
  delay(2000);
  }


After uploading the code, press the RST/EN button, and the MAC address should be displayed on the Serial Monitor.





ESP1 code to send and receive from ESP2

code
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/*
esp1 using espnow
*/

#include <ESP8266WiFi.h>
#include <espnow.h>


// REPLACE WITH THE MAC Address of your receiver 
uint8_t broadcastAddress[] = {0x94, 0xB9, 0x7E, 0x13, 0x98, 0xC3};



// Define variables to store incoming readings
float incoming_val1;
char incoming_val2[16];

// Updates DHT readings every 10 seconds
const long interval = 10000; 
unsigned long previousMillis = 0;    // will store last time DHT was updated 

// Variable to store if sending data was successful
String success;

//Structure example to send data
//Must match the receiver structure
typedef struct struct_message {
    float val1;
    char val2[16];
} struct_message;

// Create a struct_message called struct_to_send_msg to hold sensor readings
struct_message struct_to_send_msg;

// Create a struct_message to hold incoming sensor readings
struct_message struct_to_receive_msg;

// Callback when data is sent
void OnDataSent(uint8_t *mac_addr, uint8_t sendStatus) {
  Serial.print("Last Packet Send Status: ");
  if (sendStatus == 0){
    Serial.println("Delivery success");
  }
  else{
    Serial.println("Delivery fail");
  }
}

// Callback when data is received
void OnDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  memcpy(&struct_to_receive_msg, incomingData, sizeof(struct_to_receive_msg));
  Serial.print("Bytes received: ");
  Serial.println(len);
  incoming_val1 = struct_to_receive_msg.val1;
   memcpy(&incoming_val2, &struct_to_receive_msg.val2, sizeof(struct_to_receive_msg.val2));

}



void printstruct_to_receive_msg(){
  // Display Readings in Serial Monitor
  Serial.println("INCOMING READINGS");
  Serial.print("val1: ");
  Serial.println(incoming_val1);
  Serial.print("val2: ");
  Serial.println(incoming_val2);

}
 
void setup() {
  // Init Serial Monitor
  Serial.begin(115200);
 
  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }

  // Set ESP-NOW Role
  esp_now_set_self_role(ESP_NOW_ROLE_COMBO);

  // 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
  esp_now_add_peer(broadcastAddress, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
  
  // Register for a callback function that will be called when data is received
  esp_now_register_recv_cb(OnDataRecv);
}
 
void loop() {
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    // save the last time you updated the DHT values
    previousMillis = currentMillis;

    //Set values to send
    struct_to_send_msg.val1 = 1111.0;
    strncpy(struct_to_send_msg.val2, "hello from ESP1", sizeof(struct_to_send_msg.val2));


    // Send message via ESP-NOW
    esp_now_send(broadcastAddress, (uint8_t *) &struct_to_send_msg, sizeof(struct_to_send_msg));

    // Print incoming readings
    printstruct_to_receive_msg();
  }
}


ESP2 code to send and receive from ESP1

code
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اقتباس
عرض
تنزيل 
	
								
/*
esp2 using espnow
*/

#include <ESP8266WiFi.h>
#include <espnow.h>


// REPLACE WITH THE MAC Address of your receiver 
uint8_t broadcastAddress[] = {0x94, 0xB9, 0x7E, 0x14, 0x59, 0xE7};



// Define variables to store incoming readings
float incoming_val1;
char incoming_val2[16];

// Updates DHT readings every 10 seconds
const long interval = 10000; 
unsigned long previousMillis = 0;    // will store last time DHT was updated 

// Variable to store if sending data was successful
String success;

//Structure example to send data
//Must match the receiver structure
typedef struct struct_message {
    float val1;
    char val2[16];
} struct_message;

// Create a struct_message called struct_to_send_msg to hold sensor readings
struct_message struct_to_send_msg;

// Create a struct_message to hold incoming sensor readings
struct_message struct_to_receive_msg;

// Callback when data is sent
void OnDataSent(uint8_t *mac_addr, uint8_t sendStatus) {
  Serial.print("Last Packet Send Status: ");
  if (sendStatus == 0){
    Serial.println("Delivery success");
  }
  else{
    Serial.println("Delivery fail");
  }
}

// Callback when data is received
void OnDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  memcpy(&struct_to_receive_msg, incomingData, sizeof(struct_to_receive_msg));
  Serial.print("Bytes received: ");
  Serial.println(len);
  incoming_val1 = struct_to_receive_msg.val1;
   memcpy(&incoming_val2, &struct_to_receive_msg.val2, sizeof(struct_to_receive_msg.val2));

}



void printstruct_to_receive_msg(){
  // Display Readings in Serial Monitor
  Serial.println("INCOMING READINGS");
  Serial.print("val1: ");
  Serial.println(incoming_val1);
  Serial.print("val2: ");
  Serial.println(incoming_val2);

}
 
void setup() {
  // Init Serial Monitor
  Serial.begin(115200);
 
  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    return;
  }

  // Set ESP-NOW Role
  esp_now_set_self_role(ESP_NOW_ROLE_COMBO);

  // 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
  esp_now_add_peer(broadcastAddress, ESP_NOW_ROLE_COMBO, 1, NULL, 0);
  
  // Register for a callback function that will be called when data is received
  esp_now_register_recv_cb(OnDataRecv);
}
 
void loop() {
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    // save the last time you updated the DHT values
    previousMillis = currentMillis;

    //Set values to send
    struct_to_send_msg.val1 = 2222.0;
    strncpy(struct_to_send_msg.val2, "hello from ESP2", sizeof(struct_to_send_msg.val2));


    // Send message via ESP-NOW
    esp_now_send(broadcastAddress, (uint8_t *) &struct_to_send_msg, sizeof(struct_to_send_msg));

    // Print incoming readings
    printstruct_to_receive_msg();
  }
}


ESP-NOW Useful Functions



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