Sending data trough UDP

Projects General Guidance
1

Hello to all,

I made a wifi connection between 2 esp8266. The program works perfectly for sending one byte (on/off). The problem arises when i try to send more value's.

The code gives on the receiving esp8266 the right value's, one byte and the floating value as a string through the serial monitor I tried creating a struct, which didn't work. Esp-now doesn't work either.

thanks in advance

The code for sending

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include<DHT.h>      // Including library for dht

// Set WiFi credentials
#define WIFI_SSID "TheOtherESP"
#define WIFI_PASS "flashmeifyoucan"

// UDP
WiFiUDP UDP;
IPAddress remote_IP(192, 168, 4, 1);
#define UDP_PORT 4210

#define dht_dpin 12       //digital pin, that DHT's data line is connected
#define DHTTYPE DHT22     //When using DHT11, put here DHT11 instead of DHT22
DHT dht(12, DHT22);       //Not sure, what this line excatly does, but same aplies here as above


float temp;
float hum;

void setup() {

  dht.begin();

  // Setup IO
  pinMode(2, INPUT);

  // Setup serial port
  Serial.begin(115200);
  Serial.println();

  // Begin WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  WiFi.mode(WIFI_STA);

  // Connecting to WiFi...
  Serial.print("Connecting to ");
  Serial.print(WIFI_SSID);
  // Loop continuously while WiFi is not connected
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(100);
    Serial.print(".");
  }

  // Connected to WiFi
  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());

  // Begin UDP port
  UDP.begin(UDP_PORT);
  Serial.print("Opening UDP port ");
  Serial.println(UDP_PORT);

}

void loop() {

  delay(500);

  temp = dht.readTemperature();
  hum = dht.readHumidity();

  // Read button
  char buttonState = digitalRead(2);

  // Send Packet
  UDP.beginPacket(remote_IP, UDP_PORT);
  UDP.write(buttonState);
   if (!UDP.endPacket()) {
    Serial.println("data has not been sent");
  } else
    Serial.println("data has been sent"); {
  }

  UDP.beginPacket(remote_IP, UDP_PORT);
  String msg = String(hum);
  UDP.write(msg.c_str());
  if (!UDP.endPacket()) {
    Serial.println("data has not been sent");
  } else
    Serial.println("data has been sent"); {
  }
  
  Serial.print("Temperature: ");        //Print text "Temperature: " in to serial monitor
  Serial.println(temp);


  Serial.print("Humidity: ");           //Print text "Humidity: " in to serial monitor
  Serial.println(hum);                  //Print variable (temperature value) in to serial port. ln for line break
  Serial.println(" ");

}

The receiver code

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

// Set AP credentials
#define AP_SSID "TheOtherESP"
#define AP_PASS "flashmeifyoucan"

// UDP
WiFiUDP UDP;
IPAddress local_IP(192, 168, 4, 1);
IPAddress gateway(192, 168, 4, 1);
IPAddress subnet(255, 255, 255, 0);
#define UDP_PORT 4210

float hum;

// UDP Buffer
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];
char  ReplyBuffer[] = "acknowledged";

void setup() {

  // Setup LED pin
  pinMode(2, OUTPUT);

  // Setup serial port
  Serial.begin(115200);
  Serial.println();

  // Begin Access Point
  Serial.println("Starting access point...");
  WiFi.softAPConfig(local_IP, gateway, subnet);
  WiFi.softAP(AP_SSID, AP_PASS);
  Serial.println(WiFi.localIP());

  // Begin listening to UDP port
  UDP.begin(UDP_PORT);
  Serial.print("Listening on UDP port ");
  Serial.println(UDP_PORT);

}

void loop() {

  // Receive packet




  int packetSize = UDP.parsePacket();

  if (packetSize) {

    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.print("From ");
    IPAddress remoteIp = UDP.remoteIP();
    Serial.print(remoteIp);
    Serial.print(", port ");
    Serial.println(UDP.remotePort());

    // read the packet into packetBufffer

    int len = UDP.read(packetBuffer, 10);
    if (len > 0) {
      packetBuffer[len] = 0;
    }

    if (packetBuffer[0]) {
      digitalWrite(2, HIGH);
    } else {
      digitalWrite(2, LOW);
    }

    Serial.println("Contents:");
    Serial.println(packetBuffer);
   

  }
}
2

You are sending two types of the packets - first with one byte and second with string. But try to read both as first type only. Obviously it won't work this way.

please show your efforts

3

Here's the code (sent/receive) with the struct in it. The led still toggle's through UDP, so it means that the byte's get trough otherwise it wouldn't turn on the onboard LED on pin 2.

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include<DHT.h>      // Including library for dht

// Set WiFi credentials
#define WIFI_SSID "TheOtherESP"
#define WIFI_PASS "flashmeifyoucan"

// UDP
WiFiUDP UDP;
IPAddress remote_IP(192, 168, 4, 1);
#define UDP_PORT 4210

#define dht_dpin 12       //digital pin, that DHT's data line is connected
#define DHTTYPE DHT22     //When using DHT11, put here DHT11 instead of DHT22
DHT dht(12, DHT22);       //Not sure, what this line excatly does, but same aplies here as above



float temp;
float hum;

typedef struct settings_t{
  byte button;
  float temp;
  float hum;
  };

const int union_size = sizeof(settings_t);

typedef union btPacket_t{
 settings_t structure;
 byte byteArray[union_size]; 
};

//create a variable using this new union we defined
btPacket_t settings;  

void setup() {

  dht.begin();

  // Setup IO
  pinMode(2, INPUT);

  // Setup serial port
  Serial.begin(115200);
  Serial.println();

  // Begin WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  WiFi.mode(WIFI_STA);

  // Connecting to WiFi...
  Serial.print("Connecting to ");
  Serial.print(WIFI_SSID);
  // Loop continuously while WiFi is not connected
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(100);
    Serial.print(".");
  }

  // Connected to WiFi
  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());

  // Begin UDP port
  UDP.begin(UDP_PORT);
  Serial.print("Opening UDP port ");
  Serial.println(UDP_PORT);

}

void loop() {

  settings.structure.button = digitalRead(2); 
  settings.structure.hum = dht.readTemperature(); 
  settings.structure.temp = dht.readTemperature(); 
  

  delay(500);

  // Send Packet
  UDP.beginPacket(remote_IP, UDP_PORT);
  for(int i=0; i < union_size; i++)
  UDP.write(settings.byteArray[i]);
   if (!UDP.endPacket()) {
    Serial.println("data has not been sent");
  } else
    Serial.println("data has been sent"); {
  }

  
  Serial.print("Temperature: ");        //Print text "Temperature: " in to serial monitor
  Serial.println(temp);


  Serial.print("Humidity: ");           //Print text "Humidity: " in to serial monitor
  Serial.println(hum);                  //Print variable (temperature value) in to serial port. ln for line break
  Serial.println(" ");

}

Here's the receive

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

// Set AP credentials
#define AP_SSID "TheOtherESP"
#define AP_PASS "flashmeifyoucan"

// UDP
WiFiUDP UDP;
IPAddress local_IP(192, 168, 4, 1);
IPAddress gateway(192, 168, 4, 1);
IPAddress subnet(255, 255, 255, 0);
#define UDP_PORT 4210

byte button;
float temp;
float hum;

typedef struct settings_t {
  byte button;
  float temp;
  float hum;
};

const int union_size = sizeof(settings_t);

typedef union btPacket_t {
  settings_t structure;
  byte byteArray[union_size];
};

//create a variable using this new union we defined
btPacket_t settings;

// UDP Buffer
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];
char  ReplyBuffer[] = "acknowledged";

void setup() {

  // Setup LED pin
  pinMode(2, OUTPUT);

  // Setup serial port
  Serial.begin(115200);
  Serial.println();

  // Begin Access Point
  Serial.println("Starting access point...");
  WiFi.softAPConfig(local_IP, gateway, subnet);
  WiFi.softAP(AP_SSID, AP_PASS);
  Serial.println(WiFi.localIP());

  // Begin listening to UDP port
  UDP.begin(UDP_PORT);
  Serial.print("Listening on UDP port ");
  Serial.println(UDP_PORT);

}

void loop() {

  

  // Receive packet

  int packetSize = UDP.parsePacket();

  if (packetSize) {

    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.print("From ");
    IPAddress remoteIp = UDP.remoteIP();
    Serial.print(remoteIp);
    Serial.print(", port ");
    Serial.println(UDP.remotePort());

    // read the packet into packetBufffer

    int len = UDP.read(packetBuffer, 255);

    if (len > 0) {

      packetBuffer[len] = 0;

    }

    

    if (Serial.available()) {
      Serial.println(button);
      Serial.println(hum);
      Serial.println(temp);
    }
    else {
      Serial.println(0);
      Serial.println(0);
      Serial.println(0);
    }

    Serial.flush();


   if (button) {
      digitalWrite(2, HIGH);
    } else {
      digitalWrite(2, LOW);
    }

  }
}