UDP WiFi or LAN Connections - Connecting

MegunoLink supports UDP connections with your Arduino through WiFi or wired ethernet connections. The ESP8266 and ESP32 boards support WiFi connections while the EtherTen and Ethernet Shield support wired LAN connections.

Plot data, build interfaces

MegunoLink works just as well over UDP as serial. Check out our article on plotting with an ESP8266 over a WiFi network or learn about interface panels and data visualization.

To create a UDP connection:

Open a connection manager visualizer
Choose UDP from the Add Connection drop-down menu

Create a new connection by selecting UDP from the Add Connection menu.

MegunoLink will create a configuration panel for the new UDP connection:

The UDP configuration panel

The title box (top-left corner) lets you give the connection a name. This is useful to keep track when you have multiple connections. The name you enter here will be displayed on the Connect button shown in visualizers.

The Receive port is the UDP port that MegunoLink will listen on. Values less than 1,023 are reserved by the system while values between 1024 and 49,152 may be used by other applications. Generally any number between 49,152 and 65,535 should be fine.

The Destination IP address and port is the address that MegunoLink will send commands or messages to. The IP address 255.255.255.255 is a broadcast address. Messages will be sent to all devices listening on the destination port.

Click the Connect button to open the connection and begin receiving data. Only one program can use the port at any time so MegunoLink will show an error if another program already has the port open.

Sending UDP Data from an ESP8266 Arduino

This example sketch demonstrates plotting data and sending messages through a UDP connection receiving on port 52,791. It uses the ESP8266 Arduino toolchain.

#include "ESP8266WiFi.h"
#include "WiFiUdp.h"

#include "MegunoLink.h"
#include "ArduinoTimer.h"

const int SourcePort = 52790;
const int DestinationPort = 52791;
const IPAddress DestinationIp(255, 255, 255, 255);

WiFiUDP UdpConnection;
ArduinoTimer SendTimer;

// Setup WiFi credentials (SSID and password). 
#define USE_WIFI_CONFIG_FILE // Comment out this line to use Option 2 below
#ifdef USE_WIFI_CONFIG_FILE

// Include SSID and password from a library file. See:
// https://www.megunolink.com/articles/wireless/how-do-i-connect-to-a-wireless-network-with-the-esp32/
#include "WiFiConfig.h"

#else

// Option 2
const char *SSID = "Your SSID";
const char *WiFiPassword = "Your Password";

#endif

void setup() 
{
  Serial.begin(9600);
  Serial.println("UDP Plotting Example");

  // Setup the WiFi connection, waiting until it is ready. 
  WiFi.begin(SSID, WiFiPassword);
  auto Result = WiFi.waitForConnectResult();
  if (Result == WL_CONNECTED)
  {
    Serial.print(F("Connected. My IP address: "));
    Serial.println(WiFi.localIP());
    UdpConnection.begin(SourcePort);
  }
}

void loop() 
{
  // Periodically send data when the connection is available. 
  if (WiFi.isConnected() && SendTimer.TimePassed_Milliseconds(400))
  {
    // Send a message
    UdpConnection.beginPacket(DestinationIp, DestinationPort);
    UdpConnection.println("A wireless hello");
    UdpConnection.endPacket();
  
    // Send data for plotting
    UdpConnection.beginPacket(DestinationIp, DestinationPort);
    TimePlot Plot("ADC", UdpConnection);
    Plot.SendData("A0", analogRead(A0));
    UdpConnection.endPacket();
  }
}

#include "ESP8266WiFi.h"

#include "WiFiUdp.h"

#include "MegunoLink.h"

#include "ArduinoTimer.h"

const int SourcePort = 52790;

const int DestinationPort = 52791;

const IPAddress DestinationIp(255, 255, 255, 255);

WiFiUDP UdpConnection;

ArduinoTimer SendTimer;

// Setup WiFi credentials (SSID and password).

#define USE_WIFI_CONFIG_FILE // Comment out this line to use Option 2 below

#ifdef USE_WIFI_CONFIG_FILE

// Include SSID and password from a library file. See:

// https://www.megunolink.com/articles/wireless/how-do-i-connect-to-a-wireless-network-with-the-esp32/

#include "WiFiConfig.h"

#else

// Option 2

const char *SSID = "Your SSID";

const char *WiFiPassword = "Your Password";

#endif

void setup()

{

Serial.begin(9600);

Serial.println("UDP Plotting Example");

// Setup the WiFi connection, waiting until it is ready.

WiFi.begin(SSID, WiFiPassword);

auto Result = WiFi.waitForConnectResult();

if (Result == WL_CONNECTED)

{

Serial.print(F("Connected. My IP address: "));

Serial.println(WiFi.localIP());

UdpConnection.begin(SourcePort);

}

void loop()

{

// Periodically send data when the connection is available.

if (WiFi.isConnected() && SendTimer.TimePassed_Milliseconds(400))

{

// Send a message

UdpConnection.beginPacket(DestinationIp, DestinationPort);

UdpConnection.println("A wireless hello");

UdpConnection.endPacket();

// Send data for plotting

UdpConnection.beginPacket(DestinationIp, DestinationPort);

TimePlot Plot("ADC", UdpConnection);

Plot.SendData("A0", analogRead(A0));

UdpConnection.endPacket();

}

Processing Commands sent over a UDP Connection

This example sketch demonstrates receiving commands sent over a UDP connection. Commands are sent to port 52790 and processed using the command dispatcher. The sketch handles Hello and GetADCValue commands replying with a greeting and a measurement from the adc converter, respectively. The ADC value is sent to a MegunoLink table. You can open the Arduino code and MegunoLink project file from MegunoLink’s Library Examples menu.

/* ******************************************************************************
 *  Demonstrate processing commands sent over a UDP connection
 *  See "Handle UDP Commands.mlx" file in example's folder for a MegunoLink 
 *  project to send commands and show the results. 
 *  Download a free trial of MegunoLink from www.MegunoLink.com
 *  Check out: https://www.megunolink.com/documentation/connecting/udp-connections/
 *  for more information on UDP connections. 
 */

#include "DNSServer.h"
#include "ESP8266WebServer.h"
#include "ESP8266WiFi.h"
#include "WiFiUdp.h"

#include "MegunoLink.h"
#include "CommandDispatcher.h"

const int SourcePort = 52790;
const int DestinationPort = 52791;
const IPAddress DestinationIp(255, 255, 255, 255);

WiFiUDP UdpConnection;

// -------------------------------------------------------------------------------
// Connection settings for the WiFi network to use:
// Setup WiFi credentials (SSID and password). 
#define USE_WIFI_CONFIG_FILE // Comment out this line to use Option 2 below
#ifdef USE_WIFI_CONFIG_FILE

  // Include SSID and password from a library file. See:
  // https://www.megunolink.com/articles/wireless/how-do-i-connect-to-a-wireless-network-with-the-esp32/
  #include "WiFiConfig.h"
#else
  // Option 2
  const char *SSID = "Your SSID";
  const char *WiFiPassword = "Your Password";
#endif
// -------------------------------------------------------------------------------
// Handling commands
const int MaxCommands = 10; 
CommandDispatcher Commands;

void Cmd_GetADCValue(CommandParameter &p)
{
  uint16_t ADCValue = analogRead(0);

  UdpConnection.beginPacket(DestinationIp, DestinationPort);
  Table MLPTable(UdpConnection);
  MLPTable.SendData("A0", ADCValue);  
  UdpConnection.endPacket();
}

void Cmd_Hello(CommandParameter &p)
{
  UdpConnection.beginPacket(DestinationIp, DestinationPort);
  UdpConnection.println(F("Hello World!"));
  UdpConnection.endPacket();
}

// Replaces the first '\r' or '\n' character with a null terminating the string. 
void TruncateAtNewLine(char *Buffer)
{
  for(char *Current = Buffer; *Current; ++Current)
  {
    if (*Current == '\r' || *Current == '\n')
    {
      *Current = '\0';
      break;
    }
  }
}
// -------------------------------------------------------------------------------
// Arduino entry points
void setup() 
{
  delay(2000);
  Serial.begin(9600);
  Serial.println("WiFi Receive Test");

  // Setup the WiFi connection, waiting until it is ready. 
  WiFi.begin(SSID, WiFiPassword);
  auto Result = WiFi.waitForConnectResult();
  if (Result == WL_CONNECTED)
  {
    Serial.print(F("Connected. My IP address: "));
    Serial.println(WiFi.localIP());
    UdpConnection.begin(SourcePort);
  }

  Commands.AddCommand(F("Hello"), Cmd_Hello);
  Commands.AddCommand(F("GetADCValue"), Cmd_GetADCValue);
}

void loop() 
{
  int PacketSize = UdpConnection.parsePacket();
  if (PacketSize != 0)
  {
    char ReceiveBuffer[100];
    int Length = UdpConnection.read(ReceiveBuffer, sizeof(ReceiveBuffer));
    if (Length >= 0 && Length < sizeof(ReceiveBuffer)) { ReceiveBuffer[Length] = 0; } else { Serial.println(F("Message too big!")); Length = 0; } Serial.print(F("Received packet of ")); Serial.print(PacketSize); Serial.print(F(" bytes, from ")); Serial.print(UdpConnection.remoteIP()); if (Length > 0)
    {
      Serial.print(F(" content: "));
      Serial.println(ReceiveBuffer);
    }

    if (Length >0 && ReceiveBuffer[0] == '!')
    { 
      TruncateAtNewLine(ReceiveBuffer);
      Commands.DispatchCommand(ReceiveBuffer + 1, UdpConnection);
    }
  }
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

/* ******************************************************************************

* Demonstrate processing commands sent over a UDP connection

* See "Handle UDP Commands.mlx" file in example's folder for a MegunoLink

* project to send commands and show the results.

* Download a free trial of MegunoLink from www.MegunoLink.com

* Check out: https://www.megunolink.com/documentation/connecting/udp-connections/

* for more information on UDP connections.

#include "DNSServer.h"

#include "ESP8266WebServer.h"

#include "ESP8266WiFi.h"

#include "WiFiUdp.h"

#include "MegunoLink.h"

#include "CommandDispatcher.h"

const int SourcePort = 52790;

const int DestinationPort = 52791;

const IPAddress DestinationIp(255, 255, 255, 255);

WiFiUDP UdpConnection;

// -------------------------------------------------------------------------------

// Connection settings for the WiFi network to use:

// Setup WiFi credentials (SSID and password).

#define USE_WIFI_CONFIG_FILE // Comment out this line to use Option 2 below

#ifdef USE_WIFI_CONFIG_FILE

// Include SSID and password from a library file. See:

// https://www.megunolink.com/articles/wireless/how-do-i-connect-to-a-wireless-network-with-the-esp32/

#include "WiFiConfig.h"

#else

// Option 2

const char *SSID = "Your SSID";

const char *WiFiPassword = "Your Password";

#endif

// -------------------------------------------------------------------------------

// Handling commands

const int MaxCommands = 10;

CommandDispatcher Commands;

void Cmd_GetADCValue(CommandParameter &p)

{

uint16_t ADCValue = analogRead(0);

UdpConnection.beginPacket(DestinationIp, DestinationPort);

Table MLPTable(UdpConnection);

MLPTable.SendData("A0", ADCValue);

UdpConnection.endPacket();

}

void Cmd_Hello(CommandParameter &p)

{

UdpConnection.beginPacket(DestinationIp, DestinationPort);

UdpConnection.println(F("Hello World!"));

UdpConnection.endPacket();

}

// Replaces the first '\r' or '\n' character with a null terminating the string.

void TruncateAtNewLine(char *Buffer)

{

for(char *Current = Buffer; *Current; ++Current)

{

if (*Current == '\r' || *Current == '\n')

{

*Current = '\0';

break;

}

// -------------------------------------------------------------------------------

// Arduino entry points

void setup()

{

delay(2000);

Serial.begin(9600);

Serial.println("WiFi Receive Test");

// Setup the WiFi connection, waiting until it is ready.

WiFi.begin(SSID, WiFiPassword);

auto Result = WiFi.waitForConnectResult();

if (Result == WL_CONNECTED)

{

Serial.print(F("Connected. My IP address: "));

Serial.println(WiFi.localIP());

UdpConnection.begin(SourcePort);

}

Commands.AddCommand(F("Hello"), Cmd_Hello);

Commands.AddCommand(F("GetADCValue"), Cmd_GetADCValue);

}

void loop()

{

int PacketSize = UdpConnection.parsePacket();

if (PacketSize != 0)

{

char ReceiveBuffer[100];

int Length = UdpConnection.read(ReceiveBuffer, sizeof(ReceiveBuffer));

if (Length >= 0 && Length < sizeof(ReceiveBuffer)) { ReceiveBuffer[Length] = 0; } else { Serial.println(F("Message too big!")); Length = 0; } Serial.print(F("Received packet of ")); Serial.print(PacketSize); Serial.print(F(" bytes, from ")); Serial.print(UdpConnection.remoteIP()); if (Length > 0)

{

Serial.print(F(" content: "));

Serial.println(ReceiveBuffer);

}

if (Length >0 && ReceiveBuffer[0] == '!')

{

TruncateAtNewLine(ReceiveBuffer);

Commands.DispatchCommand(ReceiveBuffer + 1, UdpConnection);

}