Communication between Arduino and Python via UDP

Question

I am struggling to build a communication bridge between Arduino and Python. Arduino should send an integer value to python. To enable the Udp communication I am using Ethernet shield 2 on Arduino and have to connect to IP "192.168.137.30". Now when I try to connect to bind with this Ip address, an error occurs because "192.168.137.30" is an external Ip address.

Below is my Arduino and python code :

#include <SPI.h>
#include <SD.h>
#include <Ethernet2.h>
#include <EthernetUdp2.h>         // UDP library from: [email protected] 12/30/2008

byte mac[] = {
  0xA8, 0x61, 0x0A, 0xAE, 0x2A, 0x12
};
IPAddress ip(192.168.137.30);

unsigned int localPort = 8880;      // local port to listen on

// An EthernetUDP instance to let us send and receive packets over UDP
EthernetUDP Udp;


void setup()
{


  Ethernet.begin(mac, ip);
  Udp.begin(localPort);
  Serial.begin(115200);

  }

void loop()
{

   char  ReplyBuffer[] = "acknowledged";    
    Udp.beginPacket(ip, localPort);
    Udp.write(ReplyBuffer);
    Udp.endPacket();

}

Python :

import serial
import time 
import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('192.168.137.30', 8880))
data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
sock.close()

I still can not send data from Arduino to Python. However, it is possible to send data from Python to Arduino.

IPAddress ip(169, 254, 114, 130);
IPAddress my_PC_ip(169, 254, 94, 133);
unsigned int localPort = 7476; 
unsigned int pythonPort= 7000; 

void setup()
{
  Ethernet.begin(mac, ip);
  Udp.begin(localPort);
  Serial.begin(115200);

  }

void loop()
{
    Udp.beginPacket(my_PC_ip,pythonPort);
    Udp.print("hello");
    Udp.endPacket();
}

Python : import serial import time import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('169.254.94.133', 7000))
data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
sock.close()

Joseph Sible-Reinstate Monica Joseph Sible-Reinstate Monica · Accepted Answer · 2019-03-09T23:03:43

You're not putting the right IP addresses in the right places. Here's what should be where:

In Ethernet.begin on the Arduino, you should use the Arduino's IP address.
In Udp.beginPacket on the Arduino, you should use your computer's IP address.
In sock.bind on your computer, you should use your computer's IP address.

You're currently using the same one in all three places, which doesn't make sense from a networking perspective.

Communication between Arduino and Python via UDP

1 Answers