File content as of revision 0:e0ec056e8895:

/*UDP通信サンプル
　自分：mbedAから相手：mbedBへのデータ送信方法、相手：mbedBから自分：mbedAへのデータ受信方法*/
#include "mbed.h"
#include "EthernetInterface.h" 

Serial pc(USBTX, USBRX); // tx, rx

const char* A_ADDRESS = "192.168.1.1"; 
const int A_PORT = 1000;

const char* B_ADDRESS = "192.168.1.2";
const int B_PORT = 2000;

int main() {
       
    char u_packet[2]; 
    u_packet[0]=0x41; u_packet[1]=0x42; //ex.
    char u_buff[10];

    EthernetInterface eth; 
    eth.init(A_ADDRESS, "255.255.255.0", ""); //    Use hard IP
    pc.printf("IP : %s\n", eth.getIPAddress());
    if (eth.connect() < 0) {
        pc.printf("Failed to connect\n\r");
        return -1;
    }
    
    UDPSocket sockA; 
    if (sockA.bind(A_PORT) < 0) {
        pc.printf("Failed to bind UDP Socket to PORT : %d\n\r", A_PORT);
        return -1;
    }
    else pc.printf("Bind UDP Socket to PORT : %d\n\r", A_PORT);
    sockA.set_blocking(false);
    
    Endpoint EndpointA; 
    EndpointA.set_address(A_ADDRESS, A_PORT);
    
    Endpoint EndpointB;
    EndpointB.set_address(B_ADDRESS, B_PORT);

    /*-----------
      MAIN ROOP
     -----------*/    
    while(1) { 
    /*--send--*/
        pc.printf("Send : %s\n", u_packet);
        int n_send=sockA.sendTo(EndpointB, (char*)u_packet, sizeof(u_packet));
        wait_ms(1);            
        
        if(n_send < 0){
            pc.printf("Send unsuccessfully\n");
            return 0;
        }
        else pc.printf("Sent %d bytes Successfully!\n",n_send);
    /*-receive--*/
        int n_receive=sockA.receiveFrom(EndpointB, (char*)u_buff, sizeof(u_buff));
        wait_ms(1);            

        if(n_receive < 0){
            pc.printf("Receive unsuccessfully\n");        
            return 0;
        }
        else {
             pc.printf("Received %d byte Successfully! %s\n",n_receive);
             pc.printf("Received : %s\n",u_buff);
        }
    } 
    
    sockA.close(false);
    eth.disconnect(); 
    return 0;
}