Ethernet

EthInterface class hierarchy

The EthInterface provides a C++ API for connecting to the internet over Ethernet. By default, this class does not require any configuration. It is able to pick up the default Ethernet driver for the target and select correct network stack.

Usage

To statically initialize the driver, create an object without passing any parameters:

EthernetInterface eth;

Then, if the default configuration is enough, bring up the interface:

nsapi_error_t status = eth.connect();

Now, the interface is ready to be used for network sockets.

// Open a TCP socket
TCPSocket socket;
socket.open(&eth);

// Open a UDP socket
UDPSocket socket;
socket.open(&eth);

Configuration

For EthernetInterface, there are two possible configurations:

• Use DHCP for network addressing. This is the default.
• Use statically configured IP addresses.

Refer to the API below for how to set the IP addresses by calling the set_network() function.

Troubleshooting information

Network interface connect failure causes:

• NSAPI_ERROR_NO_CONNECTION indicates that the Ethernet link up has failed. Check that the Ethernet connection is working.
• NSAPI_ERROR_DHCP_FAILURE indicates that acquiring the IP address has failed. Check that the IP address configuration service is working.

EthInterface class reference

EthInterface example

Here is an example of an HTTP client program. The program brings up Ethernet as the underlying network interface and uses it to perform an HTTP transaction over a TCPSocket:

/*
 * Copyright (c) 2006-2020 Arm Limited and affiliates.
 * SPDX-License-Identifier: Apache-2.0
 */
#include "mbed.h"
#include "EthernetInterface.h"

// Network interface
EthernetInterface net;

// Socket demo
int main()
{
    // Bring up the ethernet interface
    printf("Ethernet socket example\n");
    net.connect();

    // Show the network address
    SocketAddress a;
    net.get_ip_address(&a);
    printf("IP address: %s\n", a.get_ip_address() ? a.get_ip_address() : "None");

    // Open a socket on the network interface, and create a TCP connection to mbed.org
    TCPSocket socket;
    socket.open(&net);

    net.gethostbyname("ifconfig.io", &a);
    a.set_port(80);
    socket.connect(a);
    // Send a simple http request
    char sbuffer[] = "GET / HTTP/1.1\r\nHost: ifconfig.io\r\n\r\n";
    int scount = socket.send(sbuffer, sizeof sbuffer);
    printf("sent %d [%.*s]\n", scount, strstr(sbuffer, "\r\n") - sbuffer, sbuffer);

    // Recieve a simple http response and print out the response line
    char rbuffer[64];
    int rcount = socket.recv(rbuffer, sizeof rbuffer);
    printf("recv %d [%.*s]\n", rcount, strstr(rbuffer, "\r\n") - rbuffer, rbuffer);

    // Close the socket to return its memory and bring down the network interface
    socket.close();

    // Bring down the ethernet interface
    net.disconnect();
    printf("Done\n");
}

Related content

• Network socket API reference overview.
• Ethernet architecture.