Socket Example

This example shows usage of network-socket API.

The program brings up an underlying network interface and if it's Wifi also scans for access points. It creates a TCPSocket and performs an HTTP transaction targeting the website in the mbed_app.json config.

The example can be configured to use a TLSSocket. This works only on devices that support TRNG.

Selecting the network interface

This application is able to use any network interface it finds.

The interface selections is done through weak functions that are overridden by your selected target or any additional component that provides a network interface.

If more than one interface is provided the target configuration target.network-default-interface-type selects the type provided as the default one. This is usually the Ethernet so building on Ethernet enabled boards, you do not need any further configuration.

Configuring mbedtls

By default the examples uses a TCP socket. To enable TLS edit the mbed_app.json to turn on the use-tls-socket option:

        "use-tls-socket": {
            "value": true
        }

It might be necessary to configure the mbedtls library with appropriate macros in mbed_app.json file. Some boards (like UBLOX_EVK_ODIN_W2) will work fine without any additional configuration and some of them might require some minimal adjustment. For example K64F requires at least the following macro added:

        "K64F": {
            "target.macros_add" : ["MBEDTLS_SHA1_C"]
        }

See mbedtls configuration guidelines for more details.

Also see the API Documentation TLSSocket.

WiFi

If you want to use WiFi you need to provide SSID, password and security settings in mbed_app.json.

If your board doesn't provide WiFi as the default interface because it has multiple interfaces you need to specify that you want WiFi in mbed_app.json.

{
    "target_overrides": {
        "*": {
            "target.network-default-interface-type": "WIFI",
        }
    }
}

For more information about Wi-Fi APIs, please visit the Mbed OS Wi-Fi documentation.

Supported WiFi hardware

• All Mbed OS boards with build-in Wi-Fi module such as:
  • ST DISCO IOT board with integrated ISM43362 WiFi Inventek module.
  • ST DISCO_F413ZH board with integrated ISM43362 WiFi Inventek module.
• Boards with external WiFi shields such as:
  • NUCLEO-F429ZI with ESP8266-01

Building and flashing the example

1. Clone it to your machine. Don't forget to use --recursive to clone the submodules: git clone --recursive https://github.com/mbed-ce/mbed-os-example-sockets
2. Set up the GNU ARM toolchain (and other programs) on your machine using the toolchain setup guide.
3. Set up the CMake project for editing. We have three ways to do this:
   • On the command line
   • Using the CLion IDE
   • Using the VS Code IDE
4. If your Mbed target has upload method support, you can build the flash-mbed-os-example-sockets target to automatically upload the code to a connected device. Otherwise, build the mbed-os-example-sockets target and manually load the resultant bin or hex file to your target.

Expected output

(Assuming you are using a wifi interface, otherwise the scanning will be skipped)

Starting socket demo

2 networks available:
Network: Virgin Media secured: Unknown BSSID: 2A:35:D1:ba:c7:41 RSSI: -79 Ch: 6
Network: VM4392164 secured: WPA2 BSSID: 18:35:D1:ba:c7:41 RSSI: -79 Ch: 6

Connecting to the network...
IP address: 192.168.0.27
Netmask: 255.255.255.0
Gateway: 192.168.0.1

Resolve hostname ifconfig.io
ifconfig.io address is 104.24.122.146

sent 52 bytes: 
GET / HTTP/1.1
Host: ifconfig.io
Connection: close

received 256 bytes:
HTTP/1.1 200 OK

Demo concluded successfully 

License and contributions

The software is provided under Apache-2.0 license. Contributions to this project are accepted under the same license. Please see contributing.md for more info.

This project contains code from other projects. The original license text is included in those source files. They must comply with our license guide