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Dependencies:   ESP8266Interface WIZnetInterface_namespace mbed-src

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Dual Network Interface

Some our customers want dual network interface like below. /media/uploads/SteveKim/dual-nic-2.jpg

So, I decided to implement dual network interface with ESP8266(WiFi) and WIZwiki-W7500(Ethernet).

Implementation

But, I had some troubles because of the below.

  • There is no abstract class for all network interface
  • Same header file name in two library WIZnetInterface(EthernetInterface) and ESP8266Interface
  • Same class name in two library WIZnetInterface and ESP8266Interface

If I can modify Makefile, there will be better way to solve this problem. But, I couldn't modify Makefile in mbed.

So I solved this problem using namespace. Of course, there may be another way to change all class name and file name in the library. But, I wanted to minimize the changes of original library.

First, I changed the header file name in WIZnetInterface from <*.h> to <*.hpp>.

Declaration namespace in header file

// Endpoint.hpp
namespace wiznet_space {
   class Endpoint {
       friend class UDPSocket;
       ....................
   }
}

// Socket.hpp
namespace wiznet_space {

  class Socket {
  public:
       Socket();
  ..........................
  }
}
..........................
..........................

Using namespace in source file

// main.c
..........................

ESP8266Interface wifi(D1, D0, D2, "WizFiDemoAP","12345678",115200); // tx, rx for
wiznet_space::EthernetInterface eth;

bool InitializeWiznetEthernet()
{
    uint8_t mac_addr[6] = {0x00, 0x08, 0xDC, 0xFF, 0x11, 0x22};
 
    eth.init(mac_addr, "192.168.3.102", "255.255.255.0", "192.168.3.1"); //Use DHCP

    .......................................................................................................................    
}

bool InitializeESP8266()
{   
    wifi.init();

    .......................................................................................................................    
}

int main()
{
    ....................................................................

    // Ethernet : WIZnet hardwired TCP/IP in W7500
    if ( InitializeWiznetEthernet() )
    {
        // Send TCP/IP data via Ethernet
        ProcessDataViaEthernet();
    }    
    
    // WiFi : ESP8266
    if ( InitializeESP8266() )
    {
        // Send TCP/IP data via WiFi
        ProcessDataViaWiFi();
    }

    ....................................................................
}

// ProcessDataViaEthernet.cpp
void ProcessDataViaEthernet()
{
    wiznet_space::TCPSocketConnection eth_sock;
    
    eth_sock.connect("192.168.3.64", 6000);
    char send_data[] = "This is from Ethernet Interface\r\n";
    eth_sock.send_all(send_data, sizeof(send_data)-1);
    eth_sock.close();
}

// ProcessDataViaWiFi.cpp
void ProcessDataViaWiFi()
{
    ::TCPSocketConnection wifi_sock;
    
    wifi_sock.connect("192.168.3.64", 6000);    
    char send_data[] = "This is from WiFi Interface\r\n";
    wifi_sock.send_all(send_data, sizeof(send_data)-1);
    wifi_sock.close();
}

And, here are screenshots of this test. /media/uploads/SteveKim/esd01-2.jpg /media/uploads/SteveKim/esd01-3.jpg

Conclusion

I know that this way is a kind of work-around way. Best way is to design a new network-abstract-class and hierarchical network-interface-classes based on the network-abstract-class.

  • Ethernet : lwIP, WIZnet hardwired TCP/IP
  • WiFi : ESP8266, WiFly, WizFi250, CC3000, ....
  • Other interfaces(3G/4G, BT, .....)

I believe that mbed-team will release a new network classes based on a hierarchical architecture .

Until then, you can refer to the this code for dual network interface, temporarily.


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