Wi-Fi Direct: Managing Wi-Fi Direct™

This tutorial demonstrates how you can manage Wi-Fi Direct™ connections.

This feature is supported in mobile applications only.

Warm-up

Become familiar with the Wi-Fi Direct API basics by learning about:

• Initializing Wi-Fi Direct™

  Initialize Wi-Fi Direct™ for using all Wi-Fi Direct™ functions.

• Activating Wi-Fi Direct™

  Activate the Wi-Fi Direct™ local device asynchronously.

• Peers and groups
  • Getting the Wi-Fi Direct™ Peer Device Information

    Obtain the Wi-Fi Direct™ peer device information.

  • Connecting to a Specific Wi-Fi Direct™ Peer Device

    Connect to a specific Wi-Fi Direct™ peer device.

  • Managing Wi-Fi Direct™ Groups

    Create a Wi-Fi Direct™ group, and manage group members and information.

• Deactivating Wi-Fi Direct™

  Deactivate the Wi-Fi Direct™ local device asynchronously.

Initializing Wi-Fi Direct™

To be able to use all Wi-Fi Direct™ functions, initialize Wi-Fi Direct™:

1. To use the functions and data types of the Wi-Fi Direct API, include the <wifi_direct.h> header file in your application:

   #include <wifi_direct.h>
   

2. Call the wifi_direct_initialize() function:

   int error_code;
   
   error_code = wifi_direct_initialize();
   

   When Wi-Fi Direct™ is no longer needed (or application is exiting), release it:

   wifi_direct_deinitialize();
   

3. To get the Wi-Fi Direct™ activation and deactivation events, set up the wifi_direct_device_state_changed_cb() callback:

   int error_code;
   void device_state_changed_cb(wifi_direct_error_e error_code, wifi_direct_device_state_e device_state, void *user_data);
   
   error_code = wifi_direct_set_device_state_changed_cb(device_state_changed_cb, NULL);
   

   When this callback is no longer needed or the application is exiting, unset it:

   wifi_direct_unset_device_state_changed_cb(NULL);
   

4. To get the Wi-Fi Direct™ discovery events, set up the wifi_direct_discovery_state_changed_cb callback:

   int error_code;
   void discovery_state_changed_cb(wifi_direct_error_e error_code, wifi_direct_discovery_state_e discovery_state, void *user_data);
   
   error_code = wifi_direct_set_discovery_state_changed_cb (discovery_state_changed_cb, NULL);
   

   When this callback is no longer needed or the application is exiting, unset it:

   wifi_direct_unset_discovery_state_changed_cb(NULL);
   

5. To get Wi-Fi Direct™ connection events, set up the wifi_direct_connection_state_changed_cb callback:

   int error_code;
   void connection_state_changed_cb(wifi_direct_error_e error_code, wifi_direct_connection_state_e connection_state, void *user_data);
   
   error_code = wifi_direct_set_connection_state_changed_cb(connection_state_changed_cb, NULL);
   

   When this callback is no longer needed or the application is exiting, unset it:

   wifi_direct_unset_connection_state_changed_cb(NULL);
   

Activating Wi-Fi Direct™

To activate and deactivate a Wi-Fi Direct™ local device and to check the Wi-Fi Direct™ local device state:

1. Activate a Wi-Fi Direct™ local device

   Define the device_state_changed_cb() callback function. When a Wi-Fi Direct™ local device activates or deactivates, an information message is printed in the console (or you can show it to the user some other way).

   static void device_state_changed_cb ((wifi_direct_error_e error_code, wifi_direct_discovery_state_e discovery_state, void *user_data)
   {
      if (device_state == WIFI_DIRECT_DEVICE_STATE_ACTIVATED) 
      {
         printf("Activate Wi-Fi Direct™ device!\n");
         // Handle the event
      } 
      else if (device_state == WIFI_DIRECT_DEVICE_STATE_DEACTIVATED) 
      {
         printf("Deactivate Wi-Fi Direct™ device!\n");
         // Handle the event
      }
   }
   

2. Switch on the Wi-Fi Direct™ local device with the wifi_direct_activate() function. After the wifi_direct_activate() function is completed, the wifi_direct_device_state_changed_cb() callback is called, if you set it before.

   error_code = wifi_activate(NULL);
   

3. Check the Wi-Fi Direct™ state.

   You can check the Wi-Fi Direct™ local device state using the wifi_direct_get_state() function:

   wifi_direct_state_e state = WIFI_DIRECT_STATE_DEACTIVATED;
   wifi_direct_get_state(&state);
   printf("Wi-Fi Direct™ state: %d.\n", state);
   

Getting the Wi-Fi Direct™ Peer Device Information

To discover nearby Wi-Fi Direct™ peer devices, and after discovering, to print the results of the discovery, such as Wi-Fi Direct™ peer device information:

1. Define a callback function for the discovery, to be called when the discovery state is changed.

   In this tutorial, the example callback is discovery_state_changed_cb().

   void discovery_state_changed_cb(wifi_direct_error_e error_code, wifi_direct_discovery_state_e discovery_state, void *user_data)
   {
      switch (discovery_state) 
      {
         case WIFI_DIRECT_ONLY_LISTEN_STARTED:
            // Handle the event
            return "DISCOVERY_STATE: ONLY_LISTEN_STARTED";
         case WIFI_DIRECT_DISCOVERY_STARTED:
            // Handle the event
            return "DISCOVERY_STATE: DISCOVERY_STARTED";
         case WIFI_DIRECT_DISCOVERY_FOUND:
            // Handle the event
            return "DISCOVERY_STATE: DISCOVERY_FOUND";
         case WIFI_DIRECT_DISCOVERY_FINISHED:
            // Handle the event
            return "DISCOVERY_STATE: DISCOVERY_FINISHED";
         default:
            return "UNKNOWN_DISCOVERY_STATE";
      }
   
      return "UNKNOWN_DISCOVERY_STATE";
   }
   

2. Start the discovery to scan nearby devices.

   When the Wi-Fi Direct™ discovery state changes, the wifi_direct_discovery_state_changed_cb() function is called.

   wifi_direct_start_discovery (false, 0);
   

3. Show the search results.

   Show the discovery result using the wifi_direct_discovered_peer_cb() callback, which is invoked by the wifi_direct_foreach_discovered_peers() function. In this tutorial, the Wi-Fi Direct™ peer device information is printed.

   bool discovered_peer_cb(wifi_direct_discovered_peer_info_s *peer, void *user_data) 
   {
      if (NULL != peer) 
      { 
         printf("\nDevice Name: %s", peer->device_name);
         printf("\nMac Address: %s", peer->mac_address);
         // Handle the event
         return 1;
      } 
      else 
      {
         return false;
      }
   }
   int rv = wifi_direct_foreach_discovered_peers(discovered_peer_cb, NULL);
   

   You can also get other information, including the connection state, device type, Wi-Fi display information, and WPS type.

Connecting to a Specific Wi-Fi Direct™ Peer Device

To connect to a specific device:

1. Define the callback function for the connection state.

   The connection event received from the Wi-Fi Direct™ framework invokes the wifi_direct_connection_state_changed_cb() callback function. This example defines the connection_state_changed_cb() callback to handle all Wi-Fi Direct™ connection events.

   static void connection_state_changed_cb(wifi_direct_error_e error_code, wifi_direct_connection_state_e connection_state, const char *mac_address, void *user_data) 
   {
      printf("Connection state changed to: [%d] [%s]\n", connection_state, test_wfd_convert_connection_state_to_string(connection_state));
   
      bool accept_connection = false;
      int rv = 0;
   
      switch (connection_state)
      {
         case WIFI_DIRECT_CONNECTION_WPS_REQ:
         {	
            // Outgoing requests
            wifi_direct_wps_type_e wps_mode;
            wifi_direct_get_local_wps_type(&wps_mode);
            // Handle the event	
         }
            break;
         case WIFI_DIRECT_CONNECTION_REQ:
         {
            // Incoming requests
            wifi_direct_wps_type_e wps_mode;
            wifi_direct_get_local_wps_type(&wps_mode);
            // Handle the event	
         }
            break;
         case WIFI_DIRECT_INVITATION_REQ:
         {
            // Invitation request from peer
            // Handle the event
         }
            break;
         case WIFI_DIRECT_DISASSOCIATION_IND:
         case WIFI_DIRECT_DISCONNECTION_IND:
            printf("Peer : [%s] disconnected.\n" , mac_address);
            // Handle the event
            break;
   	
         case WIFI_DIRECT_CONNECTION_IN_PROGRESS:
            printf("Connection in progress\n");
            // Handle the event
         case WIFI_DIRECT_CONNECTION_RSP:
         {
            if (error_code == WIFI_DIRECT_ERROR_CONNECTION_FAILED) 
            {
               printf(MAKE_RED"Time Out or connection failed"RESET_COLOR"\n");
               // Handle the event
            }
         }
            break;
         case WIFI_DIRECT_GROUP_CREATED:
            // Handle the event
            break;
         case WIFI_DIRECT_GROUP_DESTROYED:
            // Handle the event
            break;
         case WIFI_DIRECT_DISCONNECTION_RSP:
            // Handle the event
            break;
         default:
         {
            printf("Unknown State Received\n");
         }
      }
   }
   

2. Connect with a Wi-Fi Direct™ peer device.

   Check whether Wi-Fi Direct™ is activated using the wifi_direct_get_state() function, and then get the specific device address from the user. Call the wifi_direct_foreach_discovered_peers() function to get a specific device address as a result of the device discovering process.

   char * mac_address = NULL;
   wifi_direct_state_e state;
   int error_code;
   
   wifi_direct_get_state(&state);
   if (state < WIFI_DIRECT_STATE_ACTIVATED)
      return -1;
   	
   mac_address = calloc(1, 32*sizeof(char));
   if (!mac_address) 
   {
      printf("cannot allocate memory");
   
      return -1;
   }
   
   printf("\nEnter Mac_address: ");
   if (scanf(" %s", mac_address) < 1) 
   {
      free(mac_address);
   
      return -1;
   }
   if (strlen(mac_address) > 23)
   {
      printf("\nWrong Mac_address");
   }
   
   error_code = wifi_direct_connect(mac_address);
   if (error_code != WIFI_DIRECT_ERROR_NONE) 
   {
      printf("Fail to connect\n");
   
      return -1;
   }
   
   printf("Connection step finished\n");
   

3. Disconnect from a specific Wi-Fi Direct™ device:

   char * mac_address = NULL;
   wifi_direct_state_e state;
   int error_code;
   
   wifi_direct_get_state(&state);
   if (state < WIFI_DIRECT_STATE_ACTIVATED)
      return -1;
   	
   mac_address = calloc(1, 32*sizeof(char));
   if (!mac_address) 
   {
      printf("cannot allocate memory");
   
      return -1;
   }
   
   printf("\nEnter Mac_address: ");
   if (scanf(" %s", mac_address) < 1) 
   {
      free(mac_address);
   
      return -1;
   }
   if (strlen(mac_address) > 23)
   {
      printf("\nWrong Mac_address");
   }
   
   error_code = wifi_direct_disconnect(mac_address);
   if (error_code != WIFI_DIRECT_ERROR_NONE)
   {
      printf("Fail to disconnect\n");
   
      return -1;
   }
   
   printf("Disconnection step finished\n");
   

Managing Wi-Fi Direct™ Groups

To create an autonomous Wi-Fi Direct™ group without connection and to make your device an autonomous group owner:

1. Create a Wi-Fi Direct™ group and become a group owner:

   wifi_direct_state_e state;
   int error_code;
   
   wifi_direct_get_state(&state);
   if (state < WIFI_DIRECT_STATE_ACTIVATED || state > WIFI_DIRECT_STATE_DISCOVERING) 
   {
      return -1;
   }
   
   error_code = wifi_direct_create_group();
   if (error_code != WIFI_DIRECT_ERROR_NONE) 
   {
      printf("Fail to create wifi direct group\n");
   
      return -1;
   }
   
   printf("Connection step finished\n");
   

2. Destroy all connections and the group:

   wifi_direct_state_e state;
   int error_code;
   
   wifi_direct_get_state(&state);
   if (state < WIFI_DIRECT_STATE_CONNECTED) 
   {
      return -1;
   }
   
   error_code = wifi_direct_destroy_group();
   if (error_code != WIFI_DIRECT_ERROR_NONE) 
   {
      printf("Fail to destroy wifi direct group\n");
   
      return -1;
   }
   
   printf("Disconnection step finished\n");
   

3. When Wi-Fi Direct™ connections or group is no longer needed, destroy all the Wi-Fi Direct™ connections and group.

Deactivating Wi-Fi Direct™

To power off the local device when Wi-Fi Direct™ is no longer needed (or the application is exiting), use the wifi_direct_deactivate() function:

wifi_direct_deactivate(NULL);