Wi-Fi: Managing Wi-Fi and Monitoring Its State

This tutorial demonstrates how you can manage Wi-Fi connections and monitor the state of Wi-Fi.

Warm-up

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

Initializing Wi-Fi
Initialize Wi-Fi for use.
Activating a Wi-Fi Device
Activate the Wi-Fi device asynchronously.
Scanning for Access Points
Scan the nearby access points and retrieve information about them.
Connecting to a Specific Access Point
Connect to a specific access point after scanning.
Deactivating the Wi-Fi Device
Deactivate the Wi-Fi device asynchronously.

Initializing Wi-Fi

To use the functions and data types of the Wi-Fi API (in mobile and wearable applications), include the <wifi.h> header file in your application:

#include <wifi.h>

To be able to use all Wi-Fi functions, initialize Wi-Fi using the wifi_initialize() function:

int error_code;

error_code = wifi_initialize();
if (error_code != WIFI_ERROR_NONE)
   return;

When Wi-Fi is no longer needed or the application is exiting, release Wi-Fi:

wifi_deinitialize();

Activating a Wi-Fi Device

To activate and deactivate a local Wi-Fi device, and to check that Wi-Fi is activated:

Activate a Wi-Fi device using the wifi_activate() function. After the wifi_activate() function is completed, the __wifi_activated_cb() function is invoked.
```
error_code = wifi_activate(__wifi_activated_cb, NULL);
```
Define the __wifi_activated_cb() function for a callback. In case of Wi-Fi device activation, an information message is printed using dlog util (or shown to the user in another way).
```
static void __wifi_activated_cb(wifi_error_e result, void *user_data) 
{
   if (result == WIFI_ERROR_NONE)
      dlog_print(DLOG_INFO, LOG_TAG, "Success to activate Wi-Fi device!");
}
```

Check the Wi-Fi connection using the wifi_is_activated() function. The parameter indicates, whether Wi-Fi is activated.

bool wifi_activated = false;
wifi_is_activated(&wifi_activated);
if (wifi_activated)
{
   dlog_print(DLOG_INFO, LOG_TAG, "Success to get Wi-Fi device state.");
}
else 
{
   dlog_print(DLOG_INFO, LOG_TAG, "Fail to get Wi-Fi device state.");
}

Scanning for Access Points

To scan nearby access points, and after scanning, to print the result of the scan, such as the AP name and state:

Scan nearby access points asynchronously. When the scan is finished, the __scan_request_cb() function is called.
```
wifi_scan(__scan_request_cb, NULL);
```
Define a callback function to be called when the scan is finished. In this tutorial, the callback is the __scan_request_cb() function. It invokes the wifi_foreach_found_aps() function for getting information on the found AP. The wifi_foreach_found_aps() function gets the result of the scan. The __wifi_found_ap_cb() function is called when you get the found access point repeatedly.
```
void __scan_request_cb(wifi_error_e error_code, void *user_data)
{
   error_code = wifi_foreach_found_aps(__wifi_found_ap_cb, NULL);
   if (error_code != WIFI_ERROR_NONE) 
      dlog_print(DLOG_INFO, LOG_TAG, "Fail to scan");
}
```

Show the result of the scan using the __wifi_found_ap_cb() callback function, which is invoked by the wifi_foreach_found_aps() function. In this tutorial, print the AP name and connection state.

bool __wifi_found_ap_cb(wifi_ap_h ap, void *user_data) 
{
   int error_code = 0;
   char *ap_name = NULL;
   wifi_connection_state_e state;


   error_code = wifi_ap_get_essid(ap, &ap_name);
   if (error_code != WIFI_ERROR_NONE) 
   {
      dlog_print(DLOG_INFO, LOG_TAG, "Fail to get AP name.");

      return false;
   }
   error_code = wifi_ap_get_connection_state(ap, &state);
   if (error_code != WIFI_ERROR_NONE) 
   {
      dlog_print(DLOG_INFO, LOG_TAG, "Fail to get state.");

      return false;
   }
   dlog_print(DLOG_INFO, LOG_TAG, "AP name : %s, state : %s", ap_name, print_state(state));

   return true;
}

static const char* print_state(wifi_connection_state_e state) 
{
   switch (state) 
   {
   case WIFI_CONNECTION_STATE_DISCONNECTED:
      return "Disconnected";
   case WIFI_CONNECTION_STATE_ASSOCIATION:
      return "Association";
   case WIFI_CONNECTION_STATE_CONNECTED:
      return "Connected";
   case WIFI_CONNECTION_STATE_CONFIGURATION:
      return "Configuration";
   }
}

You can get other information, including frequency, IP address, and security type. For more information, see the Wi-Fi guide.

Connecting to a Specific Access Point

To make a connection using a specific access point:

Select an access point.

Check whether Wi-Fi is activated using the wifi_is_activated() function, and then receive the specific AP name from the user. Call the wifi_foreach_found_aps() function to compare the AP name with the result of the scan and connecting to the AP.

char ap_name[33];
bool state = false;

wifi_is_activated(&state);
if (state == false)
   return -1;
dlog_print(DLOG_INFO, LOG_TAG, "Input a part of AP name to connect : ");
error_code = scanf("%32s", ap_name);

error_code = wifi_foreach_found_aps(__found_connect_ap_cb, ap_name);
if (error_code != WIFI_ERROR_NONE) 
{
   dlog_print(DLOG_INFO, LOG_TAG, "Fail to connect (can’t get AP list)");

   return -1;
}

dlog_print(DLOG_INFO, LOG_TAG, "Connection step finished");

Make a connection with an access point.

The wifi_foreach_found_aps() function called above invokes a callback function, which is __found_connect_ap_cb(). Define the __found_connection_ap_cb() callback. This function compares user_data (the AP name from the user input) with the name of the found AP. If it is correct, the function checks whether the AP requires a passphrase. Set the passphrase using the wifi_ap_set_passphrase() function.

Finally, connect to a specific AP using the wifi_connect() function.

static bool __found_connect_ap_cb(wifi_ap_h ap, void *user_data) 
{
   int error_code = 0;
   char *ap_name = NULL;
   char *ap_name_part = (char*)user_data;

   error_code = wifi_ap_get_essid(ap, &ap_name);
   if (error_code != WIFI_ERROR_NONE) 
   {
      dlog_print(DLOG_INFO, LOG_TAG, "Fail to get AP name");

      return false;
   }

   if (strstr(ap_name, ap_name_part) != NULL) 
   {
      bool required = false;

      if (wifi_ap_is_passphrase_required(ap, &required) == WIFI_ERROR_NONE)
         dlog_print(DLOG_INFO, LOG_TAG, "Passphrase required: %s", required ? "True" : "False");
      else
         dlog_print(DLOG_INFO, LOG_TAG, "Fail to get Passphrase required");

      if (required) 
      {
         char passphrase[100];
         dlog_print(DLOG_INFO, LOG_TAG, "Input passphrase for %s :", passphrase);
         error_code = scanf("99%s", passphrase);

         error_code = wifi_ap_set_passphrase(ap, passphrase);
         if (error_code != WIFI_ERROR_NONE) 
         {
            dlog_print(DLOG_INFO, LOG_TAG, "Fail to set passphrase");

            return false;
         }
      }

      error_code = wifi_connect(ap, __connected_cb, NULL);
      if (error_code != WIFI_ERROR_NONE)
         dlog_print(DLOG_INFO, LOG_TAG, "Fail to connection request");
      else
         dlog_print(DLOG_INFO, LOG_TAG, "Success to connection request");

      free(ap_name);

      return false;
   }

   free(ap_name);

   return true;
}

Provide a notification about the result of the connection.

The wifi_connect() function called earlier invokes the __connected_cb() function. With this function, you can provide the result of the connection.

static void __connected_cb(wifi_error_e result, void* user_data) 
{
   if (result == WIFI_ERROR_NONE)
      dlog_print(DLOG_INFO, LOG_TAG, "Wi-Fi Connection Succeeded");
   else
      dlog_print(DLOG_INFO, LOG_TAG, "Wi-Fi Connection Failed!");
}

Deactivating the Wi-Fi Device

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

wifi_deactivate(NULL, NULL);