How to switch from connectable mode to beacon mode after disconnection

[VISHNU D PAI]

Currently I have been able to advertise and connect through debug app using nRF52 DK. My target is:

1. After the link is lost the bluetooth gets disconnected and at this time I want the DK to advertise in the beacon mode.

2. My purpose is that when some one with the app comes near I can send him the advertisement and the lost user can track the item.

How to implement this switch from connectable mode to beacon mode after disconnection

[Hung Bui]

Hi Vishnu, 

Could you please let us know the SDK you are using ? 

Have you get your self familiar with how to do connectable advertising and non-connectable advertising ? 

Have you designed how should the device return to connectable advertising after it start non-connectable advertising ? 

I have a blog here about advertising that might be useful for you: https://devzone.nordicsemi.com/guides/nrf-connect-sdk-guides/b/software/posts/building-a-ble-application-on-ncs-comparing-and-contrasting-to-softdevice-based-ble-applications

[VISHNU D PAI]

Hung Bui said:

Could you please let us know the SDK you are using

I am currently using nRF5 SDK  and working on Proximity example from ble_pheripheral. Here I wanted to change the advertising to beacon mode when the app gets disconnected from the nRF52 DK. 

Hung Bui said:

I have a blog here about advertising that might be useful for you

this blog is based on nRF-connect-SDK, which is not what I need. Can you give some example based on nRF5 SDK.  

Hung Bui said:

Have you designed how should the device return to connectable advertising after it start non-connectable advertising ? 

Can you provide some example based on the same.

[Hung Bui]

Hi Vishnu, 

What you need to do is in advertising_init() you need to set: 

init.config.ble_adv_on_disconnect_disabled=true. 

This will disable the feature to start advertising automatically when disconnect. 

Then after that you can write your own code in the BLE_GAP_EVT_DISCONNECTED event handler inside ble_evt_handler() function in main.c to start advertising  in beacon mode. I assume you are planning to do non-connectable advertising. Please follow what we have in the beacon example. 

[VISHNU D PAI]

I have tried implementing what you have suggested, but after disconnection it stops advertising rather than going to beacon advertising mode. I have added an advertising_beacon_init function and advertising_beacon_start function. Inside the BLE_GAP_EVT_DISCONNECTED I called the advertising_beacon_start function to start beacon mode. Is this the right way to proceed or is there anything I need to do extra.

[Hung Bui]

Hi Vishnu,

Please provide the code you used. I don't know what you have inside advertising_beacon_start (). 
Please get familiar with how you can stop and re-start advertising. 

[VISHNU D PAI]

void advertising_beacon_start(bool erase_bonds)
{

   if (erase_bonds == true)
    {
        delete_bonds();
        // Advertising is started by PM_EVT_PEERS_DELETED_SUCEEDED event
    }
    else
    {
        ret_code_t err_code;

      err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
      APP_ERROR_CHECK(err_code);

      err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
      APP_ERROR_CHECK(err_code); 

    }
    
}

This is the advertising_beacon_start function and this is called in BLE_GAP_EVT_DISCONNECTED as follows

 
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected.");
            
             advertising_beacon_start(erase_bonds);
             
            // LED indication will be changed when advertising starts.
            break;

Please can you give a light on what is wrong here. If possible can you give a similiar example on how to tackle this problem. 

Hung Bui said:

Please get familiar with how you can stop and re-start advertising.

can you give an example or link on how to familiarize with the same

[Hung Bui]

Hi ,

Please find the example attached. See how I added the advertising_init_beacon() with 

    adv_params.properties.type = BLE_GAP_ADV_TYPE_NONCONNECTABLE_SCANNABLE_UNDIRECTED;

and calling it inside BLE_GAP_EVT_DISCONNECTED  event. 

When you see something doesn't work please try to debug it. You can use the UART log to see if there is any assert. And you can add DEBUG into the project's preprocessor symbols to have more information about the assert.