BLE Central connect to same device mulitple times, and client service reacts to events twice.

RE: BLE Central connect to same device mulitple times, and client service reacts to events twice.

shn — Wed, 27 Nov 2019 13:17:02 GMT

Hey,

I solved the problem, my application was reacting to the event twice.

This happened by, using both:

ble_bas_c_on_ble_evt(p_ble_evt, &m_bas_c);

void event_dispatcher(ble_evt_t const* p_ble_evt, void* p_context) {
    uint16_t conn_handle = p_ble_evt->evt.gap_evt.conn_handle;  // connection handle
    uint16_t role        = ble_conn_state_role(conn_handle);    // fetch role
        
   if(role == BLE_GAP_ROLE_PERIPH || ble_evt_is_advertising_timeout(p_ble_evt)) {

        on_ble_peripheral_event(p_ble_evt);

    } else if((role == BLE_GAP_ROLE_CENTRAL) || (p_ble_evt->header.evt_id == BLE_GAP_EVT_ADV_REPORT)) {

        on_ble_central_event(p_ble_evt);
        ble_bas_c_on_ble_evt(p_ble_evt, &m_bas_c);
  
}

and

ble_bas_on_db_disc_evt(&m_bas_c, p_scan_evt);

in the db_discovery_handler.

This made the event happen simultaneously, in retrospect this makes sense. I've revmoved the first occurance.

RE: BLE Central connect to same device mulitple times, and client service reacts to events twice.

shn — Wed, 27 Nov 2019 10:07:59 GMT

Hey,

Okay - I will look into why the db_discovery handler get's called twice.
It seems to a duplication of events or calls... I will update on when i find the error.

Then I will start creating the address table - Does the SDK have anything i should use to create this?

RE: BLE Central connect to same device mulitple times, and client service reacts to events twice.

Vidar Berg — Wed, 27 Nov 2019 09:54:55 GMT

Hi,

We don't have any examples of this that I know of, unfortunately. One of the sides (Central or peripheral) is usually limited to one connection so it's normally not a problem. The peer address is included in the adv. report event and the GAP connect event. I would maybe add the address to the table on the connect event, and remove it when it disconnects. You can use the connection handle as an index for your table.

RE: BLE Central connect to same device mulitple times, and client service reacts to events twice.

shn — Wed, 27 Nov 2019 09:26:56 GMT

Hey,

.connect_if_match is enabled. So a good idea to do the address table - is there any example of how to implement that?

The "SD READ/WRITE API returns error." happens the very first time, on connection... The error code is 17 - So I think it's just because the central device makes requests a READ twice 🙂

RE: BLE Central connect to same device mulitple times, and client service reacts to events twice.

Vidar Berg — Wed, 27 Nov 2019 09:13:58 GMT

Hi,

In the first problem, It looks like the read request is being sent twice. I suggest to add more logging in ble_bas_c.c::tx_buffer_process() to confirm if the read request is duplicated. Also, do you always get the "SD Read/Write API returns error. This message sending will be attempted again.." message when reading the battery characteristic? Please check the returned error code from sd_ble_gattc_read() in that case.

The scanner module will connect to anything matching the filter settings when it's initialized with ".connect_if_match" enabled. So I suggest to disable this option and instead make the decision to connect in your scanner callback. One way to do it could be to manage a RAM table with the addresses of all connected peers, then when you get the NRF_BLE_SCAN_EVT_FILTER_MATCH you can check if the discovered device is already in the address list or not.