Multilink Example - long time needed to establish connection and enable notifications

[muhkuhns]

The m_client_count is like instantly increased when I power up another (or the first) peripheral.

But with increasing connection interval the time till the central finally enables notifications on the peripheral is dramatically increased - why is that?

peripheral - main.c - Connected and bonded with nRFMaster Panel and notifications enabled in no time -> Problem is the central?

RTT Output:

It seems like the time is indeed lost/needed for securing the link. As the first few lines come in pretty fast. Looking at the clock I would say

Scan gestartet // of course instant as always
GAP_EVT_ADV_REPORT // from here
EVT_DEVICE_CONTEXT_LOADED
EVT_CONNECTION
GAP_EVT_ADV_REPORT
EVT_DEVICE_CONTEXT_LOADED
EVT_CONNECTION
GAP_EVT_ADV_REPORT
EVT_DEVICE_CONTEXT_LOADED
EVT_CONNECTION
GAP_EVT_ADV_REPORT
EVT_DEVICE_CONTEXT_LOADED
EVT_CONNECTION // till here only a few seconds (3~4)
EVT_LINK_SECURED //but to reach this takes the biggest part
DM_EVT_LINK_SECURED
0;0;97962;22826;0;0;0;0
0;0;97965;22820;0;0;0;0
0;0;97964;22826;0;0;0;0
0;0;97963;22840;0;0;0;0
EVT_LINK_SECURED
DM_EVT_LINK_SECURED
0;0;97966;22843;0;0;0;0
0;0;97958;22850;0;0;0;0
0;0;97950;22843;0;0;0;0
0;0;97950;22850;98044;22856;0;0
0;0;97951;22856;98040;22846;0;0
0;0;97953;22863;98044;22860;0;0
EVT_LINK_SECURED
DM_EVT_LINK_SECURED
0;0;97952;22856;98046;22853;0;0
0;0;97945;22856;98042;22860;0;0
0;0;97946;22856;98041;22863;0;0
0;0;97945;22863;98028;22860;97952;22713
0;0;97946;22863;98033;22870;97951;22706
0;0;97952;22866;98032;22870;97954;22706
EVT_LINK_SECURED
DM_EVT_LINK_SECURED
0;0;97944;22860;98031;22876;97956;22716
0;0;97949;22866;98025;22870;97955;22713
0;0;97947;22870;98024;22883;97955;22716
98015;22686;97941;22870;98023;22876;97944;22726
98017;22696;97945;22873;98021;22886;97940;22726

Above with 4seconds conn_int => >2,5minutes till 4th peripheral send first measurement.

With 50ms it is quite fast. (Same time for the evt_conn but like no time for link_secured for all 4 peripherals vs. ~40seconds each with 4second interval.)

30seconds till last peripheral is link_secured with 500ms interval.

So what is the easiest way to change connection intervall after all inks are secured?

central - main.c

central - client_handling.c

//Edit:

The measurements on the left come in fine.. the 1*interval delay (2nd from top) can happen..

But on the right the 4times connection interval doesn't make sense to me. at least I can't explain it..

4s timer on peripherals does: Measurement + sd_ble_gatts_hvx();

4s timer on central ouputs the values received by

	case BLE_GATTC_EVT_HVX:
	for (int i=0; i<8; i++) {
	empf_buffer[i] = p_ble_evt->evt.gattc_evt.params.hvx.data[i];
	}
	modul_nr = empf_buffer[7];
	zaehler[modul_nr] = 0;
	druck[modul_nr] = empf_buffer[0]<<16 | empf_buffer[1]<<8 | empf_buffer[2];
	temperatur[modul_nr] = empf_buffer[3]<<16 | empf_buffer[4]<<8 | empf_buffer[5];
	spannung[modul_nr] = empf_buffer[6];

so no buffering of data.. or does sd_ble_gatts_hvx(); a sort of buffering?

[muhkuhns]

There is a dm_security_setup_req(&handle); in the multilink_central_example in the case DM_EVT_SECURITY_SETUP shouldn't this perform bonding?

//Edit:

// Slave securtiy request received from peer, if from a non bonded device, 
            // initiate security setup, else, wait for encryption to complete.

I edited the question to include all relevant files, so everyone may have an easy look at. For me it seems like they should bond witih the code thats already there.

[Hung Bui]

@muhkuhns: No, It's when the bonding is requested from the peripheral, which is not usual. Calling dm_security_setup_req() is how you start bonding from the central side.

[muhkuhns]

I tried around with it but it always reboots.. where/when is a good/correct place/time to call the function? My guess was after the service discovery.. (looking at the hrs example)

[Hung Bui]

@muhkuhns: It can be called at anytime after the connection is established and before the link is already encrypted. You can try to do that after service discovery. Please make sure you receive NRF_SUCCESS return err_code when you call the function. If there is assertion, please add a break point at the assert error handler to see what causes the issue.

[muhkuhns]

I tried to call the function in

client_handling.c
static void db_discovery_evt_handler(ble_db_discovery_evt_t * p_evt)
 if (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE)
    if (is_valid_srv_found)

It returns a 0 but the device reboots.