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

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

muhkuhns — Mon, 29 Jun 2015 11:42:38 GMT

Thanks for the hint! I already opened up a new question for this: devzone.nordicsemi.com/.../

Can I remove the queue (i.e. make the buffer only 1 notification long) ?

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

Hung Bui — Mon, 29 Jun 2015 11:40:27 GMT

@muhkuhns: The thread getting long. I would suggest when you have new question to create a new case. If you queued too many notification (max 6 in the buffer), and if the central device doesn't support multiple packet per connection, they will be stack up and be transmitted in the next connection events. So you will have your notification comes pretty late compare to the time it's queued.

Also if the RF link is not good, with lots of re-transmission, you will have larger latency.

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

muhkuhns — Fri, 26 Jun 2015 19:07:43 GMT

It basically works. Called it after the link secured. Everything is smooth and fine BUT strangely at least one of the 4 peripherals sends data that seems to be ~4-5 conection intervals old.. But looking at the code that makes no sense to me.. there is no queue.. it shouldn't be able to have a larger delay than one times the connection interval..

Peripherals do measurements every 4seconds and then sd_hvx them.. Central outputs every 4seconds all 4measurements he received...

So how can one value have like 20seconds delay?

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

Hung Bui — Wed, 24 Jun 2015 07:44:09 GMT

@muhkuhns: You should call sd_ble_gap_conn_param_update() with the parameter of your choice.

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

muhkuhns — Tue, 23 Jun 2015 18:27:26 GMT

What function shall I have a look at to change the intervall after the link has been secured?

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

Hung Bui — Tue, 23 Jun 2015 09:30:43 GMT

@muhkhuns: 37 seconds needed when the connection interval is 4 second is quite reasonable.

It's only 9 connection events. Doing a service discovery process often take longer than 9 connection events.

But 5 seconds when the connection interval is 50ms is pretty strange. Because this meant it take 100 connection events before the notification is sent.

Anyway, 4 seconds connection interval is pretty long one.

My suggestion is you stick with 50ms connection interval at the begining. Then after you have the first notification, you can try to update the connection interval to the longer one, e.g 4 seconds. Make sure you also set the connection timeout accordingly, suggesting at least 3 times the connection interval.

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

muhkuhns — Mon, 22 Jun 2015 13:54:54 GMT

Of course my tablet is running real Windows 8.1, not RT. I would just like to be able to use the internal chip..

Also I got ONE nRF51-DK! But it can't act as central and sniffer at once. And I am not going to let the university buy another one just for this one time use during my master-thesis.

It should be possible to track down the problem without a sniffer.. 37seconds between connection and link secured with 4000ms conn_int. It shouldn't take that long, right?

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

Hung Bui — Mon, 22 Jun 2015 12:21:19 GMT

@muhkuhns: The nRF51 DK or nRF51 dongle wouldn't cost much more than a module when offering much more features. So I would suggest you to get one.

Windows 8.x should work fine with the nRFSniffer , but not the Windows 8.x RT. You would need a Surface Pro tablet. Note that you still need to connect a dongle/DK to the PC to be able to sniff.

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

muhkuhns — Fri, 19 Jun 2015 15:41:12 GMT

Why is there no application for Windows 8 to sniff BLE :( I bought a Windows 8.1 tablet with Bluetooth 4.0 and BLE compatible.. but there is just no useful software :/

I need to get another module then to act as a central.. the problem is my modules are based on revision 1 and the DK on rev3.. so I can't just use on of them to act as a central.. to free up the DK for use as a sniffer

I got another module now bases on rev 2 chip and without the 32mhz clock so I changed the centrals sd init function to use NRF_CLOCK_LFCLKSRC_RC_250_PPM_250MS_CALIBRATION and the ram size to 0x2000 But it does not seem to work..

www.i-syst.com/.../IMM-NRF51822_RefMan.pdf

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

Hung Bui — Fri, 19 Jun 2015 15:15:44 GMT

@muhkuhns: I strongly recommend you to get hold of a nRF51 dongle, or nRF51 DK kit to use as a sniffer to sniff the connection. I saw you mentioned that you have a nRF51 DK , so it should be possible. With the sniffer trace we can easily spot what cause the slow encryption.

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

muhkuhns — Thu, 18 Jun 2015 16:31:23 GMT

I just left my workplace so I can't try out anything till tomorrow. But for advertise and scanning it is:

APP_ADV_INTERVAL                   MSEC_TO_UNITS(20, UNIT_0_625_MS)

SCAN_INTERVAL                    0x0029                                         /** in units of 0.625 millisecond. */
SCAN_WINDOW                      0x0028                                         /** in units of 0.625 millisecond. */

Connection interval at beginning 4000ms when it takes 37seconds.. down to 5seconds with 50ms interval e.g.

Is there a way to log time with RTT?

I am back atr work now and put in some more RTT_printfs...

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

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

Hung Bui — Thu, 18 Jun 2015 16:23:18 GMT

@muhkuhns: 37 seconds for the first notification is a little bit strange. How frequently do you advertise, could you try to print something when it's connected ? Which connection interval you set at the begining ? I think you can have a look at the ble_app_hrs_c. It usually don't take more than few seconds to get the first notification.

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

muhkuhns — Tue, 16 Jun 2015 13:11:18 GMT

Sadly I don't have the required hardware for the sniffer tool :/

I never had this before.. but after setting the lines and commenting them out again it sometimes does not connect at all ?? When is the pstorage deleted? How can I easily wipe it to make sure it does not cause this problem?

Does ERASE ALL in nrfgo Studio erases the pstorage?

//Edit:

There is no reason but it seems like this behaviour is only with one of the peripherals and also only when I power it from the DK and not the battery.

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

Hung Bui — Tue, 16 Jun 2015 12:48:21 GMT

@muhkuhns: Please attach a sniffer trace. I don't quite understand what was outputted on the RTT trace.

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

muhkuhns — Tue, 16 Jun 2015 11:12:09 GMT

uint32_t err_code = dm_security_setup_req(&p_client->handle); APP_ERROR_CHECK(err_code);

I use this to call the function. I tried it directly after is_valid_srv_found = true; now and at least it does no longer reboots.

I will update the original question with RTT output and updated files.

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

Hung Bui — Tue, 16 Jun 2015 11:07:23 GMT

@muhkuhns: Please also post the code where you call the function, which handle did you feed to the function ? Note that it should be the dm_handle_t corresponding for the client you are handling.

Please set the compiler macro with DEBUG mode then add a breakpoint in app_error_handler() in app_error to find the error code , line number and file name when it hit the breakpoint. The device should not restart on its on, usually because of the NVIC_SystemReset() in the app_error_handler().

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

muhkuhns — Tue, 16 Jun 2015 08:00:44 GMT

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.

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

Hung Bui — Tue, 16 Jun 2015 07:52:28 GMT

@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.

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

muhkuhns — Mon, 15 Jun 2015 15:04:33 GMT

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)

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

Hung Bui — Mon, 15 Jun 2015 14:54:08 GMT

@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.

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

muhkuhns — Mon, 15 Jun 2015 14:33:49 GMT

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.

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

Hung Bui — Mon, 15 Jun 2015 12:59:49 GMT

@muhkhuns: it's actually implemented in our ble_app_hrs_c example. In this example, we trigger pairing after finish with service discovery. Please have a look at BLE_HRS_C_EVT_DISCOVERY_COMPLETE event in hrs_c_evt_handler.

The rest is already implemented in the device_manager_central.c event the CCCD re-enabling (m_service_context_load)

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

muhkuhns — Sat, 13 Jun 2015 08:24:34 GMT

Could you maybe hint out some specific functions I should look up in the dic for this purpose?

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

Hung Bui — Fri, 12 Jun 2015 11:32:45 GMT

@muhkuhns: I'm not sure how much we have implemented, but it seems from the code that the bonding handling and restore system attribute is already there in the device manager peripheral, you just need to call from the application.

Increasing connection interval would be pretty simple.

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

muhkuhns — Fri, 12 Jun 2015 09:21:11 GMT

For the m_client_count thing: I just thought in the beginning that the time to connect increased as a whole.. forget about that part.

What of your two suggestions should I try out first? As in the end there are 1 master and 4peripherals I guess the bonding would be a good idea. But I was thinking this were already implemented in the multilink example?

I will have a look at how to increase connection interval after initial setup.