SDK15 pm_conn_secure() doesn't bond

[Mikhail]

Hi!

After connected and get log info "Connected." I start bonding:

// Initiate bonding.
err_code = pm_conn_secure(p_ble_evt->evt.common_evt.conn_handle, false);
if (err_code != NRF_ERROR_INVALID_STATE)
{
    APP_ERROR_CHECK(err_code);
}

but there is no any success message. 

 0> <info> app: Heart Rate collector example started.
 0> <info> app: Starting scan.
 0> <info> app: Connected.
 0> <info> app: Disconnected, reason 0x8.
 0> <info> app: Starting scan.
 0> <info> app: Connected.
 0> <info> app: Disconnected, reason 0x8.
 0> <info> app: Starting scan.
 0> <info> app: Connected.
 0> <info> app: Disconnected, reason 0x8.
 0> <info> app: Starting scan.
 0> <info> app: Connected.
 0> <info> app: Disconnected, reason 0x8.
 0> <info> app: Starting scan.

Therefore nRF52 SDK15 can't to made secure bond.

Why?

[FormerMember]

The SDKs do only provide a higher level abstraction, so different SDK version should not matter. In the application, for both central and peripheral, could you set the logging level to "debug"? And also enable logging for the "peer manager" module?

With the above settings, could you do the following bonding tests:

• SDK15 <--> SDK13: not working
• SDK15 <--> SDK 15: working (for the peripheral, use a SDK example)
• SDK13 <--> SDK 13: working (for the central, use a SDK example)

And then upload the logs here.

[Mikhail]

Hi! I use RTT debugging. How to set logging for peer manager?

SDK15--SDK15- all OK

SDK13--SDK13- all OK

SDK15 perph --- SDK13 central- OK

SDK15 central ---- SDK 13 periph- doesn't works.

how to enable logging for peer manager?

[Mikhail]

I sniffed traffic.

Attached. One more. This is central SDK15 and periph SDK13. Doesn't bond

centr_SDK15---periph_SDK13.pcapng

[FormerMember]

In the sniffer log, there are no encryption events.

What happens is that the central (SDK 15) sends a MTU exchange request, but the peripheral never responds. To make it work, the peripherhal has to respond to the MTU exchange request, using sd_ble_gatts_exchange_mtu_reply(), described in this message sequence chart. In SDK 15, this is "natively" implemented, but in SDK 13, it is not.

 

(I'm sorry for the late reply, this thread was for some reason in the wrong "queue", so I didn't see it..)

[Mikhail]

Thanks, I'll answer little bit later. Day-two.

[Mikhail]

Yes, I understand it. But I have periph SDK13 as it is and I should make compatible old project on the SDK13 periph with new SDK15. Tell me best- how to escape this request for MTU in the central SDK15?

[FormerMember]

To make the application support MTU exchange request, your application (peripheral SDK13) has to handle the event BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST. For how to handle the event, see the message sequence chart, and also see how it's handled in SDK15.

[Mikhail]

I mean that on the central (SDK15) disable MTU request to SDK13. Is it possible?

[FormerMember]

Yes, you can disable MTU request in the SDK15 central by not calling sd_ble_gattc_exchange_mtu_request().

[Mikhail]

in wich case should I do it? In wich part of code.

[FormerMember]

Instead of disabling MTU exchange request in SDK 15, it is better to add support for it in your SDK 13  peripheral. If max MTU size for the SDK 13 peripheral should remain 23, you can do something like this in on_ble_evt() in main.c:

 

case BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
    ret_code_t err_code;
    uint16_t mtu_size_supported_by_peripheral = 23;
    
     err_code = sd_ble_gatts_exchange_mtu_reply(conn_handle, mtu_size_supported_by_peripheral);

    if (err_code != NRF_SUCCESS)
    {
        NRF_LOG_ERROR("sd_ble_gatts_exchange_mtu_reply() returned unexpected value 0x%x.",
                      err_code);
    }

 

 

[Mikhail]

Yes, I understand it that better was add MTU in the SDK13. But If we already have project on the SDK13 and don't want any change it? Is it possible to disable MTU request on central side SDK15?