Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Sat, 30 Mar 2019 10:20:34 GMT

My question is if no MTU exchange procedure happen, why softdevice can notify applicaiton layer? I want solve if peer device won't send ATT MTU exachange request, when should the N52832 send this request to peer device, Now it seems that we cannot send the MTU exchange request upon the connection is established. My protocol needs to know the maximum ATT payload. If no MTU exachange request send by peer device, the N52832 must initiate to send the request.

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 14:42:45 GMT

The result after the mtu exchange will send the notification event to application layer. It can use as the indicator.

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Fri, 29 Mar 2019 14:33:06 GMT

So. This is the problem. How can I know the peer device will or not initiate MTU request?

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 14:08:25 GMT

IOS will send the MTU request all the time. but the android would not initialize the mtu request.

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Fri, 29 Mar 2019 14:05:37 GMT

OK thanks. In the thread https://devzone.nordicsemi.com/f/nordic-q-a/44825/ios-mtu-size-why-only-185-bytes/176316#176316 you mentioned to comment the processing code if I modified the MTU size. That is, the peripheral device needs to wait the central device to send MTU exchange request to exchange their MTU size. If the central device won't initiate the MTU exchange request. Where should I trigger the MTU exchanging procedure?

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 13:13:22 GMT

Data length extension. It has already included the gatt_init. You can find it at the documentation of the Softdevice.

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Fri, 29 Mar 2019 13:10:39 GMT

Hi, DLE request? How to start a DLE request? Which API should I call?

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 12:57:34 GMT

hi,

if you work with IOS, you need to do the DLE request first and wait the MTU request from IOS.

Otherwise, you would only get the MTU = 185.

you can refer to https://devzone.nordicsemi.com/f/nordic-q-a/44825/ios-mtu-size-why-only-185-bytes

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 12:57:24 GMT

hi,

if you work with IOS, you need to do the DLE request first and wait the MTU request from IOS.

Otherwise, you would only get the MTU = 185.

you can refer to https://devzone.nordicsemi.com/f/nordic-q-a/44825/ios-mtu-size-why-only-185-bytes

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Fri, 29 Mar 2019 12:52:00 GMT

Thanks for your replay. Jimmy, have you tried to enlarge the MTU size? in SDK 15.0?

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Jimmy Wong — Fri, 29 Mar 2019 12:33:45 GMT

hi,

The attached is the main.c from SDK 15.0. I added the PM handler on this example.

You can try on the SDK 15.0 with IOS first.devzone.nordicsemi.com/.../3058.main.c

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

Bing — Fri, 29 Mar 2019 11:54:40 GMT

Yes I have done 4 modifications to ble_peripheral\ble_app_ancs_c exmaple in the SDK.

1 adveritisng init with white list disable

2 allow repairing by adding the proccessing in peer_manager_handler.c -> pm_handler_pm_evt_log() -> switch (p_pm_evt->evt_id) -> PM_EVT_CONN_SEC_CONFIG_REQ:

pm_conn_sec_config_t conn_sec_config = {.allow_repairing = true};
pm_conn_sec_config_reply(p_pm_evt->conn_handle, &conn_sec_config);

3 Modify the NRF_SDH_BLE_GATT_MAX_MTU_SIZE to 163 in the sdk_config.h

4 Adjust the RAM start address reported by ret_code_t nrf_sdh_ble_enable(uint32_t * const p_app_ram_start).

And the tested Apple devices are iPhone 5s and iPhone XR. And the iOS version is 12.1.4.

Without change to NRF_SDH_BLE_GATT_MAX_MTU_SIZE. The default is 23. Then there will be no any problem.

But our project need to transfer large packet with smart phones. Once I modified the MAX MTU, the problem will apper 100% each time it reconnect with iPhone.

I have tested the newest SDK 15.3. The same problem exists. Please help me. Thanks.

RE: Apple Device terminates connection after 30 seconds the connection establishment when reconnect with the a bonded N52832

run_ar — Fri, 29 Mar 2019 11:13:57 GMT

Hi,

Which apple device are you testing with (hw and sw version)?

Are you testing with the ANCS example in the SDK? Have you done any modifications to this?