Buttonless DFU Error: Enabling indications failed

RE: Buttonless DFU Error: Enabling indications failed

Vidar Berg — Thu, 24 May 2018 13:56:19 GMT

jmag999, do you have a sniffer trace showing the packet exchange when you press the DFU icon? That might give a clue as to what's wrong.

RE: Buttonless DFU Error: Enabling indications failed

Vidar Berg — Thu, 24 May 2018 13:51:53 GMT

Hi Andy, I suspect this is related to attribute caching as you mentioned, and not directly related to issue reported by OP. The central may have used an invalid attribute handle cached from a previous session to enable the indication. Cache gets cleared if you reboot or toogle flight mode/ bluetooth enable, which could explain why the rebooting the phone helped in your case.

For devices that support DFU it is important to implement handling for the service changed characteristic in both bootloader and application to ensure that the client performs rediscovery of the attribute table when it changes (e.g., when transitioning between app and bootloader dfu mode).

nRF connect on iOS doesn't display this characteristic, but you can use the same app on Android if you're unsure if you had it enabled or not.

Service changed characteristic displayed in nRF connect on Android:

More information about attribute caching can be found in BT Core spec v.5, vol. 3, Part G, section 2.5.2.

RE: Buttonless DFU Error: Enabling indications failed

jmag999 — Thu, 24 May 2018 11:51:47 GMT

We noticed the same thing. Rebooting the phone sometimes resolves the issue. We are on SDK 14 and are still seeing the issue occasionally. The strange thing is that without rebooting the phone, some devices work and some don't. The ios app certainly has a number of bugs, I imagine this is another one. I think it cropped up recently because we had no issues in the past.

RE: Buttonless DFU Error: Enabling indications failed

Andy — Thu, 24 May 2018 11:42:15 GMT

Yes I just confirmed that. I turned off Bluetooth, restarted the phone, and tried again. Now I'm getting SD requirement not met, but I guess that's better now.

RE: Buttonless DFU Error: Enabling indications failed

Andy — Thu, 24 May 2018 11:38:59 GMT

Hello, I am having the same problem too. I'm using NRF Connect on iOS. I can see that the phone connects and I get the following events:

BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST
BLE_GAP_EVT_DATA_LENGTH_UPDATE
BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST
BLE_GAP_EVT_DISCONNECTED

Then the app reports "Enabling notifications failed". I'm using a bootloader based on SDK 13.1, it's weird because it was working before. I was working on a new bootloader based on SDK 15.0, all good, then I returned to test updating the BL+SD with NRF Connect on my old bootloader and it doesn't want to connect anymore. Could it be that iOS has something cached from the newest bootloader that the old bootloader doesn't support?

RE: Buttonless DFU Error: Enabling indications failed

Vidar Berg — Wed, 09 May 2018 13:04:09 GMT

Hello,

I haven't seen reports of this behavior before, and it's a bit strange that it fails on only 2 out of 300+ units. If possible I would suggest to attach a debugger to the failing units and place breakpoints in ble_dfu.c::on_ctrlpt_write to see if is_ctrlpt_indication_enabled is true when receiving the DFU start command. Which SDK version have you based this on?