disconnection issue in 2M PHY mode

[eric ding]

Hi team,

customer used SDK v15 and the default s140 softdevice in it.

When the 52840 is configured in the 2M phy mode after connecting with Iphone 8/x, it can't be successfully disconnected even if the termination request is sent and acked in the sniffer log file.

The 52840 restarted advertising until 3 minutes later after the termination request. 

This can be analyzed in the attached sniffer log.

And we found that no BLE_GAP_EVT_DISCONNECTED event is reported from the softdevice.

there isn't  this disconnection error when configured in normal 1M phy mode.

So is there some limitation on the softdevice on this ?

Could you help to check it?

thanks.

Eric

Best Regards

iphone8_error_log.rar

[Vidar Berg]

Hi Eric,

Was unable to reproduce this issue here. I received the BLE_GAP_EVT_DISCONNECTED as soon as I disconnected the link from the iphone. Also made sure that 2M phy was used. Can you try the same with a different example?

Best regards,

Vidar

 

[eric ding]

Hi Vidar,

After further investigation, we found that it's related to the softdevice event irq priority.

The BLE_GAP_EVT_DISCONNECTED event is delayed by other application tasks.

I found that in the SDK v15 the SD_EVT_IRQn priority for S132 is APP_IRQ_PRIORITY_LOWEST.

But not sure what's the default priority setting for S140?

Thanks.

Eric 

[Vidar Berg]

Hi Eric, 

default priority is 6, but is being set to 7 (lowest) by the softdevice handler in SDK 15.0.0. Note that this was changed in SDK 15.2.0:

Removed the workaround in nrf_sdh.c overriding the default priority level on SWI interrupt SD_EVT_IRQn and RADIO_NOTIFICATION_IRQn used by the SoftDevice. - Changed the default interrupt priority level for the peripherals from 7 to 6. This is done to be aligned with the priority of the SWI coming from the SoftDevice.

[eric ding]

Got it, thanks.