Observing reduced TX packets per connection interval in SDK 14.2 vs SDK 12.2

RE: Observing reduced TX packets per connection interval in SDK 14.2 vs SDK 12.2

ovrebekk — Thu, 19 Apr 2018 14:23:58 GMT

Sorry for the slow response.

I will check this with the stack team and get back to you.

What SoftDevice type and version are you using?

Best regards
Torbjørn

RE: Observing reduced TX packets per connection interval in SDK 14.2 vs SDK 12.2

jumpingfool — Mon, 09 Apr 2018 09:37:04 GMT

We managed to solve this issue by explicitly reducing the connection interval during the transfer events using sd_ble_gap_ppcp_set, then increasing it again when the transfer event has finished.

Strangely though when we make the second call (after the transfer has finished) we get an NRF_ERROR_BUSY response for quite some time - around 20 seconds after the transfer completes. To ensure the connection interval definitely does revert to the longer setting we've had to set up a timer that calls sd_ble_gap_ppcp_set repeatedly until a NRF_SUCCESS response is received.

What might possibly cause this behaviour? Is there any way to see what the softdevice is busy doing? There is no data transfer happening when this occurs.

RE: Observing reduced TX packets per connection interval in SDK 14.2 vs SDK 12.2

ovrebekk — Wed, 04 Apr 2018 06:41:02 GMT

Could you try increasing the NRF_SDH_BLE_GAP_EVENT_LENGTH parameter in sdk_config.h?

If you have a long connection interval then this could limit the number of packets you are able to send on each connection event.

Best regards
Torbjørn