Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Scribble — Thu, 06 Dec 2018 16:18:29 GMT

Thanks, this solved the issue, we went from ~2KB/s to ~12KB/s and then after forcing BLE5 to our S8 to ~20KB/s

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Sigurd — Thu, 06 Dec 2018 14:13:32 GMT

[quote user="alistair_rpd"]what the best approach is to determine the most appropriate value for NRF_SDH_BLE_GAP_EVENT_LENGTH? i.e. what are the factors in selecting a value?[/quote]

The suggested intervals and windows chapter in the SDS have some information about this. See this link.

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Scribble — Thu, 06 Dec 2018 11:00:57 GMT

Hi Sigurd,

This looks like it may have improved things, I'm no longer seeing missed connection intervals. I'll profile it later today to confirm, in the meantime can I ask what the best approach is to determine the most appropriate value for NRF_SDH_BLE_GAP_EVENT_LENGTH? i.e. what are the factors in selecting a value?

Many thanks

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Sigurd — Wed, 05 Dec 2018 14:02:44 GMT

Hi,

[quote user="alistair_rpd"]I'll try the sniffer later on in the week, is there any easy way to confirm packets per interval without using the sniffer?[/quote]

After one or more notifications are sent, you will get an event BLE_GATTS_EVT_HVN_TX_COMPLETE with count field showing "Number of notification transmissions completed.". But you could get several of these events within the same connection interval, so you would need to e.g. use the app_timer and add some logic to see how often you get these events, and then calculate the numbers of packets that is transmitted within the connection interval. Personally, I use the sniffer for this kind of debugging.

[quote user="alistair_rpd"]NRF_SDH_BLE_GAP_EVENT_LENGTH 6[/quote]

Try to increase this value. Set it to e.g. 320.

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Scribble — Tue, 04 Dec 2018 15:08:57 GMT

Thanks Sigurd,

I'll try the sniffer later on in the week, is there any easy way to confirm packets per interval without using the sniffer?

NRF_SDH_BLE_GAP_DATA_LENGTH 27
NRF_SDH_BLE_GAP_EVENT_LENGTH 6

NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23

I am limiting the MTU size on purpose as I'm trying to ensure it's not a factor in this test.

RE: Slow transfer rate when sending Notifications to Android (Samsung Galaxy S8)

Sigurd — Tue, 04 Dec 2018 12:45:11 GMT

Hi,

How many packets per connection interval are you seeing?

What is the value of NRF_SDH_BLE_GAP_DATA_LENGTH, NRF_SDH_BLE_GAP_EVENT_LENGTH and NRF_SDH_BLE_GATT_MAX_MTU_SIZE in sdk_config.h ?

If you want to see exactly what is happening on-air, I would recommend the nRFSniffer(v2).