Sending multiple notify packets per connection interval

[Neil_CPD]

Hi,

Device: NRF53

I'm trying to send 3 notify packets in a 15ms connection internal but I can send 2.

I'm using Nrf connect and Zephyr.  is there a limit or a define to set this.

Thank you for any guidance and help

Regards

[Neil_CPD]

Thanks for the update Simon.

[Simon]

I tried to increase the buffers in both the ble host as well as the controller, but it didn't help. I've asked internally about this and waiting for an answer.

[Hung Bui]

Hi again Neil,

Could you send a sniffer trace  ? 
Could you show how you send the notification in your code ? With and without the delay. 

Which firmware you use on the central side ? 

Would be nice if you can provide some minimal code so that I can test here (on both sides)

[Neil_CPD]

Hi Hung,

Please bear with me as i'm away from my desk for a couple of days but basically my setup was:

NCS 1.6.0 peripheral_uart example with the connection set to 15ms.

Central was my phone Sony XQ-AS52 with Android 11

while(1)

{

     loop 3 times

     {

         bt_gatt_notify_cb(.....)

      }

       k_sleep( 30 ms) or k_sleep( 5 ms) 

}

when I wait 30 ms I see 3 packets on the sniffer per.. but If I reduce the delay so it's every interval only 2 packets.

I'm not going to be able to send an nrf sniffer output for a week or so,  but the code is quite basic.

[Hung Bui]

Hi Neil, 
 I suspect that the central was not able to handle more than 2 packets per connection event. A sniffer trace would be very helpful to reveal this. 

[Neil_CPD]

Hi,

I will try to get you a sniifer trace but I do remember the more data flag being set to false on the second packet.

I also thought that Simon had tried this test with two nrf dk's.  Could you do a sniifer trace of it working with an nrf dk central please. If it's a limitation of the central then I can explain this to my customer.

Thanks

[Hung Bui]

There is a chance that it's hitting the limit of the stack. But we do need a sniffer trace to really understand the situation. 
Please also look at the throughput example. As far as I know you can reach around 700kbps at 1Mbps.given that the ATT_MTU is configured correctly and Data length extension is applied.