Expected throughput on nrf52840

[Gary]

Hi,

I have two nrf52840 boards and I am using the ble_app_att_mtu_throughput test app. The tests seem to be working OK, but I am not getting the throughput I was expecting. The boards are next to each other.

With BLE_GAP_PHY_2MBPS I get 1046.48 Kbps, which I guess it in the right ball park, but for BLE_GAP_PHY_1MBPS I am only getting 262.27 Kbps.

Also for BLE_GAP_PHY_CODED with the boards next to each other I am only getting 26.20 Kbps.

I was expecting more for 1MBPS and CODED. I have tried with S140_nrf52840_5.0.0-2.alpha and S140_nrf52840_5.0.0-3.alpha and the numbers seem to be around the same.

Any thoughts, comment suggestions?

Thanks, Gary.

[Gary]

Daniel, thanks for your comment. I was using a MTU size of 247 and a conn interval of 7.5ms. I wrongly assumed that 7.5ms was the best. However I tried 50ms and I am getting better throughout now. I see from the blog post that this is because of the "connection event length extension". Duly noted!

So now the 2MBPS and 1MBPS links are performing as I would expect: 1336.79 Kbps and 746.94 Kbps respectively. However the best I can get out of the CODED is 56.98 Kbps with a 400ms interval and a MTU of 247.

Any thoughts on how I could improve the CODED throughput?

Thanks, Gary.