nRF52840 (DK) throughput is very low with SDK v15.2.0

[Kevin C]

I am testing BLE 5 throughput with the following hardware and firmware:

- two newly purchased nRF52840 DK boards, one as host  and the other as peripheral.

- latest nRF5 SDK v15.2.0, programed both DK boards with this SDK provided S140 SoftDevice hex image.

- test throughput with the SDK v15.2.0 provided 'ble_app_att_mtu_throughput' example project under 'pca10056'

- use SEGGER Embedded Studio for ARM V4.12 (64-bit) on Windows 10

the result I got is about 300 Kbps, only 30% of 1000 Kbps as expected:

However, I then use the same hardware but with v14.2.0 SDK and the same throughput example project included in this version of the SDK.

Now I achieved over 1000 Kbps throughput!

Question:

Why I could only achieve 300 Kbps throughput with the latest v15.2.0 SDK?

- We need the latest SDK providing the same throughput performance as for v14.2.0 SDK.

[Sigurd]

Hi,

The default setting for NRF_SDH_BLE_GAP_DATA_LENGTH (found in sdk_config.h) was changed from 251 bytes in SDK v14 to only 27 in SDK v15.

Solution:
Set NRF_SDH_BLE_GAP_DATA_LENGTH back to 251 in sdk_config.h to fix the issue.

[Kevin C]

Hi Sigurd,

That fixed the issue, thank you very much for your help!