STM32WB55 - Data length extension supported with CFG_BLE_DATA_LENGTH_EXTENSION = 0?

[Adrian Eggenberger]

Hi

We have a project that uses the STM32WB55 with the full BLE stack in version 1.10.1. Today I recorded some air traffic between my PC and the device and struggled over something that confused me.

In our project we have disabled the data length support by:

 #define CFG_BLE_DATA_LENGTH_EXTENSION  0

But in the air trace I see two things that make me think that DLE is enabled even with the configuration that should disable it.

1) In the LL_FEATURE_RSP that comes from the STM32WB we see that it tels us that it supports DLE:

2) In a response to a LL_LENGTH_REQ we get a nomal response with an extended RX length:

Is this a normal behavior? I would expect that the DLE feature is not activated and the LL_LENGTH_REQ is rejected.

Regards Adrian

[Vincent H]

I observed the very same thing, and I am really curious to know why the CFG_BLE_DATA_LENGTH_EXTENSION has no effect.