BLE6.0 channel sounding CS_DRBG

[mike_al]

Dear Technical Support Team, I am currently developing with the nRF54L15-DK development board, using the official Nordic channel_sounding_ras_initiator example project.

During bidirectional communication between the Channel Sounding initiator and reflector devices, the generation of the access address as well as the determination of the channel hopping sequence both rely on the CS_DRBG function.

I would like to inquire whether the parameters of the CS_DRBG function can be configured via hardware registers. By doing so, I aim to precisely compute and predict the access address and the channel hopping order used during communication between the initiator and reflector.

[Kenneth]

Hello,

DRBG is internal part of the controller and not direct accessible, can you described a bit more what you are trying to do, maybe there are other ways it can be solved.

Kenneth

[mike_al]

When conducting Channel Sounding tests, I wish that the channel hopping between the initiator and the reflector would proceed in a sequential frequency order, rather than in the random channel sequence calculated by the channel selection algorithm.

Specifically, I have configured the channel_map to cover the frequency range from 2406 MHz to 2420 MHz, encompassing a total of 15 channels. I expect that during each step of the communication process between the two devices, the channel hopping will follow a sequential order, such as 2406 MHz → 2407 MHz → 2408 MHz → … → 2420 MHz, instead of adhering to the channel_map sequence scrambled by the CSA#3b algorithm.

[Kenneth]

Hello

Overriding channels order violates the spec and therefore it is not possible in the regular CS samples.

However, if you only need it for testing you can have a look into CS Test command. There are zephyr samples using these commands:
https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/bluetooth/channel_sounding/cs_test 

The CS Test sample shows how to use the CS test command to override randomization of certain channel sounding parameters, experiment with different configurations, or evaluate the RF medium.

Please note we don't have any detailed documentation for the samples, and also it should only be used for testing/evaluation purposes, they are not intended for the production usage.

Hope that helps,
Kenneth

[mike_al]

Hi Kenneth

Thank you for your help—the issue has been resolved. However, I have run into a new problem and have posted a new help thread. Could you please take a look at it?https://devzone.nordicsemi.com/f/nordic-q-a/127860/channel-sounding