Channel sounding with 2 antennas

RE: Channel sounding with 2 antennas

Edvin — Mon, 16 Mar 2026 14:33:11 GMT

Hello,

Try changing this line in your initiator:

.preferred_peer_antenna = BT_LE_CS_PROCEDURE_PREFERRED_PEER_ANTENNA_1,

.preferred_peer_antenna = BT_LE_CS_PROCEDURE_PREFERRED_PEER_ANTENNA_1 | BT_LE_CS_PROCEDURE_PREFERRED_PEER_ANTENNA_2,

And see if that helps.

Best regards,

Edvin

RE: Channel sounding with 2 antennas

rsaboret — Mon, 16 Mar 2026 11:43:11 GMT

Hello Edvin,

Thank you for your time and sorry for the delay, I was out of office.

The setup I was using already had those configurations but didnt work :

>>For the one with two antennas:

CONFIG_BT_RAS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_NUM_ANTENNAS=2

>>For the one with one antenna:

CONFIG_BT_RAS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_NUM_ANTENNAS=1

For the P0.0 and P0.1 pins, they are hardwired in my PCB. I previously confirmed I can set them on and off to select the different antennas. As for the configuration, im using:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n

Here I can upload the simplest code about channel sounding with two antennas:
devzone.nordicsemi.com/.../channel_5F00_sounding_5F00_ras_5F00_sample_5F00_323_5F00_two_5F00_antennas.zip
It it literally the sample code from ncs/v3.2.3/nrf/samples/bluetooth with the only changes being the antennas number in prj.conf and the BT_LE_CS_TONE_ANTENNA_CONFIGURATION_A1_B2 setting in the code.

When I flash this code on two nRF54L15DK (one initiator, one reflector), the initiator fails after the connection is established when it tries to call bt_le_cs_set_procedure_parameters:

I: CS security enabled.
W: opcode 0x2093 status 0x12 
E: Failed to set procedure parameters (err -22)

The nRF54L15DK doesnt have a RF switch connected to pins P1.11, P1.12, P1.13 and P1.14 (as specified in nrf54l15dk_nrf54l15_cpuapp.overlay) but that shouldnt be a problem: the channel sounding procedure will just use twice the same antenna, thinking it has switched in between.

Regards,

R. Saboret

RE: Channel sounding with 2 antennas

Edvin — Wed, 11 Mar 2026 10:21:11 GMT

Hello,

Can you try the following confituration on both your devices, please:

For the one with two antennas:

CONFIG_BT_RAS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_NUM_ANTENNAS=2

For the one with one antenna:

CONFIG_BT_RAS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_MAX_ANTENNA_PATHS=2
CONFIG_BT_CTLR_SDC_CS_NUM_ANTENNAS=1

Let me know if that doesn't work.

If it does not, can you please upload your entire application (or a strip down version), so that I can build it and see what you are seeing?

One thing that struck me is that you are using P0.0 and P0.1. By default these are the LFXTAL pins. Did you set the device to use the internal RC Oscillator? (I can't tell from the snippets you provided). Is it possible to test with another set of pins, or are they hardwired on your PCB?

Best regards,

Edvin