Separate transmit power setting for BLE and Thread when using MPSL

[Jon]

Hello,

I have a design where I am using an nRF52840 along with a SKY66112-11 and am using Zephyr/MPSL for both BLE and Thread. Some questions:

1) The .dts node has pa_gain_db and lna_gain_db parameters, which default to ~20dBm and ~11dBm for the skyworks part. What are these parameters actually used for by the MPSL library? Do they affect CSMA thresholds, etc?

2) How do I reduce BLE transmit power such that BLE still operates at ~0dBm (which is our desired operation for BLE) while still allowing the Thread packets to transmit at high power?

I noticed that there is a CONFIG_BT_CTLR_TX_PWR setting in Zephyr but that does not seem to have any effect.

Thanks

Jon

[Susheel Nuguru]

Hi, 
Sorry for the delays and thanks for your patience. Very slim staffing due to summer holidays are contributing to the delays.

I have tried to set this up at my personal MacBook (which I never used for any NCS related things) and I did not manage to run docker correctly. 

But I asked the R&D team for the SD controller to assist with some help and tare not sure if we support CONFIG_BT_CTLR_TX_PWR_DYNAMIC_CONTROL in the SD controller. 

[Jon]

Susheel,

Any update on this? I need to find a way to escalate this issue as we are nearing commitment to this design and need to ensure we will be able to continue to support the external FEM.

Thanks, Jon

[Simonr]

Hi

Again, sorry for the delays. This is due to the staff shortage during summer that Susheel has mentioned. He is taking some time off, so I have been assigned this case in his place. According to the internal thread we have on this, the R&D team can confirm that Dynamic TX Power control is supported by the SoftDevice Controller.

Best regards,

Simon

[Jon]

Simon, will you be responding with more information about "the R&D team can confirm that Dynamic TX Power control is supported by the SoftDevice Controller" statement? Obviously we have not had any success getting TX power control to work on our end...

Thanks,

Jon

[Simonr]

Hi Jon

The application must instruct the controller to change the TX power correctly. Have you checked out the set_tx_power() function in the hci_pwr_ctrl sample in the Zephyr SDK? This function should give you a good idea of how this should be done.

Best regards,

Simon