Dynamically setting transmit power of ISO channels

[aspearDS]

Hello,

Is there a method of setting the transmit power of ISO channels using BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL?

I used the connection handle of the struct bt_conn object from struct bt_bap_stream but the SoftDevice returns BT_HCI_ERR_UNKNOWN_CONN_ID.

Do you have an example of setting the transmit power dynamically of a ISO channel?

Thanks,

Andrew

[Amanda Hsieh]

Hi, 

I am working on your case and will update it when I collect enough information. 

Regards,
Amanda H.

[Amanda Hsieh]

Hi, 

Here is the PR:https://github.com/nrfconnect/sdk-nrf/pull/17413 to fix the issue, also in the main version now. 

If you update the TX power of the ACL (on the main branch), the CIS will also be updated.

-Amanda H.

[aspearDS]

Amanda,

Amanda Hsieh said:

If you update the TX power of the ACL (on the main branch), the CIS will also be updated.

Just to clarify, I am using BIS (broadcast) ISO, not CIS (connected).

Amanda Hsieh said:

Here is the PR:https://github.com/nrfconnect/sdk-nrf/pull/17413 to fix the issue, also in the main version now.

Looking at the PR, it is not clear what is the fix.  Can you provide a code example of how I would set the transmit power of the BIS stream?

I also see another ticket that was entered a day after this one that is very similar:  https://devzone.nordicsemi.com/f/nordic-q-a/114812/how-to-set-tx-power-for-bis-iso-streams-alone.  That ticket is using 2.7 instead of 2.6, but I expect the resolutions of the tickets to be similar. 

Thanks,

Andrew

[Amanda Hsieh]

Hi, 

The new PR to support BIS is merged into the main version and will be released in v2.8.0. 

It contains an addition to sdc_hci_cmd_vs_zephyr_write_tx_power which allows setting broadcaster TX power using the BIG handle, so this allows to change the TX power after the BIS was created.

When a BIS broadcaster is set up, it initially uses the same TX power as the associated periodic advertiser.

-Amanda H.