Changing tx power has no effect under Zephyr

[AndyM]

Hello
I don't see any change in RSSI with different TX power values under Zephyr. 1.9.1

It used to work with Nordic SDK 3.2.0  (see table below)
The HCI  API in Zephyr  that is used to set TX power does not return any errors and query reports the saved tx power, but there is no measurable RSSI difference

API used

bt_hci_cmd_send_sync(BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL,...)

to write and 

bt_hci_cmd_send_sync(BT_HCI_OP_VS_READ_TX_POWER_LEVEL,...) 

to read

The functions return no errors

Under Nordic SK 3.2.0 the  following RSSI was reported at 1m 

TX Power	Measured Power (1 M RSSI -dBM) Max,Average
0 (default)	55,61
8	52,54
7	52,54
6	52,55
5	52,56
4	53,57
3	53,59
2	53,60
-4	60,60
-8	63,62
-12	68,65
-16	73,69
-20	76,72
-40	Not detected,Not detected

In Zephyr it stays the same, around -55 regardless of TX power setting

Any ideas?

Thanks

[AndyM]

The sample does work.

NOTE 

The sample proj.conf has 

CONFIG_BT_CTLR_ADVANCED_FEATURES enabled. That gives a warning that a 

CONFIG_BT_LL_SW_SPLIT dependency is missing

But it builds and works with and without  CONFIG_BT_LL_SW_SPLIT 
The problem is somewhere else. Our program uses mesh. I'll investigate and update.

If you have any pointers that would be appreciated.

Question

What's the advantage of using ( or not using ) SoftDevice Controller vs Zephyr BT stack ( CONFIG_BT_LL_SW_SPLIT  =y)?

Thanks

[AndyM]

UPDATE
The issue was due to the fact that my application has

CONFIG_BT_EXT_ADV_MAX_ADV_SET=2 as it needs 2 adv sets - one for mesh and one for beacon advertising

However the code that set the tx power only updated tx power in the first adv set

struct bt_hci_cp_vs_write_tx_power_level *cp;

cp->handle = sys_cpu_to_le16(0);

So the second adv set ( which is used for beacon advertising ) was never updated.

cp->handle = sys_cpu_to_le16(1); does the trick

 

Thanks for help!

[tesc]

Hi,

I am happy to see you solved the main issue, through addressing both advertising sets.

When it comes to Bluetooth Controller, the SoftDevice Controller (SDC) is our proprietary BLE controller based on the link layer of our SoftDevice BLE stack. The SoftDevice Controller is the preferred controller to use with nRF Connect SDK. It is specially tailored for nRF SoCs, and this is also the controller we qualify with the Bluetooth SIG for use with our SDK, resulting in a QDID you can use for the qualification of your product. If using the Zephyr Controller then you must do the corresponding qualification yourself or rely on a third party having already done so. Regardless of which controller you use, the host layer will be the Zephyr BLE host which we also qualify for nRF Connect SDK releases.

Regards,
Terje