How to setting TX power through HCI command?

[Hsu]

Hi Sir,

We reference example "/nrf/samples/bluetooth/hci_uart" and test on nRF52833.

Now we want to set the Tx power by sending appropriate HCI commands from the host.

We tried the below command but got an error.

"hcitool -a hci0 inqtpl 4"

Can't set inquiry transmit power level on hci0: Input/output error (5)

Could you share the command for how to set the TX power level?

Thank you.

BRs, Han

[dejans]

Hi,

When using hcitool note that inq and tpl are two different commands.
hcitool should be used with -i option.
Full command would look like this hcitool [-i <hciX>] [command [command_parameters]]
inq - used for inquiries of remote devices
tpl - command used for displaying transmit power level
In your case, this would be hcitool -i hci0 tpl <bdaddr> [type]

If you want to use inqtpl command then consider using hciconfig:
hciconfig inqtpl 4 - sets the inquiry transmit power level to 4
hciconfig inqtpl    - gets the inquiry transmit power level

Best regards,
Dejan

[Hsu]

Hi Dejan,

I follow the command but got the error as below.

sudo hciattach -s 115200 /dev/ttyACM1 any 115200 noflow nosleep

sudo hciconfig inqtpl 4

I also tried "hcitool".

sudo hcitool -i hci0 tpl 00:00:00:00:00:00 4

Does any step go wrong?

Thank you.

BRs, Han

[dejans]

Hi,

Which SDK are you using on your nRF52833 board?

Best regards,

Dejan

[Hsu]

Hi Dejan,

I'm using NCS 1.8.0, and building w/ below command.

"west build -b nrf52833dk_nrf52833"

Thank you.

BRs, Hanyu

[dejans]

Hi,

There are several things you could try
1. set the option CONFIG_BT_HCI_VS_EXT=y in zephyr/samples/bluetooth/hci_uart/prj.conf
2. set command BT_HCI_OP_VS_READ_STATIC_ADDRS as raw bytes using hcitool -i hci0 cmd as shown in BlueZ: sending LE directed adverts from the command line

You might also want to read more here and here.

However, hcitool is deprecated in Bluez and it is recommended to use blutoothctl.

Best regards,
Dejan

[Hsu]

Hi Dejan,

As studied the link you provided, the <cmd> of hcitool fellows the Bluetooth Specifiation, Version 5.x, Vol 2, Part E, Chapt 7.8.

And in the Chapt 7.8, there is no command definition for set TX power, but I can find the read TX power.

I tried to read the TX power w/ below result.

LE Read Advertising Channel TX Power

8

7

And I also tried to use the bluetoothctl or btmgmt, there is no "set TX power" command from "help".

Is it correct for my understanding that there is no HCI command to set tx power?

Thank you.

BRs, Han

[Hsu]

Hi Dejan,

Update the test result for add "CONFIG_BT_HCI_VS_EXT=y" on "prj.conf"

Thank you.

BRs, Han

[dejans]

Hi,

Have you tried the second option?

Best regards,

Dejan

[Hsu]

Hi Dejan,

The result of second option as below. And I can see the "success" from "btmon".

But what is the result stand for?

And which command can set the tx power?

# Terminal

# btmon

Thank you.

BRs, Han

[dejans]

Hi,

The ogf part of the opcode has 6 bits and it denotes the opcode group field. In your case 0x3f is reserved for vendor specific command. The ocf part has 10 bits and it is known as opcode command field. A Command Complete HCI Event specifies the corresponding Vendor specific debug command opcode. For more information, please refer to the bluetooth specification.

One good explanation of the hcitool command output can be found here. 

Setting the transmit power value is vendor specific command. Please check hci_zephyr and hci_softdevice.

There is also an example in zephyr\samples\bluetooth\hci_pwr_ctrl.

Best regards,
Dejan

[dejans]

Hi, 

As said previously, please note that hcitool is deprecated in BlueZ and should not be used anymore. Instead, you should use bluetoothctl tool.

For BlueZ related questions, please consider joining BlueZ mailing list.

Best regards,
Dejan

[Hsu]

Hi Dejans,

Unfortunately, I cannot set the tx power from "Write Tx Power Level" and also from bluetoothctl command.

Below is the test result.

Sorry that I'm not familiar w/ hci tool, could you share the hint which step or concept I missed.

1. Write TX power, but got fail return "unknow hci command".

    sudo hciattach -s 115200 /dev/ttyACM0 any 115200 noflow nosleep

    sudo hciconfig hci0 up // bring up device

    sudo hciconfig hci0

    sudo hcitool -i hci0 cmd 0x3f 0x000e 0x00 0x6461 4 //set tx power level 4

    sudo hcitool -i hci0 cmd 0x3f 0x000e 0x02 0x6461 4

2. bluetoothctl

I tried to use "bluetootlctl", but i cannot find the parameter for tx power level setting from help.

Does the command of tx power level has been hidden? or this is a sub command?

Thank you.

BRs, Hanyu