How to set inquiry TX power on Plugable bluetooth 4.0 usb device (bcm20702) in Linux


#1

Using a dual mode bluetooth 4.0 usb device (bcm20702?) I am trying to set the inquiry tx power in Linux (Ubuntu 14.04) - using the command e.g.
sudo hciconfig hci0 inqtpl 1
The command is succesful according to hcidump but the hciconfig inqtpl always reads back zero.

Is this beacse a) the plugable device firmware is not configured to use this hci command or b) this command is only avaiable onthe UARt and not USB c) other?

def


#2

Hello Def,

Thank you for contacting Plugable Support! I am unsure as to why the device is not switching inquiry tx power, but I am looking into it.

Answering your question will require some research on my part, but I’ll get back to you as soon as possible.

Sincerely,
Ivan
Plugable Support


#3

Thanks Ivan, I look forward to your reply.

Since my previous post, I have been investigating the Bluetooth specs (yes, I am a bluetooth noob!). It seems the power control is an integral part of the LMP between host and device(s) and power control is only mandatory for class 1 devices. I also read somewhere that the LMP uses the RSSI to determin if the power needs increasing automatically.

Are these things true?
def


#4

Hello Def,

I’m seeing the same behaviour that you describe in my testing. The command goes through, but the setting does not change.

Our USB Bluetooth Adapter is a Class 2 device, and thus the Inquiry Response Transmit Power Level is not configurable by software on this class of device.

You would need a Class 1 device in order to achieve this.

I appologize that it took me so long to reply to you, I just wanted to make sure that I had the correct information to relay to you.

Sincerely,
Ivan
Plugable Support


#5

Thanks for your reply Ivan.

One last thing, do you guys have the full bcm20702 datasheet as I am struggling to get a response from Broadcom?

def


#6

Def,

I am sorry to say but we don’t have any more detail information on the chip besides what is available plublicly.

http://www.broadcom.com/products/Blue…

Sincerely,
Ivan
Plugable Support


#7