[Bluez-devel] absolute clock

[Bluez-devel] absolute clock

[paolo2278]

Hi Folks

I have a great problem, I'd like to know wich is the structure where I can find the value of the bluetooth's absolute clock, or the function that I could call for read this value.
I created the hci command packet to get this information, but what I can see is only the lenght of the event parameters but not their values.
P.S. I have a CSR Bluetooth

Best Regards Paolo Sperandio

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Re: [Bluez-devel] absolute clock

[Marcel Holtmann]

Hi Paolo,

> I have a great problem, I'd like to know wich is the structure where I can find the value of the bluetooth's absolute clock, or the function that I could call for read this value.
> I created the hci command packet to get this information, but what I can see is only the lenght of the event parameters but not their values.

about what clock are you talking? With Bluetooth 1.1 you can only read
the clock offset of a remote device. With 1.2 you can also read the
local and remote clock values. Look at the HCI specification.

Regards

Marcel




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Re: [Bluez-devel] absolute clock

[Marcel Holtmann]

Hi Paolo,

> >about what clock are you talking? With Bluetooth 1.1 you can only read the clock 
> >offset of a remote device. With 1.2 you can also read the
> >local and remote clock values. Look at the HCI specification.
> >
> Are you sure of it? Now I'm reading the BCCMD Baic Commands of July 2003 of the CSR (page 13 BT_Clock), and it doesn't specify if it is refer to 1.1 or 1.2 version.
> And, like I sayed before, when I use the hcitool_cmd with Varid, type, etc., the event is formed of 4 fields: the num. of HCI packets, the OPCODE of the command, and the lenght of the event paramenters. I'd like to read not the lenght of the parameters, but the content of this parameters.

I am sure about it, but you don't understand the difference between the
HCI specification and special vendor commands. What you are talking
about is a CSR specific command to read the local Bluetooth clock. And
because of the fact that this is CSR specific, you should start asking
them.

Regards

Marcel




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Re: [Bluez-devel] absolute clock

[Steven Singer]

paolo2278@freemail.it wrote:
> I have a great problem, I'd like to know wich is the structure where I
> can find the value of the bluetooth's absolute clock, or the function
> that I could call for read this value.
[...]
> P.S. I have a CSR Bluetooth

As Marcel pointed out in another message, there's no standard HCI
command to read the Bluetooth clock in BT 1.1 but there is in BT 1.2.

However, if you have a CSR BT 1.1 device there are vendor specific
commands. If you use CSR's BCCMD mechanism then there are two IDs of
interest: BCCMDVARID_BT_CLOCK (0x2c00) returns the local Bluetooth clock
of the controller; BCCMDVARID_PICONET_INSTANT (0x3009) returns the
current Bluetooth clock for the a given piconet (it expects you to pass
in an ACL handle for any link on that piconet).

If you have access to the CSR support website (www.csrsupport.com) then
it's all fully documented. Don't forget that you may need to tunnel the
commands over HCI. Alternatively, you might find it easier to dig through
the BlueZ source and find out where it sends the commands to change the
uart baud rate - that should give you a good example to work from.

I can't recall if BlueZ has a tool that allows you to send arbitrary
BCCMDs to CSR chips - if not, it sounds like a good project for
someone.

	- Steven
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Re: [Bluez-devel] absolute clock

[Marcel Holtmann]

Hi Steven,

> If you have access to the CSR support website (www.csrsupport.com) then
> it's all fully documented. Don't forget that you may need to tunnel the
> commands over HCI. Alternatively, you might find it easier to dig through
> the BlueZ source and find out where it sends the commands to change the
> uart baud rate - that should give you a good example to work from.

the better example code will be in utils/tools/csr.[ch].

> I can't recall if BlueZ has a tool that allows you to send arbitrary
> BCCMDs to CSR chips - if not, it sounds like a good project for
> someone.

A program like btcli don't exists for Linux.

Regards

Marcel




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