RE: [usb] USB-to-Bluetooth

[Marc Reinig <mreinig@pacbell.net>]

Because  of the turn-around time (and some other issues), you cannot just convert transmissions from the PC host and send them to the device on the other side of the Bluetooth net (and vice versa) because the Bluetooth protocol will not be able to respond in time for the USB protocol requirements.  So, the USB device must "dummy" up responses from the remote Bluetooth device until actual responses are received.  This requires extra horsepower at the USB dongle end.  Same issue for the USB-to-Bluetooth adapter to act as a hub.

 

In any case, the USB is just a bus to attach the Bluetooth adapter to the PC Host, Bluetooth can already accept multiple connections, what would be the function of trying to make the USB-to-Bluetooth adapter look like a hub?

 

Marc Reinig

System Solutions

 

-----Original Message-----
From: owner-usb@opencores.org [mailto:owner-usb@opencores.org]On Behalf Of Ricky Nite
Sent: Wednesday, February 12, 2003 11:13 PM
To: usb@opencores.org
Subject: Re: [usb] USB-to-Bluetooth

Hello Marc,

 

Thanks for the reply - so a USB-to-Bluetooth Adapter 

is just another USB device as seen by the PC , but I'm

still wondering what you meant with a "smart" USB 

device (?)

 

I'm also trying to find out if it's possible for the PC-attached

USB-to-Bluetooth adapter to emulate a hub, with the

peripheral-attached adapters seen as slave devices (?) 

 

PC-->USB-BT adapter (hub)----->USB-BT adapters -->peripherals (slaves)

 

 

Rgds,

 

Ricky Nite

 

----- Original Message -----

From: Marc Reinig

To: usb@opencores.org

Sent: Thursday, February 13, 2003 12:31 PM

Subject: RE: [usb] USB-to-Bluetooth

 

-----Original Message-----
From: owner-usb@opencores.org [mailto:owner-usb@opencores.org]On Behalf Of Ricky Nite
Sent: Wednesday, February 12, 2003 7:17 PM
To: usb@opencores.org
Subject: [usb] USB-to-Bluetooth

 

 > I need some clarification on Bluetooth-to-USB transmission. 

 > As you know, some Bluetooth modules now have an on-chip

 > USB interface, used for device firmware upgrade and as HCI

 > transport.  Future Bluetooth firmware upgrades will also allow

 > you to change the USB descriptors in the module so you can

 > receive data over USB and transmit it over the air.

 

 > However, I was told that this will not allow me to layer additional

 > firmware over the embedded Bluetooth stack to do an exact

 > USB cable replacement using a USB-to-Bluetooth adapter/dongle

 > device, because:

 

 > (1) USB has strict timings which would be violated if the adapter/

 > dongle had to transmit the request over the air and wait for a

 > response.

 

Correct, though this can be overcome with a "smart" device.

 

 > (2) The Bluetooth module is not capable of being a USB master,

 

 > (3) The code doesn't fit on chip - USB is "normally" for PC apps

 > where you have ample resources on the host.   

 

These are really part of the same issue.  USB has a master/slave concept.  The logic/code to be a slave is relatively small compared to that required to be a master.

 

 > As there are already a lot of USB-to-Bluetooth adapters/dongles

 > available in the market, I was just wondering how these devices 

 > use USB for their applications.  Can anybody shed some light

 > on this?

 

They are devices and can be used, as you mentioned, for firmware upload, the connecting bus to the PC, ... 

 

But in general, they are devices (slaves) not hosts (masters).

 

Marc Reinig

System Solutions