> 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
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